Adsorption of sulfamethoxazole in an aqueous environment onto a novel magnetic sporopollenin-cellulose triacetate.

Abstract

Antibiotics are emerging environmental contaminants posing critical health risks due to their tendency to concentrate in living things and eventually infiltrate the human body. Sulfamethoxazole (SMZ) is among the commonly detected antibiotics in wastewater requiring effective removal approach. A sustainable, thermally stable and easily separable magnetic sporopollenin-cellulose triacetate (Msp-CTA) was developed via a simple step synthesis for eliminating SMZ from aqueous solution. The assessment of Msp-CTA characteristics via instrumentations revealed a mesoporous adsorbent having COO-, -OH, CO, and Fe - O as its potential adsorption binding sites. Improved stability gained from blending sporopollenin (Sp) and cellulose triacetate (CTA) was affirmed through TGA analysis. Minimal competition for the adsorption sites by H⁺ and OH^- favours efficient SMZ adsorption onto Msp-CTA at pH 3 and 5 with %removal of 78.7 and 83.1 %, respectively, using 40 mg/L initial SMZ concentration. The monolayer adsorption capacities 15.14 and 15.52 mg/g were obtained from nonlinear and linear Langmuir isotherms, respectively. The adsorption process is best described by Temkin > Hill > Langmuir > Freundlich isotherms based on proximity of correlation coefficient R² to 1. The best fit to Temkin suggests that SMZ adsorption's energy decreases proportionally with increasing surface coverage of Msp-CTA. The adsorption process is arbitrated to conform best to pseudo-second order (PSO) kinetic, though a bias is perceived in the linear fitting. Msp-CTA shows reusable potential with 65.9 % desorption at third cycle. The thermodynamic studies revealed an endothermic process. Hence, Msp-CTA demonstrates potential as an alternative adsorbent for sulfonamide-based antibiotics' removal from wastewater.