Capacity and Modeling of Acid Blue 113 Dye Adsorption onto Chitosan Magnetized by Fe2O3 Nanoparticles

Abstract A chitosan polymer was magnetized by coating with magnetite Fe2O3 nanoparticles, and the resultant material (C–Fe2O3) was first characterized through scanning electron microscopy equipped with energy–dispersive X-ray spectroscopy, transmission electron microscopy, atomic force microscopy, thermogravimetric, X-ray diffractometry, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller, and point of zero charge analyses. C–Fe2O3 was then employed as a separable and efficient adsorptive agent to remove acid blue 113 (AB113) dye from aqueous solution. The removal efficiency was optimized at different environmental parameter values (pH: 3–11, C–Fe2O3 dose: 0.1–1 g/L, initial AB113 dye concentration: 10–100 mg/L, adsorption time: 0–300 min, and temperature: 388–318 K). Under optimum conditions, an AB113 dye removal efficiency of 99.68% was achieved. In addition, the effect of the presence of NaCl, NaNO3, Na2CO3, and MgSO4 ions on the AB113 dye removal efficiency could be ranked as NaCl > NaNO3 > MgSO4 > Na2CO3. The statistical analysis using the coefficient of determination, root mean square error, chi-square test, sum of squared errors, and average relative error showed that the Freundlich and pseudo-second-order equations were the best mathematical models for fitting the isothermal and kinetics data. Further kinetics analyses showed that the adsorption of AB113 molecules on C–Fe2O3 active sites was dominated by the intraparticle diffusion process. Thermodynamic parameters indicated that the AB113 dye adsorption process was favorable, endothermic, and spontaneous. Furthermore, an increase in temperature had a positive impact on AB113 dye removal. The regeneration study confirmed the excellent shelf life of C–Fe2O3, with only a slight loss in the removal efficiency (< 7%) being detected after six operational cycles of AB113 dye adsorption. Compared with other adsorbents, C–Fe2O3 was more effective for the adsorption of AB113 dye, with an adsorption uptake up to 128 mg/g.