Preparation of Chitosan-Modified Bentonite and Its Adsorption Performance on Tetracycline

In this study, chitosan-modified bentonite was synthesizedusingthe coprecipitation method. When the Na2CO3 contentwas 4% (weight of soil) and the mass ratio of chitosan to bentonitewas 1:5, the adsorption performance of the chitosan/bentonite compositewas best. The adsorbent was characterized by scanning electron microscopy,X-ray diffraction, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Tellermeasurement. Various characterization results demonstrate that chitosansuccessfully entered the bentonite interlayer and increased layerspacing but did not modify bentonite's laminar mesoporous structure,and the -CH3 and -CH2 groups ofchitosan appeared on chitosan-modified bentonite. Tetracycline wasused as the target pollutant in the static adsorption experiment.The adsorption capacity was 19.32 mg/g under optimal conditions. Theadsorption process was more consistent with the Freundlich model andthe pseudo-second-order kinetic model, indicating that it was a nonmonolayerchemisorption process. The adsorption process is a spontaneous, endothermic,entropy-increasing process, according to thermodynamic characteristics.