Metolachlor Adsorption by Walnut Shell Biochar with the Different Contents of Kaolin in Soil

Abstract

Walnut shell biochar (WBC) was used to adsorb metolachlor (MET) in soils with different kaolin contents. 0%, 10%, and 20% of kaolin were added to the pretreated soil to prepare experimental soil. Adsorption kinetics, pH value, adsorbent dosage, ionic strength, and isotherm adsorption models are all used to characterize the adsorbent, and the removal effects of WBC on MET in different experimental soils were studied. The saturation adsorption capacities of MET on WBC in the soil with 0%, 10%, and 20% kaolin are 39.38, 44.44, and 52.08 mg g−1, respectively, according to the fitting findings of the Langmuir isotherm model. In the experiment, the kaolin can increase the adsorption of MET by the soil itself and promote the MET adsorption by WBC. This study provides a theoretical basis for minerals’ influence on the adsorption of biochar under natural conditions.