低分子量有机酸对可变电荷土壤吸附性氟解吸的影响

EFFECT OF LOW-MOLECULAR-WEIGHT ORGANIC ACIDS ON DESORPTION OF ADSORBED F FROM VARIABLE CHARGE SOILS

低分子量有机酸可增加可变电荷土壤中吸附性F的解吸,4种有机酸对F解吸影响的大小顺序为:草酸>丙二酸>柠檬酸>苹果酸。有机酸对F解吸的增加作用随有机酸浓度的增加和pH的升高而增加。有机酸可以通过两种机制来增加F的解吸量,一是有机酸阴离子与F对土壤表面吸附位的竞争作用;另一机制是有机酸通过促进土壤氧化铝的溶解来增加F的解吸量。从短程反应看,第一种机制是主要的。

The presence of low-molecular-weight organic acids increased desorption of adsorbed F and their effects on F desorption were in a decreasing order of oxalic acid > malonic acid > citric acid > malic acid. The desorption of F increased with the concentration of organic acids and pH. Organic acids enhanced F desorption through two mechanisms; (1) competition for F adsorption sites and (2) dissolution of aluminum oxides. Based on short-term reactions, the former is the main one.