Abstract
A chemically exfoliated graphene, functionalized with hydroxide, was prepared and used as an adsorbent for the removal of amoxicillin from aqueous solutions. This nanocomposite was recovered from chemically exfoliated graphite rods present in spent zinc-carbon batteries. The graphene-OH was determined to have a sheet-like morphology with high surface area (As,BET = 181 m2 g-1) . Its adsorption characteristics were observed at different adsorption time, initial amoxicillin concentrations, and adsorbent dosage to establish the kinetics, isotherm, and optimal adsorption conditions. Pseudo-first-order and pseudo-second-order models were used to study the kinetics, while Freundlich and Langmuir models were used to study the adsorption isotherms. Results showed that amoxicillin adsorption fitted with Langmuir isotherm with higher correlation than the Freundlich isotherm and followed the pseudo-second-order rate model. The removal efficiency increased as the adsorbent dosage was also increased. Similarly, increasing the adsorbent dosage from 1 g/L to 20 g/L, the adsorption capacity decreased from 36 mg/g to 4 mg/g. For recyclability, the adsorptivity of graphene – OH was shown to be slightly decreasing over the 5-cycles (99.75 % to 95.37 %). Based on the results, hydroxyl-functionalized graphene demonstrated high industrial potential for amoxicillin wastewater treatment.
