Thiol and amino co-grafting modification of sugarcane bagasse lignin nanospheres to enhance the adsorption capacity of cadmium ion

Divalent cadmium ions in the water environment are a serious threat to human health. The purpose of this study is to develop a biodegradable bio-adsorbent based on bagasse lignin and can effectively adsorb cadmium ions. In this study, it was found that the thiol amino co-grafted lignin nanospheres (TALNPs) had been successfully prepared by the Mannich reaction system, and the performance tests indicate that TALNPs have good adsorption potential. The evaluation experiment shows that factors such as pH value, dosage, time, initial concentration, and temperature significantly affect the ability of TALNPs to adsorb cadmium ions. The simulation calculation of isothermal adsorption experiment shows that the adsorption of cadmium ions follows the Langmuir model, and the adsorption kinetics is pseudo-second order. Compared with unmodified lignin, the ability of TALNPs has increased by about 3.5 times. Using XPS to analyze the structure of TALNPs in the adsorption and desorption process shows that only the bridge bond changes, indicating that it is a relatively stable adsorbent and can be reused. In general, the design strategy of thiol-amino co-grafting to modify lignin nanospheres can enhance the adsorption of cadmium ions, and also provide a new way for the development and utilization of bagasse lignin.