重金属在淀山湖沉积物上的吸附研究

A STUDY ON THE ADSORPTION OF HEAVY METALS ON DIANSHAN LAKE'S SEDIMENTS

本文以淀山湖沉积物作为研究对象 ,研究了 Cu、Zn、Pb和 Cd在淀山湖沉积物上的等温吸附和沉积物对重金属吸附的影响因素。结果表明 ,重金属 Cu、Zn、Pb和 Cd在淀山湖沉积物上的等温吸附符合 L angmuir模型 ,淀山湖沉积物对重金属饱和吸附量的大小顺序为 Zn>Cu>Pb>Cd。淀山湖沉积物的组成对重金属吸附有较大的影响 ,其中沉积物中粘粒对 Cu、Zn、Pb和 Cd的吸附最强。沉积物中有机质对 4种重金属也有较强的吸附 ,特别对 Zn的吸附最强。碳酸盐对 Zn的吸附较弱 ,而对 Cu、Pb和 Cd有较强的吸附。 p H值对重金属吸附也有较大的影响 ,吸附量随着 p H值的升高而增大。

Taking Dianshan Lake, Shanghai, as a case study of the influence of the heavy metal absorption on the lake sediments, the present paper has done a series of experiments with such metals as copper, zinc, lead and cadmium for their corresponding absorption for the sediments and the factors affecting the due adsorption. It was found from the data of our experiments that the amount adsorbed of Cu, Zn, Pb and Cd on the Lake's sediments steadily increase with the increase of the concentration of the respective heavy metals in water. The ratio of the amount adsorbed to the equilibrium concentration corresponds with S-model. To be exact, the amount adsorbed of Zn on the sediments proves the largest among the four metals while that of Cu, Zn, Pb and Cd on the sediments conforms to Langmuir model. The saturated amount adsorbed on the sediments, as shown in our experiments, proceeds in the order of Zn>Cu>Pb>Cd. The experimental results of ours also indicate that the contents of the organic substance, such as carbonate and clay particles(<0.002 mm) in the Lake's sediments work out at about 0.8%, 1.34% and 8.91%, respectively. Such constituents in turn reveal an obvious influence upon the adsorption of the heavy metals to the sediments. In addition, the organic elements gained from the sample sediments prove to adsorb heavy metals to a certain degree, with Zn taking the lead in particular. Whereas carbonate in the sediments absorbs Zn slightly, it adsorbs Cu, Pb and Cd rather intensively. Compared with the organic substances and carbonate, clay particles in the Lake produce the strongest adsorption to the heavy metals. pH also has an important effect on such adsorption, especially in case of with the increased amounts in the lake water. And, finally, some effect has also been found with the change of temperature with the water on such adsorption.