针铁矿及腐殖质对水体重金属离子的吸附作用

ADSORPTION OF HEAVY METAL IONS IN AQUEOUS-SOLUTION ONTO GOETHITE AND HUMIN

采用针铁矿、腐殖质、针铁矿 -腐殖质复合微粒对重金属离子进行了吸附 -解吸实验。结果表明它们对Cu2 + 、Zn2 + 有强烈的吸附作用。针铁矿对 Cu2 + 和 Zn2 + 的吸附边界 p H值分别为 4 .3和 5 .8,且吸附率可达 95 %以上。腐殖质对 Cu2 +和 Zn2 +的吸附边界 p H值分别为 4 .1和 5 .6 ,且在 p H值为 8时 ,吸附率可达 96 %以上。针铁矿与腐殖质形成的稳定复合微粒不仅对重金属离子具有良好的吸附作用 ,还具有均匀性好和沉降稳定的特点 。

In the present paper, the capabilities of adsorption of heavy metals by goethite, humin and goethite humin are studied by experiments. Heavy metals are considered as highly toxic substances. There are usually high heavy metal levels in mine water and soil. The heavy metal ions are removed from aqueous solutions by sorption onto synthetic goethite, humin and compound particles of goethite with humin during laboratory experiments. The experimental results show that the adsorption of Cu 2+ and Zn 2+ on goethite and humin surfaces are intense. There is an obvious adsorptive bound pH value and the solution pH value is an important parameter for sorption. To the goethite the bound pH values of Cu 2+ and Zn 2+ are 4.3 and 5.8. The adsorptive percentage is increased from 8 % to 95 %. To the humin the bound pH values of Cu 2+ and Zn 2+ are 4.1 and 5.6. The adsorptive percentage is increased to 100 % at pH values of 7.1 and 8.0. Their adsorptive rates of heavy metal ions are showed in Fig.1 and Fig.2. At the same time goethite has a good adsorption of humin. They combine to a steady goethite humin particulate at pH values of 7～9. They have a good adsorption capability of the adsorption of Cu 2+ and Zn 2+ . And this capability is steady in the area of pH values of 6～8. These figures show that adsorptive percentage is increased from 8 % to 95 %. The adsorptive rate of heavy metal ions on goethite humin is showed in Fig.4. The results of the experiment are discussed and the reaction mechanism of the adsorption is analyzed in the present paper. Then two conclusions are obtained in the end. First, goethite is a ubiquitous mineral and the most stable iron oxide in soil environments. It is one of the most important minerals. Humin is also one of soil characteristic factors. There is a good view to control capacity of soil for sorption of toxic metals with goethite and humin. Second, goethite and humin particulate have many strongpoints to be used to deal with waste water. So it is efficient approach to use to retain soil fertility and remedy soil pollution of heavy metal.