Study on the preparation of amino Salix powder and its adsorption properties for chlortetracycline

Natural materials were used to remove chlortetracycline (CTC) pollution from water in an environmentally friendly and efficient manner. Salix psammophila powder (SPP) was, therefore, amino-modified to enhance its ability to adsorb CTC. The results indicated that the optimal modification effect on amino Salix powder (ASPP) was achieved when the amount of NaOH added was 1.5 g, the amount of NH₄Cl was 1.5 g, the volume of PEI was 25 mL, and the pH of the modified solution was maintained within the range of 8 to 9. The maximum adsorption capacity of ASPP for CTC reached 288.76 mg/g. By fitting the pseudo-first-order and pseudo-second-order kinetics, it was determined that chemical adsorption was the primary mechanism rather than physical adsorption. Simultaneously, through fitting three isotherm models, it was observed that ASPP’s adsorption of CTC adhered to the Freundlich isotherm model, indicating multi-molecular layer adsorption. SEM, FT-IR, and XRD analyses were utilized to characterize SPP, ASPP, and ASPP after CTC adsorption. It was observed that the surface morphology of ASPP changed, becoming filled with CTC molecules. Additionally, the modified functional groups were successfully introduced, altering the crystal structure of ASPP.