负载腐植酸生物炭对矿区土壤淋溶液中Mn^(2+)吸附性能的影响  

Effect of humic acid-loaded biochar on the adsorption performance of Mn^(2+)in soil leachate from mining area

作　　者：代泽宇 周剑林 刘伟银[3] 秦平 陈荣 陈章 李志贤 陈国梁 DAI Zeyu;ZHOU Jianlin;LIU Weiyin;QIN Ping;CHEN Rong;CHEN Zhang;LI Zhixian;CHEN Guoliang(College of Resource Environment and Safety Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;Hunan Province Key Laboratory of Clean Utilization of Coal Resources and Mine Environmental Protection,Hunan University of Science and Technology,Xiangtan411201,China;College of Chemistry and Chemical Engineering,Hunan University of Science and Technology,Xiangtan 411201,China)

机构地区：[1]湖南科技大学资源环境与安全工程学院,湖南湘潭411201 [2]湖南科技大学煤炭资源清洁利用与矿山环境保护湖南省重点实验室,湖南湘潭411201 [3]湖南科技大学化学化工学院,湖南湘潭411201

出　　处：《煤炭学报》2024年第9期4006-4018,共13页Journal of China Coal Society

基　　金：湖南省自然科学基金资助项目(2021JJ50124,2024JJ5154);湖南省教育厅科研基金资助项目(23A0378)。

摘　　要：利用玉米秸秆基生物炭(CSB)负载腐植酸制备腐植酸改性生物炭(CSB-HA),用于吸附矿区土壤淋溶液中Mn^(2+)并分析其吸附特性。借助SEM、BET、XRD、XPS和FT-IR等方法对制备得到的样品进行表征分析,CSB-HA比表面积为7.911 m^(2)/g,孔隙以介孔居多。优良的孔隙结构提供大量吸附点位,并促进与污染物的接触,使吸附性能提升。CSB-HA表面富含C=O、O=C—O和—COOH等含氧官能团,其中氧原子能与重金属离子进行络合配位形成配位键,从而去除Mn^(2+)。CSB-HA对Mn^(2+)的最大吸附量为21.493 mg/g,准一级动力学模型、准二级动力学模型、Langmuir等温式和Temkin等温式能较好拟合吸附过程,Temkin常数b<1 kJ/mol,能证明吸附过程存在物理吸附。准二级动力学模型和Langmuir等温式拟合度更高且更接近实际检测值,故吸附过程为单分子层吸附,受物理吸附和化学吸附共同作用,且化学吸附占主导地位。因此含氧官能团种类和质量分数对CSB-HA吸附Mn^(2+)产生重要影响。由液膜扩散模型和颗粒内扩散模型分析扩散过程,液膜扩散模型拟合线与纵轴截距较小,因此该过程不是控速阶段。颗粒内扩散模型可拟合为膜扩散阶段(0~60 min)和颗粒内扩散阶段(60~240 min),后者吸附速率明显降低(k_(id1)=1.159>k_(id2)=0.287),且拟合线均不通过原点,故颗粒内扩散阶段是吸附过程的控速关键阶段。热力学模拟中,分离系数R_(L)均在0.4~0.6,ΔH=15.41 kJ/mol>0,且ΔG均为负数并随温度升高而减小,表明吸附过程是可逆且自发吸热的,升温能促进吸附反应进行。ΔS=49.90 J/(mol·K)>0,证明吸附过程中固液界面随机性增加。模拟淋溶液吸附实验表明CSB-HA吸附Mn^(2+)效果较好且对淋溶液pH有调节作用。Humic acid modified biochar(CSB-HA)was prepared using corn stover-based biochar(CSB)loaded with humic acid for the adsorption of Mn^(2+)from the soil leachate in the mining area and its adsorption characteristics were analyzed.With the help of SEM,BET,XRD,XPS and FT-IR,the prepared samples were characterized and analyzed.The results show that the specific surface area of CSB-HA is 7.911 m^(2)/g,which is 1.98 times that of CSB,and the pores are mostly mesoporous.The excellent pore structure provides a large number of adsorption sites and promotes the contact with pollutants,so that the adsorption performance is enhanced.The surface of CSB-HA is enriched with the oxygen-containing functional groups such as C=O,O=C—O and—COOH,and the oxygen atoms in the functional groups can be complexed and coordinated with heavy metal ions to form a stable ligand bond,thus removing Mn^(2+).The maximum adsorption of Mn^(2+)by CSB-HA is 21.493 mg/g,and the quasi-primary kinetic model,quasi-secondary kinetic model,Langmuir isotherm and Temkin isotherm can fit the adsorption process well,and the Temkin constant b<1 kJ/mol can prove that the adsorption process Physical adsorption exists.The quasi-secondary kinetic model and Langmuir isotherm fit the adsorption process better and closer to the actual detection value,so the adsorption process is a single molecule layer adsorption,which is subject to the joint action of physical adsorption and chemical adsorption,and the chemical adsorption is dominant.Therefore,the type and mass fraction of oxygen-containing functional groups have an important effect on the adsorption of Mn^(2+)by CSB-HA.The diffusion process was analyzed by the liquid-film diffusion model and the intra-particle diffusion model.The fitted line of the liquid-film diffusion model has a small intercept with the longitudinal axis,so the process is not a velocity-controlled phase.The intra-particle diffusion model can be fitted into a membrane diffusion stage(0−60 min)and an intra-particle diffusion stage(60−240 min),

关 键 词：碳材料 腐植酸 尾矿土 吸附模型 扩散模型 

分 类 号：TK62[动力工程及工程热物理—生物能] TQ424.1[化学工程]