Abstract:In order to determine the feasibility of biochar to repair glyphosate-contaminated soil, the adsorption effect of soil on glyphosate was studied by adding different proportions and types of biochar to the soil. After adsorption kinetics fitting, isothermal adsorption analysis and infrared spectroscopy were used. The results showed that glyphosate was strongly adsorbed in soil, rice husk carbon, bamboo charcoal and bamboo fillet carbon. Compared with soil, the other three biochars had the shorter adsorption equilibrium time. Adsorption kinetics conformed to the quasi-second-order kinetic equation, and isothermal adsorption conformed to the Freundlich adsorption isotherm equation. In the Freundlich adsorption isotherm equation, all 1/n values were < 1, which showed that the adsorption of glyphosate by soil and three biochars was non-linear, and the degree of non-linearity was bamboo fillet carbon > bamboo charcoal > red soil > rice husk carbon. Adding biochar to red soil could increase the adsorption of glyphosate in red soil. The higher the ratio of biochar addition, the higher the amount of glyphosate adsorbed by the soil. When the proportions of biochar added in soil were the same, bamboo charcoal was added to red soil to make the highest amount of glyphosate adsorbed on soil, followed by bamboo charcoal, and rice husk charcoal. The infrared spectra before and after the adsorption of glyphosate by three biochars demonstrated that phenol, amine, aromatic hydrocarbon, carboxylic acid, carboxylate and adipoether played the important role in the adsorption process.