红壤腐殖酸及其与重金属离子作用的荧光特性研究

Study on the Fluorescence Characteristics of Red Soil Humid Acid and Its Complexation with Heavy Metal Ion

利用三维荧光激发-发射光谱,并结合紫外可见光谱、傅立叶变换红外光谱,从腐殖酸的浓度、溶液的pH值和离子强度3方面分析了红壤腐殖酸的光谱特性及其结构的关系,结果显示,离子强度对腐殖酸的三维荧光光谱特性影响非常小,而腐殖酸的浓度和溶液pH对其三维荧光光谱特性影响较大,荧光量子产率为2.1%～2.5%,荧光指数为1.0～1.2.红壤腐殖酸对Cu2+的络合能力比Cd2+强,其平均络合比分别为1:1.22和3.2:1,络合常数分别为1.6×106和1.5×107.

In this study, the three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEMs）, ultraviolet-visible （UV-Vis） and Fourier-transform infrared （FTolR） were applied to study the fluorescence characteristics and structure of red soil humid acid （RHA） in China. The effects of concentration of HA, pH and ionic strength on the fluorescence behaviors were investigated. The results indicate that ionic strength over the range from 0 to 0.05 mol/L NaNO3 did not affect the 3DEEMs of RHA. The concentration of RHA and pH of the test solution had obvious effects on the 3DEEM. Its fluorescence quantum yield and fluorescence index are 2.1%-2.5% and 1.0-1.2, respectively. Complex ability of RHA with Cu^2＋ was stronger than Cd^2＋, the mean coordination of RHA with Cu^2＋ and Cd^2＋ are 1：1.22, 3.2：1 respectively, and the complex constants for Cu^2＋ and Cd^2＋ associated with RHA are respectively 1.6× 10^6. 1.5× 10^7.