Removal of cationic dyes in single as well as binary dye systems from aqueous solution using Zinc ferrite-rice husk silica composite.

Magnetic green adsorbents have been gaining importance in wastewater treatment field due to their versatile properties. In this study, a novel magnetic green adsorbent Zinc Ferrite-Rice Husk Silica (ZFN-RHS) composite has been prepared by extracting silica from rice husk. ZFN-RHS is characterised using variety of techniques which includes FESEM, FT-IR, XRD, BET, pHzpc and EDS. Effect of various parameters like time, concentration, pH, adsorbent amount and temperature was assessed using the batch adsorption method to remove cationic dyes (Methylene Blue and Crystal Violet) from aqueous solution in single as well binary dye solutions. Results showed that Lagergren pseudo-second order kinetic model best fitted with the adsorption data indicating chemisorption. In adsorption isotherm study, Freundlich as well as Langmuir adsorption isotherms fitted better than other isotherms. Maximum adsorption capacities for removal of CV and MB dyes in this study have been found to be 138.8 and 84.8 mg/g respectively. From the positive values of ΔH°, it has been observed that the process of removal of MB and CV from aqueous solution using ZFN-RHS was endothermic in nature and the negative ΔG° values confirmed the spontaneous nature of the process. Regeneration studies were also conducted with significant outcomes in five cycles. The research study revealed that ZFN-RHS can be used as an adsorbent to remove other cationic dyes also. [ABSTRACT FROM AUTHOR]