Srivastava A, Srivastava P C
Department of Soil Science, G. B. Pant University of Agriculture and Technology, Pantnagar-263145, India.
Environ Pollut. 1990;68(1-2):171-80. doi: 10.1016/0269-7491(90)90020-d.
Batch studies were carried out to investigate the adsorption of zinc(II) from fresh waters on an iron(III) hydroxide surface maintained at the pH of zero point of charge of hydroxide (ZPC, 6.85) and also on both the acidic (5.5) and alkaline (8.2) sides of pH of ZPC, at 15 and 35 degrees C. Zinc(II) adsorption on iron(III) hydroxide increased with an increase in pH. The rise in temperature from 15 to 35 degrees C increased zinc(II) adsorption at pH 5.5 and 6.85, but decreased it at alkaline pH (8.2). In none of the cases did adsorption attain a maximum adsorption density. The results indicate the presence of heterogeneous sites of varying affinity on the adsorbent. Zinc(II) adsorption followed Langmuir behaviour only at small adsorption densities (less than 10(-2.95) M Zn/kg at pH 5.5) and at higher adsorption densities, the availability of strongest binding sites decreased. Nonspecifically adsorbed zinc(II) (reversible to Ba(II)) decreased with the increase in pH and temperature. Sequential desorption experiments also revealed that desorption of adsorbed zinc(II) decreased with an increase in pH.
进行了批次研究，以研究在15℃和35℃下，淡水锌（II）在保持在氢氧化铁零电荷点pH值（ZPC，6.85）的氢氧化铁表面上的吸附情况，以及在ZPC的酸性（5.5）和碱性（8.2）pH值两侧的吸附情况。锌（II）在氢氧化铁上的吸附随pH值的增加而增加。温度从15℃升高到35℃，在pH值为5.5和6.85时增加了锌（II）的吸附，但在碱性pH值（8.2）时降低了吸附。在所有情况下，吸附均未达到最大吸附密度。结果表明吸附剂上存在亲和力不同的异质位点。锌（II）吸附仅在小吸附密度下（在pH值为5.5时小于10（-2.95）M Zn/kg）遵循朗缪尔行为，在较高吸附密度下，最强结合位点的可用性降低。非特异性吸附的锌（II）（对钡（II）可逆）随pH值和温度的升高而降低。顺序解吸实验还表明，吸附的锌（II）的解吸随pH值的增加而降低。
