Sodium Alginate/Carboxymethyl Chitosan Hydrogel Microbeads for Antibiotic Adsorption in Single and Binary Systems

The use of pharmaceuticals to treat human and animal diseases has resulted in the increase of antibiotic traces in the water system and soil, thus raising concerns about the environmental aspect. In this study, sodium alginate (SA) and carboxymethyl chitosan (CMCS) hydrogel microbeads were developed to enhance the adsorption of antibiotics by applying electrostatic spray in the fabrication of microbeads. Two hydrogel microbead sizes, SC-400 (~400 µm) and SC-2000 (~2000 µm), were used for the adsorption of tetracycline (TC) and ciprofloxacin (CIP) antibiotics in single and binary systems. The microbeads exhibited a good adsorption capacity and were able to achieve a maximum adsorption at pH 7 and 25 °C. Adsorption kinetics expressed suitability in the pseudo-second-order kinetic model for TC and CIP antibiotics. These results demonstrate that both single and binary systems align well with the Freundlich and Temkin isotherm models, indicating their suitability in explaining the adsorption mechanisms. These mechanisms predominantly involve electrostatic interactions between the SA/CMCS hydrogel microbeads and the antibiotics TC and CIP. This study highlights the capability of using SA/CMCS hydrogel microbeads for antibiotic removal and other environmental applications.