Sustainable Biomass-based Filter for High-efficiency PM 0.3 Filtration

Sustainable Biomass-based Filter for High-efficiency PM 0.3 Filtration | 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 Article Sustainable Biomass-based Filter for High-efficiency PM 0.3 Filtration Guangping Han, Qingxaing Wang, Zhaoxuan Niu, Wanli Cheng, Ming Yang, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4142629/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 17 Jul, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Low-value biomass materials recently can be widely used in various important industry to achieve a carbon-neutral sustainable society. To transform low-value agricultural wastes into structural materials, here we show a heterogeneous corn-based precursor technique, to self-assemble two-dimensional fabrics consisted of alternating fibers with micro- and nano-architectures. The unique solute-solvent system involves zein protein, combined with cellulose extracted from corn straw, to achieve the greenness of the production, fabrication and filtration. Manipulation of the ambient humidity and addition of the cellulose nanofibers enable a novel incomplete nonsolvent-induced phase separation, leading to a corn-based degradable and disposable sanitary filter with dual-network structure which exceeds that of typical or commercial filters. Moreover, the mechanism of full-structure filtration for particulate pollutant as well as excellent adsorption for formaldehyde is demonstrated, providing a promising pathway to green and sustainability for biomass waste. Earth and environmental sciences/Environmental sciences/Environmental chemistry/Pollution remediation Earth and environmental sciences/Environmental social sciences/Sustainability Figures Figure 1 Figure 2 Figure 3 Introduction From the depths of the sea to the vastness of space, there are many large-scale and high-tech engineering masterpieces in the feat of human conquest and transformation of nature, including expanding the cultivated land to meet the growing demand for food. Increasingly people realize that the development of science and technology has plunged human society into a deep and inescapable ecological crisis, leading to a rapid increase in environmental pollution, especially for particulate matters (PMs) pollution 1 , 2 , 3 . Public tackles this issue with outdoor protective equipment, which are huge, bulky and heavy, and present inevitable conflict between air resistance and filtration efficiency, while the enhancement of indoor air quality often counts on high-priced and energy-sucking ventilation systems or centrality air-condition systems 4 , 5 , 6 . Nature puts a simple but effective thought related to material assembly: designing a heterogeneous and continuous network of fibers can score substantial gains in material utilization and its resultant performance 7 , 8 , 9 , 10 . Our previous work fabricated a cobweb-like 2D nanowebs by adding enough cellulose nanocrystals 11 . In addition to addressing the fiber diameter and connectivity in electrospun nanofibers, these 2D nanowebs consisted of ultrafine fibers evolved from cellulose possess characteristic diameters below 100 nm, not only overcomes the limitations of most existing fibrous networks, including non-uniform pore size and limited porosity, but also makes up the insufficiency of mechanical performance required for the practical applications. However, solvents with high solvability are difficult to remove completely during electrospinning, and the residue will cause bad consequence. For example, residual toxic solvents or non-solvents can lead to serious complications in air filtration, especially for human breath filtration, when solvents enter the body through the exchange with physiological fluids, which may differ from the original purposes 12 . In this context, forestry and agricultural residues, such as corn straw, are emerging as viable options. Such low-value agricultural wastes have already been widely used in various important industry to achieve a carbon-neutral sustainable society. Moreover, sources of zein protein is widespread, mainly from corn gluten meal, which is a protein feed produced as a by-product in the deep processing of corn starch 13 , 14 . Therefore, the filters based on zein protein and reinforced with the nanocellulose should therefore have the prospect of air cleaning devices with low energy-consumption and high efficiency. And there have been to our knowledge no published research on such structure and composition as filters for PM 0.3 removal. Here, we introduce a heterogeneous precursors technique of low-value biomass (straws, chips and residues) to assemble 2D self-assembled dual-network architectures that consist of nanoscale fibers (70–400 nm) and microscale fibers (1–5 µm) with desirable nano-structural features. Such a ‘fiber-shaping’ process affected by the nonsolvent-induced phase separation is considered as a way to endow the materials with high performance. Such D-nets filters are based on agricultural residues (zein protein) and hydrophilic lignocellulosic biomass (TEMPO-mediated cellulose nanofibers). Hence, the biodegradable fabric is formed by dual-network structures comprised of alternating fibers with micro- and nano-architectures, leading to superior filtration and formaldehyde adsorption performance, which can compare or exceed that of traditional commercial filters. This specific structure can effectively intercept the PM 0.3 to embed precisely in the isotropic groove of microscale fibers and flow adequately among the nanoscale fibers, achieving full-structure filtration, finally resulting in an enhanced filtration efficiency and reduced pressure drop. This heterogeneous precursor technique is simple and efficient to transform residual or waste corn straw into high-performance structural filters, which offers a pathway to advance the circular bioeconomy based on the farming surplus. Results We propose a heterogeneous biomass-based precursors technique to assemble alternating fibers with micro- and nano-architectures, including smooth ribbon fiber, groove rod fiber and dual-net fibers (as illustrated in Fig. 1 a). The unique solute-solvent system was collected solely using zein protein from corn and cellulose extracted from corn straw as solute. The solvent system, which achieved the purpose of “Killing Two Birds with One Stone”, not only endowed the material with a rough surface structure in the phase separation, but also improved the greenness of the electrospinning process. It is notable, too, that the phase separation can be precisely controlled to achieve on-demand distribution of fibers at the micro level by tailoring the ambient humidity (30%-90%) during electrospinning. Each component of this filter fabric all come from nature and finally return to the nature, therefore perpetuating a closed loop cycle. Shortly, “from nature to nature” is the aim of our design concept, reflecting the harmony of man and nature, which is the principal feature differentiates from other air filter media. To elaborate the structural control and evolution process of the obtained self-assembled architectures, we focused on a different protein, zein, to serve as a proof-of-concept model (Fig. S1 ). The solubility is indeed an inherent feature of the zein, because it cannot dissolve in either water or ethanol but can surprisingly dissolve in 60%-90% ethanol solution (Fig. S2). It would have meant combining those two solvents is very important for dissolving zein. That is, removal or partial removal of either component from this solvent system can cause zein to precipitate (Supplementary discussion I). This characteristic is also approved by a neat experiment, after evaporation in the atmosphere for about 2 h, a robust protein film is formed on the solution surface (Fig. S3). Hence, from the macroscopic point of view during electrospinning, based on the fact that the rate of ethanol volatilization is faster than water, it is quite reasonable to suppose that the phase separation of zein fibers will occur if we regulate the relative humidity (30% − 90%). Therefore, in our electrospinning system, we chose the ethanol and the water (80 wt.%: 20 wt.%) as the solvent and tailored the relative humidity (30% − 90%). Ambient relative humidity during fiber formation not only causes the liquid-liquid phase separation in polymer-rich and polymer-poor regions, but also affects the solidification rate of polymer from either the single-phase or polymer-rich regions 7 , 15 . Attributed to the volatile difference of the nonsolvent phase and the solvent phase, a common one of the phase separation during electrospinning is nonsolvent-induced phase separation (NIPS) 16 . Apart from the viscoelastic behavior, the selected polymer-solvent-non-solvent ternary system also determines the kinetics and mechanism of phase separation, all of which will influence the morphological characteristics of the fibers 17 . However, the NIPS are not the appropriate mechanism in our case. To understand what mechanism may be responsible for this behavior, one needs to consider a ternary composition of zein/H 2 O/ethanol in the jet is a consideration (Fig. S4). Based on the Flory-Huggins theory, a theoretical diagram of ternary phase for zein/H 2 O/ethanol was illustrated. The mass transfer of three components during fiber formation was calculated for representative ideal conditions, and the resulting mass transfer path was overlayed on the diagram. Given that the vapor in the spin beam can be absorbed into the electrically charged liquid jet and be part of the solvent system, it is unlikely to increase the water content of the solvent system to a value high enough (> 40%) to make the skin layer solid instantaneously. To reveal the humidity-induced self-assembled architectures, we designed a tubular structural model to mimic the deformation of individual fiber during electrospinning (Fig. 1 b), which could link the solvent properties and ambient humidity to the forms and dynamics of the individual fiber. In the morphology evolution, the solvent evaporation induced by relative humidity plays an important role 18 . Both water and ethanol have low electrical conductivity, and their jets have less induction force to the electric field, which makes the surface tension of the jets greater than the electric field force. During fiber formation, the jet was stretched at a high speed by the electric field force and was separated into the solvent-rich phase and the polymer-rich phase rapidly due to the high volatility of ethanol. And then the surface jet reached the polymer-rich phase faster and wrapped the solvent-rich phase during the evaporation process due to the high volatilization rate of the surface jet 19 . The composition or proportion of the solvent components on the fiber-air interface could be very different from the initial state in theory, which promoted the phase separation. As the skin layer dried to a certain extent, the size of the skin layer is fixed, and the jet forms a tubular structure with a polymer skin layer wrapped in the spinning solution. Therefore, we can consider a single fiber as a tubular structure, and the final fiber morphology is determined by the evaporation rate of the surface solvent and the diffusion rate of the inner layer solvent. Furthermore, the effect of mechanical stresses of tubular structural model is another important consideration on such structure development. As shown in Fig. 1 c, the three main major dynamic force on the tubular structure are electric field force (F e ), radial compressive stress (F r ) and hoop compressive stress (F t ). Electric field force in axial leading to jet ejection from Taylor cone overcomes the competing liquid surface tension (F γ ) and adhesive force (F η ) (Fig. 1 d). Enlarging portions of the skin layer by differential evolution method, the internal pressure caused by the diffusion of the inner solvent acts radially on the inner wall (Fig. 1 e). Meanwhile, any force perpendicular to the cross-section of the tube will create a hoop compressive stress in the skin layer (Fig. 1 f). According to the real situations, as the solvent evaporates from the bulk, if the skin remains stationary, it will produce a negative gauge pressure at the bulk. This pressure difference (ΔP) can be related to the compressive stress (σ r ) of the skin layer by the force balance given by $$\frac{{\sigma }_{r}}{r}=\frac{\varDelta P}{\varDelta R}$$ where r is the average radius of the skin layer and ΔR is its thickness 20 . It is obvious that when the skin layer is much thinner than the fiber radius, the stress would be large enough under different humidity conditions to cause various degree of collapse of the fiber wall during electrospinning. Therefore, a common curiosity is how the structure will evolve, would this structure at last shrink to an isotropic grooved rod or flatten into a flat smooth ribbon? Figure 1 g (I type and II type) represents two typical examples of the general structures (smooth ribbon-like fiber and grooved rod-like fiber) which can be observed in the present system of the fiber formation. In the first case of a low ambient humidity (≈ 30%), the as-spun zein fibers with the average fiber diameter of 2.39 µm have smooth surfaces and ribbon shapes (Fig. S5a and Fig. 1 g I Type). The evaporation rate of the surface solvent is greater than the diffusion rate of the inner solvent, which can availably increase the F r and smooth the F t . With the rapid evaporation of the surface layer solvent, the inner volume gradually decreases and the fiber forms a hollow structure instantaneously. As the solvent continues to evaporate, the flexible tube would likely collapse under the relatively high radial compressive stress and the ribbon-like fibers with smooth surface would form. In the second case of a high ambient humidity (≈ 90%), the as-spun zein fibers with average fiber diameter of 0.79 µm have grooved surfaces and rod shapes (Fig. S5b and Fig. 1 g II Type). Under this circumstance, the solidification rate of skin layer is faster since the vapor absorbing from the environment into the jet can act as a nonsolvent for zein, and the water in the solvent can promote water vapor from the environment to enter the jet at the same time. However, the solvent in the bulk is not easy to volatilize, and the jet remains in the state of charged fluid and is continuously stretched by the electric field force. It can be inferred that the inner solvent diffused outwards faster, the volume in the skin layer decreases rapidly, the evaporation rate of the surface solvent is less than the diffusion rate of the inner solvent, the F t is stronger than the F r , resulting in the longitudinal deformation of the epidermis, and the longitudinal grooves and convex edges are generated on the surface after the shrinkage. During the same time interval, the diameter of the jet decreases due to stretching, its surface area increases, the unit charge density decreases and the axial instability of the jet increases. The origin of wrinkles may be formed as a result of the lateral contraction effect from the electric field force, which is ascribed to the continuous jet stretching, and/or the buckling of the thin-wall cylindrical shell of the polymer under the action of radial compressive stress, which is ascribed to solvent removal from the core of the jet. To validate this humidity-induced association, the morphologies of fibers under different relative humidity (RH) conditions (30%, 50%, 70% and 90%) are shown in Fig. S6. To sum up, for the smooth ribbon-like fibers, the behavior is a classic example for a fiber system dominated by diffusion with moving boundaries, and is essentially the same result found in the earlier models of Corbriere and Paul 21 ; for the grooved rod-like fibers, it is likely to be an example of the propagation of front (kink) wave, which is a typical result of nonlinear reaction-diffusion. Now comes a following challenging part, that is, the fiber created from the protein always has a large diameter, which may increase the pore size and decrease the porosity, and exert significant indirect effects on the chance of particles being capture. In our previous work, the effect of abundant nanocellulose was developed and applied as a reinforcement for filtration membrane, which exhibited desired cobweb-like structure with integrated properties of ultrafine diameters, small pores and excellent mechanical property, thus showing great potential for filtration process. Therefore, on the basis of the second case, we manipulate the addition amount of the cellulose nanofibers (CNFs) which are same-rooted born of corn crop to enable the creation of dual nets. The reaction process of TEMPO-mediated CNFs is illustrated in Fig. 2 a and Supplementary discussion II. The TEMPO-mediated oxidation converted the hydroxyl groups at C6 to carboxyl group, which broke the hydrogen bonding between fibrils and introduced the electrostatic repulsion, thus preventing the aggregation of cellulose in precursor 22 , 23 . The as-prepared CNFs presented long fiber morphology with average diameter of 7.5 nm (Fig. 2 b and Fig. S7). X-ray diffraction (XRD) patterns characterized the effect of TEMPO-mediated oxidation on crystallization and the degree of crystallinity of CNFs is 64% (Fig. 2 c). The surface charge density of the CNFs was 1.4 mmol/g was determined effectively by acid-alkali neutralization titrimetric method (Fig. 2 d). After the introduction of CNFs, more ultrafine fibers split from the original coarse fiber can be observed on the membrane (Fig. 2 e). Compared with the second case (RH ~ 90%, contains no cellulose), what we may find interesting is that the wrinkle on the surface of the slightly collapsed fiber is deepen, and develop a severely collapsed fiber (Fig. 1 g III Type), which means that adjusting the precursor properties by adding CNFs may be a feasible method to control the formation of D-nets in the membrane. Therefore, the significant effect of the cellulose on the protein-based fibers should also be understood; we had probed and disserted it from three aspects. Firstly, CNFs can be entangled with long chains of amino acids of zein protein, and thus increasing the overall concentration of the solution and its viscosity. This point can be confirmed by using a parallel dynamic rheometer to study how the solution viscosity changes with the evaporation time in the atmosphere (Fig. 2 f). The viscosity increases dramatically after incorporating CNFs into the precursor solution and reaches 10,000 Pa·s only at about 100 s, indicating a phase transition from liquid to solid near the sample surface. Secondly, a small addition amount of CNFs in solution can strengthen the structural connections and create additional connections between zein protein molecules when they enter and disperse in the zein protein network. The effect of CNFs in this case is similar to that of adding salt in the electrospinning system, both of which promote the fiber splitting by increasing the solution conductivity. Thirdly, the addition of CNFs will block the continuity of protein molecules to some extent, so the splitting occurs during the electrospinning 24 . The CNFs, as a dispersion phase, is more difficult to stretch, so it can be speculated that the concave part might be the corn protein rich area, and the prominent part might be the cellulose rich area. The infrared spectrum of the D-nets fibers after adding CNFs is almost no difference compared with that of pure zein protein fiber, indicating that the binding between corn protein and cellulose is physical in nature (Fig. 2 g). There are mainly three forms of binding: the first is hydrogen bonding, which will not be explained in detail here. The second form, the denatured zein, may interact with CNFs by the electrostatic interaction, which is formed by the attraction of electronegative hydroxyl and carboxyl groups on the CNFs surface to electropositive amino groups on the amino acid chain. The third form is the relationship between proton acceptor and proton donor. Both zein and CNFs contain hydroxyl groups, which provide protons. The carbonyl group in the protein molecule may act as a proton acceptor. The fabrics prepared by electrospinning the mixture of zein/CNFs is expected to have fluffy structure and high structure stability. The synergistic effect of high relative humidity and cellulose content deepens the wrinkles, which made it have larger specific surface area, thereby establishing a high surface electrostatic potential of the fibers, and thus enhancing the adsorption and retention capacity for PMs 22 , 25 . This structure tackles key technical bottlenecks in manufacturing the net-structure with large gap, low coverage rate, fatal empty space and discontinuous and random distribution. The analysis of pore structures (pore size and porosity) also proves the content of D-nets structure in membranes. From Fig. 2 h, the increase of water in the atmosphere caused by the increase of relative humidity will accelerate the solute precipitation, thus promoting the phase separation process, which leads to an increase in the porosity of the membranes (from 56.62–73.08%). Manipulation of the content of D-nets by controlling the CNFs concentration also enabled an obvious increase in porosity (from 73.08–94.62%), and this increase caused a crucial decrease in the pore sizes (from 4.45 µm to 200–300 nm) of the membranes (Fig. 2 i). This phenomenon exactly corresponds with the emergence of the nanofibers arises from the microfiber splitting (Fig. 2 j). It’s the same the other way round, both the increase of the concave parts and the decrease of the bonding structure of fibers caused by the emergence of the emerging ultrafine fibers (≈ 74 nm) improved the porosity of the membranes. Moreover, the water (water vapor, humidity) can be regarded as a special non-solvent in the solvent system, the miscible ethanol and water solution system can promote the water in the environment into the jet, accelerate the phase separation during electrospinning, and thus further improve the fiber porosity. It should be pointed out that, although the water vapor entering the jet can promote the formation of holes in the core layer of the fiber, however, it will make the fiber surface less vulnerable to the pore structure, and even inhibits the formation of surface porous structure. From Fig. 2 k-l, both the ribbon-like fiber and the rod-like fiber have no pores in skin layer. The main reason is that the composition of the solvent inside the jet is fairly uniform. The water vapor in the air will continuously reduce the solubility of the solvent to the zein, accelerate the zein protein precipitate from 80% ethanol solution (phase separation), and make the jet surface solidify into a uniform layer of soft shell in advance. Moreover, continuous stretching of fibers and phase separation could result in the formation of ideal dual networks assembled by the altering micro- and nanofibers. Evidence of the splitting process arise from the transmission electron microscopy (TEM) image of the architectures (Fig. 2 m). Benefiting from the lateral infinity of dual networks with hierarchical nanostructures, the as-prepared membranes exhibited extremely small pore sizes while maintaining a strikingly high porosity. Zooming in and out on the D-nets revealed that an integrated, uniform and continuous network appeared and was laterally Voronoi like with scaffold pores, as shown in Fig. 2 n. These concave parts caused by the high humidity during electrospinning were much stable and thus fundamentally enhanced the sieving properties of the filters. Furthermore, in contrast to the ribbon fibers prepared at relatively low-humidity and the rod fibers prepared without the addition of CNFs, the formation of curled fiber induced by the high-humidity environment led to a fluffy fibrous accumulation, which was in correspondence with the common wisdom that a fluffy structure tended to do benefit for the reduction of the pressure drop (Fig. 2 o). PM pollution, especially for more-penetrating particles (PM 0.3), has become a significant burden on public health and even global economies 26 , 27 . Here, in considering the integrated properties of fluffy structure, high porosity and small pore size, applications in air filtration by the corn-based D-nets fabrics are possible. Our self-standing D-nets provides an innovative degradable and disposable sanitary material with the performances of low resistance and high efficiency, which can be used as the filter element for mask or filter to protect the human body and indoor air quality through natural passive ventilation. As presented in Fig. 3 a, the ribbon-like fibrous filter with a base weight of 10.0 g·m − 2 had low filtration capacity for intercepting particles: 82.2204% PM 0.3 removal at a pressure drop of 80 Pa. The rod-like fibrous filter with a base weight of 8.9 g·m − 2 were slightly better at a pressure drop of 69 Pa, but showed 76.8854% for PM 0.3 removal. After the introduction of the CNFs, the D-nets filters demonstrated excellent results in the sternest PM 0.3 removal. Surprisingly, filters with a superlight weight of 8.0 g·m − 2 resulted in 99.4168% at pressure drop of 42 Pa. These could be attributed to the hierarchical and multilevel fiber structure, a structure which could simultaneously improve the PM capture capacity and reduce the airflow resistance. A quantitative study was carried out concerning how the base weight affected the air-flow resistance of the D-nets fabrics (Fig. 3 b). Benefited from the complex changes in hierarchical porous structure, the pressure drops of the fabrics increased nonlinearly, which might be related to the increasing numbers of layers of fibers. More strikingly, an increased base weight of 10.2 g·m − 2 of our corn-based D-nets filters showed 99.9994% for PM 0.3 removal, which qualified for the standard for ultralow penetration air (ULPA) filters of > 99.999%. To evaluate the overall performance of the D-nets fabrics, the quality factor (QF), which is related to the ratio between the particulate removal efficiency (η) of the air filter and the pressure drop (ΔP) due to air flow across the filter, was calculated and shown in Fig. 3 c. In the meanwhile, the pressure drop of the corn-based D-nets filter (8.0 g·m − 2 ) under the airflow velocity of 5.33 cm·s − 1 was 42 Pa, which was negligible compared with the atmospheric pressure (only 0.04% of the atmospheric pressure). As the airflow velocity increased from 5.33 to 16.6 cm·s − 1 , the corn-based D-nets filters remained a nearly unchanged filtration efficiency for PM 0.3 and a slightly increased pressure drop (Fig. 3 d). For instance, under a high velocity of 16.6 cm·s − 1 (standard for personal breathing apparatus), the D-nets filters exhibited a steady efficiency for PM 0.3 (> 98.5257%) and a slightly increase from 42 Pa to 109 Pa for pressure drop, which could be attributed to the way of sieving derived from the D-nets structures. Correspondingly, all these corn-based D-nets filters proved higher quality factors for PM 0.3 removal and better performance than most advanced commercial filters, such as PAN 6 , PAI 28 and HEPA. The comparison between the efficacy for PM 0.3 of our corn-based D-nets filters and of previously reported filters is showed (Fig. 3 e). Our D-nets filters, in obvious contrast, presented an outstanding filtration capacity for more-penetrating particles by virtue of their flexible and progressive fiber structure, while having a lighter weight and fluffy structure. Compared to conventional micro-fibrous filters whose base weights usually exceed 100 g·m – 2 , that of D-nets filters were negligible. We reasonably construe that the superior removal capacity efficacy of corn-based D-nets fibers depend on high interface energy and small pore size, and low pressure drop is attributed to their fluffy structure, high porosity and heterogeneous biomass-based precursors technique to assemble alternating fibers with micro- and nano-architectures. In addition to a robust removal efficacy for more-penetrating particles, this corn-based fabrics also proved excellent adsorption capacity for HCHO. HCHO is a kind of molecule with size much smaller than the PM 0.3, and we suggest that the HCHO removal is controlled by an interaction-based filtration mechanism provided by this D-nets architecture, which will be discussed later. The relation curves that HCHO adsorption efficiency varied with the testing time for the corn-based fabrics with different structures were obtained (Fig. 3 f). By comparison, the adsorption efficiency for HCHO by commercial HEPA filter paper without rich functional groups on the surface of their fibers was also tested. The HCHO adsorption efficiency of the D-nets fabrics dropped from 81.36–71.25% steadily after 120 min of testing time and further to 52.66% after 240 min, while the HCHO removal efficiency of the commercial HEPA filter was below 6.45% and decreased to less than 3.6% after about 240 min, which is mainly caused by the lack of active sites on the surface of the materials. An increase in the weight of captured pollutants was also measured after testing (Fig. 3 g). After 240 min of testing, the total weight of captured pollutants on the corn-based D-nets fabrics increased from 2.4 to 8.3 mg, while that of the HEPA filter increased slightly from 0.8 to 2.8 mg. The ratio of the weight gain of captured pollutants (W p ) and the weight of the filter before testing (W f ) is used to describe the ability to absorb pollutants. For the corn-based D-nets fabric, the W p /W f increased from 0.36 to 1.26 with the increase of the testing time from 40 to 240 min, while that of the HEPA filter at evenly spaced intervals increased slightly from 0.005 to 0.017. In general, this fabric can capture amounts of pollutants, weighing even heavier than the material itself, which is similar to the cobwebs that can trap huge particles despite its light weight. To further understand the unique performance of this corn-based D-nets fabrics, we propose a full structure filtering mechanism based on the characterization analysis of both the PM 0.3 pollutants and the formaldehyde pollutant. Generally, the filtration efficiency for particles heavily relies upon fiber morphology due to four primary sized-based filtration mechanisms. The schematic diagram of the potential interaction among zein protein, CNFs chains, PM particles, and HCHO is illustrated in Fig. 3 h, which establishes a reinforcement mechanism based on strong fiber-pollutant interactions. Zein, as has been noted, contains many active functional groups, which can interact with the toxic chemicals and even the solid particles in polluted air. The aldehyde groups in HCHO may interact with not only the carboxylic groups of CNFs, but the carboxylic and amine groups of zein. Additionally, there are three types of interactions which PM and HCHO may undergo, including charge-charge, polar-polar, and hydrogen-bonding interactions. The hypothetical structure model was also created for the corn-based D-nets fabrics, which could demonstrate an all-structure filtration mechanism for the structure of multilevel hierarchy, with a range from integrated filters to dual networks to fibers (Fig. 3 i). From a view of integration, sieving, as a main filtration mechanism, can partly block the penetration of the PM particles, even for the particles with sizes smaller than the pore sizes of the filters (200–300 nm). From a view of dual networks, due to the continuously welded and fully covered networks assembled by the alternating fibers with micro- and nano-architectures, our air filters can prevent the leaking of PM 0.3 effectively. From a view of single fiber, it needs to introduce an embedded policy to explain, that is, the PMs can embed in the groove structure on the coarse fiber based on the tubular model. On the other hand, the inhomogeneous mixing of zein protein and cellulose resulted in interfacial polarization. Due to the difference in electron cloud density, there are usually varied degree of interfacial polarization between the crystalline and amorphous regions of cellulose, which is the inherent dielectric property of the cellulose. Since the cellulose molecule itself has dipole moment, when added cellulose to the zein protein matrix, it will additionally undergo its own dipole orientation polarization and Maxwell interface polarization with zein protein under the action of the electric field, which results in a higher relative permittivity 29 . Therefore, the extra load of cellulose will produce many interfacial regions within zein protein, and the huge difference between the two further intensifies the interfacial polarization, thereby increasing the adhesion of more-penetrating particles on the surfaces of micro/nano- fibers. Owing to a slip effect, the air velocity at the surface of the fibers was nonzero. When the air travelled laterally through the micro/nano- fibers, the momentum of particles let them more likely to collide along their route. In consequence, the effects of diffusion and interception for capturing more penetrating particles were greatly enhanced. Hence, this adhesive effect was also attributed to the stable removal efficacy of the D-nets filters in addition to their small pore size. The structure with fluffiness, high porosity, and small pore size endows the filter with high PM 0.3 removal efficacy while maintaining a maximal air penetrability, which necessarily requires a robust mechanical strength. From Fig. 3 j, this free-standing corn-based D-nets fabric (~ 370 nm) could support a plastic frame weighing 15 g with one finger, and could be bent or stretched without any damage, suggesting superior robustness, softness and flexibility. Moreover, this filter was expected to bear tensile strain caused by the airflow moving at 16.6 cm·s − 1 . In other words, this corn-based filters are supposed to overcome the bottleneck of constructing fluffy membranes with good mechanical properties, thereby making it possible to be used as filters 30 . How to develop a sustainable and environmentally friendly material to reduce the energy demand for controlling air pollution is a matter of significant importance facing sustainable development. From a perspective of life cycle, air filters are always discarded after use. Our corn-based D-nets filters meet the requirements of environmental protection and land degradation, and its advantages are further embodied in their purification rate, energy-saving capacity and degradable and disposable performance. Since the component of the biomass-based fabrics, zein protein and cellulose, are biodegradable, this D-nets filters could gradually degrade after being buried in the soil for biodegradation after utilization and will not cause white pollution. In considering that the alternating fibers with micro- and nano-architectures could be directly deposited on personal protective equipment and indoor air purifier, our D-nets filters are believed to provide a simple and cost-effective strategy to purify the polluted air facilely. Obviously, a conclusion can be drawn that a good consistency was obtained between the model prediction and the actual pressure drop of our corn-based D-nets filters. Compared with commercial filters, it surpasses the others in terms of comprehensive factors including process simplicity, low cost, high filtration efficiency, environmental friendliness (including biodegradability after service) and potential for wide application. Moreover, based on the novel synthesis methodology, the full-structure filtration model of the corn-based D-nets filters we established was further regulated vertically on the map of structural characteristic and airflow resistance. Further regulating the assembled architectures, such as the packing density, thickness and nets coverage, could build varieties of air filters with optimized pressure drops and designed removal efficiencies, which was applied in PM 0.3 filtration, overcoming the limitation of the trade-off between air permeability and capture efficacy. Discussion In conclusion, we have demonstrated a novel synthesis methodology for the preparation of high-efficiency dual-network air filters by heterogeneous biomass-based precursors technique. The continuously welded dual networks consisted of alternating fibers with micro- and nano-architectures were assembled into fabrics with properties of ideal fluffy structure and desirable pore structure. And by virtue of the synergistic effect of micro/nano- scale fibers and well-controlled self-assembled network, this completely degradable corn-based D-nets filter exhibits robust mechanical strength and superior functionality for PM 0.3 filtration. Moreover, this filter could filtrate PM 0.3 with a removal efficiency of > 99.4168%, pressure drops of < 42 Pa, which all thanks to their derived full-structure filtration effect, extremely low thickness, together with the integrated properties of superlight base weight (8.4 g m − 2 ). We envision that such intriguing dual-network fabrics, which can operate as a stand-alone filter or in combination with respirators, window screenings and filter canisters, will herald vast potentials for biomass-based high-performance filters toward personal protection, engine intakes, ventilation systems and medical devices. Methods Materials and chemicals. The mature corn plants were harvested and collected in October 2022 at a corn field in ACheng District, Harbin, Heilongjiang Province, China (N45°32′29.184″, E126°58′30.9′′). The whole corn straw residue was cut at the bottom and air-dried, then shredded into small pieces as the corn straw. Zein protein, sodium chlorite (NaClO 2 , 80%), acetic acid, ethyl alcohol (EtOH) and potassium hydroxide (KOH) were purchased from Aladdin Chemistry Co. Ltd. (Shanghai, China). Deionized water was used for solvent. Fabrication of corn-based D-nets fabrics. The nanofibrils were produced from corn straw using TEMPO-mediated oxidation. For simplicity, we refer to the oxidized cellulose nanofibrils as CNFs. CNFs were prepared by a previously reported method. The detailed fabrication process was presented in Supplementary Methods I. The electrospinning process was performed by a conventional electrospinning device (Yong Kang Le Ye Co., Beijing, China). The detailed fabrication process was presented in Supplementary Methods II. The spinning solutions were prepared by dissolving 25 wt. % zein in 80% ethanol solution, while CNFs concentrations were tuned to 0 and 1wt. % in zein solutions, respectively. The solutions were ejected with feed rate of 0.1 ml h − 1 with distance of 20 cm by a DC voltage of 15 kV. The base weight of the corn-based fabrics is controlled by carefully adjusting the spinning time. Characterization. The morphological structures and crystallinity of CNC were characterized using transmission electron microscopy (TEM, Hitachi-7650, Japan) and X-ray diffraction (XRD, D/max-2200VPC, Japan). The viscosity of the zein solution and zein/CNFs solutions was determined by a hybrid rheometer (HAAKE MARS, Thermo Scientific, USA). The nanoparticles of the zein solutions and zein/CNFs solutions were determined by dynamic laser light scattering (Zetasizer Nano, Malvern Instruments). The morphologies and structures of the micro- and nano-structured architectures were characterized using scanning electric microscope (SEM, Apreo S HiVac, Thermo Scientific, USA, precoated with gold for 120 s) and TEM. The particulate sizes of CNFs and diameter distribution of fibers was measured by randomly selecting 100 fibers and were determined by the Nanomeasure software. The thickness of the corn-based D-nets fabrics was measured by a thickness gauge (AIPLI0-10mm, readability of 1 µm. Fourier transform infrared (FTIR) spectrometry was conducted using a NICOLET 6700 spectrophotometer (Thermo Fisher Scientific Inc. USA), with the samples from 4000 to 600 cm − 1 were recorded. The pore structure of the corn-based D-nets fabrics was characterized by CFP-1100AI capillary flow porometer (Porous Materials Inc., USA). The porosity (ε) of the corn-based D-nets fabrics was analyzed by gravimetric strategy and calculated by the following equation \({\epsilon }\left(\%\right)=\frac{\left({M}_{wet}-{M}_{dry}\right)/{\rho }_{w}}{\left({M}_{wet}-{M}_{dry}\right)/{\rho }_{w}+{M}_{dry}/{\rho }_{M}}\) , where M wet and M dry were the wet and dry weight of the corn-based fabrics; ρ w and ρ M were the densities of silicone oil and the corn-based fabrics, respectively. PM 0.3 filtration efficiency and pressure drop of the corn-based fabrics were measured by a filter equipment (TSI 8130A, USA). The concentrations of HCHO were diluted in a glass bottle to the level that was measured by a particle counter (PPM-400 ST) with chemical sensors for HCHO. The process was utilized and detailed in Supplementary Method III. Declarations Acknowledgements This work was financially supported by the National Natural Science Foundation of China (Grant No. 31470580) and the Natural Science Foundation of Heilongjiang Province, China (Grant No. LH2020C039). Author contributions Q.W. and G.H. designed the experiments along with directions by S.Z. and B.D. The experiments were carried out by Q.W. The assistance of Z.N. was instrumental in creating the three-dimensional illustrations. Q.W., M.Y., J.L. J.Y. and H. Y. performed material characterizations. Q.W., W.C., Y.Y., Y. W., D.W., S. Z., B.D., and G. H. collectively wrote the paper. All authors commented on the final manuscript. Competing interests The authors declare no competing interests. References Zhang S, Liu H, Tang N, Ge J, Yu J, Ding B. Direct electronetting of high-performance membranes based on self-assembled 2D nanoarchitectured networks. Nature Communications 10 , (2019). Zhang Q , et al. Transboundary health impacts of transported global air pollution and international trade. Nature 543 , 705-709 (2017). Nel A. Air Pollution-Related Illness: Effects of Particles. Science 308 , 804-806 (2005). Huang R-J , et al. High secondary aerosol contribution to particulate pollution during haze events in China. Nature 514 , 218-222 (2014). Lelieveld J, Evans JS, Fnais M, Giannadaki D, Pozzer A. The contribution of outdoor air pollution sources to premature mortality on a global scale. Nature 525 , 367-371 (2015). Liu C , et al. Transparent air filter for high-efficiency PM2.5 capture. Nature Communications 6 , (2015). Zhang S, Liu H, Tang N, Zhou S, Yu J, Ding B. Spider‐Web‐Inspired PM0.3 Filters Based on Self‐Sustained Electrostatic Nanostructured Networks. Advanced Materials 32 , (2020). Wang C , et al. Highly Transparent Nanofibrous Membranes Used as Transparent Masks for Efficient PM0.3 Removal. ACS Nano 16 , 119-128 (2021). Lang C, Fang J, Shao H, Ding X, Lin T. High-sensitivity acoustic sensors from nanofibre webs. Nature Communications 7 , (2016). Wang X, Ding B, Sun G, Wang M, Yu J. Electro-spinning/netting: A strategy for the fabrication of three-dimensional polymer nano-fiber/nets. Progress in Materials Science 58 , 1173-1243 (2013). Wang Q , et al. Spider-web-inspired membrane reinforced with sulfhydryl-functionalized cellulose nanocrystals for oil/water separation. Carbohydrate Polymers 282 , (2022). Zhang Z, Ji D, He H, Ramakrishna S. Electrospun ultrafine fibers for advanced face masks. Materials Science and Engineering: R: Reports 143 , (2021). Oliviero M , et al. Dielectric Properties of Sustainable Nanocomposites Based on Zein Protein and Lignin for Biodegradable Insulators. Advanced Functional Materials 27 , (2017). Kasaai MR. Zein and zein -based nano-materials for food and nutrition applications: A review. Trends in Food Science & Technology 79 , 184-197 (2018). Szewczyk PK, Stachewicz U. The impact of relative humidity on electrospun polymer fibers: From structural changes to fiber morphology. Advances in Colloid and Interface Science 286 , (2020). Müller M, Abetz V. Nonequilibrium Processes in Polymer Membrane Formation: Theory and Experiment. Chemical Reviews 121 , 14189-14231 (2021). Zhang S, Chen K, Yu J, Ding B. Model derivation and validation for 2D polymeric nanonets: Origin, evolution, and regulation. Polymer 74 , 182-192 (2015). Ji D , et al. Electrospinning of nanofibres. Nature Reviews Methods Primers 4 , (2024). . Guenthner AJ, Khombhongse S, Liu W, Dayal P, Reneker DH, Kyu T. Dynamics of Hollow Nanofiber Formation During Solidification Subjected to Solvent Evaporation. Macromolecular Theory and Simulations 15 , 87-93 (2005). Paul DR. Diffusion during the coagulation step of wet‐spinning. Journal of Applied Polymer Science 12 , 383-402 (2003). Qin H , et al. Flexible nanocellulose enhanced Li+ conducting membrane for solid polymer electrolyte. Energy Storage Materials 28 , 293-299 (2020). Niu Z , et al. Recent advances in cellulose-based flexible triboelectric nanogenerators. Nano Energy 87 , 106175 (2021). Fan X , et al. A Nanoprotein-Functionalized Hierarchical Composite Air Filter. ACS Sustainable Chemistry & Engineering 6 , 11606-11613 (2018). Peng Z , et al. Self-charging electrostatic face masks leveraging triboelectrification for prolonged air filtration. Nature Communications 13 , (2022). Zhang Y , et al. Continuous air purification by aqueous interface filtration and absorption. Nature 610 , 74-80 (2022). Brunekreef B. The continuing challenge of air pollution. European Respiratory Journal 36 , 704-705 (2010). Hua Y , et al. Dual-bionic, fluffy, and flame resistant polyamide-imide ultrafine fibers for high-temperature air filtration. Chemical Engineering Journal 452 , (2023). Niu Z , et al. Electrospun Cellulose Nanocrystals Reinforced Flexible Sensing Paper for Triboelectric Energy Harvesting and Dynamic Self-Powered Tactile Perception. Small n/a , 2307810 (2023). Li Y, Cao L, Yin X, Si Y, Yu J, Ding B. Ultrafine, self-crimp, and electret nano-wool for low-resistance and high-efficiency protective filter media against PM0.3. Journal of Colloid and Interface Science 578 , 565-573 (2020). Additional Declarations There is NO Competing Interest. Supplementary Files SupportingInformation.docx Cite Share Download PDF Status: Published Journal Publication published 17 Jul, 2025 Read the published version in Nature Communications → Version 1 posted 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. 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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-4142629","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":288704853,"identity":"d2bb30b3-34a4-4954-9c61-07b1dec60966","order_by":0,"name":"Guangping 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10:11:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4142629/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4142629/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41467-025-61863-2","type":"published","date":"2025-07-17T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":54669793,"identity":"ebe00e66-ec77-4e43-be15-6831f82a3ebd","added_by":"auto","created_at":"2024-04-15 04:37:20","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1384528,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eProcessing, structural models and architectures of corn-based fibers.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e Schematic diagram showing a design philosophy conducive to the green, circular and low-carbon development. \u003cstrong\u003eb\u003c/strong\u003e A tubular structural model which mimics the deformation of individual fiber during electrospinning. \u003cstrong\u003ec\u003c/strong\u003e Three main major dynamic force on the tubular structure, which including \u003cstrong\u003ed\u003c/strong\u003e electric field force in axial (F\u003csub\u003ee\u003c/sub\u003e), \u003cstrong\u003ee\u003c/strong\u003e radial compressive stress (F\u003csub\u003er\u003c/sub\u003e), \u003cstrong\u003ef\u003c/strong\u003e hoop compressive stress (F\u003csub\u003et\u003c/sub\u003e). \u003cstrong\u003eg\u003c/strong\u003e Fiber section diagrams and SEM images of \u003cstrong\u003eI Type\u003c/strong\u003e smooth ribbon fibers, \u003cstrong\u003eII Type\u003c/strong\u003e groove rod fibers and\u003cstrong\u003e III Type\u003c/strong\u003e dual networks (D-nets). The D-nets consist of microscale fibril (5.43 μm in diameter) and nanoscale fibrils (0.06 μm in diameter), with structural characteristics of uniform groove structure (0.62 μm in diameter) and laterally infinite 2D dual networks.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4142629/v1/0a6f4ed9485f3dc5bfac85d7.png"},{"id":54669796,"identity":"dd99b2b0-cf00-4605-989c-5024b7b498b5","added_by":"auto","created_at":"2024-04-15 04:37:20","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1308062,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComposition, fabrication, and structural performances of D-nets fabrics.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e Photographs of the straw, cellulose extracted from straw and TEMPO-mediated cellulose nanofibers (CNFs). \u003cstrong\u003eb\u003c/strong\u003e TEM image of CNFs. \u003cstrong\u003ec\u003c/strong\u003e XRD patterns of CNFs. \u003cstrong\u003ed\u003c/strong\u003e Conductometric titration curve of CNFs. \u003cstrong\u003ee\u003c/strong\u003e Particle size of the zein solution and zein/CNFs solution. \u003cstrong\u003ef\u003c/strong\u003e Viscosity of spinning solution changes with evaporation time. \u003cstrong\u003eg\u003c/strong\u003e FTIR spectroscopy of CNFs, pristine zein, zein-based membrane and zein/CNFs membranes. \u003cstrong\u003eh\u003c/strong\u003e Porosity and \u003cstrong\u003e(i-j)\u003c/strong\u003e pore size distribution plots of the fabrics with various architectures. SEM images of fiber cross section of \u003cstrong\u003ek\u003c/strong\u003e ribbon structure and \u003cstrong\u003el\u003c/strong\u003e rod structure. \u003cstrong\u003em\u003c/strong\u003e TEM image of dual-nets fibers shows the junction of the microfiber and nanofiber. \u003cstrong\u003en\u003c/strong\u003e SEM image shows that D-nets have structural characteristics of laterally Voronoi-like networks assembled by two levels of fibers. \u003cstrong\u003eo \u003c/strong\u003eFlow resistance of zein/CNFs solution generating self-standing D-nets fibers.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4142629/v1/034742c876f3706def2c7013.png"},{"id":54669794,"identity":"1b67d02e-5b1a-4819-a1af-8e0fe12e45ba","added_by":"auto","created_at":"2024-04-15 04:37:20","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":841290,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFunctionality and mechanism of combining the air filtration and formaldehyde adsorption.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e PM 0.3 filtration efficiency and pressure drop of the corn-based fabrics of different architectures. Airflow velocity, 5.33 cm s\u003csup\u003e−1\u003c/sup\u003e. \u003cstrong\u003eb\u003c/strong\u003e PM 0.3 filtration efficiency and pressure drop of the corn-based D-nets fabrics with various base weights. Airflow velocity, 5.33 cm s\u003csup\u003e−1\u003c/sup\u003e.\u003cstrong\u003ec\u003c/strong\u003e Quality factor of the corn-based D-nets fabrics with various base weights. Airflow velocity, 5.33 cm s\u003csup\u003e−1\u003c/sup\u003e. \u003cstrong\u003ed\u003c/strong\u003e PM 0.3 filtration efficiency and pressure drop of the corn-based D-nets fabrics with various airflow velocity. Base weight, 8.0 g m\u003csup\u003e−2\u003c/sup\u003e. \u003cstrong\u003ee\u003c/strong\u003e Comparison of quality factor between commercial fabrics and the D-nets fabrics. Base weight, 8.0 g m\u003csup\u003e−2\u003c/sup\u003e. \u003cstrong\u003ef\u003c/strong\u003e HCHO adsorption efficiency of the corn-based D-nets fabrics. \u003cstrong\u003eg\u003c/strong\u003e Time-dependent behavior of the relative weight gains from the HCHO of the corn-based D-nets fabrics \u003cstrong\u003eh\u003c/strong\u003e Simplified representation of the interaction-based filtration mechanism for corn-based D-nets fabrics. \u003cstrong\u003ei\u003c/strong\u003e Schematics show the filtering behaviors consisting of full-structure filtering and sieving, as well as the capture mechanisms including embedded policy for PM 0.3 by the corn-based D-nets fabrics. \u003cstrong\u003ej \u003c/strong\u003eSnapshot images show the flexible, foldable, bendable and sustainable properties of the free-standing corn-based D-nets fabrics.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4142629/v1/a4b7412b61595114fc2484a6.png"},{"id":88505933,"identity":"758385e8-0e6b-421a-8a9b-4ccf03817a31","added_by":"auto","created_at":"2025-08-07 07:29:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4638206,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4142629/v1/6d997588-bbd3-4e40-8318-6e931582a682.pdf"},{"id":54669795,"identity":"b5cd01e8-3da0-42a9-a6ae-f1c1711fa056","added_by":"auto","created_at":"2024-04-15 04:37:20","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1322286,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4142629/v1/c88a6e53493ccea6c1b41622.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Sustainable Biomass-based Filter for High-efficiency PM 0.3 Filtration","fulltext":[{"header":"Introduction","content":"\u003cp\u003eFrom the depths of the sea to the vastness of space, there are many large-scale and high-tech engineering masterpieces in the feat of human conquest and transformation of nature, including expanding the cultivated land to meet the growing demand for food. Increasingly people realize that the development of science and technology has plunged human society into a deep and inescapable ecological crisis, leading to a rapid increase in environmental pollution, especially for particulate matters (PMs) pollution\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Public tackles this issue with outdoor protective equipment, which are huge, bulky and heavy, and present inevitable conflict between air resistance and filtration efficiency, while the enhancement of indoor air quality often counts on high-priced and energy-sucking ventilation systems or centrality air-condition systems\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Nature puts a simple but effective thought related to material assembly: designing a heterogeneous and continuous network of fibers can score substantial gains in material utilization and its resultant performance\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Our previous work fabricated a cobweb-like 2D nanowebs by adding enough cellulose nanocrystals\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. In addition to addressing the fiber diameter and connectivity in electrospun nanofibers, these 2D nanowebs consisted of ultrafine fibers evolved from cellulose possess characteristic diameters below 100 nm, not only overcomes the limitations of most existing fibrous networks, including non-uniform pore size and limited porosity, but also makes up the insufficiency of mechanical performance required for the practical applications. However, solvents with high solvability are difficult to remove completely during electrospinning, and the residue will cause bad consequence. For example, residual toxic solvents or non-solvents can lead to serious complications in air filtration, especially for human breath filtration, when solvents enter the body through the exchange with physiological fluids, which may differ from the original purposes\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. In this context, forestry and agricultural residues, such as corn straw, are emerging as viable options. Such low-value agricultural wastes have already been widely used in various important industry to achieve a carbon-neutral sustainable society. Moreover, sources of zein protein is widespread, mainly from corn gluten meal, which is a protein feed produced as a by-product in the deep processing of corn starch\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Therefore, the filters based on zein protein and reinforced with the nanocellulose should therefore have the prospect of air cleaning devices with low energy-consumption and high efficiency. And there have been to our knowledge no published research on such structure and composition as filters for PM 0.3 removal.\u003c/p\u003e \u003cp\u003eHere, we introduce a heterogeneous precursors technique of low-value biomass (straws, chips and residues) to assemble 2D self-assembled dual-network architectures that consist of nanoscale fibers (70\u0026ndash;400 nm) and microscale fibers (1\u0026ndash;5 \u0026micro;m) with desirable nano-structural features. Such a \u0026lsquo;fiber-shaping\u0026rsquo; process affected by the nonsolvent-induced phase separation is considered as a way to endow the materials with high performance. Such D-nets filters are based on agricultural residues (zein protein) and hydrophilic lignocellulosic biomass (TEMPO-mediated cellulose nanofibers). Hence, the biodegradable fabric is formed by dual-network structures comprised of alternating fibers with micro- and nano-architectures, leading to superior filtration and formaldehyde adsorption performance, which can compare or exceed that of traditional commercial filters. This specific structure can effectively intercept the PM 0.3 to embed precisely in the isotropic groove of microscale fibers and flow adequately among the nanoscale fibers, achieving full-structure filtration, finally resulting in an enhanced filtration efficiency and reduced pressure drop. This heterogeneous precursor technique is simple and efficient to transform residual or waste corn straw into high-performance structural filters, which offers a pathway to advance the circular bioeconomy based on the farming surplus.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eWe propose a heterogeneous biomass-based precursors technique to assemble alternating fibers with micro- and nano-architectures, including smooth ribbon fiber, groove rod fiber and dual-net fibers (as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). The unique solute-solvent system was collected solely using zein protein from corn and cellulose extracted from corn straw as solute. The solvent system, which achieved the purpose of \u0026ldquo;Killing Two Birds with One Stone\u0026rdquo;, not only endowed the material with a rough surface structure in the phase separation, but also improved the greenness of the electrospinning process. It is notable, too, that the phase separation can be precisely controlled to achieve on-demand distribution of fibers at the micro level by tailoring the ambient humidity (30%-90%) during electrospinning. Each component of this filter fabric all come from nature and finally return to the nature, therefore perpetuating a closed loop cycle. Shortly, \u0026ldquo;from nature to nature\u0026rdquo; is the aim of our design concept, reflecting the harmony of man and nature, which is the principal feature differentiates from other air filter media.\u003c/p\u003e \u003cp\u003eTo elaborate the structural control and evolution process of the obtained self-assembled architectures, we focused on a different protein, zein, to serve as a proof-of-concept model (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). The solubility is indeed an inherent feature of the zein, because it cannot dissolve in either water or ethanol but can surprisingly dissolve in 60%-90% ethanol solution (Fig. S2). It would have meant combining those two solvents is very important for dissolving zein. That is, removal or partial removal of either component from this solvent system can cause zein to precipitate (Supplementary discussion I). This characteristic is also approved by a neat experiment, after evaporation in the atmosphere for about 2 h, a robust protein film is formed on the solution surface (Fig. S3). Hence, from the macroscopic point of view during electrospinning, based on the fact that the rate of ethanol volatilization is faster than water, it is quite reasonable to suppose that the phase separation of zein fibers will occur if we regulate the relative humidity (30% \u0026minus;\u0026thinsp;90%). Therefore, in our electrospinning system, we chose the ethanol and the water (80 wt.%: 20 wt.%) as the solvent and tailored the relative humidity (30% \u0026minus;\u0026thinsp;90%). Ambient relative humidity during fiber formation not only causes the liquid-liquid phase separation in polymer-rich and polymer-poor regions, but also affects the solidification rate of polymer from either the single-phase or polymer-rich regions\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Attributed to the volatile difference of the nonsolvent phase and the solvent phase, a common one of the phase separation during electrospinning is nonsolvent-induced phase separation (NIPS)\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. Apart from the viscoelastic behavior, the selected polymer-solvent-non-solvent ternary system also determines the kinetics and mechanism of phase separation, all of which will influence the morphological characteristics of the fibers\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. However, the NIPS are not the appropriate mechanism in our case. To understand what mechanism may be responsible for this behavior, one needs to consider a ternary composition of zein/H\u003csub\u003e2\u003c/sub\u003eO/ethanol in the jet is a consideration (Fig. S4). Based on the Flory-Huggins theory, a theoretical diagram of ternary phase for zein/H\u003csub\u003e2\u003c/sub\u003eO/ethanol was illustrated. The mass transfer of three components during fiber formation was calculated for representative ideal conditions, and the resulting mass transfer path was overlayed on the diagram. Given that the vapor in the spin beam can be absorbed into the electrically charged liquid jet and be part of the solvent system, it is unlikely to increase the water content of the solvent system to a value high enough (\u0026gt;\u0026thinsp;40%) to make the skin layer solid instantaneously.\u003c/p\u003e \u003cp\u003eTo reveal the humidity-induced self-assembled architectures, we designed a tubular structural model to mimic the deformation of individual fiber during electrospinning (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb), which could link the solvent properties and ambient humidity to the forms and dynamics of the individual fiber. In the morphology evolution, the solvent evaporation induced by relative humidity plays an important role\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. Both water and ethanol have low electrical conductivity, and their jets have less induction force to the electric field, which makes the surface tension of the jets greater than the electric field force. During fiber formation, the jet was stretched at a high speed by the electric field force and was separated into the solvent-rich phase and the polymer-rich phase rapidly due to the high volatility of ethanol. And then the surface jet reached the polymer-rich phase faster and wrapped the solvent-rich phase during the evaporation process due to the high volatilization rate of the surface jet\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. The composition or proportion of the solvent components on the fiber-air interface could be very different from the initial state in theory, which promoted the phase separation. As the skin layer dried to a certain extent, the size of the skin layer is fixed, and the jet forms a tubular structure with a polymer skin layer wrapped in the spinning solution. Therefore, we can consider a single fiber as a tubular structure, and the final fiber morphology is determined by the evaporation rate of the surface solvent and the diffusion rate of the inner layer solvent. Furthermore, the effect of mechanical stresses of tubular structural model is another important consideration on such structure development. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec, the three main major dynamic force on the tubular structure are electric field force (F\u003csub\u003ee\u003c/sub\u003e), radial compressive stress (F\u003csub\u003er\u003c/sub\u003e) and hoop compressive stress (F\u003csub\u003et\u003c/sub\u003e). Electric field force in axial leading to jet ejection from Taylor cone overcomes the competing liquid surface tension (F\u003csub\u003eγ\u003c/sub\u003e) and adhesive force (F\u003csub\u003eη\u003c/sub\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). Enlarging portions of the skin layer by differential evolution method, the internal pressure caused by the diffusion of the inner solvent acts radially on the inner wall (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee). Meanwhile, any force perpendicular to the cross-section of the tube will create a hoop compressive stress in the skin layer (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef). According to the real situations, as the solvent evaporates from the bulk, if the skin remains stationary, it will produce a negative gauge pressure at the bulk. This pressure difference (ΔP) can be related to the compressive stress (σ\u003csub\u003er\u003c/sub\u003e) of the skin layer by the force balance given by\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\frac{{\\sigma }_{r}}{r}=\\frac{\\varDelta P}{\\varDelta R}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere r is the average radius of the skin layer and ΔR is its thickness\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. It is obvious that when the skin layer is much thinner than the fiber radius, the stress would be large enough under different humidity conditions to cause various degree of collapse of the fiber wall during electrospinning. Therefore, a common curiosity is how the structure will evolve, would this structure at last shrink to an isotropic grooved rod or flatten into a flat smooth ribbon?\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg (I type and II type) represents two typical examples of the general structures (smooth ribbon-like fiber and grooved rod-like fiber) which can be observed in the present system of the fiber formation. In the first case of a low ambient humidity (\u0026asymp;\u0026thinsp;30%), the as-spun zein fibers with the average fiber diameter of 2.39 \u0026micro;m have smooth surfaces and ribbon shapes (Fig. S5a and Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg I Type). The evaporation rate of the surface solvent is greater than the diffusion rate of the inner solvent, which can availably increase the F\u003csub\u003er\u003c/sub\u003e and smooth the F\u003csub\u003et\u003c/sub\u003e. With the rapid evaporation of the surface layer solvent, the inner volume gradually decreases and the fiber forms a hollow structure instantaneously. As the solvent continues to evaporate, the flexible tube would likely collapse under the relatively high radial compressive stress and the ribbon-like fibers with smooth surface would form. In the second case of a high ambient humidity (\u0026asymp;\u0026thinsp;90%), the as-spun zein fibers with average fiber diameter of 0.79 \u0026micro;m have grooved surfaces and rod shapes (Fig. S5b and Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg II Type). Under this circumstance, the solidification rate of skin layer is faster since the vapor absorbing from the environment into the jet can act as a nonsolvent for zein, and the water in the solvent can promote water vapor from the environment to enter the jet at the same time. However, the solvent in the bulk is not easy to volatilize, and the jet remains in the state of charged fluid and is continuously stretched by the electric field force. It can be inferred that the inner solvent diffused outwards faster, the volume in the skin layer decreases rapidly, the evaporation rate of the surface solvent is less than the diffusion rate of the inner solvent, the F\u003csub\u003et\u003c/sub\u003e is stronger than the F\u003csub\u003er\u003c/sub\u003e, resulting in the longitudinal deformation of the epidermis, and the longitudinal grooves and convex edges are generated on the surface after the shrinkage. During the same time interval, the diameter of the jet decreases due to stretching, its surface area increases, the unit charge density decreases and the axial instability of the jet increases. The origin of wrinkles may be formed as a result of the lateral contraction effect from the electric field force, which is ascribed to the continuous jet stretching, and/or the buckling of the thin-wall cylindrical shell of the polymer under the action of radial compressive stress, which is ascribed to solvent removal from the core of the jet. To validate this humidity-induced association, the morphologies of fibers under different relative humidity (RH) conditions (30%, 50%, 70% and 90%) are shown in Fig. S6. To sum up, for the smooth ribbon-like fibers, the behavior is a classic example for a fiber system dominated by diffusion with moving boundaries, and is essentially the same result found in the earlier models of Corbriere and Paul\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e; for the grooved rod-like fibers, it is likely to be an example of the propagation of front (kink) wave, which is a typical result of nonlinear reaction-diffusion.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNow comes a following challenging part, that is, the fiber created from the protein always has a large diameter, which may increase the pore size and decrease the porosity, and exert significant indirect effects on the chance of particles being capture. In our previous work, the effect of abundant nanocellulose was developed and applied as a reinforcement for filtration membrane, which exhibited desired cobweb-like structure with integrated properties of ultrafine diameters, small pores and excellent mechanical property, thus showing great potential for filtration process. Therefore, on the basis of the second case, we manipulate the addition amount of the cellulose nanofibers (CNFs) which are same-rooted born of corn crop to enable the creation of dual nets. The reaction process of TEMPO-mediated CNFs is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and Supplementary discussion II. The TEMPO-mediated oxidation converted the hydroxyl groups at C6 to carboxyl group, which broke the hydrogen bonding between fibrils and introduced the electrostatic repulsion, thus preventing the aggregation of cellulose in precursor\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. The as-prepared CNFs presented long fiber morphology with average diameter of 7.5 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb and Fig. S7). X-ray diffraction (XRD) patterns characterized the effect of TEMPO-mediated oxidation on crystallization and the degree of crystallinity of CNFs is 64% (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). The surface charge density of the CNFs was 1.4 mmol/g was determined effectively by acid-alkali neutralization titrimetric method (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). After the introduction of CNFs, more ultrafine fibers split from the original coarse fiber can be observed on the membrane (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee). Compared with the second case (RH\u0026thinsp;~\u0026thinsp;90%, contains no cellulose), what we may find interesting is that the wrinkle on the surface of the slightly collapsed fiber is deepen, and develop a severely collapsed fiber (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg III Type), which means that adjusting the precursor properties by adding CNFs may be a feasible method to control the formation of D-nets in the membrane. Therefore, the significant effect of the cellulose on the protein-based fibers should also be understood; we had probed and disserted it from three aspects. Firstly, CNFs can be entangled with long chains of amino acids of zein protein, and thus increasing the overall concentration of the solution and its viscosity. This point can be confirmed by using a parallel dynamic rheometer to study how the solution viscosity changes with the evaporation time in the atmosphere (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef). The viscosity increases dramatically after incorporating CNFs into the precursor solution and reaches 10,000 Pa\u0026middot;s only at about 100 s, indicating a phase transition from liquid to solid near the sample surface. Secondly, a small addition amount of CNFs in solution can strengthen the structural connections and create additional connections between zein protein molecules when they enter and disperse in the zein protein network. The effect of CNFs in this case is similar to that of adding salt in the electrospinning system, both of which promote the fiber splitting by increasing the solution conductivity. Thirdly, the addition of CNFs will block the continuity of protein molecules to some extent, so the splitting occurs during the electrospinning\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. The CNFs, as a dispersion phase, is more difficult to stretch, so it can be speculated that the concave part might be the corn protein rich area, and the prominent part might be the cellulose rich area. The infrared spectrum of the D-nets fibers after adding CNFs is almost no difference compared with that of pure zein protein fiber, indicating that the binding between corn protein and cellulose is physical in nature (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eg). There are mainly three forms of binding: the first is hydrogen bonding, which will not be explained in detail here. The second form, the denatured zein, may interact with CNFs by the electrostatic interaction, which is formed by the attraction of electronegative hydroxyl and carboxyl groups on the CNFs surface to electropositive amino groups on the amino acid chain. The third form is the relationship between proton acceptor and proton donor. Both zein and CNFs contain hydroxyl groups, which provide protons. The carbonyl group in the protein molecule may act as a proton acceptor.\u003c/p\u003e \u003cp\u003eThe fabrics prepared by electrospinning the mixture of zein/CNFs is expected to have fluffy structure and high structure stability. The synergistic effect of high relative humidity and cellulose content deepens the wrinkles, which made it have larger specific surface area, thereby establishing a high surface electrostatic potential of the fibers, and thus enhancing the adsorption and retention capacity for PMs\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. This structure tackles key technical bottlenecks in manufacturing the net-structure with large gap, low coverage rate, fatal empty space and discontinuous and random distribution. The analysis of pore structures (pore size and porosity) also proves the content of D-nets structure in membranes. From Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eh, the increase of water in the atmosphere caused by the increase of relative humidity will accelerate the solute precipitation, thus promoting the phase separation process, which leads to an increase in the porosity of the membranes (from 56.62\u0026ndash;73.08%). Manipulation of the content of D-nets by controlling the CNFs concentration also enabled an obvious increase in porosity (from 73.08\u0026ndash;94.62%), and this increase caused a crucial decrease in the pore sizes (from 4.45 \u0026micro;m to 200\u0026ndash;300 nm) of the membranes (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ei). This phenomenon exactly corresponds with the emergence of the nanofibers arises from the microfiber splitting (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ej). It\u0026rsquo;s the same the other way round, both the increase of the concave parts and the decrease of the bonding structure of fibers caused by the emergence of the emerging ultrafine fibers (\u0026asymp;\u0026thinsp;74 nm) improved the porosity of the membranes. Moreover, the water (water vapor, humidity) can be regarded as a special non-solvent in the solvent system, the miscible ethanol and water solution system can promote the water in the environment into the jet, accelerate the phase separation during electrospinning, and thus further improve the fiber porosity. It should be pointed out that, although the water vapor entering the jet can promote the formation of holes in the core layer of the fiber, however, it will make the fiber surface less vulnerable to the pore structure, and even inhibits the formation of surface porous structure. From Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ek-l, both the ribbon-like fiber and the rod-like fiber have no pores in skin layer. The main reason is that the composition of the solvent inside the jet is fairly uniform. The water vapor in the air will continuously reduce the solubility of the solvent to the zein, accelerate the zein protein precipitate from 80% ethanol solution (phase separation), and make the jet surface solidify into a uniform layer of soft shell in advance. Moreover, continuous stretching of fibers and phase separation could result in the formation of ideal dual networks assembled by the altering micro- and nanofibers. Evidence of the splitting process arise from the transmission electron microscopy (TEM) image of the architectures (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003em). Benefiting from the lateral infinity of dual networks with hierarchical nanostructures, the as-prepared membranes exhibited extremely small pore sizes while maintaining a strikingly high porosity. Zooming in and out on the D-nets revealed that an integrated, uniform and continuous network appeared and was laterally Voronoi like with scaffold pores, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003en. These concave parts caused by the high humidity during electrospinning were much stable and thus fundamentally enhanced the sieving properties of the filters. Furthermore, in contrast to the ribbon fibers prepared at relatively low-humidity and the rod fibers prepared without the addition of CNFs, the formation of curled fiber induced by the high-humidity environment led to a fluffy fibrous accumulation, which was in correspondence with the common wisdom that a fluffy structure tended to do benefit for the reduction of the pressure drop (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eo).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePM pollution, especially for more-penetrating particles (PM 0.3), has become a significant burden on public health and even global economies\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. Here, in considering the integrated properties of fluffy structure, high porosity and small pore size, applications in air filtration by the corn-based D-nets fabrics are possible. Our self-standing D-nets provides an innovative degradable and disposable sanitary material with the performances of low resistance and high efficiency, which can be used as the filter element for mask or filter to protect the human body and indoor air quality through natural passive ventilation. As presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, the ribbon-like fibrous filter with a base weight of 10.0 g\u0026middot;m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e had low filtration capacity for intercepting particles: 82.2204% PM 0.3 removal at a pressure drop of 80 Pa. The rod-like fibrous filter with a base weight of 8.9 g\u0026middot;m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e were slightly better at a pressure drop of 69 Pa, but showed 76.8854% for PM 0.3 removal. After the introduction of the CNFs, the D-nets filters demonstrated excellent results in the sternest PM 0.3 removal. Surprisingly, filters with a superlight weight of 8.0 g\u0026middot;m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e resulted in 99.4168% at pressure drop of 42 Pa. These could be attributed to the hierarchical and multilevel fiber structure, a structure which could simultaneously improve the PM capture capacity and reduce the airflow resistance. A quantitative study was carried out concerning how the base weight affected the air-flow resistance of the D-nets fabrics (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). Benefited from the complex changes in hierarchical porous structure, the pressure drops of the fabrics increased nonlinearly, which might be related to the increasing numbers of layers of fibers. More strikingly, an increased base weight of 10.2 g\u0026middot;m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e of our corn-based D-nets filters showed 99.9994% for PM 0.3 removal, which qualified for the standard for ultralow penetration air (ULPA) filters of \u0026gt;\u0026thinsp;99.999%. To evaluate the overall performance of the D-nets fabrics, the quality factor (QF), which is related to the ratio between the particulate removal efficiency (η) of the air filter and the pressure drop (ΔP) due to air flow across the filter, was calculated and shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec. In the meanwhile, the pressure drop of the corn-based D-nets filter (8.0 g\u0026middot;m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e) under the airflow velocity of 5.33 cm\u0026middot;s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was 42 Pa, which was negligible compared with the atmospheric pressure (only 0.04% of the atmospheric pressure). As the airflow velocity increased from 5.33 to 16.6 cm\u0026middot;s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the corn-based D-nets filters remained a nearly unchanged filtration efficiency for PM 0.3 and a slightly increased pressure drop (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). For instance, under a high velocity of 16.6 cm\u0026middot;s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (standard for personal breathing apparatus), the D-nets filters exhibited a steady efficiency for PM 0.3 (\u0026gt;\u0026thinsp;98.5257%) and a slightly increase from 42 Pa to 109 Pa for pressure drop, which could be attributed to the way of sieving derived from the D-nets structures. Correspondingly, all these corn-based D-nets filters proved higher quality factors for PM 0.3 removal and better performance than most advanced commercial filters, such as PAN\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, PAI\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e and HEPA. The comparison between the efficacy for PM 0.3 of our corn-based D-nets filters and of previously reported filters is showed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee). Our D-nets filters, in obvious contrast, presented an outstanding filtration capacity for more-penetrating particles by virtue of their flexible and progressive fiber structure, while having a lighter weight and fluffy structure. Compared to conventional micro-fibrous filters whose base weights usually exceed 100 g\u0026middot;m\u003csup\u003e\u0026ndash;\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e, that of D-nets filters were negligible. We reasonably construe that the superior removal capacity efficacy of corn-based D-nets fibers depend on high interface energy and small pore size, and low pressure drop is attributed to their fluffy structure, high porosity and heterogeneous biomass-based precursors technique to assemble alternating fibers with micro- and nano-architectures.\u003c/p\u003e \u003cp\u003eIn addition to a robust removal efficacy for more-penetrating particles, this corn-based fabrics also proved excellent adsorption capacity for HCHO. HCHO is a kind of molecule with size much smaller than the PM 0.3, and we suggest that the HCHO removal is controlled by an interaction-based filtration mechanism provided by this D-nets architecture, which will be discussed later. The relation curves that HCHO adsorption efficiency varied with the testing time for the corn-based fabrics with different structures were obtained (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef). By comparison, the adsorption efficiency for HCHO by commercial HEPA filter paper without rich functional groups on the surface of their fibers was also tested. The HCHO adsorption efficiency of the D-nets fabrics dropped from 81.36\u0026ndash;71.25% steadily after 120 min of testing time and further to 52.66% after 240 min, while the HCHO removal efficiency of the commercial HEPA filter was below 6.45% and decreased to less than 3.6% after about 240 min, which is mainly caused by the lack of active sites on the surface of the materials. An increase in the weight of captured pollutants was also measured after testing (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg). After 240 min of testing, the total weight of captured pollutants on the corn-based D-nets fabrics increased from 2.4 to 8.3 mg, while that of the HEPA filter increased slightly from 0.8 to 2.8 mg. The ratio of the weight gain of captured pollutants (W\u003csub\u003ep\u003c/sub\u003e) and the weight of the filter before testing (W\u003csub\u003ef\u003c/sub\u003e) is used to describe the ability to absorb pollutants. For the corn-based D-nets fabric, the W\u003csub\u003ep\u003c/sub\u003e/W\u003csub\u003ef\u003c/sub\u003e increased from 0.36 to 1.26 with the increase of the testing time from 40 to 240 min, while that of the HEPA filter at evenly spaced intervals increased slightly from 0.005 to 0.017. In general, this fabric can capture amounts of pollutants, weighing even heavier than the material itself, which is similar to the cobwebs that can trap huge particles despite its light weight.\u003c/p\u003e \u003cp\u003eTo further understand the unique performance of this corn-based D-nets fabrics, we propose a full structure filtering mechanism based on the characterization analysis of both the PM 0.3 pollutants and the formaldehyde pollutant. Generally, the filtration efficiency for particles heavily relies upon fiber morphology due to four primary sized-based filtration mechanisms. The schematic diagram of the potential interaction among zein protein, CNFs chains, PM particles, and HCHO is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eh, which establishes a reinforcement mechanism based on strong fiber-pollutant interactions. Zein, as has been noted, contains many active functional groups, which can interact with the toxic chemicals and even the solid particles in polluted air. The aldehyde groups in HCHO may interact with not only the carboxylic groups of CNFs, but the carboxylic and amine groups of zein. Additionally, there are three types of interactions which PM and HCHO may undergo, including charge-charge, polar-polar, and hydrogen-bonding interactions. The hypothetical structure model was also created for the corn-based D-nets fabrics, which could demonstrate an all-structure filtration mechanism for the structure of multilevel hierarchy, with a range from integrated filters to dual networks to fibers (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ei). From a view of integration, sieving, as a main filtration mechanism, can partly block the penetration of the PM particles, even for the particles with sizes smaller than the pore sizes of the filters (200\u0026ndash;300 nm). From a view of dual networks, due to the continuously welded and fully covered networks assembled by the alternating fibers with micro- and nano-architectures, our air filters can prevent the leaking of PM 0.3 effectively. From a view of single fiber, it needs to introduce an embedded policy to explain, that is, the PMs can embed in the groove structure on the coarse fiber based on the tubular model. On the other hand, the inhomogeneous mixing of zein protein and cellulose resulted in interfacial polarization. Due to the difference in electron cloud density, there are usually varied degree of interfacial polarization between the crystalline and amorphous regions of cellulose, which is the inherent dielectric property of the cellulose. Since the cellulose molecule itself has dipole moment, when added cellulose to the zein protein matrix, it will additionally undergo its own dipole orientation polarization and Maxwell interface polarization with zein protein under the action of the electric field, which results in a higher relative permittivity\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. Therefore, the extra load of cellulose will produce many interfacial regions within zein protein, and the huge difference between the two further intensifies the interfacial polarization, thereby increasing the adhesion of more-penetrating particles on the surfaces of micro/nano- fibers. Owing to a slip effect, the air velocity at the surface of the fibers was nonzero. When the air travelled laterally through the micro/nano- fibers, the momentum of particles let them more likely to collide along their route. In consequence, the effects of diffusion and interception for capturing more penetrating particles were greatly enhanced. Hence, this adhesive effect was also attributed to the stable removal efficacy of the D-nets filters in addition to their small pore size. The structure with fluffiness, high porosity, and small pore size endows the filter with high PM 0.3 removal efficacy while maintaining a maximal air penetrability, which necessarily requires a robust mechanical strength. From Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ej, this free-standing corn-based D-nets fabric (~\u0026thinsp;370 nm) could support a plastic frame weighing 15 g with one finger, and could be bent or stretched without any damage, suggesting superior robustness, softness and flexibility. Moreover, this filter was expected to bear tensile strain caused by the airflow moving at 16.6 cm\u0026middot;s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. In other words, this corn-based filters are supposed to overcome the bottleneck of constructing fluffy membranes with good mechanical properties, thereby making it possible to be used as filters\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHow to develop a sustainable and environmentally friendly material to reduce the energy demand for controlling air pollution is a matter of significant importance facing sustainable development. From a perspective of life cycle, air filters are always discarded after use. Our corn-based D-nets filters meet the requirements of environmental protection and land degradation, and its advantages are further embodied in their purification rate, energy-saving capacity and degradable and disposable performance. Since the component of the biomass-based fabrics, zein protein and cellulose, are biodegradable, this D-nets filters could gradually degrade after being buried in the soil for biodegradation after utilization and will not cause white pollution. In considering that the alternating fibers with micro- and nano-architectures could be directly deposited on personal protective equipment and indoor air purifier, our D-nets filters are believed to provide a simple and cost-effective strategy to purify the polluted air facilely. Obviously, a conclusion can be drawn that a good consistency was obtained between the model prediction and the actual pressure drop of our corn-based D-nets filters. Compared with commercial filters, it surpasses the others in terms of comprehensive factors including process simplicity, low cost, high filtration efficiency, environmental friendliness (including biodegradability after service) and potential for wide application. Moreover, based on the novel synthesis methodology, the full-structure filtration model of the corn-based D-nets filters we established was further regulated vertically on the map of structural characteristic and airflow resistance. Further regulating the assembled architectures, such as the packing density, thickness and nets coverage, could build varieties of air filters with optimized pressure drops and designed removal efficiencies, which was applied in PM 0.3 filtration, overcoming the limitation of the trade-off between air permeability and capture efficacy.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn conclusion, we have demonstrated a novel synthesis methodology for the preparation of high-efficiency dual-network air filters by heterogeneous biomass-based precursors technique. The continuously welded dual networks consisted of alternating fibers with micro- and nano-architectures were assembled into fabrics with properties of ideal fluffy structure and desirable pore structure. And by virtue of the synergistic effect of micro/nano- scale fibers and well-controlled self-assembled network, this completely degradable corn-based D-nets filter exhibits robust mechanical strength and superior functionality for PM 0.3 filtration. Moreover, this filter could filtrate PM 0.3 with a removal efficiency of \u0026gt;\u0026thinsp;99.4168%, pressure drops of \u0026lt;\u0026thinsp;42 Pa, which all thanks to their derived full-structure filtration effect, extremely low thickness, together with the integrated properties of superlight base weight (8.4 g m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e). We envision that such intriguing dual-network fabrics, which can operate as a stand-alone filter or in combination with respirators, window screenings and filter canisters, will herald vast potentials for biomass-based high-performance filters toward personal protection, engine intakes, ventilation systems and medical devices.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e \u003cb\u003eMaterials and chemicals.\u003c/b\u003e The mature corn plants were harvested and collected in October 2022 at a corn field in ACheng District, Harbin, Heilongjiang Province, China (N45\u0026deg;32\u0026prime;29.184\u0026Prime;, E126\u0026deg;58\u0026prime;30.9\u0026prime;\u0026prime;). The whole corn straw residue was cut at the bottom and air-dried, then shredded into small pieces as the corn straw. Zein protein, sodium chlorite (NaClO\u003csub\u003e2\u003c/sub\u003e, 80%), acetic acid, ethyl alcohol (EtOH) and potassium hydroxide (KOH) were purchased from Aladdin Chemistry Co. Ltd. (Shanghai, China). Deionized water was used for solvent.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFabrication of corn-based D-nets fabrics.\u003c/b\u003e The nanofibrils were produced from corn straw using TEMPO-mediated oxidation. For simplicity, we refer to the oxidized cellulose nanofibrils as CNFs. CNFs were prepared by a previously reported method. The detailed fabrication process was presented in Supplementary Methods I. The electrospinning process was performed by a conventional electrospinning device (Yong Kang Le Ye Co., Beijing, China). The detailed fabrication process was presented in Supplementary Methods II. The spinning solutions were prepared by dissolving 25 wt. % zein in 80% ethanol solution, while CNFs concentrations were tuned to 0 and 1wt. % in zein solutions, respectively. The solutions were ejected with feed rate of 0.1 ml h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with distance of 20 cm by a DC voltage of 15 kV. The base weight of the corn-based fabrics is controlled by carefully adjusting the spinning time.\u003c/p\u003e \u003cp\u003e \u003cb\u003eCharacterization.\u003c/b\u003e The morphological structures and crystallinity of CNC were characterized using transmission electron microscopy (TEM, Hitachi-7650, Japan) and X-ray diffraction (XRD, D/max-2200VPC, Japan). The viscosity of the zein solution and zein/CNFs solutions was determined by a hybrid rheometer (HAAKE MARS, Thermo Scientific, USA). The nanoparticles of the zein solutions and zein/CNFs solutions were determined by dynamic laser light scattering (Zetasizer Nano, Malvern Instruments). The morphologies and structures of the micro- and nano-structured architectures were characterized using scanning electric microscope (SEM, Apreo S HiVac, Thermo Scientific, USA, precoated with gold for 120 s) and TEM. The particulate sizes of CNFs and diameter distribution of fibers was measured by randomly selecting 100 fibers and were determined by the Nanomeasure software. The thickness of the corn-based D-nets fabrics was measured by a thickness gauge (AIPLI0-10mm, readability of 1 \u0026micro;m. Fourier transform infrared (FTIR) spectrometry was conducted using a NICOLET 6700 spectrophotometer (Thermo Fisher Scientific Inc. USA), with the samples from 4000 to 600 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were recorded. The pore structure of the corn-based D-nets fabrics was characterized by CFP-1100AI capillary flow porometer (Porous Materials Inc., USA). The porosity (ε) of the corn-based D-nets fabrics was analyzed by gravimetric strategy and calculated by the following equation \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\epsilon }\\left(\\%\\right)=\\frac{\\left({M}_{wet}-{M}_{dry}\\right)/{\\rho }_{w}}{\\left({M}_{wet}-{M}_{dry}\\right)/{\\rho }_{w}+{M}_{dry}/{\\rho }_{M}}\\)\u003c/span\u003e\u003c/span\u003e, where M\u003csub\u003ewet\u003c/sub\u003e and M\u003csub\u003edry\u003c/sub\u003e were the wet and dry weight of the corn-based fabrics; ρ\u003csub\u003ew\u003c/sub\u003e and ρ\u003csub\u003eM\u003c/sub\u003e were the densities of silicone oil and the corn-based fabrics, respectively. PM 0.3 filtration efficiency and pressure drop of the corn-based fabrics were measured by a filter equipment (TSI 8130A, USA). The concentrations of HCHO were diluted in a glass bottle to the level that was measured by a particle counter (PPM-400 ST) with chemical sensors for HCHO. The process was utilized and detailed in Supplementary Method III.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was financially supported by the National Natural Science Foundation of China (Grant No. 31470580) and the Natural Science Foundation of Heilongjiang Province, China (Grant No. LH2020C039).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eQ.W. and G.H. designed the experiments along with directions by S.Z. and B.D. The experiments were carried out by Q.W. The assistance of Z.N. was instrumental in creating the three-dimensional illustrations. Q.W., M.Y., J.L. J.Y. and H. Y. performed material characterizations. Q.W., W.C., Y.Y., Y. W., D.W., S. Z., B.D., and G. H. collectively wrote the paper. All authors commented on the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eZhang S, Liu H, Tang N, Ge J, Yu J, Ding B. Direct electronetting of high-performance membranes based on self-assembled 2D nanoarchitectured networks. \u003cem\u003eNature Communications\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, (2019).\u003c/li\u003e\n\u003cli\u003eZhang Q\u003cem\u003e, et al.\u003c/em\u003e Transboundary health impacts of transported global air pollution and international trade. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e543\u003c/strong\u003e, 705-709 (2017).\u003c/li\u003e\n\u003cli\u003eNel A. Air Pollution-Related Illness: Effects of Particles. \u003cem\u003eScience\u003c/em\u003e \u003cstrong\u003e308\u003c/strong\u003e, 804-806 (2005).\u003c/li\u003e\n\u003cli\u003eHuang R-J\u003cem\u003e, et al.\u003c/em\u003e High secondary aerosol contribution to particulate pollution during haze events in China. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e514\u003c/strong\u003e, 218-222 (2014).\u003c/li\u003e\n\u003cli\u003eLelieveld J, Evans JS, Fnais M, Giannadaki D, Pozzer A. The contribution of outdoor air pollution sources to premature mortality on a global scale. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e525\u003c/strong\u003e, 367-371 (2015).\u003c/li\u003e\n\u003cli\u003eLiu C\u003cem\u003e, et al.\u003c/em\u003e Transparent air filter for high-efficiency PM2.5 capture. \u003cem\u003eNature Communications\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, (2015).\u003c/li\u003e\n\u003cli\u003eZhang S, Liu H, Tang N, Zhou S, Yu J, Ding B. Spider‐Web‐Inspired PM0.3 Filters Based on Self‐Sustained Electrostatic Nanostructured Networks. \u003cem\u003eAdvanced Materials\u003c/em\u003e \u003cstrong\u003e32\u003c/strong\u003e, (2020).\u003c/li\u003e\n\u003cli\u003eWang C\u003cem\u003e, et al.\u003c/em\u003e Highly Transparent Nanofibrous Membranes Used as Transparent Masks for Efficient PM0.3 Removal. \u003cem\u003eACS Nano\u003c/em\u003e \u003cstrong\u003e16\u003c/strong\u003e, 119-128 (2021).\u003c/li\u003e\n\u003cli\u003eLang C, Fang J, Shao H, Ding X, Lin T. High-sensitivity acoustic sensors from nanofibre webs. \u003cem\u003eNature Communications\u003c/em\u003e \u003cstrong\u003e7\u003c/strong\u003e, (2016).\u003c/li\u003e\n\u003cli\u003eWang X, Ding B, Sun G, Wang M, Yu J. Electro-spinning/netting: A strategy for the fabrication of three-dimensional polymer nano-fiber/nets. \u003cem\u003eProgress in Materials Science\u003c/em\u003e \u003cstrong\u003e58\u003c/strong\u003e, 1173-1243 (2013).\u003c/li\u003e\n\u003cli\u003eWang Q\u003cem\u003e, et al.\u003c/em\u003e Spider-web-inspired membrane reinforced with sulfhydryl-functionalized cellulose nanocrystals for oil/water separation. \u003cem\u003eCarbohydrate Polymers\u003c/em\u003e \u003cstrong\u003e282\u003c/strong\u003e, (2022).\u003c/li\u003e\n\u003cli\u003eZhang Z, Ji D, He H, Ramakrishna S. Electrospun ultrafine fibers for advanced face masks. \u003cem\u003eMaterials Science and Engineering: R: Reports\u003c/em\u003e \u003cstrong\u003e143\u003c/strong\u003e, (2021).\u003c/li\u003e\n\u003cli\u003eOliviero M\u003cem\u003e, et al.\u003c/em\u003e Dielectric Properties of Sustainable Nanocomposites Based on Zein Protein and Lignin for Biodegradable Insulators. \u003cem\u003eAdvanced Functional Materials\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e, (2017).\u003c/li\u003e\n\u003cli\u003eKasaai MR. Zein and zein -based nano-materials for food and nutrition applications: A review. \u003cem\u003eTrends in Food Science \u0026amp; Technology\u003c/em\u003e \u003cstrong\u003e79\u003c/strong\u003e, 184-197 (2018).\u003c/li\u003e\n\u003cli\u003eSzewczyk PK, Stachewicz U. The impact of relative humidity on electrospun polymer fibers: From structural changes to fiber morphology. \u003cem\u003eAdvances in Colloid and Interface Science\u003c/em\u003e \u003cstrong\u003e286\u003c/strong\u003e, (2020).\u003c/li\u003e\n\u003cli\u003eM\u0026uuml;ller M, Abetz V. Nonequilibrium Processes in Polymer Membrane Formation: Theory and Experiment. \u003cem\u003eChemical Reviews\u003c/em\u003e \u003cstrong\u003e121\u003c/strong\u003e, 14189-14231 (2021).\u003c/li\u003e\n\u003cli\u003eZhang S, Chen K, Yu J, Ding B. Model derivation and validation for 2D polymeric nanonets: Origin, evolution, and regulation. \u003cem\u003ePolymer\u003c/em\u003e \u003cstrong\u003e74\u003c/strong\u003e, 182-192 (2015).\u003c/li\u003e\n\u003cli\u003eJi D\u003cem\u003e, et al.\u003c/em\u003e Electrospinning of nanofibres. \u003cem\u003eNature Reviews Methods Primers\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, (2024).\u003c/li\u003e\n\u003cli\u003e\u0026lt;ma802529h.pdf\u0026gt;.\u003c/li\u003e\n\u003cli\u003eGuenthner AJ, Khombhongse S, Liu W, Dayal P, Reneker DH, Kyu T. Dynamics of Hollow Nanofiber Formation During Solidification Subjected to Solvent Evaporation. \u003cem\u003eMacromolecular Theory and Simulations\u003c/em\u003e \u003cstrong\u003e15\u003c/strong\u003e, 87-93 (2005).\u003c/li\u003e\n\u003cli\u003ePaul DR. Diffusion during the coagulation step of wet‐spinning. \u003cem\u003eJournal of Applied Polymer Science\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 383-402 (2003).\u003c/li\u003e\n\u003cli\u003eQin H\u003cem\u003e, et al.\u003c/em\u003e Flexible nanocellulose enhanced Li+ conducting membrane for solid polymer electrolyte. \u003cem\u003eEnergy Storage Materials\u003c/em\u003e \u003cstrong\u003e28\u003c/strong\u003e, 293-299 (2020).\u003c/li\u003e\n\u003cli\u003eNiu Z\u003cem\u003e, et al.\u003c/em\u003e Recent advances in cellulose-based flexible triboelectric nanogenerators. \u003cem\u003eNano Energy\u003c/em\u003e \u003cstrong\u003e87\u003c/strong\u003e, 106175 (2021).\u003c/li\u003e\n\u003cli\u003eFan X\u003cem\u003e, et al.\u003c/em\u003e A Nanoprotein-Functionalized Hierarchical Composite Air Filter. \u003cem\u003eACS Sustainable Chemistry \u0026amp; Engineering\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, 11606-11613 (2018).\u003c/li\u003e\n\u003cli\u003ePeng Z\u003cem\u003e, et al.\u003c/em\u003e Self-charging electrostatic face masks leveraging triboelectrification for prolonged air filtration. \u003cem\u003eNature Communications\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, (2022).\u003c/li\u003e\n\u003cli\u003eZhang Y\u003cem\u003e, et al.\u003c/em\u003e Continuous air purification by aqueous interface filtration and absorption. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e610\u003c/strong\u003e, 74-80 (2022).\u003c/li\u003e\n\u003cli\u003eBrunekreef B. The continuing challenge of air pollution. \u003cem\u003eEuropean Respiratory Journal\u003c/em\u003e \u003cstrong\u003e36\u003c/strong\u003e, 704-705 (2010).\u003c/li\u003e\n\u003cli\u003eHua Y\u003cem\u003e, et al.\u003c/em\u003e Dual-bionic, fluffy, and flame resistant polyamide-imide ultrafine fibers for high-temperature air filtration. \u003cem\u003eChemical Engineering Journal\u003c/em\u003e \u003cstrong\u003e452\u003c/strong\u003e, (2023).\u003c/li\u003e\n\u003cli\u003eNiu Z\u003cem\u003e, et al.\u003c/em\u003e Electrospun Cellulose Nanocrystals Reinforced Flexible Sensing Paper for Triboelectric Energy Harvesting and Dynamic Self-Powered Tactile Perception. \u003cem\u003eSmall\u003c/em\u003e \u003cstrong\u003en/a\u003c/strong\u003e, 2307810 (2023).\u003c/li\u003e\n\u003cli\u003eLi Y, Cao L, Yin X, Si Y, Yu J, Ding B. Ultrafine, self-crimp, and electret nano-wool for low-resistance and high-efficiency protective filter media against PM0.3. \u003cem\u003eJournal of Colloid and Interface Science\u003c/em\u003e \u003cstrong\u003e578\u003c/strong\u003e, 565-573 (2020).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4142629/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4142629/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLow-value biomass materials recently can be widely used in various important industry to achieve a carbon-neutral sustainable society. To transform low-value agricultural wastes into structural materials, here we show a heterogeneous corn-based precursor technique, to self-assemble two-dimensional fabrics consisted of alternating fibers with micro- and nano-architectures. The unique solute-solvent system involves zein protein, combined with cellulose extracted from corn straw, to achieve the greenness of the production, fabrication and filtration. Manipulation of the ambient humidity and addition of the cellulose nanofibers enable a novel incomplete nonsolvent-induced phase separation, leading to a corn-based degradable and disposable sanitary filter with dual-network structure which exceeds that of typical or commercial filters. Moreover, the mechanism of full-structure filtration for particulate pollutant as well as excellent adsorption for formaldehyde is demonstrated, providing a promising pathway to green and sustainability for biomass waste.\u003c/p\u003e","manuscriptTitle":"Sustainable Biomass-based Filter for High-efficiency PM 0.3 Filtration","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-15 04:37:15","doi":"10.21203/rs.3.rs-4142629/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d9cd410c-ea66-41b0-860e-73e12f62dd29","owner":[],"postedDate":"April 15th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":30392286,"name":"Earth and environmental sciences/Environmental sciences/Environmental chemistry/Pollution remediation"},{"id":30392287,"name":"Earth and environmental sciences/Environmental social sciences/Sustainability"}],"tags":[],"updatedAt":"2025-08-07T07:08:31+00:00","versionOfRecord":{"articleIdentity":"rs-4142629","link":"https://doi.org/10.1038/s41467-025-61863-2","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2025-07-17 04:00:00","publishedOnDateReadable":"July 17th, 2025"},"versionCreatedAt":"2024-04-15 04:37:15","video":"","vorDoi":"10.1038/s41467-025-61863-2","vorDoiUrl":"https://doi.org/10.1038/s41467-025-61863-2","workflowStages":[]},"version":"v1","identity":"rs-4142629","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4142629","identity":"rs-4142629","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}