大叶种茶树根细胞壁对锗(Ⅳ)的吸附特性  

Adsorption Characteristics of Ge(Ⅳ)by Root Cell Walls of Large-leaf Tea Plant

作　　者：杨婉秋 陈英贺 高林玉 张柳叶 YANG Wanqiu;CHEN Yinghe;GAO Linyu;ZHANG Liuye(School of Chemistry and Chemical Engineering,Kunming University,Kunming,Yunnan,China 650214)

机构地区：[1]昆明学院化学化工学院,云南昆明650214

出　　处：《昆明学院学报》2024年第6期24-32,共9页Journal of Kunming University

基　　金：国家自然科学基金项目(31960057);昆明学院化学化工学院科学研究基金项目(HY2024009).

摘　　要：富锗大叶种茶叶因其潜在的营养和保健价值受到广泛关注.根细胞壁作为锗(Ge)进入茶树植体的首要屏障,研究其吸附机理对理解锗在茶树中的吸收至关重要.土壤溶液中的锗主要以Ge(Ⅳ)形式存在,研究其在茶树根细胞壁的吸附特性对提高其植物有效性具有重要意义.通过吸附动力学和热力学实验,揭示了茶树根细胞壁对Ge(Ⅳ)的吸附特性.结果表明,大叶种茶树根细胞壁对Ge(Ⅳ)的吸附符合准二级动力学方程(R^(2)>0.99),吸附过程主要受化学吸附控制.在298~313 K的温度范围内,吸附过程可以用Langmiur模型和Freundlich模型进行描述,相关系数(R^(2))分别大于0.983和0.943,表明吸附过程具有单层吸附特征,可能是均质吸附.且吸附过程为自发(ΔG^(0)<0)、吸热(ΔH^(0)>0)的熵增(ΔS^(0)>0)驱动过程,最大吸附容量超过2 mg/g.红外光谱分析表明,Ge(Ⅳ)可能与木质素、芳香族化合物中的苯环结构形成络合物,或与木质素、半纤维素及多糖中的含氧官能团发生化学吸附,形成Ge-O键.总体而言,茶树根细胞壁对Ge(Ⅳ)具有较好的吸附能力,有助于锗从土壤液中迁移至茶树根系,这为提高大叶种茶树锗植物有效性提供了一定的理论支持.Germanium(Ge)-rich Large-leaf Tea has gained widespread attention due to its potential nutritional and health benefits.The root cell walls serve as the primary barrier for germanium uptake into the tea plant,making the study of its adsorption mechanism scientifically significant.In soil solution,germanium primarily exists in the form of Ge(Ⅳ).To better understand the germanium absorption mechanism in Large-leaf Tea roots and enhance its phytoavailability,this study investigates the kinetics and thermodynamics of Ge(Ⅳ)adsorption by tea root cell walls.The results indicated that the adsorption of Ge(Ⅳ)by the root cell walls follows a pseudo-second-order kinetic model(R^(2)>0.99),suggesting that chemisorption is the primary controlling step.Within the temperature range of 298 K to 313 K,the adsorption process showed a higher degree of conformity with the Langmuir model,indicating a monolayer adsorption characteristic,which may imply homogeneous adsorption.Thermodynamic analysis revealed that the adsorption process is spontaneous(ΔG^(0)<0),endothermic(ΔH^(0)>0),and entropy-driven(ΔS^(0)>0),with a maximum adsorption capacity exceeding 2 mg/g.Infrared spectroscopy analysis indicated that Ge(Ⅳ)likely forms complexes or chemical bonds with phenolic structures in lignin or aromatic compounds on the cell wall,and also chemically adsorbs with oxygen-containing functional groups in lignin,hemicellulose,and polysaccharides,forming Ge-O bonds.This study provides a theoretical basis for understanding the mechanism of Ge(Ⅳ)uptake by tea root systems and its application in the environment.It also offers theoretical support for enhancing the plant availability of Ge in large-leaf tea and for the development of Ge-rich tea research.

关 键 词：大叶种茶树 根细胞壁 Ge(Ⅳ) 吸附特性 

分 类 号：TS272[农业科学—茶叶生产加工]