Magnetic gelatin-activated biochar synthesis from agricultural biomass for the removal of sodium diclofenac from aqueous solution: adsorption performance and external influence

Abstract

ABSTRACT Pharmaceutical and personal care products have received increasing more attention worldwide. Diclofenac was found to be one of the most detected pharmaceuticals in environmental matrixes and has acute toxicity against micro-living organisms. The present study aimed to investigate the application of magnetic gelatin modified peanut shell biochar (PBG) as an environmentally friendly adsorbent for the removal of sodium diclofenac (DCF) in the aqueous phase. Through SEM, EDS, BET, XRD, XPS, and FTIR characterisation techniques, the surface morphology, element components, specific surface area as surface functional groups of PBG were different from the pristine biochar. Batch adsorption experiment showed that PBG performed very high DCF adsorption capacity (qmax = 348.9 mg/g at pH = 6.5, T = 298 K). The adsorption capacity was significantly affected by pH solution with a decrease trend when pH >6. The experimental results could be satisfactorily fitted by Pseudo-second order kinetic model, and Temkin isotherm model. Thermodynamic study indicated that the adsorption process was non-spontaneous and endothermic. Some external agents such as humic acid and common ions exhibited a negative effect on the removal of DCF in the co-solute system. The adsorption capacity of the PBG adsorbent remained at 71.5% even after five cycles of regeneration, which demonstrated the stability and reusability for further removal of DCF. Besides, the proposed adsorption mechanism might contain electrostatic interactions, hydrogen bonds interactions, and π-π interactions. Considering the simple fabrication approach and the excellent adsorption performance, the PBG adsorbent can be evaluated as a potential material for environmental remediation applications.