Metformin-Embedded Biocompatible Chitosan/Poly(vinyl alcohol) Beads with Superior Adsorption Properties toward Lead(II) and Levofloxacin

In this contemporary era, chitosan has gained exceptional attention as a sustainable biopolymer in the adsorption process due to its nontoxic nature, biocompatibility, accessibility, and pH-responsive active surface charge. This study developed a high-performance chitosan/poly­(vinyl alcohol) adsorbent through metformin functionalization. The incorporation of poly­(vinyl alcohol) (PVA), along with the metformin-activated surface, remarkably ameliorated its physiochemical properties. The abundance of inter- and intrahydrogen and chemical bonds in the porous structure enhances the specific surface area up to 83.8 m2/g. Series characterization methods are utilized to investigate the adsorbents’ characteristics in all aspects and the removal performance. Furthermore, the key factors for the adsorption process, including the influence of pH, adsorbent quantity, time intervals, and preliminary concentration, were studied and optimized. The optimal pH was observed in the neutral moiety, which is crucial from an industrial perspective. Due to the presence of countless nitrogen and oxygen atom-containing backbones, the CS/PVA-Pr-Met biocomposite has demonstrated considerable adsorption capacity toward Pb­(II) ions and levofloxacin with the highest adsorption capacities of 313.162 mg/g for Pb­(II) and 2872.927 mg/g for levofloxacin concerning their molecular and ionic nature and various adsorption mechanisms. In accordance with the correlation coefficient and estimated parameters, the adsorption of Pb­(II) and levofloxacin onto the beads mostly follows the pseudo-second-order kinetics (R 2 ≥ 0.997) and the Langmuir adsorption isotherm model (R 2 ≥ 0.995). The exceptional adsorption capacity coupled with the porous structure of the modified hydrogel beads has promising applications for efficient wastewater treatment