Removal of Cr(VI) Using Citric Acid and Phosphoric Acid-Modified Groundnut Shells

The increasing industrialization leads to toxic pollutants in wastewater and it has a considerable impact on human health due to toxicity, accumulation, and persistence in nature. The study concentrated on the adsorption of chromium (VI) ions using groundnut shells modified with phosphoric (PA-GNS) and citric acid (CA-GNS) in aqueous solutions. Several factors were examined, encompassing contact time, pH, adsorbent dose, and initial chromium concentration, were systematically examined to understand their impact on the adsorption process. The findings revealed that, under optimized conditions of pH ۲, stirring speed at ۲۰۰ rpm, initial metal ion concentration of ۵۰ mg/۱۰۰ mL, adsorbent dose of ۱۵۰۰ mg/۱۰۰ mL solution, a contact time of ۱۲۰ minutes (۴۵ minutes for PA-GNS) for stirring, and a temperature of ۲۵°C, the maximum removal percentages for Cr(VI) were ۹۶.۹۵% and ۹۳.۶۹% for PA-GNS and CA-GNS, respectively. The biosorption of Cr(VI) ions by both PA-GNS and CA-GNS was found to conform to the Langmuir and Freundlich isotherm models. Regarding the kinetics of the adsorption process, it followed a pseudo-second-order model with rate constants of ۳.۲۵ and ۳.۳۱۱ (g/mg.min) for PA-GNS and CA-GNS, respectively.

کلیدواژه ها:

Bio-sorption ، Cr(IV) ions ، Phosphoric acid ، Citric acid ، Langmuir isotherm ، Freundlich Isotherm