微纳米粒径生物炭的结构特征及其对Cd2+吸附机制  

Structural Characteristics of Micro-nano Particle Size Biochar and Its Adsorption Mechanism for Cd2+

作　　者：马文艳 裴鹏刚 高歌 孙约兵 MA Wen-yan;PEI Peng-gang;GAO Ge;SUN Yue-bing(Key Laboratory of Original Agro-Environmental Pollution Prevention and Control,Ministry of Agriculture and Rural Affairs,Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety,Agro-Environmental Protection Institute,Ministry of Agriculture and Rural Affairs,Tianjin300191 China)

机构地区：[1]农业农村部环境保护科研监测所农业农村部产地环境污染防控重点实验室天津市农业环境与农产品安全重点实验室,天津300191

出　　处：《环境科学》2022年第7期3682-3691,共10页Environmental Science

基　　金：国家重点研发计划项目(2018YFD0800300);国家自然科学基金项目(31971525)。

摘　　要：为探究不同微纳米粒径生物炭的结构特性和对Cd^(2+)吸附性能的影响.通过筛分法和球磨法制备不同粒径(180~250、50~75和≤20μm,分别表示为BC-1、BC-2和BC-3)玉米秸秆生物炭,利用元素分析、激光粒度分析、SEM、BET、FTIR和XPS等手段对生物炭的结构进行了表征,采用静态吸附实验研究了不同初始Cd^(2+)浓度、吸附时间和pH条件下生物炭对Cd^(2+)的吸附行为与机制.结果表明,随粒径减小,生物炭表现为pH值和Zeta电位均下降、芳香性和极性降低、比表面积和孔体积增大.不同粒径生物炭对Cd^(2+)的吸附动力学符合准二级动力学模型,以化学吸附为主,其平衡时间依次为:BC-1(540 min)>BC-2(360 min)>BC-3(80 min).Langmuir模型能更好拟合Cd^(2+)在不同粒径生物炭上的吸附等温过程(R^(2)>0.97),Cd^(2+)最大吸附量随粒径减小而增大,表现为:BC-3(74.43 mg·g^(-1))>BC-2(45.71 mg·g^(-1))>BC-1(44.59 mg·g^(-1)).生物炭吸附Cd^(2+)主要机制有静电吸引、表面络合和阳离子-π作用.The aim of this study was to investigate the structural characteristics of biochar with different micro/nano particle sizes and its effect on the adsorption performance of Cd^(2+).Corn stalk biochar with different particle sizes(180-250μm,50-75μm,and≤20μm,denoted as BC-1,BC-2,and BC-3,respectively)were prepared using the sieving and ball milling method.The structural properties of different particle sizes of biochar were analyzed via elemental analysis,laser particle size analysis,SEM,BET,FTIR,and XPS.Additionally,the adsorption mechanisms of Cd^(2+) by three particle sizes of biochar under initial Cd^(2+) concentrations,adsorption times,and pH conditions were comparatively studied using static adsorption experiments.The results showed that with the decrease in particle size,the pH and zeta potential of biochar were reduced;the aromaticity and polarity decreased;the specific surface area and pore volume increased;and the intensity of the characteristic peaks containing OH,■groups increased.The adsorption kinetics of Cd^(2+) with different particle diameters of biochar were in accordance with the pseudo-secondary kinetic model,with chemisorption dominating.The equilibrium times were in the decreasing order of BC-1(540 min)>BC-2(360 min)>BC-3(80 min).The Langmuir model could better fit the adsorption isotherm process of Cd^(2+) on biochar of different particle sizes(R^(2)>0.97),and the maximum adsorption capacity of Cd^(2+) increased with the decrease in particle size,which was expressed as BC-3(74.43 mg·g^(-1))>BC-2(45.71 mg·g^(-1))>BC-1(44.59 mg·g^(-1)).The main mechanisms of Cd^(2+) adsorption by biochar were electrostatic attraction,surface complexation,and cation-πinteraction.

关 键 词：生物炭 微纳米粒径 镉(CD) 球磨 吸附机制 

分 类 号：X131[环境科学与工程—环境科学]