Adsorption of antibiotics by polydopamine-modified salecan hydrogel: Performance, kinetics and mechanism studies

This study investigated the preparation, characterization, and capacity of polydopamine-modified salecan hydrogel (PMSH) to remove antibiotics from aqueous solutions. The incorporated polydopamine enabled the physical properties of PMSH to be regulated and enhanced the antibiotic adsorption capacity. The antibiotics adsorption by PMSH3 was relatively fast, reaching equilibrium within 10 h with the maximum adsorption capacity of 134.85, 134.65, and 82.24 mg/g for chlorhexidine acetate, minocycline, and erythrocin, respectively. The pseudo-second-order model exhibited the best kinetic fitting data, suggesting that all the PMSH3 adsorption sites had an equal affinity for the antibiotics and that the adsorption process was chemical. The Freundlich model best described the isotherm adsorption of antibiotics, and adsorption on PMSH3 was multilayer adsorption. The antibiotics were adsorbed on the PMSH3 through hydrogen bonding, electrostatic and π-π interactions based on the changes observed in the FTIR spectra and zeta potential of PMSH3 after adsorption. Moreover, it is found that PMSH3 possesses superior recyclability and biocompatibility. Also, antibiotics regenerated by PMSH3 showed high antimicrobial properties toward Staphylococcus aureus and Escherichia coli. Altogether, our data demonstrate that the proposed strategy has the potential as an antibiotic adsorbent for sustained wastewater treatment.