Eco-friendly activated carbon developed from rice hulls for chromium and iron ion removal

Abstract
Rice hulls (RH), a harmful biowaste, was used to produce nanosized activated carbon (RHAC) by combustion and phosphoric acid treatment. The developed RHAC was characterized using various structural and morphological techniques (SEM, XRD, FTIR, and N2 adsorption). The prepared RHAC was used to remove heavy metal ions (Fe(III) and Cr(VI)) by the adsorption mechanism. Adsorption parameters, e.g., contact time, the dose, initial concentration of the heavy metals ions, were investigated. Five adsorption models (2 & 3 parameters) were studied. Also, the adsorption kinetic through the intraparticle diffusion model was applied. RHAC shows adsorption capacities of 47.00 and 45.00 mg/g for Fe(III) and Cr(VI), respectively. The findings recommend using RHAC as low-cost and eco-friendly for metal ions removal and water treatment applications.