摘要
土壤腐殖物质在金属离子的累积、迁移和转化过程中起着重要作用,目前关于土壤胡敏酸(HA)与金属离子相互作用关系的研究较多,而胡敏素(HU)的报道则很少。以黑钙土为供试土壤,在对HU进行结构表征的基础上,应用批量平衡法研究了两者对Cu^2+的吸附热力学特性,并与HA进行了比较。结果表明:与HA相比,HU的腐殖化程度、脂族化程度和疏水化程度较高而氧化程度较低;HU和HA对Cu^2+的吸附量随Cu^2+浓度和反应温度的增加而增加,但HU对Cu^2+的吸附量低于HA;吸附等温数据能用Langmuir和Freundlich方程很好地拟合,而以Freundlich方程的拟合程度更好,HU和HA对Cu^2+的最大吸附量分别在250.0-285.7 mg/g和212.8~238.1 mg/g;Cu^2+在HU和HA表面上的吸附是自发的、吸热的和无序度增加的过程;对于Cu^2+而言,HA和HU均具有能量不均一的吸附表面,同时HU的表面能量不均一性程度高于HA。
Humic substances play an important role for accumulation,transfer and transformation of metal ions.At present,a great majority of studies published to date have focused on the interactions of metal ions with base-soluble fractions humic acids.However,reports on humin are rarely available.In this study,humin isolated from a chrenozem was characterized using elemental analysis and solid-state13C CPMAS NMR spectroscopy.The adsorption thermodynamic characteristics of Cu^2+ion from aqueous solution onto humin were evaluated at three different temperatures(298,318 and 338 K)by batch isotherm experiments.The differences of structural characteristics and Cu^2+adsorption properties between humin and humic acid were also compared.Results showed that humin was structurally different from humic acid.The increase of temperature had a positive effect on the adsorption process.Freundlich equation described the equilibrium data better with respect to Langmuir equation.Thermodynamic parameters(i.e.△G°,,and△S°)revealed that Cu^2+adsorption by humin and humic acid were a feasible,spontaneous and endothermic process with an increase in disorder.The values of isosteric heat of adsorption(△Hx)increased with increasing surface Cu^2+loading,and the increase in△Hx values was smaller for humin than for humic acid.The results indicated that humin and humic acid possessed energetically heterogeneous surfaces.Humin had greater surface heterogeneity than corresponding humic acid.
作者
易彩霞
王帅
吉凡
李翠兰
张晋京
Yl Caixia;WANG Shuai;JI Fan;LI Cuilan;ZHANG Jinjing(College of Resources and Environment,Jilin Agricultural University,Key Laboratory of Soil Resource Sustainable Utilization far Commodity Grain Bases of Jilin Province,Changchun 130118,China;College of Plant Science,Jilin Agricultural Science and Technology College,Jilin 132101,China)
出处
《吉林农业大学学报》
CAS
CSCD
北大核心
2019年第5期577-584,共8页
Journal of Jilin Agricultural University
基金
国家自然科学基金项目(41471196)
国家科技支撑计划项目(2013BAD07B02)
吉林省科技发展计划项目(LFGC14301)
