硝酸改性秸秆水热炭结构表征与铅吸附机制研究  

Structure Characterization and Pb^(2+) Adsorption Mechanism of Nitric Acid Modified Hydrochars from Straw

作　　者：董良杰[1] 李金铭 赵博骏 王艺婷 陈光[3] 刘冬冬 DONG Liangjie;LI Jinming;ZHAO Bojun;WANG Yiting;CHEN Guang;LIU Dongdong(College of Engineering and Technology,Jilin Agricultural University,Changchun 130118,China;Department of Chemical and Biochemical Engineering,Western University,London N6A5B7,Canada;Key Laboratory of Straw Biology and Utilization,Ministry of Education,Jilin Agricultural University,Changchun 130118,China)

机构地区：[1]吉林农业大学工程技术学院,长春130118 [2]韦仕敦大学化学与生化工程系,伦敦N6A5B7 [3]吉林农业大学秸秆生物学与利用教育部重点实验室,长春130118

出　　处：《农业机械学报》2021年第5期267-278,共12页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(51806080);中国博士后科学基金项目(2020M681053);2020年度吉林省博士后科研人员择优资助项目;吉林省教育厅“十三五”科学技术项目(JJKH20200325KJ)

摘　　要：以玉米秸秆为原料,采用不同质量分数(10%和30%)的硝酸溶液在水热炭化前、后对样品进行改性处理,结合理化结构表征以及等温吸附模型、吸附动力学模型的拟合结果,探究了硝酸改性秸秆水热炭对铅离子的吸附机制。结果表明,经硝酸改性处理的秸秆水热炭均会形成丰富的含氧基团,水热炭化前,经HNO_(3)改性的秸秆炭(10%N-JG和30%N-JG)呈现粗糙多孔的表面形貌和发达的中孔结构,并形成了三维无序的大尺寸微晶结构;水热炭化后,经HNO_(3)改性的秸秆炭(JG 10%N和JG 30%N)产生了大量分布均匀、尺寸相近的微孔,并形成了三维有序的小尺寸微晶结构。通过对比发现,10%N-JG和30%N-JG对铅离子吸附效果最优,分别在3.5 h和3 h达到吸附平衡,理论最大吸附量可达247.51 mg/g和280.09 mg/g。10%N-JG和30%N-JG均符合准一级、准二级动力学模型以及Freundlich等温吸附模型,说明物理扩散和化学吸附在铅离子吸附过程中的作用同等重要。研究发现,秸秆水热炭主要依靠含氧官能团的化学吸附作用脱除水中的铅离子,其发达的中孔结构更有利于铅离子进入颗粒内部,增大了内部孔道上含氧基团对铅离子的捕捉机率,从而保证了水热炭对铅离子的高效吸附。Corn straw was used as raw material,and different concentrations(10%and 30%)of HNO_(3) were used to modify the samples before/after hydrothermal carbonization.Pb^(2+)adsorption mechanism of hydrochars modified by HNO_(3) was studied by the results of the structure characterization,isotherm adsorption model and adsorption kinetics model.The results showed that hydrochars modified by HNO_(3) could form rich oxygen-containing groups.Straw carbon modified by HNO 3 before hydrothermal treatment(10%N JG and 30%N JG)presented rough porous surface morphology and developed mesoporous structure,forming three-dimensional disordered large-scale microcrystalline structure.Straw carbon modified by HNO 3 after hydrothermal treatment(JG 10%N and JG 30%N)produced a large number of micropores with uniform distribution and similar size,forming three-dimensional ordered small-size microcrystalline structure.10%N JG and 30%N JG had the best Pb 2+adsorption efficiency in all samples,they could reach adsorption equilibrium at 3.5 h and 3 h,respectively,and their theoretical maximum adsorption capacities were 247.51 mg/g and 280.09 mg/g.Pb^(2+)adsorption of 10%N JG and 30%N JG was in accordance with pseudo first and second-order kinetic model and Freundlich isotherm adsorption model,indicating that physical diffusion and chemical adsorption were equally important in Pb 2+adsorption.It was found that hydrochars mainly depended on the chemical adsorption of oxygen-containing functional groups to remove Pb^(2+)from water.The well-developed mesoporous structure was more conducive to Pb 2+entering into the particles,which increased the capture probability of oxygen groups on the internal channels to Pb^(2+),and ensured the efficient adsorption of Pb^(2+)by hydrochars.

关 键 词：秸秆 水热炭 硝酸 结构特性 铅吸附 

分 类 号：S216[农业科学—农业机械化工程]