Effects of biochar on adsorption of nofloxacin in tropical soils

A series of biochar were prepared by pyrolyzing sugarcane bagasses，a typical tropical agricultural wastes，at three different pyrolysis temperatures（350，450，550℃），which were referred as BC350，BC450 and BC550. The effects of biochar on adsorption of nofloxacin on Latosols and the dominant mechanism of nofloxacin environmental behavior in biochar soils were studied. Results showed that adsorption on Latosols and biochar-amended soils（W/W，1.0%）included two steps，the fast reaction and the slow reaction. The adsorption kinetics of nofloxacin on Latosols and biochar-amended soils（W/W，1.0%）accorded with the pseudo-second-order kinetics equation（r ≥ 0.963，P ＜ 0.01）. When biochar amendment rates were set as 0.1%，0.2%，0.5%，0.8% and 1.0%（W/W）of soils， it could significantly increase the adsorption of nofloxacin on Latosols，and the adsorption quantity increased with the increasing quantity of biochar. The single-point adsorption values of nofloxacin on biochar-amended soils were 1.04-2.34 times higher than the on Latosols. The adsorption and desorption data over the entire range of antibiotics concentrations were well described by the Freundlich equation，Langmuir equation and Tekmin equation with r ≥ 0.910 and P ＜ 0.05. Mechanism of adsorption of nofloxacin on biochar-amended soils included surface adsorption，partition and other weak forces. Application of biochar in soil could increase the adsorption of organic pollutant in soil to decrease the ecology risk.