Self-cleaning MOC fabricated from dolomite ore

Self-cleaning MOC fabricated from dolomite ore | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Self-cleaning MOC fabricated from dolomite ore Luis Felipe Rodríguez Alfaro, Leticia Myriam Torrez Martínez, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7123900/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Jan, 2026 Read the published version in Waste and Biomass Valorization → Version 1 posted 5 You are reading this latest preprint version Abstract This study explores the sustainable synthesis of magnesium oxychloride cement (MOC) using reactive MgO derived from dolomite, coupled with photocatalytic and supplementary cementitious materials (SCMs) to optimize both mechanical and self-cleaning performance. The synthesis of MgO from dolomite was performed using a fractional design of experiments 2 5−1 to identify the main factors that affect the purity and the surface area of the powders. The analysis of the design of experiments revealed that acid treatment temperature and reaction time during MgO synthesis significantly influenced surface area and MgO content. After the identification of the best conditions to synthesize a high-purity MgO from dolomite, a series of MOC formulations were prepared by incorporating TiO 2 , fly ash, and slag. The physicochemical, optical, mechanical, and photocatalytic properties of the resulting composites were systematically investigated. TiO 2 incorporation clearly enhanced light absorption, while combinations with slag or fly ash modulated this property, which is an important property for photocatalytic self-cleaning applications. In photocatalytic assays under simulated sunlight, TiO 2 -containing cements outperformed the unmodified MOC, with fly ash–based formulations achieving the highest self-cleaning efficiency. Blended systems with SCMs introduced trade-offs between durability and functionality, with photocatalyst nanoparticles achieving an optimal balance, showing excellent moisture stability and photocatalytic performance (> 92%) under sunlight irradiation. These results highlight the potential of combining alternative MgO sources with functional additives to engineer eco-efficient, durable, and photocatalytically active MOC materials for advanced construction applications. Magnesium oxychloride cement MOC Self-cleaning Dolomite Fractional design of experiment Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1. Introduction MOC cement is fabricated from three base components that form its ternary system MgO-MgCl 2 -H 2 O, being the most important MgO. This compound cannot be extracted directly from nature, since the mineral periclase (MgO) is relatively rare and its hydration product, brucite [Mg(OH) 2 ], is found only in a limited number of commercially viable geological formations [ 1 ]. MgO is generally obtained by two methods: (1) by dry process from calcination of mined magnesite (MgCO 3 ) deposits, or (2) by wet process from brine or seawater solutions containing magnesium [ 2 ]. Most of the worldwide MgO production is carried out by the first method due to its lower energy requirements compared to wet production. Furthermore, the wet process presents higher complexity, as it involves the precipitation of MgO from a magnesium-rich solution under specific conditions and additional treatments [ 3 ]. In the dry route, the process begins with the extraction of magnesite ore, which is then crushed, ground, and pulverized to reduce it to a size suitable for calcination, which step is critical to ensure efficient and homogeneous calcination. The crushed magnesite is subsequently heated in kilns at temperatures ranging from 700 to 1000°C, depending on the quality of the magnesite, transforming MgCO 3 into MgO and releasing CO 2 in the process [ 4 ]. Magnesite is a magnesium carbonate generally found in nature associated with other elements such as calcite, aragonite, dolomite, quartz, brucite, serpentinite, among others [ 5 ]. When obtaining MgO by the calcination method, a large amount of CO2 is liberated into the atmosphere during the process (approximately 1.1 kg CO 2 /kg MgO), which some consider to be an environmentally unfriendly method [ 6 ]. Furthermore, magnesite is less common than calcite and dolomite, limiting the relative number of outcrops available for practical exploitation [ 7 ]. Most magnesite deposits and production are concentrated in China, which entails additional CO 2 emissions due to transportation from the source to shipping worldwide destinations [ 8 ]. Despite these concerns, Jankovsky et al. proposed that MOC cement prepared by the dry calcination method of magnesite to obtain MgO can still be considered more sustainable compared to Portland cement, given the considerably low emissions of polluting gases (up to 40%) [ 9 ]. Furthermore, they suggested that the use of alternative magnesium-rich materials that are more abundant and easily extracted to improve their sustainability and costs. Among them, and the most important for the present study, is dolomite. Dolomite is a double carbonate mineral of calcium and magnesium [CaMg(CO 3 ) 2 ] ubiquitous in the Earth's crust. After calcite, it is the second most abundant carbonate mineral in the world [ 10 ]. It occurs in massive forms or as small geodes and due to their impurities, mostly iron and manganese, their color can vary. Economically, it represents great importance, e.g., more than 50% of gas and oil deposits are in dolomitic formations [ 11 ]. Also, this mineral is considered more environmentally friendly in contrast to magnesite during the process of obtaining MgO to produce MOC through the dry calcination method. According to theoretical calculations, approximately 2.49 tons of dolomites are required to produce 1 ton of MOC, which creates as a byproduct 1.38 tons of synthetic aragonite (CaCO 3 ), harmless to the environment, and 0.58 tons of CO 2 that is emitted into the air [ 12 ]. Likewise, the amount of dolomite required to produce MOC can be reduced by adding some type of filler, for example, fly ash or other recycled material, in turn promoting a decrease in CO 2 emissions, and reducing the total cost of the materials. The thermal decomposition of dolomite by dry calcination occurs in two stages: (1) the decomposition of dolomite to MgO, CaCO 3 , and CO 2 at approximately 700°C (Eq. 1), and (2) the decomposition of CaCO 3 to CaO and CO 2 at > 700°C (Eq. 2) [ 13 , 14 ]. However, the exact decomposition conditions will depend on the unique properties of each dolomite, the calcination conditions (e.g., temperature and time), and the presence of impurities (e.g., SiO 2 and CaO), so these temperatures should not be taken as absolute values. \(\:CaMg(C{O}_{3}{)}_{2}\:\underrightarrow{\varDelta\:}MgO+C{O}_{2}+CaC{O}_{3}\:\:\) ( 1) \(\:CaC{O}_{3}\:\underrightarrow{\varDelta\:}CaO+C{O}_{2}\:\) ( 2) Some reports have proposed the use of calcined dolomite as a raw material for producing MgO-based cements, including reactive magnesia cements [ 15 ], magnesium oxysulfate cements [ 16 ], magnesium phosphate cement [ 17 ], and magnesium oxychloride cements [ 18 ]. However, the direct use of calcined dolomite for producing MOC has been hampered by the presence of impurities such as CaCO 3 in low-temperature processes (Eq. 1) as well as the presence or excess of CaO in high-temperature processes (Eq. 2) [ 15 ]. These impurities can cause changes in the setting, phase composition, mechanical properties, and in some cases, volumetric instability in MOC. Therefore, it is important to remove or exclude impurities from dolomite before using it to manufacture MOC. Considering these challenges, this work proposes a novel, simple, and economical method for producing MgO from dolomite for the manufacture of MOC samples. The method, explained in general terms, consists of mixing calcined dolomite with D-(+)glucose (C 6 H 12 O 6 ) in water to endorse the reaction with CaCO 3 (from the calcined dolomite) to produce calcium gluconate (C 12 H 22 CaO 14 ) in solution, promoting the formation of high quality MgO for MOC manufacturing. It is worth to mention that calcium gluconate is an important value-added material widely used in medicine [ 19 ], corrosion inhibitor on mild steel [ 20 ], retarder for calcium aluminate cement hydration [ 21 ], flame-retardant for epoxy resin [ 22 ], and recently it was demonstrated its use as sacrificial agent to generate green hydrogen by heterogeneous photocatalysis [ 23 ]. In addition, based on the synthesis of magnesium oxide from dolomite, magnesium oxychloride cements were formulated with self-cleaning properties. To improve and optimize the MOC formulation, supplementary cementitious materials (SCMs) such as fly ash and blast furnace slag were incorporated, along with titanium dioxide as a photocatalytic additive. These modifications aim not only to preserve or enhance the mechanical performance of the material but also to boost its photocatalytic activity, contributing to the development of sustainable and multifunctional MOC formulations. 2. Methodology 2.1. Synthesis of MgO from dolomite ore Dolomite ore was donated by a local company, which chemical composition, obtained by X-ray Fluorescence, is shown in Table 1 . Table 1 Chemical composition of the dolomite ore. Component CaO MgO SiO 2 Na 2 O Al 2 O 3 Fe 2 O 3 Ag 2 O K 2 O Others % 78.2 17.7 1.9 0.6 0.6 0.3 0.3 0.3 < 0.4 The synthesis method begins with the mechanical grinding of natural dolomite ore in a ball mill to reduce particle size and enhance its reactivity (1). The pulverized dolomite is then subjected to calcination at temperatures ranging from 800 to 1000°C (2), promoting the thermal decomposition of the carbonate phases (Eq. 1). Subsequently, the powders were mixed with an aqueous solution of glucose (C 6 H 12 O 6 , Aldrich, 99%), and the suspension was stirred to ensure homogeneous interaction (3) until the formation of a red suspension (4). During this process, the reaction leads to the formation of a water-soluble complex of C 12 H 22 CaO 14 (CG), while MgO was selectively precipitated (Eq. 3). The amount of each \(\:MgO+6\:Ca{CO}_{3}+11\:{C}_{6}{H}_{12}{O}_{6}\to\:6{C}_{12}{H}_{22}Ca{O}_{14}+MgO\downarrow\:\) ( 3) The resulting MgO precipitate is recovered by centrifugation and washed four times with distilled water to remove residual byproducts (5). The purified solid is then dried in an oven at 80°C for 12 h. Finally, thermal treatment is applied at temperatures between 500 and 700°C for 2 h (6) to obtain MgO powders with controlled crystallinity and particle morphology (7). A schematic representation of the synthesis process is shown in Fig. 1 . For these experiments, a 2 5−1 factorial design was carried out to identify the conditions that favored the highest yield of MgO from dolomite (Table 2 ). The factors selected were dolomite mass (DM, 1), temperature of the activation (AT, 2), reaction time (RT, 3), temperature and calcination time (HTT and T, 7). The design of experiments was analyzed in the Minitab® software. Table 2 Fractional factorial design 2 5−1 used for MgO synthesis. Sample Dolomite mass (1) (g) Activation temperature (2) (°C) Reaction time (3) (h) Heat treatment time (7) (h) Temperature (7) (°C) M1 10 1000 4 5 500 M2 15 1000 4 2 500 M3 15 800 4 5 500 M4 10 800 4 2 500 M5 15 1000 4 5 600 M6 10 1000 4 2 600 M7 10 800 4 5 600 M8 15 800 4 2 600 M9 15 1000 2 5 500 M10 10 1000 2 2 500 M11 10 800 2 5 500 M12 15 800 2 2 500 M13 10 1000 2 5 600 M14 15 1000 2 2 600 M15 15 800 2 5 600 M16 10 800 2 2 600 The numbers in the superscripts refer to the steps shown in Fig. 1 . 2.2. Fabrication of MOC with MgO recovered from dolomite To fabricate the MOC samples, the following (general) procedure was employed: First, magnesium chloride hexahydrate (MgCl₂·6H 2 O, DEQ, 99%) was dissolved in distilled water using a magnetic stirrer at a moderate speed. Then, the MgO powder (commercial-99% or derived from dolomite via a glucose-mediated process) was gradually added to the solution until a homogeneous paste with consistent viscosity was obtained. The resultant MOC paste was subsequently cast into a cylindrical plastic mold with a diameter of 20 mm and a height of 3 mm. The mold was filled and left to cure at room temperature for seven days. After the curing process, the solid MOC samples were carefully extracted from the molds for the testing and characterization. To enhance the sustainability of magnesium oxychloride cement materials, several modifications were introduced to the baseline formulation, including the use of alternative raw materials and supplementary additives. Among these, a previously optimized formulation developed by our research group was selected as a reference [ 24 ]. This composition employs a MgO/H₂O (M/H) ratio of 5/15 and incorporates 1 wt.% citric acid, 3 wt.% fly ash, and 3 wt.% TiO 2 . It demonstrated excellent properties, including a compressive strength of 39 MPa at early ages, high moisture resistance, and complete self-cleaning efficiency (100%) under solar irradiation. In this work, further formulations were explored to assess the impact of incorporating blast furnace slag as a partial replacement material and to evaluate the performance of MgO derived from dolomite calcination. These compositions were compared to a commercial reactive-grade MgO reference (RMOC) to determine their suitability for use in self-cleaning cementitious systems. Table 3 summarizes the mix designs of the investigated MOC pastes, including both commercial (RMOC) and dolomite-based (D) variants with photocatalytic nanoparticles (P) to provide the self-cleaning effect. Table 3 Mix design for self-cleaning MOC pastes. Sample M/H Citric acid (%) Fly ash (%) Slag (%) TiO 2 (%) RMOC 5/15 - - - - RDMOC - - - - PDMOC - - - 3 PDFMOC 1 3 - 3 PDSMOC 1 - 3 3 2.3 Characterization The samples were characterized by different techniques. The crystal phases were identified using X-ray diffraction (XRD) on a Bruker D8 Advance diffractometer equipped with a high-speed Vantec detector. Measurements were collected over a 2θ range of 10° to 70° with a step size of 0.022° using CuKα radiation (40 kV, 40 mA). Fourier-transform infrared (FTIR) spectroscopy was used to identify functional groups in a Nicolet IS50 instrument from Thermo Electron Corp., equipped with an attenuated total reflectance accessory. The morphology by Scanning Electron Microscopy (SEM) using a JEOL Instruments JSM-6490LV. To ensure conductivity, the MOC samples were sputter-coated with a thin layer of gold/palladium (Au/Pd) and mounted on carbon tape. Surface area measurements using the Brunauer-Emmet-Teller (BET) method were conducted on a Quantachrome Instruments Nova 2000e surface area analyzer. The MOC samples were degassed under vacuum at 150°C for 3 h before being loaded into 12 mm glass bulbs. N 2 adsorption-desorption isotherms were registered at -196°C to determine the specific surface area. To evaluate the moisture stability, the samples were exposed to highly humid conditions in an accelerated weathering machine (Q-Sun Xenon model Xe-3 test chamber) following the parameters specified in ISO 6270–1:2017 (HR 95% and 38 ± 2 ◦C). This standard was proposed to evaluate the moisture stability of cement-based materials under continuous condensation steps. Before and after this exposition, the mechanical properties of MOC samples were evaluated using various techniques. Surface hardness was assessed using nanoindentation, with a Fischerscope model HM2000-5 nanoindenter. Five indentations were performed on each sample surface using a diamond Vickers indenter with a square base and pyramidal geometry to obtain a statistically relevant mean value. Each indentation involved a 50 mN load applied for 60 seconds with no creep time. The compressive strength of the MOC samples was determined using three cubic specimens. Measurements were conducted using a Shimadzu AGX-Plus Universal Compressive Testing Machine at a constant loading rate of 1 mm/min. To obtain quantitative analysis of the moisture stability of the MOC, it was proposed the use of the Moisture Stability Coefficient (MSC), shown in Eq. 4 , using the final (H f ) and initial (H 0 ) hardness. In this equation, a value near to 1 indicates an optimal performance (or high moisture stability). $$\:MSC=\:\frac{{H}_{f}}{{H}_{0}}$$ 4 2.4. Self-cleaning assays The self-cleaning efficiency of the MOC samples was evaluated using a concentrated solution of reactive black 5 (50 ppm) as model pollutant. Afterward, the contaminated sample was maintained at dark conditions during 12 h to ensure the adsorption-desorption equilibrium of the pollutant on the surface. Then, the samples were introduced into an accelerated weathering chamber to emulate real outdoor conditions for 3 cycles (4.48 h), following the the ASTM G155-13 conditions. To quantify the self-cleaning activity, the samples were analyzed by UV-Vis spectrophotometry using a Agilent Technologies Cary 5000. The photocatalytic self-cleaning efficiency was calculated using the Eq. 5 : $$\:\%Efficiency=\:\frac{{C}_{0}-C}{{C}_{0}}*100\%$$ 5 Where C 0 is the initial dye concentration, and C is the dye concentration after the photocatalytic reaction at different times. 3. Results and discussion The results are presented in two sections; first, the physicochemical characterization of MgO synthesized from dolomite is discussed, highlighting the influence of processing parameters on its properties. Subsequently, the preparation, characterization, and performance evaluation of different MOC formulations are addressed, with particular focus on their mechanical behavior, stability under moisture exposure, and self-cleaning photocatalytic efficiency. 3.1. Characterization of MgO synthesized from dolomite ore The synthesized samples using the 2 5−1 fractional factorial design of experiments were characterized by XRD. The results showed that all the samples contained three crystalline phases: CaCO 3 (ICDD 00-085-1108), SiO 2 (ICDD 01-085-0335), and MgO (ICDD 01-075-0447) (Fig. 2 ). CaCO 3 was the predominant phase in most specimens, as evidenced by the highest number and intensity of reflections, particularly at 2θ = 39.49°. This implies an incomplete removal of CaO under the experimental conditions studied, leading to its reaction with atmospheric CO 2 and subsequent formation of calcium carbonates. SiO 2 was also present in most samples, identified with a single weak reflection at 2θ = 26.64°. The MgO phase was detected in all samples with reflections at 2θ = 36.93°, 42.91°, and 62.30°, with some exceptions. For example, MgO-1 and MgO-9 samples showed more intense MgO reflections but still contained significant amounts of CaCO 3 , which led to their exclusion from further analysis. Notably, MgO-13 sample exclusively exhibited MgO reflections with a minor presence of SiO 2 . This result represents the best combination of experimental conditions to extract MgO from dolomite ore. The FTIR spectra revealed similar patterns for most of the specimens synthesized (Fig. 3 ). Four absorption bands were mainly detected, which correspond to calcite. The absorption bands at 713 cm -1 and 871 cm -1 correspond to the bending nodes of the planes that belong to the C-O bonds, respectively [ 25 ]. The bands at 1402 cm -1 and 1790 cm -1 are characteristic of the asymmetric stretching nodes for the O − C−O molecular bonds of calcite [ 26 ]. In the MgO-1 sample, a lower relative intensity was observed in these absorption bands, possibly due to a lower presence of this chemical compound (Fig. 3 a). The MgO-13 sample was the only one without CaCO 3 absorption bands, confirming its absence (Fig. 3 b). The identification of MgO was not allowed by this technique due to the nature of the ionic bonds; meanwhile the identification of calcite was possible because of its covalent bonds. Figure 4 shows the SEM micrographs of the synthesized samples (M1 to M16), which contain varying proportions of MgO, CaCO 3 , and SiO 2 . All images were captured at a magnification of 3000× with a scale bar of 5 µm. In general, samples M1-M12 exhibit heterogeneous morphologies characterized by irregularly shaped particles with sharp edges and varying degrees of agglomeration, i.e., M2, M4, M6, and M9 samples show more compact agglomerates, suggesting differences in phase composition probably influenced by their composition. In contrast, sample M13 shows a markedly different microstructure. The morphology appears more homogeneous (e.g., sphere-like, see closer magnification at Fig. 4 m) and compact, with a significantly finer texture compared to the other samples. The absence of distinct grain boundaries and the smoother surface suggest a higher degree of sintering or particle interaction due to the predominance of MgO. Samples M14 to M16 also reveal a trend toward denser surfaces, though not to the same extent as M13, possibly indicating intermediate compositions or reaction extents. Also, the textural properties of the synthesized samples were analyzed by the BET method from N 2 isotherms. Figure 5 displays the nitrogen adsorption–desorption isotherms at -196°C for the synthesized samples. The isotherms show clear distinctions, reflecting the influence of compositional variation—particularly the MgO content—on textural properties. A progressive and systematic increase in adsorbed nitrogen volume was observed across the series, revealing a clear trend in porosity development as a function of composition. The first samples (e.g., M1–M5) exhibit relatively low adsorption volumes, with low slopes and minimal hysteresis at the high relative pressure region. This behavior is characteristic of materials with low surface area and limited porosity. These features are likely related to a higher content of CaCO 3 or SiO 2 , which may result in more compact or less porous structures, as supported by SEM observations. As the sample number increases—from M6 onward—the isotherms show a noticeable rise in adsorbed volume and the development of more pronounced hysteresis loops. This indicates the emergence of mesoporosity, enhanced surface area, and greater pore connectivity. In particular, samples M13 to M15 exhibit the highest nitrogen uptake, with steep increases at relative pressures above 0.8, suggesting the presence of capillary condensation in well-developed mesoporous or even macroporous networks. Sample M13, which contains the highest proportion of MgO, presents a significant jump in adsorption capacity compared to earlier samples, consistent with its more homogeneous and compact microstructure seen in SEM analysis. This implies that MgO plays a critical role in promoting the formation of porous textures, possibly by affecting particle packing, sintering behavior, or reaction by-products during synthesis. The progressive increase in surface accessibility and porosity from M1 to M16 suggests that the compositional tuning of MgO–CaCO 3 –SiO 2 systems directly impacts textural features, which may have significant implications for applications such as photocatalysis, adsorption, or hydration reactivity in cement pastes. The evolution of nitrogen adsorption–desorption isotherms across samples correlates strongly with the measured BET surface areas. As shown in Table 4 , the specific surface area varies considerably throughout the series, ranging from as low as 8.1 m²/g (M15) to as high as 146.1 m 2 g − 1 (M13). This variation is consistent with the observed adsorption isotherms (Fig. 5 ), where samples exhibiting higher nitrogen uptake, particularly M11, M12, and M13, also demonstrate significantly larger surface areas (81.9, 87.7, and 146.1 m 2 g − 1 , respectively). These samples show pronounced mesoporous characteristics, with steep adsorption increases at high relative pressures (> 0.8), indicative of capillary condensation. Conversely, M4, M5, and M16 samples, which display the lowest surface areas (9.9, 8.1, and 13.8 m 2 g − 1 , respectively), correspond to flatter isotherms with minimal hysteresis, suggesting limited porosity. Interestingly, while the M14 sample has a moderate surface area (37.8 m 2 g − 1 ), it shows higher adsorption capacity than M15 and M16, reflecting potential differences in pore structure and connectivity. In summary, these results demonstrated that the tuning of MgO–CaCO 3 –SiO 2 composition leads to marked differences in textural properties, where optimal MgO proportions (e.g., M13) contribute to highly porous materials with large surface areas, which are desirable for surface-sensitive applications such as self-cleaning applications. Table 4 Surface area of the synthesized samples. Sample Surface area (m 2 g − 1 ) Sample Surface area (m 2 g − 1 ) M1 40.8 M9 23.7 M2 28.0 M10 13.2 M3 24.6 M11 81.9 M4 9.9 M12 87.7 M5 16.3 M13 146.1 M6 14.6 M14 37.8 M7 34.6 M15 8.1 M8 17.6 M16 13.8 3.2. Analysis of the design of experiment A fractional factorial design 2 5−1 was employed to assess the effects of five process variables—dolomite mass (DM), activation temperature (AT), reaction time (RT), heat treatment time (HTT), and treatment temperature (T)—on two responses: MgO content (%) and surface area. The resolution of the design of experiments allows for the estimation of main effects and two-factor interactions, optimizing the number of experimental runs and enabling the identification of the most influential parameters. The analysis of variance (ANOVA) for MgO content revealed that among the linear effects, activation temperature (AT) showed a statistically significant effect (p = 0.022), confirming that higher activation temperatures promote greater decomposition of dolomite and enhance MgO formation ( Table S1 ). Heat treatment time (HTT) was also significant (p = 0.049), suggesting that prolonged post-synthesis heating favors further decomposition or stabilization of MgO phases. Dolomite mass (DM) had a near-significant effect (p = 0.053), indicating its importance in determining the MgO yield. The effects of reaction time (RT) and treatment temperature (T) were less pronounced (p > 0.2), although they may still influence MgO content through interactions. Regarding two-way interactions, the DM × AT interaction was notable (p = 0.053), indicating a synergistic relationship between precursor quantity and activation intensity. Similarly, DM × HTT (p = 0.079) and AT × HTT (p = 0.058) suggested that combining high precursor mass with extended thermal treatment can enhance MgO production. These interactions highlight the complex interplay between material loading and thermal exposure in governing phase transformation. These statistical findings are supported by the main effects plot (Fig. 6 a), where a steep increase in MgO content is observed with increasing activation temperature—from 800 to 1000°C—highlighting the enhanced decomposition of dolomite and formation of MgO at higher thermal input. The plot also shows that a longer HTT slightly increases MgO yield, and that a larger DM contributes positively to MgO content. In contrast, RT and T exhibit flatter trends, suggesting a more limited direct effect. On the other hand, the surface area was most strongly affected by reaction time (RT) (p = 0.026), suggesting that longer exposure during reaction promotes porosity, potentially through gas evolution and structural reorganization ( Table S1 ). Heat treatment time (HTT) (p = 0.069) and activation temperature (AT) (p = 0.077) also had considerable effects, likely related to thermal-driven phase changes and sintering dynamics. Among the interactions, DM × HTT emerged as the most significant (p = 0.018), pointing to a sensitive relationship between precursor quantity and thermal treatment in controlling porosity. Likewise, the AT × T interaction (p = 0.025) revealed that higher combined activation and treatment temperatures promote higher surface area, likely due to accelerated decomposition and enhanced textural development. The interactions DM × T (p = 0.073) and RT × T (p = 0.102) also contributed, underscoring the importance of thermal synergy. In contrast to the MgO response, surface area was more influenced by interaction terms than by individual factors, indicating that porosity development is governed by more complex multivariable dependencies than the decomposition process alone. The corresponding main effects plot of the surface area (Fig. 6 b) reveals a pronounced increase in surface area at lower RT (2 h), followed by a steep decline at longer RT (4 h), suggesting that extended reaction times may lead to sintering or pore collapse. A similar, though less dramatic, trend is observed with HTT: shorter heat treatment favors higher surface area. The effect of AT is nonlinear—higher activation temperatures promote surface area, possibly due to enhanced gas release and porosity generation during decomposition. The influence of DM and T is relatively minor, though surface area slightly increases at the higher T level (600°C), hinting at residual structural modification during final treatment. Overall, the analysis revealed that MgO content is primarily driven by activation temperature, heat treatment time, and dolomite mass, while surface area is more sensitive to reaction time, thermal parameters, and their interactions. These findings underscore the importance of a multivariate optimization approach: while high temperatures may enhance MgO yield, they may also reduce surface area due to sintering. Thus, the balance between thermal activation and controlled porosity must be carefully managed depending on the target application. Therefore, the fractional factorial design 2 5−1 proved effective for rapidly identifying key factors and interactions with lower experiments, offering a solid foundation for optimization or scale-up. 3.3. Characterization of MOC fabricated with MgO from dolomite ore Since sample M13 exhibited the highest MgO content along with the most favorable microstructural and textural properties—including high surface area, porosity, homogeneous morphology, and higher purity—it was selected as the primary raw material for the development of self-cleaning MOC pastes. Based on this material, a series of formulations were designed following the compositional framework presented in Table 3 , incorporating functional additives such as citric acid, fly ash, slag, and TiO 2 to enhance workability, durability, and photocatalytic activity. Figure 7 shows SEM micrographs of the different MOC-based formulations. The reference sample RMOC, prepared with commercial MgO, exhibits the characteristic morphology of MOC phase 5, composed of interlocked needle-like morphology (Fig. 7 a). In contrast, the RDMOC sample, synthesized using MgO derived from dolomite, shows a more refined needle-like morphology, indicative of enhanced crystallinity and phase purity due to the tailored reactivity of the MgO source (Fig. 7 b). The incorporation of TiO 2 nanoparticles in PDMOC results in a mixed morphology, where both needle-like crystals and some particles with a gel-like phase coexist (Fig. 7 c). This suggests that TiO 2 may interfere with the crystallization process, possibly by altering hydration kinetics, leading to partial amorphization of the structure. In PDFMOC, the addition of citric acid and fly ash in the optimized formulation significantly promoted the formation of a predominantly gel-like morphology (Fig. 7 d). This transformation is likely due to the chelating effect of citric acid on Mg 2+ ions, which hinders the growth of crystalline phases, and the pozzolanic reaction of fly ash, which contributes to the formation of a denser, less crystalline matrix. Similarly, in the PDSMOC sample, which replaces fly ash with blast furnace slag, the morphology remains as a partially needle-like morphology but also shows signs of densification and reduced crystallinity (Fig. 7 e, f). The slag appears to influence the matrix structure, although to a lesser extent than fly ash. These observations highlight how raw material selection and additive incorporation profoundly influence morphology and likely the performance of MOC-based composites. The XRD patterns of the MOC fabricated with different additives are shown in Fig. 8 . The analysis of the diffractogram of the reference sample (RMOC) revealed that it was composed of the crystalline phase 5 (7-0420 card) and the formation of secondary phases, e.g., phase 3 was not detected. Similarly, the sample prepared with the MgO synthesized from the dolomite ore exhibited the same reflections associated with phase 5, with additional reflections related to calcite (5-0586 card). The incorporation of TiO 2 is evident in the patterns of the PDMOC and PDSMOC, marked with an asterisk, that matches with the anatase polymorph of TiO 2 (21-1272 card). Among these, the PDSMOC sample presents the most intense TiO 2 peak, likely due to the combined influence of slag and citric acid, which may enhance the dispersion or stabilization of TiO 2 within the matrix. On the other hand, the PDFMOC sample did not exhibit a significant reflection of this oxide, which could be due to fly ash contains amorphous and partially crystalline phases that contribute to background noise, thereby masking weak signals from minor crystalline components, e.g., TiO 2 . The samples containing supplementary materials (PDFMOC and PDSMOC) maintain the integrity of the MOC phase 5, indicating that the addition of fly ash or slag, even in the presence of citric acid, does not disrupt the formation of the primary phase. Calcium carbonate was observed in these samples, suggesting carbonation due to the presence of reactive fillers. The UV-Vis absorbance spectra of the reference and modified MOC formulations are shown in Figure S1 . All samples display a characteristic absorption edge in the UV region (350–400 nm), which is consistent with the presence of TiO 2 [ 27 ]. However, differences in absorbance magnitude and spectral shape among the formulations provide insight into their compositional and structural variations. For example, the reference samples (RMOC and RDMOC) exhibit the lowest absorbance in the UV region; meanwhile, the samples with TiO 2 (PFMOC, PDFMOC, and PDSMOC) exhibited a high absorbance in this region. These results suggest that the semiconductor particles are well-dispersed in the MOC matrix and contribute to enhanced light harvesting, and thus, the self-cleaning activity as will be further discussed. The increased absorbance may also reflect improved interface contact between TiO 2 and the binder phases, especially in the presence of supplementary cementitious materials, which can modulate surface chemistry and charge transfer. Figure 9 presents the compressive strength values for the reference MOC formulation (RMOC) and its modified counterparts incorporating TiO 2 , fly ash, slag, and MgO obtained from dolomite. The results demonstrate that compositional modifications influenced the mechanical performance of the MOC systems. The RMOC sample exhibited the highest compressive strength, with an average value exceeding 29 MPa. This is consistent with the use of high-purity MgO, which promotes the formation of well-crystallized phase 5, widely known for its mechanical performance [ 28 ]. In contrast, the RDMOC sample showed a marked decrease in compressive strength (≈ 18 MPa). This reduction is likely due to the presence of impurities in the dolomite-derived MgO, which may hinder the formation of the main binding phases or introduce porosity and structural defects. The TiO 2 -modified samples exhibited intermediate strengths (20–26 MPa). The partial recovery of strength in PDMOC suggests that TiO 2 contributes to matrix densification due to its filler effect. The slightly lower strength in PDSMOC, despite the presence of both TiO 2 and slag, may be related to potential interactions between slag components and MOC hydration products, which could compromise the mechanical performance. It is worth to mention that both SCM-containing samples (PDFMOC and PDSMOC) exhibit lower variability, indicating a more homogeneous matrix formation, possibly due to better particle dispersion. 3.4. Self-cleaning efficiency of MOC formulations Figure 10 a presents the self-cleaning performance of the various MOC formulations under simulated sunlight for 24 h (1.1 W/m 2 , 35% RH, 43ºC). As shown, all samples exhibit a rapid increase in efficiency within the first 6 h of irradiation, followed by a more gradual progression up to 24 h. The enhanced photocatalytic activity of the modified formulations was clearly evident when compared to the reference sample RMOC, which achieved an efficiency of 85.3%. Notably, the addition of TiO 2 significantly boosted the degradation performance, as observed in PDMOC, which reached the highest mean efficiency of 92.3%. Formulations containing both TiO 2 and SCMs also showed high photocatalytic efficiency; however, PDSMOC had the lowest performance among the modified samples (81.1%), potentially due to differences in matrix porosity or TiO 2 dispersion. Statistical analysis confirms that PDMOC, RDMOC, and PDFMOC formed a group with significantly higher efficiency than RMOC and PDSMOC (Fig. 10 b). These results highlight the key role of TiO 2 and suggest that the type and combination of SCMs influence photocatalytic behavior, likely through their impact on microstructure and light scattering properties. 3.5. Analysis of stability Figure 11 shows the moisture stability coefficient of the different MOC formulations, providing a quantitative measure of their resistance to moisture-induced degradation. The reference sample exhibited a moderate coefficient, indicating limited stability in humid conditions. Interestingly, the RDMOC sample, synthesized using MgO derived from dolomite, showed improved moisture resistance, suggesting that the alternative precursor contributed positively to matrix densification or phase stability. In contrast, the presence of TiO 2 in the pastes resulted in a lower coefficient, which may be attributed to an increase in porosity. However, the synergistic incorporation of TiO 2 with SCMs significantly enhanced moisture resistance, as evidenced by PDFMOC, which exhibited the highest coefficient (0.90) among all formulations. PDSMOC also showed good performance, though with slightly higher variability, likely due to the complex interaction between the two SCMs. Overall, these findings demonstrate that the appropriate combination of TiO 2 and SCMs can effectively enhance the long-term stability of MOC composites under humid environments. 4. Conclusions This work demonstrated the feasibility of producing reactive MgO from dolomite and its successful application in the formulation of magnesium oxychloride cement. The synthesized MgO showed suitable physicochemical properties, allowing the preparation of a sample with comparable or superior performance to commercial-based formulations. The analysis of the design of experiments revealed that acid treatment temperature and reaction time significantly influence MgO purity and surface area, which in turn affected the MOC’s mechanical and functional properties. Among the modified MOC formulations, the incorporation of TiO 2 enhanced the photocatalytic activity, while its combined use with SCMs such as fly ash and slag further optimized the balance between mechanical strength, photocatalytic performance, and durability under humid environments. Overall, this work provides a sustainable route for MOC production using alternative MgO sources and demonstrates that tailored combinations of SCMs and photocatalysts can significantly improve MOC performance, paving the way for multifunctional and durable alternative construction materials. Declarations 5. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. 6. Data availability The datasets generated will be available on request. References Walling S. A., Provis J. L.: Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future? Chem. Rev. 116(7), 4170-4204 (2016). https://doi.org/10.1021/acs.chemrev.5b.00463 Li K., Wang Y., Yao N., Zhang A.: Recent progress of magnesium oxychloride cement: Manufacture, curing, structure and performance. Constr. Build. Mater. 255, 119381 (2020). https://doi.org/10.1016/j.conbuidmat.2020.119381 Taourati R., Khaddor M., Laghzal A., Kasmi A. E.: Facile one-step synthesis of highly efficient single oxide nanoparticles for photocatalytic application. Sci. Afri. 8, e00305 (2020). https://doi.org/10.1016/j.sciaf.2020.e00305 Shand M. A.: Manufacture of magnesium oxide for magnesia cements for Magnesia Cements. Magnesia Cements from formulations to applications 1, 13-28 (2020). https://doi.org/10.1016/B978-0-12-391925-0.00008-X Scheller E. L., Swindle C., Grotzinger J., Barnhart H., Bhattacharjee S., Ehlmann B. L., Farley K., Fischer W. W., Greenberger R., Ingalls M., Martin P. E., Osorio-Rodriguez D., Smith B. P.: Formation of Magnesium Carbonates on Earth and Implications for Mars. 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Cogent Eng. 7(1), 1712155 (2020). https://doi.org/10.1080/23311916.2020.1712155 dos Santos Jr. T., Pereira C.I., Gonçalves R., Salvini V.R., Zetterström C., Wöhrmeyer C., Parr C., Pandolfelli V.C.: Gluconate action in the hydration of calcium aluminate cements: Theoretical study, processing of aqueous suspensions and hydration reactivation. J. Eur. Ceram. Soc. 39(8), 2748-2759 (2019). https://doi.org/10.1016/j.jeurceramsoc.2019.03.007 Li X.-L., Zhang F.-H., Jian R.-K., Ai Y.-F., Ma J.-L., Hui G.-J., Wang D.-Y.: Influence of eco-friendly calcium gluconate on the intumescent flame-retardant epoxy resin: Flame retardancy, smoke suppression and mechanical properties. Compos. B Eng. 176, 107200 (2019). https://doi.org/10.1016/j.compositesb.2019.107200 Luévano-Hipólito E., Torres-Alvarez D. A., Torres-Martínez L. M.: Flexible BiOI thin films photocatalysts toward renewable solar fuels production. J. Environ. Chem. Eng. 11(2), 109557 (2023). https://doi.org/10.1016/j.jece.2023.109557 Rodríguez-Alfaro L. F., Torres-Martínez L. M., Treviño-Garza M. Z., Vázquez-Guillén J. M., Rodríguez-Padilla C., Luévano-Hipólito E.: Design and fabrication of photocatalytic magnesium oxychloride cement with improved moisture stability: A step towards sustainable construction. Constr. Build. Mater. 414, 134804 (2024). https://doi.org/10.1016/j.conbuildmat.2023.134804 Gueta R., Natan A., Addadi L., Weiner S., Refson K., Kronik L.: Local Atomic Order and Infrared Spectra of Biogenic Calcite. Angew. Int. Ed. Chem. 46(1-2), 291-294 (2006). https://doi.org/10.1002/anie.200603327 Ball R. J., Ansell M. P., Su-Cadirci T. B., Baki V. A., Fletcher P. J., Lichtenberger A., Raja R., Wootton W.: Analysis of mosaic mortars from the Roman, Byzantine and Early Islamic periods sourced from Gerasa’s Northwest Quarter. Herit. Sci. 12, 168 (2024). https://doi.org/10.1186/s40494-02401277-3 Ma J., Li W., Le N. T., Díaz-Real J. A., Body M., Legein C., Światowska J., Demortière A., Borkiewicz O. J., Konstantinova E. A., Kokorin A. I., Alonso-Vante N., Laberty-Robert C., Dambournet D., Red-Shifted Absorptions of Cation-Defective and Surface-Functionalized Anatase with Enhanced Photoelectrochemical Properties. ACS Omega 4(6), 10929-10938 (2019). https://doi.org/10.1021/acsomega.9b01219 Xie Y., Wang H., Guo Y., Wang C., Cui H., Xue J.: Mechanical performance and water resistance of biochar admixture lightweight magnesium oxychloride cement, Sci. Total Environ. 912, 168773 (2024). https://doi.org/10.1016/j.scitotenv.2023.16877 Supplementary Files SI.docx Cite Share Download PDF Status: Published Journal Publication published 16 Jan, 2026 Read the published version in Waste and Biomass Valorization → Version 1 posted Reviewers agreed at journal 06 Aug, 2025 Reviewers invited by journal 03 Aug, 2025 Editor invited by journal 03 Aug, 2025 Editor assigned by journal 15 Jul, 2025 First submitted to journal 14 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7123900","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":494931364,"identity":"3cf9daf9-cc7a-4581-977d-612dc88e4caa","order_by":0,"name":"Luis Felipe Rodríguez Alfaro","email":"","orcid":"","institution":"Autonomous University of Nuevo Leon: Universidad Autonoma de Nuevo Leon","correspondingAuthor":false,"prefix":"","firstName":"Luis","middleName":"Felipe Rodríguez","lastName":"Alfaro","suffix":""},{"id":494931365,"identity":"b3206442-fa4a-4c4e-83d3-732eee06712c","order_by":1,"name":"Leticia Myriam Torrez Martínez","email":"","orcid":"","institution":"Autonomous University of Nuevo Leon: Universidad Autonoma de Nuevo Leon","correspondingAuthor":false,"prefix":"","firstName":"Leticia","middleName":"Myriam Torrez","lastName":"Martínez","suffix":""},{"id":494931366,"identity":"428c6109-319b-4bad-9ede-789466ba63df","order_by":2,"name":"Edith Luévano","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-2988-405X","institution":"Universidad Autónoma de Nuevo León","correspondingAuthor":true,"prefix":"","firstName":"Edith","middleName":"","lastName":"Luévano","suffix":""}],"badges":[],"createdAt":"2025-07-14 18:51:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7123900/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7123900/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s12649-025-03475-x","type":"published","date":"2026-01-16T16:30:21+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":88347685,"identity":"c8ca6a99-593d-4af9-9d60-856fd5eeb260","added_by":"auto","created_at":"2025-08-05 13:54:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":167409,"visible":true,"origin":"","legend":"\u003cp\u003eSynthesis of MgO from dolomite ore. (Created in https://BioRender.com).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/9cacf0dd11e7826dbee46634.png"},{"id":88347686,"identity":"174cb5a1-4db5-42a9-8962-6371069c0803","added_by":"auto","created_at":"2025-08-05 13:54:08","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":282980,"visible":true,"origin":"","legend":"\u003cp\u003eXRD diffractograms of the MgO samples synthesized from dolomite ore.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/edf911e7946ac74f32d49f2d.png"},{"id":88347692,"identity":"53abd31e-a855-4ea5-82dc-c3ade5806b40","added_by":"auto","created_at":"2025-08-05 13:54:08","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":200378,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of the samples synthesized from dolomite ore.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/09f74b3ee0b81852af169d68.png"},{"id":88348948,"identity":"39792841-93e5-496c-85e6-ddb42845c661","added_by":"auto","created_at":"2025-08-05 14:02:08","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":481333,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of the synthesized samples.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/7ba699ad5bc29d536affdd78.png"},{"id":88350739,"identity":"ec0e5afe-fafe-404b-9258-499f4090d0c3","added_by":"auto","created_at":"2025-08-05 14:18:08","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":205681,"visible":true,"origin":"","legend":"\u003cp\u003eN\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherms.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/1893dcca25558328fbd6aa77.png"},{"id":88350380,"identity":"1a6358fc-e36b-4b19-b100-c2c899e185f0","added_by":"auto","created_at":"2025-08-05 14:10:08","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":208413,"visible":true,"origin":"","legend":"\u003cp\u003eMain effects plots considering the responses: (a) MgO content (%) and (b) Surface area (m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e).\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/9f688cf0942b8e13d2d7b87b.png"},{"id":88347695,"identity":"d957d3f6-0013-45ce-beab-68c7af0b8909","added_by":"auto","created_at":"2025-08-05 13:54:08","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":538548,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of the MOC prepared under different conditions.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/82c308155759b0fb09cd04c4.png"},{"id":88350383,"identity":"5181d123-14a9-4fa5-8474-73cc84deb986","added_by":"auto","created_at":"2025-08-05 14:10:08","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":303501,"visible":true,"origin":"","legend":"\u003cp\u003eXRD spectra of the MOC prepared under different conditions.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/84f8d461bda1829b72b4638d.png"},{"id":88347713,"identity":"d5661ade-ca92-4101-85ea-00175d143a21","added_by":"auto","created_at":"2025-08-05 13:54:09","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":132650,"visible":true,"origin":"","legend":"\u003cp\u003eCompressive strength of the MOC fabricated with different formulations.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/3bea6fd1c5068e4c3c99ca06.png"},{"id":88350384,"identity":"fb1ce219-33d1-4dfd-85a2-9ea7c52545b5","added_by":"auto","created_at":"2025-08-05 14:10:08","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":195834,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Self-cleaning efficiency of the different MOC formulations under sun-like irradiation and (b) Comparison of the efficiency after 24 h of sunlight exposition (\u003cem\u003emeans that do not share a letter are significantly different\u003c/em\u003e).\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/b69d2a2ef11b715fee0f28cd.png"},{"id":88348958,"identity":"5646dc84-db82-4fec-a776-7bf0281e113e","added_by":"auto","created_at":"2025-08-05 14:02:08","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":156367,"visible":true,"origin":"","legend":"\u003cp\u003eMoisture stability coefficient (MSC) of each group of MOC samples. \u003cem\u003eMeans that do not share a common superscript letter are significantly different\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/ccb3065b4d2dabba52eea248.png"},{"id":100616177,"identity":"f1aeda7f-b695-4d6e-bb88-50b474d14460","added_by":"auto","created_at":"2026-01-19 17:41:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3774725,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/70afc496-3362-4c5e-aa09-d01f6cde0416.pdf"},{"id":88347697,"identity":"7c9bf46c-9858-4f57-b880-33cfb4f262a7","added_by":"auto","created_at":"2025-08-05 13:54:08","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":89598,"visible":true,"origin":"","legend":"","description":"","filename":"SI.docx","url":"https://assets-eu.researchsquare.com/files/rs-7123900/v1/ac6ae22d0bdee89771d68bb5.docx"}],"financialInterests":"","formattedTitle":"Self-cleaning MOC fabricated from dolomite ore","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eMOC cement is fabricated from three base components that form its ternary system MgO-MgCl\u003csub\u003e2\u003c/sub\u003e-H\u003csub\u003e2\u003c/sub\u003eO, being the most important MgO. This compound cannot be extracted directly from nature, since the mineral periclase (MgO) is relatively rare and its hydration product, brucite [Mg(OH)\u003csub\u003e2\u003c/sub\u003e], is found only in a limited number of commercially viable geological formations [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMgO is generally obtained by two methods: (1) by dry process from calcination of mined magnesite (MgCO\u003csub\u003e3\u003c/sub\u003e) deposits, or (2) by wet process from brine or seawater solutions containing magnesium [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Most of the worldwide MgO production is carried out by the first method due to its lower energy requirements compared to wet production. Furthermore, the wet process presents higher complexity, as it involves the precipitation of MgO from a magnesium-rich solution under specific conditions and additional treatments [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. In the dry route, the process begins with the extraction of magnesite ore, which is then crushed, ground, and pulverized to reduce it to a size suitable for calcination, which step is critical to ensure efficient and homogeneous calcination. The crushed magnesite is subsequently heated in kilns at temperatures ranging from 700 to 1000\u0026deg;C, depending on the quality of the magnesite, transforming MgCO\u003csub\u003e3\u003c/sub\u003e into MgO and releasing CO\u003csub\u003e2\u003c/sub\u003e in the process [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMagnesite is a magnesium carbonate generally found in nature associated with other elements such as calcite, aragonite, dolomite, quartz, brucite, serpentinite, among others [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. When obtaining MgO by the calcination method, a large amount of CO2 is liberated into the atmosphere during the process (approximately 1.1 kg CO\u003csub\u003e2\u003c/sub\u003e/kg MgO), which some consider to be an environmentally unfriendly method [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Furthermore, magnesite is less common than calcite and dolomite, limiting the relative number of outcrops available for practical exploitation [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Most magnesite deposits and production are concentrated in China, which entails additional CO\u003csub\u003e2\u003c/sub\u003e emissions due to transportation from the source to shipping worldwide destinations [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Despite these concerns, Jankovsky et al. proposed that MOC cement prepared by the dry calcination method of magnesite to obtain MgO can still be considered more sustainable compared to Portland cement, given the considerably low emissions of polluting gases (up to 40%) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Furthermore, they suggested that the use of alternative magnesium-rich materials that are more abundant and easily extracted to improve their sustainability and costs. Among them, and the most important for the present study, is dolomite.\u003c/p\u003e\u003cp\u003eDolomite is a double carbonate mineral of calcium and magnesium [CaMg(CO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e] ubiquitous in the Earth's crust. After calcite, it is the second most abundant carbonate mineral in the world [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. It occurs in massive forms or as small geodes and due to their impurities, mostly iron and manganese, their color can vary. Economically, it represents great importance, e.g., more than 50% of gas and oil deposits are in dolomitic formations [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Also, this mineral is considered more environmentally friendly in contrast to magnesite during the process of obtaining MgO to produce MOC through the dry calcination method. According to theoretical calculations, approximately 2.49 tons of dolomites are required to produce 1 ton of MOC, which creates as a byproduct 1.38 tons of synthetic aragonite (CaCO\u003csub\u003e3\u003c/sub\u003e), harmless to the environment, and 0.58 tons of CO\u003csub\u003e2\u003c/sub\u003e that is emitted into the air [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Likewise, the amount of dolomite required to produce MOC can be reduced by adding some type of filler, for example, fly ash or other recycled material, in turn promoting a decrease in CO\u003csub\u003e2\u003c/sub\u003e emissions, and reducing the total cost of the materials.\u003c/p\u003e\u003cp\u003eThe thermal decomposition of dolomite by dry calcination occurs in two stages: (1) the decomposition of dolomite to MgO, CaCO\u003csub\u003e3\u003c/sub\u003e, and CO\u003csub\u003e2\u003c/sub\u003e at approximately 700\u0026deg;C (Eq.\u0026nbsp;1), and (2) the decomposition of CaCO\u003csub\u003e3\u003c/sub\u003e to CaO and CO\u003csub\u003e2\u003c/sub\u003e at \u0026gt;\u0026thinsp;700\u0026deg;C (Eq.\u0026nbsp;2) [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, the exact decomposition conditions will depend on the unique properties of each dolomite, the calcination conditions (e.g., temperature and time), and the presence of impurities (e.g., SiO\u003csub\u003e2\u003c/sub\u003e and CaO), so these temperatures should not be taken as absolute values.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:CaMg(C{O}_{3}{)}_{2}\\:\\underrightarrow{\\varDelta\\:}MgO+C{O}_{2}+CaC{O}_{3}\\:\\:\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:CaC{O}_{3}\\:\\underrightarrow{\\varDelta\\:}CaO+C{O}_{2}\\:\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eSome reports have proposed the use of calcined dolomite as a raw material for producing MgO-based cements, including reactive magnesia cements [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], magnesium oxysulfate cements [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], magnesium phosphate cement [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and magnesium oxychloride cements [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. However, the direct use of calcined dolomite for producing MOC has been hampered by the presence of impurities such as CaCO\u003csub\u003e3\u003c/sub\u003e in low-temperature processes (Eq.\u0026nbsp;1) as well as the presence or excess of CaO in high-temperature processes (Eq.\u0026nbsp;2) [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. These impurities can cause changes in the setting, phase composition, mechanical properties, and in some cases, volumetric instability in MOC. Therefore, it is important to remove or exclude impurities from dolomite before using it to manufacture MOC. Considering these challenges, this work proposes a novel, simple, and economical method for producing MgO from dolomite for the manufacture of MOC samples. The method, explained in general terms, consists of mixing calcined dolomite with D-(+)glucose (C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e12\u003c/sub\u003eO\u003csub\u003e6\u003c/sub\u003e) in water to endorse the reaction with CaCO\u003csub\u003e3\u003c/sub\u003e (from the calcined dolomite) to produce calcium gluconate (C\u003csub\u003e12\u003c/sub\u003eH\u003csub\u003e22\u003c/sub\u003eCaO\u003csub\u003e14\u003c/sub\u003e) in solution, promoting the formation of high quality MgO for MOC manufacturing. It is worth to mention that calcium gluconate is an important value-added material widely used in medicine [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], corrosion inhibitor on mild steel [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], retarder for calcium aluminate cement hydration [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], flame-retardant for epoxy resin [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], and recently it was demonstrated its use as sacrificial agent to generate green hydrogen by heterogeneous photocatalysis [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In addition, based on the synthesis of magnesium oxide from dolomite, magnesium oxychloride cements were formulated with self-cleaning properties. To improve and optimize the MOC formulation, supplementary cementitious materials (SCMs) such as fly ash and blast furnace slag were incorporated, along with titanium dioxide as a photocatalytic additive. These modifications aim not only to preserve or enhance the mechanical performance of the material but also to boost its photocatalytic activity, contributing to the development of sustainable and multifunctional MOC formulations.\u003c/p\u003e"},{"header":"2. Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Synthesis of MgO from dolomite ore\u003c/h2\u003e\u003cp\u003eDolomite ore was donated by a local company, which chemical composition, obtained by X-ray Fluorescence, is shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eChemical composition of the dolomite ore.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComponent\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCaO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMgO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eAg\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eK\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eOthers\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e78.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe synthesis method begins with the mechanical grinding of natural dolomite ore in a ball mill to reduce particle size and enhance its reactivity (1). The pulverized dolomite is then subjected to calcination at temperatures ranging from 800 to 1000\u0026deg;C (2), promoting the thermal decomposition of the carbonate phases (Eq.\u0026nbsp;1). Subsequently, the powders were mixed with an aqueous solution of glucose (C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e12\u003c/sub\u003eO\u003csub\u003e6\u003c/sub\u003e, Aldrich, 99%), and the suspension was stirred to ensure homogeneous interaction (3) until the formation of a red suspension (4). During this process, the reaction leads to the formation of a water-soluble complex of C\u003csub\u003e12\u003c/sub\u003eH\u003csub\u003e22\u003c/sub\u003eCaO\u003csub\u003e14\u003c/sub\u003e (CG), while MgO was selectively precipitated (Eq.\u0026nbsp;3). The amount of each\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabb\" border=\"1\"\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:MgO+6\\:Ca{CO}_{3}+11\\:{C}_{6}{H}_{12}{O}_{6}\\to\\:6{C}_{12}{H}_{22}Ca{O}_{14}+MgO\\downarrow\\:\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe resulting MgO precipitate is recovered by centrifugation and washed four times with distilled water to remove residual byproducts (5). The purified solid is then dried in an oven at 80\u0026deg;C for 12 h. Finally, thermal treatment is applied at temperatures between 500 and 700\u0026deg;C for 2 h (6) to obtain MgO powders with controlled crystallinity and particle morphology (7). A schematic representation of the synthesis process is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFor these experiments, a 2\u003csup\u003e5\u0026minus;1\u003c/sup\u003e factorial design was carried out to identify the conditions that favored the highest yield of MgO from dolomite (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The factors selected were dolomite mass (DM, 1), temperature of the activation (AT, 2), reaction time (RT, 3), temperature and calcination time (HTT and T, 7). The design of experiments was analyzed in the Minitab\u0026reg; software.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFractional factorial design 2\u003csup\u003e5\u0026minus;1\u003c/sup\u003e used for MgO synthesis.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDolomite mass \u003csup\u003e(1)\u003c/sup\u003e (g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eActivation temperature \u003csup\u003e(2)\u003c/sup\u003e (\u0026deg;C)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eReaction time \u003csup\u003e(3)\u003c/sup\u003e (h)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eHeat treatment time \u003csup\u003e(7)\u003c/sup\u003e (h)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTemperature \u003csup\u003e(7)\u003c/sup\u003e (\u0026deg;C)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM2\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM3\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM4\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM5\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM6\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM7\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM8\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM9\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM10\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM11\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM12\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM13\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM14\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM15\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM16\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe numbers in the superscripts refer to the steps shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Fabrication of MOC with MgO recovered from dolomite\u003c/h2\u003e\u003cp\u003eTo fabricate the MOC samples, the following (general) procedure was employed: First, magnesium chloride hexahydrate (MgCl₂\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO, DEQ, 99%) was dissolved in distilled water using a magnetic stirrer at a moderate speed. Then, the MgO powder (commercial-99% or derived from dolomite via a glucose-mediated process) was gradually added to the solution until a homogeneous paste with consistent viscosity was obtained. The resultant MOC paste was subsequently cast into a cylindrical plastic mold with a diameter of 20 mm and a height of 3 mm. The mold was filled and left to cure at room temperature for seven days. After the curing process, the solid MOC samples were carefully extracted from the molds for the testing and characterization.\u003c/p\u003e\u003cp\u003eTo enhance the sustainability of magnesium oxychloride cement materials, several modifications were introduced to the baseline formulation, including the use of alternative raw materials and supplementary additives. Among these, a previously optimized formulation developed by our research group was selected as a reference [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. This composition employs a MgO/H₂O (M/H) ratio of 5/15 and incorporates 1 wt.% citric acid, 3 wt.% fly ash, and 3 wt.% TiO\u003csub\u003e2\u003c/sub\u003e. It demonstrated excellent properties, including a compressive strength of 39 MPa at early ages, high moisture resistance, and complete self-cleaning efficiency (100%) under solar irradiation. In this work, further formulations were explored to assess the impact of incorporating blast furnace slag as a partial replacement material and to evaluate the performance of MgO derived from dolomite calcination. These compositions were compared to a commercial reactive-grade MgO reference (RMOC) to determine their suitability for use in self-cleaning cementitious systems. Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e summarizes the mix designs of the investigated MOC pastes, including both commercial (RMOC) and dolomite-based (D) variants with photocatalytic nanoparticles (P) to provide the self-cleaning effect.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMix design for self-cleaning MOC pastes.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eM/H\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCitric acid (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eFly ash (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eSlag (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTiO\u003csub\u003e2\u003c/sub\u003e (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRMOC\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"4\" rowspan=\"5\"\u003e\u003cp\u003e5/15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRDMOC\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePDMOC\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePDFMOC\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePDSMOC\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Characterization\u003c/h2\u003e\u003cp\u003eThe samples were characterized by different techniques. The crystal phases were identified using X-ray diffraction (XRD) on a Bruker D8 Advance diffractometer equipped with a high-speed Vantec detector. Measurements were collected over a 2θ range of 10\u0026deg; to 70\u0026deg; with a step size of 0.022\u0026deg; using CuKα radiation (40 kV, 40 mA). Fourier-transform infrared (FTIR) spectroscopy was used to identify functional groups in a Nicolet IS50 instrument from Thermo Electron Corp., equipped with an attenuated total reflectance accessory. The morphology by Scanning Electron Microscopy (SEM) using a JEOL Instruments JSM-6490LV. To ensure conductivity, the MOC samples were sputter-coated with a thin layer of gold/palladium (Au/Pd) and mounted on carbon tape. Surface area measurements using the Brunauer-Emmet-Teller (BET) method were conducted on a Quantachrome Instruments Nova 2000e surface area analyzer. The MOC samples were degassed under vacuum at 150\u0026deg;C for 3 h before being loaded into 12 mm glass bulbs. N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherms were registered at -196\u0026deg;C to determine the specific surface area.\u003c/p\u003e\u003cp\u003eTo evaluate the moisture stability, the samples were exposed to highly humid conditions in an accelerated weathering machine (Q-Sun Xenon model Xe-3 test chamber) following the parameters specified in ISO 6270\u0026ndash;1:2017 (HR 95% and 38\u0026thinsp;\u0026plusmn;\u0026thinsp;2 ◦C). This standard was proposed to evaluate the moisture stability of cement-based materials under continuous condensation steps. Before and after this exposition, the mechanical properties of MOC samples were evaluated using various techniques. Surface hardness was assessed using nanoindentation, with a Fischerscope model HM2000-5 nanoindenter. Five indentations were performed on each sample surface using a diamond Vickers indenter with a square base and pyramidal geometry to obtain a statistically relevant mean value. Each indentation involved a 50 mN load applied for 60 seconds with no creep time. The compressive strength of the MOC samples was determined using three cubic specimens. Measurements were conducted using a Shimadzu AGX-Plus Universal Compressive Testing Machine at a constant loading rate of 1 mm/min. To obtain quantitative analysis of the moisture stability of the MOC, it was proposed the use of the Moisture Stability Coefficient (MSC), shown in Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e4\u003c/span\u003e, using the final (H\u003csub\u003ef\u003c/sub\u003e) and initial (H\u003csub\u003e0\u003c/sub\u003e) hardness. In this equation, a value near to 1 indicates an optimal performance (or high moisture stability).\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:MSC=\\:\\frac{{H}_{f}}{{H}_{0}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4. Self-cleaning assays\u003c/h2\u003e\u003cp\u003eThe self-cleaning efficiency of the MOC samples was evaluated using a concentrated solution of reactive black 5 (50 ppm) as model pollutant. Afterward, the contaminated sample was maintained at dark conditions during 12 h to ensure the adsorption-desorption equilibrium of the pollutant on the surface. Then, the samples were introduced into an accelerated weathering chamber to emulate real outdoor conditions for 3 cycles (4.48 h), following the the ASTM G155-13 conditions. To quantify the self-cleaning activity, the samples were analyzed by UV-Vis spectrophotometry using a Agilent Technologies Cary 5000. The photocatalytic self-cleaning efficiency was calculated using the Eq.\u0026nbsp;\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e5\u003c/span\u003e:\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:\\%Efficiency=\\:\\frac{{C}_{0}-C}{{C}_{0}}*100\\%$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eWhere C\u003csub\u003e0\u003c/sub\u003e is the initial dye concentration, and C is the dye concentration after the photocatalytic reaction at different times.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cp\u003eThe results are presented in two sections; first, the physicochemical characterization of MgO synthesized from dolomite is discussed, highlighting the influence of processing parameters on its properties. Subsequently, the preparation, characterization, and performance evaluation of different MOC formulations are addressed, with particular focus on their mechanical behavior, stability under moisture exposure, and self-cleaning photocatalytic efficiency.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Characterization of MgO synthesized from dolomite ore\u003c/h2\u003e\u003cp\u003eThe synthesized samples using the 2\u003csup\u003e5\u0026minus;1\u003c/sup\u003e fractional factorial design of experiments were characterized by XRD. The results showed that all the samples contained three crystalline phases: CaCO\u003csub\u003e3\u003c/sub\u003e (ICDD 00-085-1108), SiO\u003csub\u003e2\u003c/sub\u003e (ICDD 01-085-0335), and MgO (ICDD 01-075-0447) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). CaCO\u003csub\u003e3\u003c/sub\u003e was the predominant phase in most specimens, as evidenced by the highest number and intensity of reflections, particularly at 2θ\u0026thinsp;=\u0026thinsp;39.49\u0026deg;. This implies an incomplete removal of CaO under the experimental conditions studied, leading to its reaction with atmospheric CO\u003csub\u003e2\u003c/sub\u003e and subsequent formation of calcium carbonates. SiO\u003csub\u003e2\u003c/sub\u003e was also present in most samples, identified with a single weak reflection at 2θ\u0026thinsp;=\u0026thinsp;26.64\u0026deg;. The MgO phase was detected in all samples with reflections at 2θ\u0026thinsp;=\u0026thinsp;36.93\u0026deg;, 42.91\u0026deg;, and 62.30\u0026deg;, with some exceptions. For example, MgO-1 and MgO-9 samples showed more intense MgO reflections but still contained significant amounts of CaCO\u003csub\u003e3\u003c/sub\u003e, which led to their exclusion from further analysis. Notably, MgO-13 sample exclusively exhibited MgO reflections with a minor presence of SiO\u003csub\u003e2\u003c/sub\u003e. This result represents the best combination of experimental conditions to extract MgO from dolomite ore.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe FTIR spectra revealed similar patterns for most of the specimens synthesized (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Four absorption bands were mainly detected, which correspond to calcite. The absorption bands at 713 cm\u003csup\u003e-1\u003c/sup\u003e and 871 cm\u003csup\u003e-1\u003c/sup\u003e correspond to the bending nodes of the planes that belong to the C-O bonds, respectively [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The bands at 1402 cm\u003csup\u003e-1\u003c/sup\u003e and 1790 cm\u003csup\u003e-1\u003c/sup\u003e are characteristic of the asymmetric stretching nodes for the O\u0026thinsp;\u0026minus;\u0026thinsp;C\u0026minus;O molecular bonds of calcite [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. In the MgO-1 sample, a lower relative intensity was observed in these absorption bands, possibly due to a lower presence of this chemical compound (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). The MgO-13 sample was the only one without CaCO\u003csub\u003e3\u003c/sub\u003e absorption bands, confirming its absence (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb).\u003c/p\u003e\u003cp\u003eThe identification of MgO was not allowed by this technique due to the nature of the ionic bonds; meanwhile the identification of calcite was possible because of its covalent bonds.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the SEM micrographs of the synthesized samples (M1 to M16), which contain varying proportions of MgO, CaCO\u003csub\u003e3\u003c/sub\u003e, and SiO\u003csub\u003e2\u003c/sub\u003e. All images were captured at a magnification of 3000\u0026times; with a scale bar of 5 \u0026micro;m. In general, samples M1-M12 exhibit heterogeneous morphologies characterized by irregularly shaped particles with sharp edges and varying degrees of agglomeration, i.e., M2, M4, M6, and M9 samples show more compact agglomerates, suggesting differences in phase composition probably influenced by their composition. In contrast, sample M13 shows a markedly different microstructure. The morphology appears more homogeneous (e.g., sphere-like, see closer magnification at Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003em) and compact, with a significantly finer texture compared to the other samples. The absence of distinct grain boundaries and the smoother surface suggest a higher degree of sintering or particle interaction due to the predominance of MgO. Samples M14 to M16 also reveal a trend toward denser surfaces, though not to the same extent as M13, possibly indicating intermediate compositions or reaction extents.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAlso, the textural properties of the synthesized samples were analyzed by the BET method from N\u003csub\u003e2\u003c/sub\u003e isotherms. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e displays the nitrogen adsorption\u0026ndash;desorption isotherms at -196\u0026deg;C for the synthesized samples. The isotherms show clear distinctions, reflecting the influence of compositional variation\u0026mdash;particularly the MgO content\u0026mdash;on textural properties. A progressive and systematic increase in adsorbed nitrogen volume was observed across the series, revealing a clear trend in porosity development as a function of composition.\u003c/p\u003e\u003cp\u003eThe first samples (e.g., M1\u0026ndash;M5) exhibit relatively low adsorption volumes, with low slopes and minimal hysteresis at the high relative pressure region. This behavior is characteristic of materials with low surface area and limited porosity. These features are likely related to a higher content of CaCO\u003csub\u003e3\u003c/sub\u003e or SiO\u003csub\u003e2\u003c/sub\u003e, which may result in more compact or less porous structures, as supported by SEM observations. As the sample number increases\u0026mdash;from M6 onward\u0026mdash;the isotherms show a noticeable rise in adsorbed volume and the development of more pronounced hysteresis loops. This indicates the emergence of mesoporosity, enhanced surface area, and greater pore connectivity. In particular, samples M13 to M15 exhibit the highest nitrogen uptake, with steep increases at relative pressures above 0.8, suggesting the presence of capillary condensation in well-developed mesoporous or even macroporous networks. Sample M13, which contains the highest proportion of MgO, presents a significant jump in adsorption capacity compared to earlier samples, consistent with its more homogeneous and compact microstructure seen in SEM analysis. This implies that MgO plays a critical role in promoting the formation of porous textures, possibly by affecting particle packing, sintering behavior, or reaction by-products during synthesis. The progressive increase in surface accessibility and porosity from M1 to M16 suggests that the compositional tuning of MgO\u0026ndash;CaCO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;SiO\u003csub\u003e2\u003c/sub\u003e systems directly impacts textural features, which may have significant implications for applications such as photocatalysis, adsorption, or hydration reactivity in cement pastes.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe evolution of nitrogen adsorption\u0026ndash;desorption isotherms across samples correlates strongly with the measured BET surface areas. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the specific surface area varies considerably throughout the series, ranging from as low as 8.1 m\u0026sup2;/g (M15) to as high as 146.1 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (M13). This variation is consistent with the observed adsorption isotherms (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), where samples exhibiting higher nitrogen uptake, particularly M11, M12, and M13, also demonstrate significantly larger surface areas (81.9, 87.7, and 146.1 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively). These samples show pronounced mesoporous characteristics, with steep adsorption increases at high relative pressures (\u0026gt;\u0026thinsp;0.8), indicative of capillary condensation.\u003c/p\u003e\u003cp\u003eConversely, M4, M5, and M16 samples, which display the lowest surface areas (9.9, 8.1, and 13.8 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively), correspond to flatter isotherms with minimal hysteresis, suggesting limited porosity. Interestingly, while the M14 sample has a moderate surface area (37.8 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), it shows higher adsorption capacity than M15 and M16, reflecting potential differences in pore structure and connectivity. In summary, these results demonstrated that the tuning of MgO\u0026ndash;CaCO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;SiO\u003csub\u003e2\u003c/sub\u003e composition leads to marked differences in textural properties, where optimal MgO proportions (e.g., M13) contribute to highly porous materials with large surface areas, which are desirable for surface-sensitive applications such as self-cleaning applications.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSurface area of the synthesized samples.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSurface area (m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSurface area (m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e40.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM9\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e23.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM2\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e28.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM10\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e13.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM3\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e24.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM11\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e81.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM4\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e9.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM12\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e87.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM5\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e16.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM13\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e146.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM6\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e14.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM14\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e37.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM7\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e34.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM15\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e8.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eM8\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e17.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eM16\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e13.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Analysis of the design of experiment\u003c/h2\u003e\u003cp\u003eA fractional factorial design 2\u003csup\u003e5\u0026minus;1\u003c/sup\u003e was employed to assess the effects of five process variables\u0026mdash;dolomite mass (DM), activation temperature (AT), reaction time (RT), heat treatment time (HTT), and treatment temperature (T)\u0026mdash;on two responses: MgO content (%) and surface area. The resolution of the design of experiments allows for the estimation of main effects and two-factor interactions, optimizing the number of experimental runs and enabling the identification of the most influential parameters.\u003c/p\u003e\u003cp\u003eThe analysis of variance (ANOVA) for MgO content revealed that among the linear effects, activation temperature (AT) showed a statistically significant effect (p\u0026thinsp;=\u0026thinsp;0.022), confirming that higher activation temperatures promote greater decomposition of dolomite and enhance MgO formation (\u003cb\u003eTable S1\u003c/b\u003e). Heat treatment time (HTT) was also significant (p\u0026thinsp;=\u0026thinsp;0.049), suggesting that prolonged post-synthesis heating favors further decomposition or stabilization of MgO phases. Dolomite mass (DM) had a near-significant effect (p\u0026thinsp;=\u0026thinsp;0.053), indicating its importance in determining the MgO yield. The effects of reaction time (RT) and treatment temperature (T) were less pronounced (p\u0026thinsp;\u0026gt;\u0026thinsp;0.2), although they may still influence MgO content through interactions. Regarding two-way interactions, the DM \u0026times; AT interaction was notable (p\u0026thinsp;=\u0026thinsp;0.053), indicating a synergistic relationship between precursor quantity and activation intensity. Similarly, DM \u0026times; HTT (p\u0026thinsp;=\u0026thinsp;0.079) and AT \u0026times; HTT (p\u0026thinsp;=\u0026thinsp;0.058) suggested that combining high precursor mass with extended thermal treatment can enhance MgO production. These interactions highlight the complex interplay between material loading and thermal exposure in governing phase transformation.\u003c/p\u003e\u003cp\u003eThese statistical findings are supported by the main effects plot (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea), where a steep increase in MgO content is observed with increasing activation temperature\u0026mdash;from 800 to 1000\u0026deg;C\u0026mdash;highlighting the enhanced decomposition of dolomite and formation of MgO at higher thermal input. The plot also shows that a longer HTT slightly increases MgO yield, and that a larger DM contributes positively to MgO content. In contrast, RT and T exhibit flatter trends, suggesting a more limited direct effect.\u003c/p\u003e\u003cp\u003eOn the other hand, the surface area was most strongly affected by reaction time (RT) (p\u0026thinsp;=\u0026thinsp;0.026), suggesting that longer exposure during reaction promotes porosity, potentially through gas evolution and structural reorganization (\u003cb\u003eTable S1\u003c/b\u003e). Heat treatment time (HTT) (p\u0026thinsp;=\u0026thinsp;0.069) and activation temperature (AT) (p\u0026thinsp;=\u0026thinsp;0.077) also had considerable effects, likely related to thermal-driven phase changes and sintering dynamics. Among the interactions, DM \u0026times; HTT emerged as the most significant (p\u0026thinsp;=\u0026thinsp;0.018), pointing to a sensitive relationship between precursor quantity and thermal treatment in controlling porosity. Likewise, the AT \u0026times; T interaction (p\u0026thinsp;=\u0026thinsp;0.025) revealed that higher combined activation and treatment temperatures promote higher surface area, likely due to accelerated decomposition and enhanced textural development. The interactions DM \u0026times; T (p\u0026thinsp;=\u0026thinsp;0.073) and RT \u0026times; T (p\u0026thinsp;=\u0026thinsp;0.102) also contributed, underscoring the importance of thermal synergy. In contrast to the MgO response, surface area was more influenced by interaction terms than by individual factors, indicating that porosity development is governed by more complex multivariable dependencies than the decomposition process alone.\u003c/p\u003e\u003cp\u003eThe corresponding main effects plot of the surface area (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb) reveals a pronounced increase in surface area at lower RT (2 h), followed by a steep decline at longer RT (4 h), suggesting that extended reaction times may lead to sintering or pore collapse. A similar, though less dramatic, trend is observed with HTT: shorter heat treatment favors higher surface area. The effect of AT is nonlinear\u0026mdash;higher activation temperatures promote surface area, possibly due to enhanced gas release and porosity generation during decomposition. The influence of DM and T is relatively minor, though surface area slightly increases at the higher T level (600\u0026deg;C), hinting at residual structural modification during final treatment.\u003c/p\u003e\u003cp\u003eOverall, the analysis revealed that MgO content is primarily driven by activation temperature, heat treatment time, and dolomite mass, while surface area is more sensitive to reaction time, thermal parameters, and their interactions. These findings underscore the importance of a multivariate optimization approach: while high temperatures may enhance MgO yield, they may also reduce surface area due to sintering. Thus, the balance between thermal activation and controlled porosity must be carefully managed depending on the target application. Therefore, the fractional factorial design 2\u003csup\u003e5\u0026minus;1\u003c/sup\u003e proved effective for rapidly identifying key factors and interactions with lower experiments, offering a solid foundation for optimization or scale-up.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.3. Characterization of MOC fabricated with MgO from dolomite ore\u003c/h2\u003e\u003cp\u003eSince sample M13 exhibited the highest MgO content along with the most favorable microstructural and textural properties\u0026mdash;including high surface area, porosity, homogeneous morphology, and higher purity\u0026mdash;it was selected as the primary raw material for the development of self-cleaning MOC pastes. Based on this material, a series of formulations were designed following the compositional framework presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, incorporating functional additives such as citric acid, fly ash, slag, and TiO\u003csub\u003e2\u003c/sub\u003e to enhance workability, durability, and photocatalytic activity.\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows SEM micrographs of the different MOC-based formulations. The reference sample RMOC, prepared with commercial MgO, exhibits the characteristic morphology of MOC phase 5, composed of interlocked needle-like morphology (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea). In contrast, the RDMOC sample, synthesized using MgO derived from dolomite, shows a more refined needle-like morphology, indicative of enhanced crystallinity and phase purity due to the tailored reactivity of the MgO source (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb).\u003c/p\u003e\u003cp\u003eThe incorporation of TiO\u003csub\u003e2\u003c/sub\u003e nanoparticles in PDMOC results in a mixed morphology, where both needle-like crystals and some particles with a gel-like phase coexist (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec). This suggests that TiO\u003csub\u003e2\u003c/sub\u003e may interfere with the crystallization process, possibly by altering hydration kinetics, leading to partial amorphization of the structure. In PDFMOC, the addition of citric acid and fly ash in the optimized formulation significantly promoted the formation of a predominantly gel-like morphology (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ed). This transformation is likely due to the chelating effect of citric acid on Mg\u003csup\u003e2+\u003c/sup\u003e ions, which hinders the growth of crystalline phases, and the pozzolanic reaction of fly ash, which contributes to the formation of a denser, less crystalline matrix. Similarly, in the PDSMOC sample, which replaces fly ash with blast furnace slag, the morphology remains as a partially needle-like morphology but also shows signs of densification and reduced crystallinity (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ee, f). The slag appears to influence the matrix structure, although to a lesser extent than fly ash. These observations highlight how raw material selection and additive incorporation profoundly influence morphology and likely the performance of MOC-based composites.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe XRD patterns of the MOC fabricated with different additives are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e. The analysis of the diffractogram of the reference sample (RMOC) revealed that it was composed of the crystalline phase 5 (7-0420 card) and the formation of secondary phases, e.g., phase 3 was not detected. Similarly, the sample prepared with the MgO synthesized from the dolomite ore exhibited the same reflections associated with phase 5, with additional reflections related to calcite (5-0586 card).\u003c/p\u003e\u003cp\u003eThe incorporation of TiO\u003csub\u003e2\u003c/sub\u003e is evident in the patterns of the PDMOC and PDSMOC, marked with an asterisk, that matches with the anatase polymorph of TiO\u003csub\u003e2\u003c/sub\u003e (21-1272 card). Among these, the PDSMOC sample presents the most intense TiO\u003csub\u003e2\u003c/sub\u003e peak, likely due to the combined influence of slag and citric acid, which may enhance the dispersion or stabilization of TiO\u003csub\u003e2\u003c/sub\u003e within the matrix. On the other hand, the PDFMOC sample did not exhibit a significant reflection of this oxide, which could be due to fly ash contains amorphous and partially crystalline phases that contribute to background noise, thereby masking weak signals from minor crystalline components, e.g., TiO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e\u003cp\u003eThe samples containing supplementary materials (PDFMOC and PDSMOC) maintain the integrity of the MOC phase 5, indicating that the addition of fly ash or slag, even in the presence of citric acid, does not disrupt the formation of the primary phase. Calcium carbonate was observed in these samples, suggesting carbonation due to the presence of reactive fillers.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe UV-Vis absorbance spectra of the reference and modified MOC formulations are shown in \u003cb\u003eFigure S1\u003c/b\u003e. All samples display a characteristic absorption edge in the UV region (350\u0026ndash;400 nm), which is consistent with the presence of TiO\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. However, differences in absorbance magnitude and spectral shape among the formulations provide insight into their compositional and structural variations. For example, the reference samples (RMOC and RDMOC) exhibit the lowest absorbance in the UV region; meanwhile, the samples with TiO\u003csub\u003e2\u003c/sub\u003e (PFMOC, PDFMOC, and PDSMOC) exhibited a high absorbance in this region. These results suggest that the semiconductor particles are well-dispersed in the MOC matrix and contribute to enhanced light harvesting, and thus, the self-cleaning activity as will be further discussed. The increased absorbance may also reflect improved interface contact between TiO\u003csub\u003e2\u003c/sub\u003e and the binder phases, especially in the presence of supplementary cementitious materials, which can modulate surface chemistry and charge transfer.\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e presents the compressive strength values for the reference MOC formulation (RMOC) and its modified counterparts incorporating TiO\u003csub\u003e2\u003c/sub\u003e, fly ash, slag, and MgO obtained from dolomite. The results demonstrate that compositional modifications influenced the mechanical performance of the MOC systems. The RMOC sample exhibited the highest compressive strength, with an average value exceeding 29 MPa. This is consistent with the use of high-purity MgO, which promotes the formation of well-crystallized phase 5, widely known for its mechanical performance [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. In contrast, the RDMOC sample showed a marked decrease in compressive strength (\u0026asymp;\u0026thinsp;18 MPa). This reduction is likely due to the presence of impurities in the dolomite-derived MgO, which may hinder the formation of the main binding phases or introduce porosity and structural defects.\u003c/p\u003e\u003cp\u003eThe TiO\u003csub\u003e2\u003c/sub\u003e-modified samples exhibited intermediate strengths (20\u0026ndash;26 MPa). The partial recovery of strength in PDMOC suggests that TiO\u003csub\u003e2\u003c/sub\u003e contributes to matrix densification due to its filler effect. The slightly lower strength in PDSMOC, despite the presence of both TiO\u003csub\u003e2\u003c/sub\u003e and slag, may be related to potential interactions between slag components and MOC hydration products, which could compromise the mechanical performance. It is worth to mention that both SCM-containing samples (PDFMOC and PDSMOC) exhibit lower variability, indicating a more homogeneous matrix formation, possibly due to better particle dispersion.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.4. Self-cleaning efficiency of MOC formulations\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ea presents the self-cleaning performance of the various MOC formulations under simulated sunlight for 24 h (1.1 W/m\u003csup\u003e2\u003c/sup\u003e, 35% RH, 43\u0026ordm;C). As shown, all samples exhibit a rapid increase in efficiency within the first 6 h of irradiation, followed by a more gradual progression up to 24 h. The enhanced photocatalytic activity of the modified formulations was clearly evident when compared to the reference sample RMOC, which achieved an efficiency of 85.3%. Notably, the addition of TiO\u003csub\u003e2\u003c/sub\u003e significantly boosted the degradation performance, as observed in PDMOC, which reached the highest mean efficiency of 92.3%. Formulations containing both TiO\u003csub\u003e2\u003c/sub\u003e and SCMs also showed high photocatalytic efficiency; however, PDSMOC had the lowest performance among the modified samples (81.1%), potentially due to differences in matrix porosity or TiO\u003csub\u003e2\u003c/sub\u003e dispersion. Statistical analysis confirms that PDMOC, RDMOC, and PDFMOC formed a group with significantly higher efficiency than RMOC and PDSMOC (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eb). These results highlight the key role of TiO\u003csub\u003e2\u003c/sub\u003e and suggest that the type and combination of SCMs influence photocatalytic behavior, likely through their impact on microstructure and light scattering properties.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.5. Analysis of stability\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e shows the moisture stability coefficient of the different MOC formulations, providing a quantitative measure of their resistance to moisture-induced degradation. The reference sample exhibited a moderate coefficient, indicating limited stability in humid conditions. Interestingly, the RDMOC sample, synthesized using MgO derived from dolomite, showed improved moisture resistance, suggesting that the alternative precursor contributed positively to matrix densification or phase stability. In contrast, the presence of TiO\u003csub\u003e2\u003c/sub\u003e in the pastes resulted in a lower coefficient, which may be attributed to an increase in porosity. However, the synergistic incorporation of TiO\u003csub\u003e2\u003c/sub\u003e with SCMs significantly enhanced moisture resistance, as evidenced by PDFMOC, which exhibited the highest coefficient (0.90) among all formulations. PDSMOC also showed good performance, though with slightly higher variability, likely due to the complex interaction between the two SCMs. Overall, these findings demonstrate that the appropriate combination of TiO\u003csub\u003e2\u003c/sub\u003e and SCMs can effectively enhance the long-term stability of MOC composites under humid environments.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThis work demonstrated the feasibility of producing reactive MgO from dolomite and its successful application in the formulation of magnesium oxychloride cement. The synthesized MgO showed suitable physicochemical properties, allowing the preparation of a sample with comparable or superior performance to commercial-based formulations. The analysis of the design of experiments revealed that acid treatment temperature and reaction time significantly influence MgO purity and surface area, which in turn affected the MOC\u0026rsquo;s mechanical and functional properties. Among the modified MOC formulations, the incorporation of TiO\u003csub\u003e2\u003c/sub\u003e enhanced the photocatalytic activity, while its combined use with SCMs such as fly ash and slag further optimized the balance between mechanical strength, photocatalytic performance, and durability under humid environments.\u003c/p\u003e\u003cp\u003eOverall, this work provides a sustainable route for MOC production using alternative MgO sources and demonstrates that tailored combinations of SCMs and photocatalysts can significantly improve MOC performance, paving the way for multifunctional and durable alternative construction materials.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e5. Declaration of Competing Interest\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e6. Data availability\u003c/p\u003e\n\u003cp\u003eThe datasets generated will be available on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWalling S. A., Provis J. L.: Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future? Chem. Rev. 116(7), 4170-4204 (2016). https://doi.org/10.1021/acs.chemrev.5b.00463\u003c/li\u003e\n\u003cli\u003eLi K., Wang Y., Yao N., Zhang A.: Recent progress of magnesium oxychloride cement: Manufacture, curing, structure and performance. Constr. Build. Mater. 255, 119381 (2020). https://doi.org/10.1016/j.conbuidmat.2020.119381\u003c/li\u003e\n\u003cli\u003eTaourati R., Khaddor M., Laghzal A., Kasmi A. 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Total Environ. 912, 168773 (2024). https://doi.org/10.1016/j.scitotenv.2023.16877\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"waste-and-biomass-valorization","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wave","sideBox":"Learn more about [Waste and Biomass Valorization](http://link.springer.com/journal/12649)","snPcode":"12649","submissionUrl":"https://submission.nature.com/new-submission/12649/3","title":"Waste and Biomass Valorization","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Magnesium oxychloride cement, MOC, Self-cleaning, Dolomite, Fractional design of experiment","lastPublishedDoi":"10.21203/rs.3.rs-7123900/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7123900/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study explores the sustainable synthesis of magnesium oxychloride cement (MOC) using reactive MgO derived from dolomite, coupled with photocatalytic and supplementary cementitious materials (SCMs) to optimize both mechanical and self-cleaning performance. The synthesis of MgO from dolomite was performed using a fractional design of experiments 2\u003csup\u003e5\u0026minus;1\u003c/sup\u003e to identify the main factors that affect the purity and the surface area of the powders. The analysis of the design of experiments revealed that acid treatment temperature and reaction time during MgO synthesis significantly influenced surface area and MgO content. After the identification of the best conditions to synthesize a high-purity MgO from dolomite, a series of MOC formulations were prepared by incorporating TiO\u003csub\u003e2\u003c/sub\u003e, fly ash, and slag. The physicochemical, optical, mechanical, and photocatalytic properties of the resulting composites were systematically investigated. TiO\u003csub\u003e2\u003c/sub\u003e incorporation clearly enhanced light absorption, while combinations with slag or fly ash modulated this property, which is an important property for photocatalytic self-cleaning applications. In photocatalytic assays under simulated sunlight, TiO\u003csub\u003e2\u003c/sub\u003e-containing cements outperformed the unmodified MOC, with fly ash\u0026ndash;based formulations achieving the highest self-cleaning efficiency. Blended systems with SCMs introduced trade-offs between durability and functionality, with photocatalyst nanoparticles achieving an optimal balance, showing excellent moisture stability and photocatalytic performance (\u0026gt;\u0026thinsp;92%) under sunlight irradiation. These results highlight the potential of combining alternative MgO sources with functional additives to engineer eco-efficient, durable, and photocatalytically active MOC materials for advanced construction applications.\u003c/p\u003e","manuscriptTitle":"Self-cleaning MOC fabricated from dolomite ore","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-05 13:54:03","doi":"10.21203/rs.3.rs-7123900/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-08-06T09:05:41+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-03T15:13:01+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Waste and Biomass Valorization","date":"2025-08-03T07:42:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-15T11:21:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"Waste and Biomass Valorization","date":"2025-07-14T14:50:20+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"waste-and-biomass-valorization","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wave","sideBox":"Learn more about [Waste and Biomass Valorization](http://link.springer.com/journal/12649)","snPcode":"12649","submissionUrl":"https://submission.nature.com/new-submission/12649/3","title":"Waste and Biomass Valorization","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"c51bd030-1515-4980-8d79-985530723468","owner":[],"postedDate":"August 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-19T17:07:17+00:00","versionOfRecord":{"articleIdentity":"rs-7123900","link":"https://doi.org/10.1007/s12649-025-03475-x","journal":{"identity":"waste-and-biomass-valorization","isVorOnly":false,"title":"Waste and Biomass Valorization"},"publishedOn":"2026-01-16 16:30:21","publishedOnDateReadable":"January 16th, 2026"},"versionCreatedAt":"2025-08-05 13:54:03","video":"","vorDoi":"10.1007/s12649-025-03475-x","vorDoiUrl":"https://doi.org/10.1007/s12649-025-03475-x","workflowStages":[]},"version":"v1","identity":"rs-7123900","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7123900","identity":"rs-7123900","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}