Abstract: A novel approach was used to prepare engineered biochar from banana stem pretreated with KMnO₄ through slow pyrolysis(600℃). The physicochemical properties of biochar were characterized. Batch adsorption experiments were conducted to investigate the effect of pH values,contact time,temperature and initial Cu²⁺ concentration on the adsorption efficiency and behaviors. The adsorption types were analyzed from the aspects of kinetic,isotherms,and thermodynamic. The results showed that the engineered biochar surface was covered with MnO_x ultrafine particles. In comparison to the pristine biochar,the engineered biochar had more surface oxygen-containing functional groups and much larger surface area. The removal of the metals by the engineered biochar was mainly through surface adsorption mechanisms involving both the surface MnO_x particles and oxygen-containing groups. The biochar had strong adsorption ability to Cu²⁺ with maximum adsorption capacities of 81.36mg/g in experiments,which was significantly higher than that of the pristine biochar. The adsorption process was consistent with the pseudo-second-order model. The process was better described by the Langmuir isotherm model. ΔG⁰ was negative and ΔH⁰ was positive,indicating spontaneous and endothermic adsorption.

Key words: banana stem, biochar, copper ion, adsorption

摘要： 香蕉茎秆经过高锰酸钾氧化预处理后于600℃缓慢热解制得生物炭。采用扫描电子显微镜（SEM）、X射线光电子能谱（XPS）、元素分析仪和比表面积及微孔分析仪对生物炭进行表征，批量吸附实验考察其对Cu²⁺的吸附特性，研究pH、吸附时间、吸附温度和金属离子初始浓度对吸附的影响。从吸附动力学、吸附等温线、吸附热力学判断吸附类型。结果表明：与未处理香蕉茎秆生物炭对比发现，氧化预处理生物炭表面覆盖有MnO_x微粒，且含有更多的含氧官能团，拥有更大的表面积。其对铜离子的去除主要通过表面吸附包括表面MnO_x颗粒和含氧官能团，对Cu²⁺有很强的吸附能力，实验中最大吸附容量为81.36mg/g，吸附效果明显好于未预处理生物炭，吸附过程符合准二级动力学方程，可以用Langmuir吸附等温线模型来描述，热力学参数ΔH⁰>0，ΔG⁰<0，表明该吸附是一个自发的吸热过程。

关键词: 香蕉茎秆, 生物炭, 铜离子, 吸附