【摘要】 以法国梧桐叶片和枝条为原料在500℃下通过限氧裂解法制成生物质炭,进而采用批量吸附法探究了不同溶液初始pH、吸附时间、溶液初始Pb²⁺浓度对生物质炭吸附效果的影响,并通过拟合吸附动力学曲线和吸附等温线方法初步研究吸附机理。结果表明,与法国梧桐枝条炭相比,叶片炭矿质元素组成相对较为复杂,官能团种类较丰富。2种生物质炭均在吸附时间为24 h时、初始pH为5时达到最大吸附量,叶片炭的最大吸附量比法国梧桐枝条炭高25.6%。2种生物质炭的动力学吸附过程均符合准二级动力学方程,表明吸附速率主要受化学因素控制;2种生物质炭的吸附等温线更符合Langmuir模型,吸附以单分子层为主,也存在层间扩散的多分子层吸附。综上所述,2种生物质炭均能较好地吸附水溶液中的Pb²⁺,叶片炭的吸附效果比枝条炭更明显,在实际生产中可以将法国梧桐修剪枝和落叶炭化后用于铅污染水体修复。更多还原

【Abstract】 In the present study, two biochars derived from Platanus orientalis Linn branches and leaves respectively were prepared by pyrolysis at the temperature of 500 ℃ under the oxygen-limited condition. The batch equilibration method was used to determine the effects of different factors, such as contact time, initial Pb²⁺ concentration and initial solution pH on Pb²⁺ adsorption capacity on the biochars. The characteristics of adsorption isotherms and adsorption kinetics were analyzed to reveal associated mechanisms. The results showed that the mineral elements and functional groups were more abundant in the leaf biochar than those in the branch biochar. The maximum adsorption of Pb²⁺ on both biochars occurred at the initial pH 5 after 24 hours, and the adsorption capacity of the leaf biochar was 25.6% greater than that of the branch biochar. The adsorption of Pb²⁺could be described well by the pseudo-second-order kinetics, indicating that the adsorption process was mainly controlled by precipitation. The adsorption isotherms demonstrated that the adsorption of Pb²⁺ to the biochars fitted Langmuir model better than Freundlich model. Therefore, monolayer adsorption was proposed as the dominant adsorption process, although the multilayer adsorption was also present. In conclusion, both biochars had good capacity for adsorption of Pb²⁺ in water, and the leaf biochar was more effective than the branch biochar.更多还原