乙硫氮对土壤中Cr^(3+)和Ni^(2+)的钝化性能

Immobilization Property of Sodium Diethyl Dithiocarbamate on Cr^(3+) and Ni^(2+) in Soil

通过土柱淋滤试验考察了乙硫氮对土壤中Cr^(3+)和Ni^(2+)两种重金属离子的钝化性能.试验结果表明,乙硫氮对土壤中的Cr^(3+)和Ni^(2+)具有很好的钝化效果,而且乙硫氮对Cr^(3+)的钝化性能更为显著.随着乙硫氮用量的增加,重金属钝化率逐渐升高,在乙硫氮用量为110 g·kg-1时,Cr^(3+)和Ni^(2+)的钝化率均达到99%以上.淋滤液pH值对钝化效果有一定的影响,随着淋滤液pH值的降低,乙硫氮对Cr^(3+)和Ni^(2+)的钝化性能逐渐减弱,但钝化率仍较高,都在90%以上.Cr^(3+)的钝化率随淋滤液pH值的降低有小幅下降,但均在99.68%以上.XRD检测和配位化学分析结果表明,乙硫氮与Ni^(2+)和Cr^(3+)形成了配位数为4和6,分子式为Ni(DDTC)_2和Cr(DDTC)_3的四元环螯合物沉淀.同时,Cr(DDTC)_3的稳定性要远高于Ni(DDTC)_2,因此,乙硫氮对Cr^(3+)具有更好的钝化性能.

Immobilization property of sodium dieth yl dithiocarbamate （ DDTCNa ） on C r3＋ and Ni2＋ in polluted soil was investigated b y column lea chin gprocess. Experimental results indicated that good immobilization e f fect of heavy metals in polluted soil was obtained when DDTCNa was used . Especially,DDTCNa showed better immobilization e f fe c t on C r3 ＋. Immobilization rate o f heavy metal increased with the increase o f DDT C Na d o sa g e . Wh en D D T C N a dosage was 110 g-kg -l,more than 99% of Cr3＋ and Ni2＋ can be im m o b i l ized . A d d i t io n a l ly , leaching pH had some effect on immobilization of C r3＋ and N i2＋. With the reducing o f lea chin g p H , immobilization ef fect of Cr3 ＋ and Ni2 ＋ d e c reased . How e v e r, h igh immobilization rate o f C r3 ＋ and Ni2＋ ,which were more than 90% ,could also be obtained. A n d immobilization rate o f C r3＋ , which was higher than 99. 68% , decreased s lightly with the reduction o f lea chin g pH . The formation of metal sulfide chelating precipitates and the immobilization mechanism were systematically studied by XRD measurements and coordination chemistry an a ly s is. T h e results showed that four-membered chelating precipitates with the coordination number o f 4 and 6 , respectively , which were Ni （ DDTC ） 2 and Cr （ D DT C ） 3,cou ld b e obtained when D D T C N a reacted with the heavy me tals. Mo r e o v e r,the stability o f C r （ DDT C ） 3 was much better than Ni （ DDTC ） 2,so better immobilization property o f C r3＋ was obtained.