Effect of Corn Stalk Biochar on the Adsorption of Aureomycin from Sierozem

In order to study the effect of biochar (BC) addition on the adsorption of aureomycin (CTC) fromsierozem (HGT), BC was prepared from corn stalks at 200, 400, and 600℃, respectively. The adsorption behavior of CTC on HGT and HGT+BC was studied using the batch equilibrium method. The results showed that the equilibrium time of CTC adsorption by HGT was 240 min, and the equilibrium time was relatively prolonged by adding BC, which was in line with the pseudo-second-order adsorption kinetic model. The overall adsorption rate of CTC was controlled by both surface diffusion and intra-particle diffusion, the surface diffusion rate was faster, and the hydrophobic distribution promoted the adsorption. The adsorption of CTC in HGT and HGT+BC showed a good correlation among the three isothermal adsorption models. The addition of BC increased the adsorption distribution coefficient Kd value of HGT to CTC, and the affinity was enhanced. The difference of distribution coefficient Kd at different temperatures indicates that the adsorption process is an exothermic reaction. The results revealed different adsorption isothermal lines (L and S type) and the heterogeneity of chemical adsorption in the complex adsorption process, along with the electrostatic force and hydrogen bond interaction in the surface adsorption and physical adsorption. When the pH=3, CTC+ combined with negative sites on the surface of the soil large, cation exchange and electrostatic attraction, the adsorption capacity was the largest. The pH increased, and the CTC existence form changed, weakening the adsorption ability of HGT and BC. BC always enhanced HGT under CTC adsorption at various pHs, and the greater the amount added, the greater the CTC adsorption distribution coefficient Kd values. Adsorption is the result of the joint action of organic matter content, mineral composition, physical and chemical properties, CTC form, and HGT and BC environmental factors. Studies have shown that the appropriate addition of BC has a positive effect on the adsorption of CTC by HGT, and the effect is most significant when the pyrolysis temperature is 200℃, which can effectively promote the adsorption and fixation of CTC by HGT. © 2021, Science Press. All right reserved.