Purification of wastewater effluent from Arsenazo III using rice husk activated carbon

Abstract

The removal of dye contaminants from aqueous systems is a significant environmental challenge. In this study, activated carbon derived from rice husk (RH-Ch4) was synthesized via phosphoric acid activation followed by steam treatment and evaluated for Arsenazo III removal from aqueous media. Characterization techniques, including BET, FTIR, SEM/EDX, and TGA, confirmed the production of a meso-and micro- porous carbon structure with active functional groups contributing to adsorption. The adsorption results demonstrated that optimum Arsenazo III removal by RH-Ch4was at pH 5 and 298 K. Kinetic analysis revealed that kinetic data showed excellent agreement with the pseudo-second-order model. Equilibrium studies indicated that the Langmuir isotherm provided the best description of the adsorption system, with a maximum theoretical capacity of 86.73 mg/g. The adsorbent exhibited high selectivity and demonstrated effective regeneration using alkaline desorption. Thermodynamic analysis demonstrated that the Arsenazo III removal from aqueous media using RH-Ch4 is spontaneous and endothermic, with characteristics consistent with physisorption. Application to real wastewater samples further confirmed its practical applicability. Desorption experiments confirmed the potential reusability of the RH-Ch4 adsorbent using alkaline treatment. Application of the prepared RH-Ch4 to real wastewater samples demonstrated high removal efficiency, indicating its suitability as an inexpensive and sustainable adsorbent for dye-contaminated wastewater treatment.