Investigation into adsorption characteristics and mechanism of atrazine on nano-MgO modified fallen leaf biochar

In this study, MgO modified fallen leaf biochar (MgO-LBC) was prepared by slow pyrolysis method to enhance the removal of atrazine (AT) in water. Characterization analysis confirmed that nano-MgO was successfully loaded on the surface of MgO-LBC. The results of adsorption kinetics and isotherm showed that the second-order reaction kinetic and the Freundlich isotherm model could better describe the adsorption process of AT on MgO-LBC. Also, the experiments of initial pH, ionic strength and humic acid were carried out to explore its influence on the adsorption capacity of MgO-LBC to AT, and the results were as follows: compared with fallen leaf biochar (LBC), the adsorption capacity of MgO-LBC for AT was increased by 1.99-5.71 times, and had the largest adsorption capacity at pH = 4, reached 22.4 mg g(-1); MgO-LBC could also stably remove AT from aqueous in the presence of ions or humic acid, and still showed good reusability after five cycles of adsorption-desorption. Mechanism analysis showed that the increase in adsorption capacity of MgO-LBC was related to the surface functional groups of the biochar. The loaded MgO increased the hydrophilicity of MgO-LBC, thereby enhancing the hydrogen bonding and electrostatic attraction between it and AT. In general, the biochar prepared in this experiment can be used as effective adsorbents to remove AT from environmental waters.