铝(氢)氧化物对有机酸和磷酸根的竞争吸附研究

研究了磷 /草酸浓度比 (Cp/Cox)、草酸 (OX)与磷 (P)加入顺序、多种有机酸共存等条件下铝 (氢 )氧化物 (Al(OH)x)对有机酸和磷的吸附量变化。结果表明 :磷浓度一定时 ,随Cp/Cox减小 ,Al(OH)x吸附磷量降低 ,吸附OX量增高 ,吸附阴离子总量一般随浓度升高而增加 ;Cp/Cox相同时 ,5种加入方式吸P顺序为P/OX P -OX OX +P OX -P OX/P ;Cp/Cox不同时 ,Al (OH)x吸附配位体的总量也相应变化 ;几种有机酸共存时 ,Al(OH)x对体系中的各种阴离子均有吸附 ,且相互影响和制约 ,总吸附量取决于离子种类和浓度 ,3种有机酸影响P吸附量的顺序为柠檬酸 (CA) 草酸 (OX) 酒石酸 (Tar) ;Al (OH)x加磷后随平衡时间延长 ,先吸附的OX和CA对吸附P量的影响逐渐减弱 ,它们的相对亲合力越来越成为主导因素。

Competitive adsorption of phosphate and several organic acids on Al(OH)x surfaces

Competitive adsorption of phosphate and o rganic acid ligand onAl (OH)x surface was studied under various concentration ratio of phosphate to oxalate (Cp/Cox) or addition order, mixture of several organic acids, and equilibrium time. The results showed: (1) The effect of organic acid on decreasing phosphate adsorption varied with the addition order of them. When the organic acid was introduced before phosphate addition, the effect of organic acid on P adsorption was the most remarkable; but when the organic acid was added after phosphate addition, it was the least effective; and when they were added as a mixture or when phosphate was added after organic acid was sorbed, then discarded through centrifuging, the effect of organic acid was in the middle. (2) When phosphate was added as a mixture with two or three kinds of organic acids to Al (OH)x mineral, the reduction of phosphate adsorption amount by Al (OH)x was different with that in the system of single organic acid. The reduction degree was related to the kind and concentration of organic acids. Because of the competition among phosphate and different organic anions, the final effect was not equal to the sum of single organic acids. (3)The amount of phosphate adsorption in the presence of citrate or oxalate was increased with the equilibrium time prolonging from 1 to 7 days. The relative affinity played a more important role for competitive adsorption.