生物炭对Cu^(2+)的吸附特性及其影响因素

Cu^(2+) Adsorption Characteristic of Biochar and Its Influential Factor

[目的]研究生物炭对溶液中Cu2+的吸附特性及其影响因素。[方法]采用玉米秸在不同温度(200、350、700℃)下制备的生物炭(BC200、BC350、BC700)吸附Cu2+,探讨在不同初始浓度、吸附时间、pH、Zn2+强度条件下对Cu2+的吸附特性。[结果]随着热解温度的升高,生物炭的pH和灰分含量增加。BC350具有最大的CEC和有机碳含量。3种生物炭对Cu2+的吸附能力大小为:BC350>BC700>BC200;拟合得到的BC200、BC350、BC700的最大吸附量分别为17.1、30.6、27.2 mg/g。可以用准一级动力学模型较好地描述吸附动力学结果,BC200、BC350、BC700拟合得到的平衡吸附量与实测值接近。生物炭的铜吸附量随着溶液初始pH的增加而增大;较高的陪伴Zn2+浓度可以显著降低生物炭对Cu2+的吸附。[结论]该研究可为生物炭在环境科学中合理应用提供科学依据。

[ Objective ] The research aimed to study the adsorption characteristic of biochar on Cu2＋ and its influential factor. / Method I Corn straw was carbonized at varying temperature （200,350,700 ℃） to prepare three types of biochar （BC200, BC350, BC700）. The effects of initial Cu2＋ concentration, contact time, pH, ionic strength of Zn2＋ on the removal of Cu2＋ by biochar were investigated. [ Result ] The results showed that pH and ash content of biochar gradually increased with increasing pyrolysis temperature. Compared with BC200 and BC700, B350 had the largest CEC and organic carbon content. Ca2＋ adsorption capacity of biochar followed the order： BC350 〉 BC700 〉 BC200. The maximum sorption capacity of BC200, BC350, and B700 obtained by nonlinear fitting were 17.1,30.6, 27.2 mg/g. Adsorption kinetic curve fit- ted well with pseudo-first-order kinetic equation, and the equilibrium absorption capacity of BC200, BC350, and BC700 were 10.3, 23.2, 18.1 mg/g, which were similar to the measured adsorption capacity. Cu2＋ adsorption by biochar increased with increasing solution pH. Cu2＋ adsorption capacity of biochar decreased significantly when ionic strength of Zn2＋ was at a high level. [ Conclusion ] This research could offer scientific basis for reasonable application of biochar in environmental science.