【作者】 王微；

【导师】 李美萍；

【作者基本信息】 山西大学 ， 食品工程， 2019， 硕士

【摘要】 以农副产品和其他生物质为原料的生物质活性炭因其成本低、易获得、生态友好、可用性好、吸附量大等优点而受到越来越多的关注。同时,因其具有结构稳定、导电性能优良、比表面积高等优势,电化学性能测试表明其具有电极材料的良好潜力。本研究以辣木籽壳、杏仁壳、胡麻籽壳为原料,在不同活化温度（800、900、1000、1100℃）下热解制备生物质活性炭;并以KOH为活化剂对三种生物炭进行活化处理,在相同活化温度下热解制得改性后生物质活性炭。通过N₂吸脱附（BET）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）,对改性前后三种生物炭的结构与性能进行表征与分析。以改性前后辣木籽壳、杏仁壳、胡麻籽壳生物炭为吸附剂,研究不同热解温度、时间、溶液初始pH、离子浓度对生物炭吸附Cu²⁺性能的影响,并用动力学模型以及等温吸附模型对吸附过程进行拟合,研究生物炭吸附Cu²⁺的吸附机理。以改性前后生物炭为原料,将其制作成电极,对其进行恒流充放电测试和循环伏安测试,研究不同活化温度下生物炭电极材料的电化学性能。实验结果说明:1.经KOH改性后三种生物炭的比表面积较改性之前明显增大,可知用KOH对生物炭进行改性有助于其孔隙结构的生成;改性前后辣木籽壳、杏仁壳、胡麻籽壳生物炭中主要含有羧基、羟基、羰基等亲水性官能团。XRD测试结果表明,制得的生物炭呈无定形结构,具有典型的类石墨结构。2.经KOH改性后的生物炭对Cu²⁺的吸附效果较改性之前有明显提高。改性前辣木籽壳、胡麻籽壳生物炭的吸附行为符合Langmuir等温吸附模型,杏仁壳生物炭对Cu²⁺的吸附效果更符合Freundlich等温吸附模型;改性之后三种生物炭对Cu²⁺的吸附效果更符合Langmuir等温吸附模型。准二级动力学更接近改性前后辣木籽壳、杏仁壳、胡麻籽壳生物炭对Cu²⁺的吸附过程。3.电化学测试结果表明,在6 M KOH电解液中,三种生物炭作为电极材料具有良好的电化学性能。经KOH改性后生物炭的比电容值明显高于未改性的生物炭,在0.15 A/g的电流密度下,辣木籽壳、杏仁壳、胡麻籽壳生物炭分别在800、800、900℃下获得最大比电容值,由改性前的447.33、505.83、271.33 F/g提高到改性后的571.09、790.56、825.29 F/g。循环伏安测试结果表明,辣木籽壳、杏仁壳、胡麻籽壳生物炭的循环伏安曲线呈现良好的类矩形形状,表明其具有良好的电容性能。更多还原

【Abstract】 Biomass activated carbon based on agricultural by-products and other biomass is receiving more and more attention because of its low cost,easy availability,eco-friendliness,availability,and large adsorption capacity.Meanwhile,due to its structural stability,good electrical conductivity and high specific surface area,electrochemical performance tests show its good potential for electrode materials.In this research,the biomass activated carbon was prepared from moringa seed shell,almond shell and sesame seeds shell by pyrolysis at different activation temperatures（800,900,1000,1100 ℃）.At the same time,Modified biomass activated carbon was obtained from moringa seed shell,almond shell and sesame seeds shell by pyrolysis at the same activation temperature,using potassium hydroxide as activator.Nitrogen adsorption-desorption（BET）,X-ray diffraction（XRD）and fourier transform infrared spectroscopy（FTIR）were used to study surface area and pore structure of biomass activated carbon before and after modification prepared at different temperatures.Biomass activated carbon before and after modification were utilized for the removal of Cu（II）from aqueous solution in sorption experiences.The effects of activation temperature,contact time,p H value,concentration of adsorbates of Cu（II）were explored,the adsorption properties of activated carbon were investigated.Via the data of experience,adsorption kinetics and isotherm models were analyzed to speculate the adsorptive process.Meanwhile,the electrochemical performance of supercapacitor was investigated by constant current charge / discharge and cyclic voltammetry（CV）.The major research results are listed as following:The specific surface area of the three biochars by KOH activation is significantly higher than before,this is because the biochars by KOHactivation contribute to the formation of pore structure.The surface functional groups of the biomiss activated carbon were mainly hydrophilic groups,such as carboxyl,carbonyl,and hydroxyl.The XRD test results show that the biochars has an amorphous structure,with a typical graphite-like structure.For three kinds of unmodified biochars,the Langmuir isotherm model fits the experimental data of Cu²⁺ adsorption by moringa seed shell and sesame seeds shell biochars,the Freundich isotherm model fits the experimental data of Cu²⁺ adsorption by almond shell biochar.As for the modified biochar,the Langmuir isotherm model fits the experimental data of Cu²⁺ adsorption by three kinds of biochars.In addition,Cu²⁺adsorptions followed the second order kinetics model.Electrochemical test results show that three kinds of biochars exhibit good electrochemical properties as electrode materials in 6 mol/L of KOH solution.The maximum specific capacitance of 447.33、505.83、271.33 F/g is obtained respectively for moringa seed shell、almond shell、sesame seeds shell biochar before activeted at the current density of 0.15A/g.The modified carbons of moringa seed shell、almond shell、sesame seeds shell with potassium hydroxide shows enhanced electrochemical performance,the maximum specific capacitance of 571.09 、 790.56 、825.29 F/g is obtained respectively at the same current density of 0.15A/g.The cyclic voltammetry curve of biochars exhibit a good rectangular shape,indicating that it has good capacitive properties.更多还原