Microemulsion-driven synthesis of magnetic layered-bacterial cellulose biochar integrated gelatin-chitosan beads for targeted pharmaceutical remediation.

Abstract

The increasing emergence of pharmaceutical pollutants in aquatic environments demands the advancement of adsorbents that simultaneously provide high removal performance, rapid uptake, and facile regeneration. Herein, magnetically recoverable Fe3O4-anchored layered bacterial cellulose biochar integrated gelatin-chitosan beads (Fe3O4@LBCB-Gel-CS) were fabricated through a microemulsion-assisted crosslinking strategy for the removal of paracetamol (Para) and sulfamethoxazole (SMX). Optimization studies identified 0.1 g.L-1 adsorbent dosage, pH 5-6, and a exposure time of 70 min as the ideal conditions, under which the adsorption capacities reached 1033.87 mg.g-1 for Para and 1272.33 mg.g-1 for SMX. Model fitting demonstrated that equilibrium was best represented by the KC isotherm (R2 ≈ 0.990), whereas the Bangham (R2 ≥ 0.990) and PFO (R2 ≥ 0.988) models provided the best fits to the adsorption kinetics. The negative ΔG° (-24.31 to -24.05 kJ.mol-1 for Para; -27.74 to -27.02 kJ.mol-1 for SMX) together with ΔH° values of -29.76 and - 42.10 kJ.mol-1, respectively, indicate the spontaneous and exothermic nature of the adsorption process. The adsorption process was likely influenced by the combined contribution of H-bonding, π-π interactions and Fe-assisted interactions. The beads retained 91.8% (Para) and 72.6% (SMX) of their initial performance over eight regeneration cycles and maintained removal efficiencies above 91% and 96%, respectively, in the presence of competing ions (100 mM). Benchmarking the adsorbent using a multi-parameter approach, through the simultaneous achievement of high adsorption capacity, minimal dosage requirements, rapid kinetics, and a near-neutral environment, highlighted the overall performance of Fe3O4@LBCB-Gel-CS and its potential for the development of next-generation adsorbents.