两种木材生物炭对铜离子的吸附特性及其机制  

Characteristics and Mechanism of Copper Adsorption from Aqueous Solutions on Biochar Produced from Sawdust and Apple Branch

作　　者：王彤彤[1] 马江波[1] 曲东[1] 张晓媛[1] 郑纪勇[1,2] 张兴昌[1,2] 

机构地区：[1]西北农林科技大学资源环境学院,杨凌712100 [2]中国科学院水利部水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌712100

出　　处：《环境科学》2017年第5期2161-2171,共11页Environmental Science

基　　金：国家科技支撑计划项目(2015BAC01B01);国家自然科学基金项目(41571225);国家重点研发计划项目(2016YFC0501702)

摘　　要：为探索高效利用废弃生物质资源制备生物炭去除水体和土壤中Cu^(2+)污染的可行性,本文以常见的农林废弃物苹果树枝和梧桐木锯末为原料,采用450℃限氧热裂解法制备生物炭,通过两种生物炭对Cu^(2+)的批量吸附试验,利用4种等温吸附模型(Langmuir、Freundlich模型、Temkim、D-R模型)和4种吸附动力学模型(准一级动力学、准二级动力学、Elovich模型、颗粒内扩散模型)研究了苹果枝和锯末生物炭对Cu^(2+)的吸附行为.同时,使用FTIR红外、SEM和BET比表面积及孔径分析等技术表征了生物炭的理化性质,研究了两种生物炭对Cu^(2+)吸附机制,分析了两种生物炭之间的吸附特性差异及其影响因素.结果表明:(1)苹果枝生物炭在3 h达到吸附平衡,理论最大吸附量为15.85 mg·g^(-1),锯末生物炭在6h达到吸附平衡,理论最大吸附量为17.44 mg·g^(-1),与其他研究相比,这两种生物炭体现了较高的Cu^(2+)吸附性能;(2)两种生物炭对Cu^(2+)的热力学吸附均较好地符合Langmuir模型,表明吸附过程主要是近似单分子层的有益吸附;动力学吸附均符合准二级吸附动力学模型,表明其对Cu^(2+)的吸附包括表面吸附、颗粒内扩散和液膜扩散等多种过程;(3)吸附机制主要包括静电吸附,配体(酚羟基)/离子(H+)交换和阳离子—π键作用.In order to utilize the waste biomass resources efficiently, two raw materials of sawdust and apple branch were selected to produce biochars at 450℃ by oxygen-limited pyrolysis, and the adsorptions of Cu^2＋ in aqueous solutions were evaluated. The effects of initial Cu^2＋ concentration and contact time in batch sorption experiments were investigated by the four kinds of isothermal adsorption models （Langmuir, Freundlich, Temkim, D-R model） and the four kinds of adsorption kinetics models （Pseudo first-order, Pseudo second-order, Elovich model, Intraparticle diffusion model）. The influencing factors of adsorption characteristics about sawdust biochar （JB） and apple branch biochar （PB） were discussed by characterizing their elemental composition, functional groups, surface area, surface morphology and scanning electron microscope. The results showed that：1The adsorption equilibrium of PB and JB was reached in three hours and six hours, respectively, and the maximum adsorption capacity of PB and JB reached 15.85 mg·g^-1 and 17.44 mg·g^-1, respectively. Compared with other studies, these biochars showed higher Cu^2＋ adsorption performance. 2The adsorption kinetics was best fitted by the pseudo-second order model, while the isothermal adsorption was best described by Langmuir isotherms. This indicated that the beneficial adsorption process via monolayer was affected by intraparticle diffusion, surface adsorption and liquid film diffusion. 3The adsorption mechanism for Cu^2＋ is a complex interaction of physical and chemical factors. Electrostatic interaction of physical adsorption is mainly adsorption mechanism, Chemical adsorption mechanism includes generally ligand exchange （phenolic hydroxyl）/ion exchange （H^＋） and cationic-π. It was demonstrated that JB and PB could be considered as promising materials to immobilize heavy metals in contaminated water or soil.

关 键 词：生物炭 锯末 苹果枝 吸附特性 铜 机制 

分 类 号：X71[环境科学与工程—环境工程]