Chen Tan, Zhou Zeyu, Han Rong, Meng Ruihong, Wang Hongtao, Lu Wenjing
School of Environment, Tsinghua University, Beijing 100084, China.
School of Environmental Science and Engineering, Chang'an University, Xi'an 710064, China.
Chemosphere. 2015 Sep;134:286-93. doi: 10.1016/j.chemosphere.2015.04.052. Epub 2015 May 15.
Static equilibrium experiments were carried out to investigate the impact factors and the mechanism of cadmium adsorption on biochar derived from municipal sewage sludge. An appropriate dosage of biochar is sufficient; in the experiment, 0.2% is the optimal dosage for the largest removal capacity, while the removal capacity of biochar reduces with the increasing dosage. pH is another dominant factor of the adsorption process. The removal capacity of biochar is lower than 20 mg·g(-1) when the solution initial pH is lower than 2 pH units, comparatively retaining more than 40 mg·g(-1) at the solution initial pH higher than 3 pH units. Temperature has weak influence on the adsorptive performance. The main mechanism of the adsorption process of biochar for cadmium mainly involves (1) surface precipitation by forming insoluble cadmium compounds in alkaline condition, and (2) ion exchange for cadmium with exchangeable cations in the biochar, such as calcium ions.
开展了静态平衡实验，以研究镉吸附到城市污水污泥衍生生物炭上的影响因素及机制。生物炭的合适用量就足够了；在实验中，0.2%是去除能力最大时的最佳用量，而生物炭的去除能力会随着用量增加而降低。pH是吸附过程的另一个主要因素。当溶液初始pH低于2个pH单位时，生物炭的去除能力低于20 mg·g(-1)，而在溶液初始pH高于3个pH单位时，去除能力相对保持在40 mg·g(-1)以上。温度对吸附性能的影响较弱。生物炭对镉的吸附过程的主要机制主要包括：(1) 在碱性条件下通过形成不溶性镉化合物进行表面沉淀，以及(2) 生物炭中可交换阳离子（如钙离子）与镉进行离子交换。
