Super-magnetization of pectin from orange-peel biomass for sulfamethoxazole adsorption

Abstract: In recent decades, the release of emerging pharmaceutical contaminants has been recognized as a challenging environmental issue. This study focuses on the adsorption of sulfamethoxazole (SMX) by pectin (Pec)-based bio-adsorbent. Pec was extracted from orange peel-waste biomass (OPB) by a microwave-assisted extraction method. Further, different concentrations of Pec from OPB (Pec-OPB); 0.5, 1, 2 and 4g were super-magnetized with Fe₃O₄ nanoparticles (denoted as Fe₃O₄@Pec-OPB(0.5g), Fe₃O₄@Pec-OPB(1g), Fe₃O₄@Pec-OPB(2g) and Fe₃O₄@Pec-OPB(4g), respectively). Among these synthesized bio-adsorbents, Fe₃O₄@Pec-OPB(1g) gave significant SMX adsorption and hence studied further in detail. Surface-morphology, structure, functional-groups, magnetic-property, and elemental-composition of facile of Fe₃O₄@Pec-OPB(1g) was characterized by standard analytical techniques. Different parameters for SMX adsorption on Fe₃O₄@Pec-OPB(1g) were investigated, such as optimal pH (4.0), kinetics (best-fitted pseudo-second-order kinetic model) and isotherm models (best-fitted Redlich-Peterson model). The maximum adsorption capacity (q_m) of Fe₃O₄@Pec-OPB(1g) was 120 mg g⁻¹ of SMX. Thermodynamic analysis corroborated the endothermic nature of the adsorption process. Therefore, the nano-bio-adsorbent Fe₃O₄@Pec-OPB(1g) exhibits excellent potential for capturing the SMX from water, suggesting that Fe₃O₄@Pec-OPB(1g) could be a viable option for adsorptive reclamation of hazardous cationic pollutants from water. Graphic abstract: [Figure not available: see fulltext.]