Yu Chang-Jiang, Dong Xin-Yu, Wang Miao, Lin Qiang
Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
Key Laboratory of Water Pollution Treatment & Resource Reuse of Hainan Province, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, China.
Huan Jing Ke Xue. 2018 Aug 8;39(8):3719-3728. doi: 10.13227/j.hjkx.201711274.
A microsphere (CA/BC) was prepared using biochar (BC) encapsulated with calcium alginate (CA) as a green adsorbent for Pb(Ⅱ) removal from aqueous solution. The effects of the initial Pb(Ⅱ) concentration, initial pH value of the Pb(Ⅱ) solution, and equilibrium contact time were investigated. The isothermal thermodynamic data of the BC and CA/BC conformed to the Langmuir model. The maximum adsorption capacities of the BC and CA/BC from the Langmuir equation were 93.20 mg·g and 155.04 mg·g respectively, at pH=5. The adsorption of Pb(Ⅱ) by the BC was in good agreement with the pseudo-second-order equation, indicating that chemisorption was the rate-controlling step. The adsorption of Pb(Ⅱ) by the CA/BC was in good agreement with the pseudo-first-order model, which suggested that the rate-limiting step was governed by diffusion. Mechanism studies for Pb(Ⅱ) removal by the CA/BC showed that the nature of Pb(Ⅱ) abstraction took place through ion exchange between Ca(Ⅱ) and Pb(Ⅱ) as well as via the formation of a coordination complex.
以海藻酸钙（CA）包裹生物炭（BC）制备了微球（CA/BC），作为从水溶液中去除Pb(Ⅱ)的绿色吸附剂。研究了初始Pb(Ⅱ)浓度、Pb(Ⅱ)溶液的初始pH值和平衡接触时间的影响。BC和CA/BC的等温热力学数据符合朗缪尔模型。在pH = 5时，根据朗缪尔方程，BC和CA/BC的最大吸附容量分别为93.20 mg·g和155.04 mg·g。BC对Pb(Ⅱ)的吸附与准二级方程吻合良好，表明化学吸附是速率控制步骤。CA/BC对Pb(Ⅱ)的吸附与准一级模型吻合良好，这表明限速步骤受扩散控制。对CA/BC去除Pb(Ⅱ)的机理研究表明，Pb(Ⅱ)的提取本质是通过Ca(Ⅱ)与Pb(Ⅱ)之间的离子交换以及形成配位络合物来实现的。
