novel bio-sorbent for arsenic removal from aqueous solution: kinetics, isotherms, and thermodynamics

Arsenic is known as a potential threat to the environment. therefore, this research aims to assess the arsenic removal efficiency from an aqueous solution, by a novel bio- sorbent based on the sour-lemon peel (slp). to treat slp, a combination of two methods (treated with mineral acids and high temperature) was used, and a designed bio-sorbent called slp-activated/ carbonized. the slp-activated and slp- carbonized were also prepared using hydrochloric acid (hcl) and 400°c temperature, respectively, to compare the results of each of the three methods. afterward, adsorption parameters such as ph, initial ion concentration, bio-sorbent dosage, contact time, and temperature were assessed. it was found that the combination method has provided a higher adsorption capacity so that, up to ~99% arsenic removal was observed with slp-activated/carbonized at ph of 7.0 and 40°c. the adsorption capacities for slp- carbonized and slp-activated were 87.92% (ph:7, 60°c) and 78.50% (ph:6, 90°c), respectively. moreover, adsorption kinetics data indicated the best fit with the pseudo-second-order model. the maximum bio-sorption capacity by the langmuir isotherm model was also recorded for slp-activated/carbonized (53.47 mg/g). notably, arsenic adsorption on studied bio-sorbents takes place spontaneously and through chemisorption along with the endothermic nature of the bio-sorption process and reduction of random collisions in the solid-liquid phase.