【作者】 朱丽珺；

【导师】 张金池；

【作者基本信息】 南京林业大学 ， 水土保持与荒漠化防治， 2007， 博士

【摘要】 浙江安吉主要植被类型土壤作为研究载体，用以探求土壤不同组分与重金属之间的吸附机理，研究土壤有机质含量、阳离子交换量（CEC）、pH值及土壤颗粒组成对土壤吸附重金属Cu²⁺的影响。以土壤中主要成分黏土矿物（膨润土为代表）、腐殖质（胡敏酸代表）和水合锰氧化物为吸附材料，采用等温吸附法，分别研究重金属铜、铅、镉、镍在不同吸附剂中的吸附特征。研究双组分金属离子共存于吸附剂中的竞争吸附性能。研究结果表明：（1）不同植被类型土壤中，落叶栎林对Cu²⁺的吸附量最大，灌木林次之，茶林与常绿苦槠-青冈混交林居中，毛竹林与湿地松林吸附量最小；不同层次土壤对Cu²⁺的吸附量随土层深度增加而减少。（2）土壤有机质含量和CEC是影响供试土壤Cu²⁺吸附量的主要因素。建立了土壤有机质含量和CEC与土壤Cu²⁺吸附量的关系模型：Y(Cu²⁺吸附量)=39.65+1.57X₁（有机质含量）+3.65 X₂（CEC）（3）膨润土对Cu²⁺、Pb²⁺的吸附明显强于Cd²⁺、Ni²⁺，吸附强度大小顺序为pb²⁺＞Cu²⁺＞Ni²⁺＞Cd²⁺，对pb²⁺的吸附量约十倍于Cd²⁺。Langmuir、Freundlich和Temkin方程对这4种金属离子等温吸附的拟合均呈极显著关系。但Temkin等温式拟合Cu²⁺、Pb²⁺和Cd²⁺最佳，Ni²⁺最适合的方程为Freundlich。（4）胡敏酸对Cu²⁺的吸附强度要大于对Pb²⁺和对Cd²⁺的吸附。吸附强度顺序为Cu²⁺＞Pb²⁺＞Cd²⁺。Langmuir、Freundlich和Temkin方程对Pb²⁺、Cd²⁺的吸附呈显著关系，但其中Freundlich方程为最佳拟合方程：对Cu²⁺的吸附，Langmuir等温式拟合程度最高，Freundlich方程其次，Temkin方程则不适合。（5）红外光谱图显示，胡敏酸与Pb²⁺的结合点主要发生在酚羟基部位，与Cd²⁺的结合点主要发生在芳环上的羧基部位，而Cu²⁺与胡敏酸的结合则羧基和酚羟基都能发生。（6）水合锰氧化物中，δ-MnO₂对Pb²⁺的吸附强度高于无定型MnO₂对Pb²⁺的吸附，吸附量前者是后者的1.5倍。这是因为δ-MnO₂的晶粒小，结晶性差，比表面大，并含有表面羧基和晶胞结晶水，比无定型MnO₂能提供更多的吸附点位。（7）δ-MnO₂对pb²⁺的吸附强度要远大于Cu²⁺和Cd²⁺，吸附强度顺序为pb²⁺＞＞Cu²⁺≥Cd²⁺。Langmuir、Freundlich和Temkin方程对Pb²⁺的吸附均呈显著关系，其中Temkin方程为最佳拟合方程：对Cu²⁺的吸附Freundlich方程的拟合程度高于Temkin方程，Langmuir方程不适合：而Cd²⁺的吸附则是Langmuir方程拟合最佳，Freundlich和Temkin方程方程则不适合。（8）不同pH值对δ-MnO₂、胡敏酸、膨润土与重金属的作用影响相似。低pH值均不利于吸附剂对重金属离子的吸附，随着pH值的增加，不论吸附量还是吸附率都呈上升趋势，但吸附剂材料不同曲线上升趋势不尽相同。（9）双组分离子竞争吸附表明，δ-MnO₂、胡敏酸、膨润土对Pb²⁺、Cd²⁺、Cu²⁺均具有“选择性吸附”。双组分离子共存时，吸附剂对某一金属的吸附量均要低于单一离子存在时的吸附量。金属离子两两共存的竞争作用大小在不同的吸附剂中呈现不同的结果，但共性是Pb²⁺在三种吸附剂中均表现出更强的竞争能力。（10）同一元素在不同吸附剂中的单位吸附量作比较分析，显示δ-MnO₂对Pb²⁺、Cd²⁺、Cu²⁺的吸附量要大大高于胡敏酸和膨润土对相应离子的吸附量。这可能是由于δ-MnO₂不仅与金属离子产生表面吸附，而且在晶体内部也提供吸附点位与离子结合。更进一步机理有待以后继续研究。（11）以膨润土对Pb²⁺和Cu²⁺双组分离子竞争吸附为例，建立竞争吸附模型。传统IAS和LCA模型在高浓度时不适用本实验。对LCA模型引入一个修正系数P_i，用修正LCA模型对膨润土与pb²⁺、Cu²⁺双组分离子竞争吸附进行模拟，得到较好结果。更多还原

【Abstract】 Cu²⁺ adsorption of 24 soil samples gathered out of 4 soil layers （0～10、10～20、20～40、40～60cm） of 6 different types of forests in Anji, Zhejiang were determined to explore relationship of Cu²⁺ adsorption with organic matter content, CEC, pH and particle composition. A batch experiment was conducted to study the adsorption of copper, lead, cadmium and nickel by bentonite, humic acid and hydration manganese oxide in single component and binary systems. The result shows that:（1） In terms of Cu²⁺ adsorption the six types of forests are in the order of broadleaved deciduous forest＞shrubbery＞tea grove＞broadleaved evergreen forest＞bamboo grove＞pine forest. Cu²⁺ adsorption decreases with the depth of the profile.（2） Organic matter content and CEC are the two major factors affecting soil Cu²⁺ adsorption. Based on the findings, a model is established to illuminate the relationship of Cu²⁺ adsorption with organic matter content and CEC: Y (Cu²⁺ adsorption)=39.65+1.57X₁（organie matter）+3.65 X₂（CEC）（3） Adsorption capacity of copper and lead are higher than that for cadmium and nickel by bentonite. The order of adsorption capacity was as follows: Pb²⁺＞Cu²⁺＞Ni²⁺＞Cd²⁺. Adsorption of Pb²⁺ is decuple of Cd²⁺. The single ion equilibrium data were fitted to Langmuir, Freundlich and Temkin isotherms. Temkin isotherms is best for Pb²⁺, Cu²⁺, and Cd²⁺ and the best for Ni²⁺ is Freundlich isotherms.（4） Adsorption capacity of Cu²⁺ by humic acid was higher than Pb²⁺ and Cd²⁺. The order of adsorption capacity was as follows: Cu²⁺＞Pb²⁺＞Cd²⁺. Equilibrium data of Pb²⁺ and Cd²⁺ were fitted to Langmuir, Freundlich and Temkin isotherms, and Freundlich isotherm is the best. Langmuir isotherm is best for Cu²⁺, than Freundlich isotherm, but Temkin isotherm is not fitted very well.（5） The results of infrared spectrum show that humic acid and Pb²⁺ link mainly on phenolic hydroxyl group. Humic acid and Cd²⁺ link on carboxyl of aromatic ring. Humic acid and Cu⁺ link both on phenolic hydroxyl group and carboxyl of aromatic ring.（6） Adsorption capacity of Pb²⁺ byδ-MnO₂ is higher than non-crystal MnO₂. This is because the crystalline grain of isδ-MnO₂ smaller, crystallinity is weaker, specific surface is larger; contain more carboxyl and crystal water of unit cell. These characterstics ofδ-MnO₂ result in more absorption site than non-crystal MnO₂.（7） Adsorption capacity of Pb²⁺ is higher than that for Cu²⁺ and Cd²⁺ byδ-MnO₂. The order of adsorption capacity was as follows: Pb²⁺＞＞Cu²⁺≥Cd²⁺. The equilibrium data of Pb²⁺ is fitted to Langmuir, Freundlich and Temkin isotherms, and Temkin is the best. Freundlich isotherm is better than. Temkin for Cu²⁺, but Langmuir isotherm is not fitted very well. Langmuir isotherm for Cd²⁺ is best, but Freundlich and Temkin isotherms are not fitted very well.（8） The affects of pH to adsorption of metal ion by bentonite, humic acid andδ-MnO₂ are similar. The lower pH is not good for adsorption of metal ion. Along with the increasing of pH, both the adsorption capacity and adsorption rate increase.（9） The adsorption isotherms in binary-component systems showed that there were competition among copper, lead and cadmium byδ-MnO₂, humic acid and bentonite. Adsorption of one metal ion was depressed by the presence of other metal ion in the adsorption solution. Althoug the detail data of competition adsorption are different by virous sorbents, adsorption of Pb²⁺ is higher than other metal ion.（10） Unit adsorption capacity of different sorbents to the same metal ion is different. Adsorption capacity of metal ion byδ-MnO₂ is higher than humic acid and bentonite. This is becauseδ-MnO₂ absorbs metal ion not only by its surface but also by crystal interior site. The further mechanism will be studied later.（11） Equilibrium data for the binary adsorption of Pb²⁺ and Cu²⁺ by bentonite were analyzed by using Ideal-Adsorption-Solution （IAS） and Langmuir-Competitive-Adsorption models, but these equations weren’t fitted to data for the mixed solutions. The Modified LCA model fits the binary adsorption equilibrium data satisfactorily and adequately. Finally, binary-component competitive adsorption of copper and lead was simulated by Modified LCA model in computer.更多还原