Effects of Oxalic Acid on the Adsorption and Interaction of Cd~(2+), Zn~(2+) in Different Soils
Effects of Oxalic Acid on the Adsorption and Interaction of Cd~(2+), Zn~(2+) in Different Soils
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发表时间：
2011
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通讯作者：
D. Jing
中科院分区：
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作者：
D. Jing
研究了草酸对土娄土、黄绵土、黑绵土、黄褐土和桑迪5种土壤在Cd 2+、Zn 2+单一处理和Cd 2 + + Zn 2+复合处理下吸附Cd 2+、Zn 2+的影响，并探讨了吸附机理。结果表明，草酸对Cd ~（2+）、Zn ~（2+）单一处理和Cd ~（2+）+Zn ~（2+）复合处理的Cd ~（2+）、Zn ~（2+）吸附均有抑制作用，但在Zn ~（2+）平衡浓度较低时，草酸对Zn ~（2+）的吸附有促进作用。5种土壤对Cd ~（2+）的吸附能力大小顺序为：土娄土和黑绵土最强，桑迪最弱;草酸的存在没有改变土壤对Cd ~（2+）和Zn ~（2+）吸附的相互拮抗作用。草酸对Cd ~（2+）、Zn ~（2+）吸附的影响机理为络合作用。草酸通过降低土壤对Cd ~（2+）的静电引力而降低Cd ~（2+）在土壤中的吸附，但草酸对Zn ~（2+）吸附的影响受Zn ~（2+）平衡浓度的影响。草酸在较低Zn 2+平衡浓度下，通过在土壤氧化物表面形成三元络合物桥键，促进Zn 2+的吸附;在较高Zn 2+平衡浓度下，草酸通过与土壤有机质表面化学吸附位竞争，抑制Zn 2+的吸附。结果表明，草酸对5种土壤吸附Cd ~（2+）、Zn ~（2+）有影响，但不起决定作用，土壤性质是决定因素。
The effects of oxalic acid on the Cd2+, Zn2+ adsorption at both Cd2+or Zn2+ sole treatment and Cd2+ + Zn2+ complex treatment in 5 kind of soils, i.e. Lou soil, Loessial soil, Dark loessial soil, Yellow cinnamon soil and Sandy soil, were carried out and the adsorption mechanism were discussed also. The results showed that oxalic acid could decrease Cd2+ or Zn2+ adsorption in both Cd2+ or Zn2+ sole treatment and Cd2+ + Zn2+ complex treatment as a whole, except that oxalic acid promote Zn2+ adsoption in 5 kind of soils at lower Zn2+ equilibrium concentration. The adsorption capacity sequence of 5 kinds of soils, that Lou soil and Dark Loessial Soil had a strongest adsorption capacity while the Sandy soil′s adsorption was the least, and inter-antagonism between Cd2+ and Zn2+ adsorption in soils were not changed by coexistence of oxalic acid. The affecting mechanism of oxalic acid on the Cd2+ or Zn2+ adsorption was its complexing action. Oxalic acid decreases the Cd2+ adsorption in soils by reducing the electrostatic-attraction of soil, but the effects of oxalic acid on Zn2+ adsorption was affected by Zn2+ equilibrium concentration. Oxalic acid could promote the Zn2+ adsorption in lower Zn2+ equilibrium concentration by bridge-bonding of ternary-complex-compound formed on the surface of soil oxide mineral, but decrease the Zn2+ adsorption in higher Zn2+ equilibrium concentration by competing with the chemical adsorption sites on the surface of soil organic materials. As a results, oxalic acid could affect but not decided Cd2+ or Zn2+ adsorption in 5 kinds of soils, the soil properties were the determining factors.