Efficient removal of amoxycillin antibiotics onto magnetic graphene oxide: adsorption performance, mechanism, and regeneration exploration

Abstract

ABSTRACT The present study was done to synthesise an adsorbent, i.e. magnetic graphene oxide (MGO) nanocomposite, which was performed based on a facile precipitation method and was utilised in experiments for removing amoxycillin (AMX). The characteristics of the prepared adsorbent were defined based on commonly utilised analyses (SEM, XRD, BET, TEM, FTIR, VSM, and pHpzc). According to kinetic studies, the PSO model was found as an applicable model for describing data. Moreover, the two-step diffusion process, i.e. diffusion in the boundary layer and the porous structures, was perceived for the evaluated process based on the IPD model. The isotherm models, including Langmuir, Freundlich, Temkin, and D–R, were employed for fitting data and calculating AMX adsorption capacity, among which Langmuir was the best one; using this model, the maximum adsorption capacities for MGO were 91.4, 103.9, 112.3, and 122.5 mg/g, which were achieved at 20, 30, 40, and 50°C. In addition, a feasible, spontaneous, and endothermic process was found for the adsorption of AMX ions, according to thermodynamic studies. The highest percentage of removal (100%) was obtained for the initial concentration of 25 mg/L at 50°C using the adsorbent dose of 1.5 g/L at a pH of 5 and a contact time of 90 min. The values of 74.4 m2/g and 27.74 emu/g were detected for the specific surface area and saturation magnetisation values of the MGO, respectively. The overall results were representative of the suitability of the MGO as an adsorbent for removing AMX from aqueous media.