EPS有机质对土壤重金属的吸附效果及机理研究

Study on adsorption effect and mechanism of EPS organic matter to soil heavy metals

为了研究污泥胞外聚合物(EPS)对土壤重金属铜、镉、锌的吸附效果及机理,采用热提法从不同pH的污泥中提取EPS,淋洗含重金属的土壤。结果表明,在pH为5时,EPS对土壤中铜、镉、锌的吸附效果最好,去除率分别达63.00%、54.92%、34.86%;在污泥调理过程中,EPS有机质主要为蛋白质和多糖,且总EPS、有机碳的浓度及蛋白质/多糖的比值均呈下降趋势;在实验开始的0~2 h,EPS对土壤重金属的吸附符合一级反应动力学。三维荧光和傅里叶红外光谱测定表明,吸附过程中蛋白质起主要作用,其中起主要作用的化学基团有胺基、酰胺基、羟基、C=O基以及羧基、C—O—C基等。

To study the adsorption effect and mechanism of sludge extracellular polymeric substances( EPS) on heavy metals such as copper,cadmium,and zinc in the soil,EPS is extracted from the sludge with different pH values through thermal extraction method and used to leach the soil containing heavy metals.The results show that EPS presents the best adsorption effect on copper,cadmium and zinc in the soil when the pH is 5,and the removal rates reach 63%,54. 92%,and 34. 86%,respectively.During the sludge conditioning process,main organic matters in EPS are protein and polysaccharides,and the concentrations of total EPS and organic carbon,as well as the ratio of protein/polysaccharide show a downward trend.In the first 0-2 h of the experiment,the adsorption of heavy metals in the soil by EPS accords with the first-order reaction kinetics. The measurement by three-dimensional fluorescence and Fourier infrared spectroscopy shows that protein has played a major role in the adsorption process,among which the main contributing chemical groups include amine,amide,hydroxyl,C=O,carboxyl and C—O—C groups,etc.