邻苯二甲酸和水杨酸在可变电荷土壤中的吸附行为

研究了2种低分子量有机酸邻苯二甲酸和水杨酸在2种代表性可变电荷土壤红壤和砖红壤中的吸附行为。结果表明,可变电荷土壤对有机酸的吸附容量较大,对邻苯二甲酸的吸附亲和力大于对水杨酸的亲和力,在砖红壤中2种有机酸的吸附量大于在红壤中的,这与土壤的游离铁、铝氧化物的含量一致。土壤氧化铁在有机酸吸附中起着重要作用,粘土矿物如高岭石对有机酸的吸附量很小。有机酸的吸附涉及专性吸附和静电吸附2种机制,并以前者为主。当pH小于4.5时,pH的改变对有机酸的吸附影响不大;当pH大于4.5时,有机酸的吸附量随pH的增加而减小。

ADSORPTION BEHAVIOR OF PHTHALIC AND SALICYLIC ACIDS BY VARIABLE CHARGE SOILS

Adsorption of phthalic and salicylic acids by two variable charge soils,Haplic Acrisol and Rhodic Ferralsol,was investigated in this study.Results show that both soils were high in adsorption capacity for two organic acids and higher in affinity for phthalic acid.The quantities of the two organic acids adsorbed by Rhodic Ferralsol were larger than by Haplic Acrisol and this result consisted with the content of iron and aluminum oxides in the two soils.The iron oxides in these soils played a significant role in the adsorption of organic acids,but the soil minerals such as kaolinite showed a small adsorption capacity for organic acids.The adsorption of organic acids involved two mechanisms: specific adsorption and electrostatic attraction,but the former was the major one for the two organic acids.Little effect of pH on adsorption of the organic acids was observed below pH4.5,whilst the adsorption decreased with the increase in pH beyond pH4.5.