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小分子有机酸对恒电荷土壤胶体Pb2+吸附-解吸的影响

Effect of low molecular weight organic acids on Pb2+ adsorption and desorption by constant charge soil colloids

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【作者】 杨亚提王旭东张一平瞿爱华

【Author】 YANG Yati,WANG Xudong, ZHANG Yiping, QU Aihua(College of Life Science, Northwest Science and Technology University of Agriculture and Forestry, Yangling 712100,China)

【机构】 西北农林科技大学西北农林科技大学 杨凌712100杨凌712100杨凌712100

【摘要】 供试土壤胶体对Pb2 + 吸附及吸附态Pb2 + 的解吸等温线均符合Freundlich和Langmuir等温式 .吸附常数Ka 值大小为土娄土 >黄绵土 >黑垆土 >黄褐土 ,其大小次序与表面总电荷密度σ0 大小一致 ,表明了各土壤胶体对Pb2 + 吸附强度的大小 .在小分子有机酸作用下 ,吸附量降低 ,吸附亲和力增加 ,柠檬酸的影响大于草酸的影响 ;解吸后残留Pb2 + 吸附常数Kd 值的大小基本为土娄土 >黄褐土 >黑垆土 >黄绵土 ,反映了解吸残留Pb2 + 吸附强度的大小 ,与各土壤胶体有机质和游离氧化铁含量有关 .在NaNO3 和草酸溶液中 ,吸附 解吸等温线相距较远 ,吸附 解吸之间存在着滞后性 ;在柠檬酸作用下 ,吸附 解吸等温线基本接近 ,二者之间具有一定的可逆性 .

【Abstract】 The isothermal curves of Pb 2+ adsorption-desorption by soil colloids followed Freundlich and Langmuir equation. The adsorption constant K a showed the trend of old manured loessal soil >yellow loessal soil>dark cultivated loessal soil>yellow cinamon soil, which was consistent with surface charge density σ 0, an indicator of the strength of Pb 2+ adsorption by each soil colloid. Low molecular- weight organic acids (LMWOAs) made Pb 2+ adsorbed amount decreased and adsorption affinity increased, and the effect of citric acid was larger than that of oxalic acid. The constant Kd of residual Pb 2+ adsorption after desorption showed the trend of old manured loessal soil > yellow cinamon soil > dark cultivated loessal soil > yellow loessal soil, which reflected the adsorption strength of residual Pb 2+ after desorption, and was related to the contents of organic matter and free ferric oxide. The isothermal curves of Pb 2+ desorption from soil colloids were obvious higher than those of Pb 2+ adsorption. In NaNO 3 and oxalic acid background solution, the isothermal curves of Pb 2+ adsorption were far away from those of Pb 2+ desorption, showing that the hysteretic degree between adsorption and desorption was very large. The isothermal curves of Pb 2+ desorption from soil colloids were closed to those of Pb 2+ adsorption in citric acid background solution, which showed that the Pb adsorption and desorption was reversible.

【基金】 国家自然科学基金资助项目 (3 980 0 0 93 )
  • 【文献出处】 应用生态学报 ,Chinese Journal of Applied Ecology , 编辑部邮箱 ,2003年11期
  • 【分类号】S153.3
  • 【被引频次】40
  • 【下载频次】369
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