玉米秸秆生物质炭对外源金霉素的吸持与解吸

Retention and Desorption of Exogenous Chlortetracycline(CTC) on Corn-Straw Derived Biochar

【目的】针对环境中抗生素污染日益严重的问题,通过室内分析试验研究玉米秸秆生物质炭对外源金霉素的吸持与解吸特性,以期为合理处理含金霉素废水和消减畜禽粪便中四环素类抗生素污染提供理论参考和技术支持。【方法】采用OECD Guideline106批平衡方法研究了玉米秸秆生物质炭对金霉素的吸持动力学和吸持解吸热力学特征。【结果】玉米秸秆生物质炭对金霉素的吸持动力学过程包括快速反应和慢速平衡两个阶段,适合用伪二级动力学方程进行拟合(平均R2为0.9999),反应进行12 h时基本达到吸持平衡;不同温度下吸持等温线能用Freundlich方程进行很好地拟合(平均R2为0.9174),玉米秸秆生物质炭对金霉素有很大的吸持容量(lgKf为3.6575—3.7377)和吸持强度(1/n为0.8647—1.0478),且均随温度升高而增大,吸持等温线随温度升高由"L"型逐渐趋于线型;生物质炭对金霉素的吸持作用是自发进行的、熵推动的吸热过程,主要吸持机制为物理吸持;金霉素在生物质炭上的解吸率为2.57%—6.99%,且随环境温度的升高显著降低。【结论】玉米秸秆生物质炭能够强烈吸持溶液中的金霉素且解吸率较低,因此玉米秸秆生物质炭对外源金霉素有很好的去除效果。

【Objective】 In order to reduce chlortetracycline （CTC） pollution from waste water and animal dung, the retention and desorption characteristics of exogenous CTC onto the corn-straw derived biochar were studied. 【Method】The OECD Guideline106 batch equilibrium method was used to study the adsorption kinetics and adsorption-desorption thermodynamic characteristics of CTC onto the corn-straw derived biochar. 【Result】 The results showed that the retention kinetics of CTC onto the tested biochar included two stages of rapid response and slow balance. Twelve hours was taken to reach the retention equilibrium. The retention behavior of CTC onto the tested biochar fitted second-order kinetics model （average R2 is 0.9999） well. The retention isotherm at different temperatures fitted Freundlich model （average R2 is 0.9174） well. The adsorption capacity （lgKf = 3.6575-3.7377） and the adsorption intensity （1 / n = 0.8647-1.0478） were both high and became higher as temperature increasing. The shape of adsorption isotherm gradually changed from L-shaped to linear as temperature increasing; the retention of CTC onto the tested biochar was a spontaneous endothermic process and the main mechanism was physical retention. The desorption rate of CTC on the tested biochar varied from 2.57% to 6.99% and decreased with the temperature increasing, which meant the retention of CTC on the corn-straw derived biochar was more firm when increase the temperature.【Conclusion】As the tested corn-straw derived biochar can strongly absorb the CTC and the desorption rate was relative low, so that the tested corn-straw derived biochar has a good removal efficiency of exogenous CTC in aqueous phase.