摘要
用离子交换平衡法研究了不同pH下胡敏酸与锌、镉单独及复合存在下形成络合物的稳定性及配位数。结果表明:在Zn2+,Cd2+单独存在时,络合反应的稳定常数及配位数随着pH值的增大而增大;相同pH条件下,Zn2+和胡敏酸络合物的稳定常数及配位数大于Cd2+。在Zn2+,Cd2+复合存在时,pH的变化与胡敏酸络合金属离子的稳定常数及配位数没有明显依存关系;与单独存在时相比,在pH 3.5和pH 7.0时,Zn2+,Cd2+和胡敏酸络合物的稳定常数和配位数都减小;而在pH 5.0时,Cd2+和胡敏酸络合物的稳定常数和配位数都增大,Zn2+和胡敏酸络合物的稳定常数和配位数都减小。
The stability and co - ordination number of the complex compounds of humic acid with Zn^2+ and/or Cd^2+ at different pH levels were determined with the cation - exchange equilibrium method. The stability and co - ordination number of the complex compounds increased with pH when Zn^2+ or Cd^2+ existed separately. With the same pH, the stability and co - ordination number of the complex com- pounds of humic acid with Zn^2+ were higher than those with Cd^2+. When Zn^2+ and Cd^2+ co - existed in the soil, no reciprocal relationship was observed between the stability and co - ordination number of the complex compounds and pH. As compared with the separately existing Zn^2+ and Cd^2+ , the stability and co - ordination number of the complex compounds decreased at a pH of 3.5 or 7.0 ; at a pH of 5.0, the stability and co - ordination number of the complex compounds of Cd^2+ increased and that of Zn^2+ decreased.
出处
《西南农业大学学报(自然科学版)》
CSCD
北大核心
2005年第4期451-455,共5页
Journal of Southwest Agricultural University
基金
国家自然科学基金资助项目(400710459)
关键词
离子交换平衡法
胡敏酸
镉
锌
稳定常数
配位数
cation - exchange equilibrium method
humic acid
cadmium
zinc
stability constant
co - ordination number