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研究报告

Adsorption of lead and copper from aqueous solutions on biochar produced from walnut green husk

基金项目：国家自然科学基金(No.21307050);兰州大学中央高校基本科研业务费专项资金(No.lzujbky-2014-129,lzujbky-2015-214)

摘要：采用500℃限氧裂解法将农林废弃物核桃青皮制成核桃青皮生物炭,进行了核桃青皮生物炭对铅、铜的批量吸附实验.同时,利用扫描电镜、FTIR红外等方法探讨了核桃青皮炭吸附Pb²⁺、Cu²⁺的特性,探究了吸附时间、溶液初始浓度、吸附温度、吸附剂投加量、溶液初始pH等因素对核桃青皮生物炭吸附Pb²⁺、Cu²⁺作用的影响,讨论了吸附动力学特性及吸附等温特性.结果表明:温度298.15K、pH为3~6条件下,核桃青皮生物炭吸附Pb²⁺和Cu²⁺在20min内即可达到吸附平衡,核桃青皮炭最佳投加量分别为0.8、1.5g·L^-1,最大吸附量分别为476.190、153.846mg·g^-1;吸附过程符合准二级动力学方程,等温吸附曲线符合Langmuir方程,说明其吸附过程主要是近似单分子层的化学吸附.

Abstract：In this study, the adsorptions of Pb²⁺ and Cu²⁺ in aqueous solutions by biochar derived from walnut green husk at pyrolysis temperature of 500 ℃ were evaluated. The characteristics of adsorbent before and after adsorption were mainly observed by Scanning Electron Microscope and FTIR spectra. The effects of contact time, initial Pb²⁺ and Cu²⁺ concentration, temperature of experiment, adsorbent dose and initial pH in batch sorption experiments were investigated. The sorption capability was evaluated by adsorption kinetics and isotherm models. The maximum Pb²⁺ and Cu²⁺ adsorption capacity of walnut green husk biochar reached 476.190 and 153.846 mg·g^-1, respectively. The optimum adsorption conditions were found to occur at reaction time of 20 min, 0.8 (Pb²⁺), 1.5 (Cu²⁺) g·L^-1 adsorbent dose and initial pH 3~6. Furthermore, the adsorption kinetics was best fitted by the pseudo-second order model, while the adsorption equilibrium was best described by linear and Langmuir isotherms. This indicated that Pb²⁺ and Cu²⁺ ions were adsorbed onto the walnut green husk biochar by chemical interactions via monolayer.