模拟酸化下水稻土微团聚体Cu^(2+)吸附与解吸的影响

Effect of simulated acidification on the adsorption and desorption of Cu^(2+) by size fractions of micro-aggregates of paddy solls

采用低能量超声波分散和冷冻机干燥法提取太湖地区水稻土(黄泥土)微团聚体颗粒,用平衡液吸附法和CaCl2与HCl溶液的连续解吸法研究了它们在pH2～6范围内pH对Cu2+的静电吸附和专性吸附的影响。结果表明,不同粒径的微团聚体颗粒对Cu2+的吸附等温线可都用Freundlich模型来描述。Cu2+吸附量大小以下序递减,粘粒级、砂粒级、粉砂级、粗粉砂级;吸附量受其中游离氧化铁、氧化铝和有机质含量的控制。吸附量随pH升高而增加。低pH条件下利于静电吸附,吸附过程H+减少使平衡液pH上升;高pH条件下主要是专性吸附所控制,释放H+使平衡液pH下降。

Size fractions of micro-aggregates were separated from undisturbed paddy soil samples in Tai Lake region, the effects of electrostatic sorption and the special sorption of Cu^2＋ by microaggregates in the range of pH 2-6 were studied by using equilibrium adsorption method and continue desorption method of CaCl2 and HCl solution. The sorption of Cu^2＋ under different size fractions of micro-aggregates fitted well with the Freundlich Isotherm. The clay fraction had the greatest adsorption capacity, then sand fraction, powder sand fraction and coarse powder sand fraction in turn. Sorption amounts of Cu^2＋, which increased as the increase of pH, were controlled by the contents of free iron oxides, free aluminium oxides and organic matter, sorption amounts. Low pH helped to electrostatic sorption and reduced H^＋, which increased the pH of balance solution; while high pH leaded to special sorption and released H^＋, which decreased the pH of balance solution.