摘要
研究聚丙烯酸钠PAASS与模拟废水中Cd2+络合反应动力学,结果表明:当pH为6、Cd2+浓度为10mg·L-1和PAASS浓度为5000mg·L-1时,络合反应符合拟一级速率方程。考察负载比对Cd2+截留系数R的影响,可得PAASS络合容量为0.033gCd·(gPAASS)-1。考察pH和竞争络合剂对R的影响,发现当pH从5增大到6时,R迅速增大;竞争络合剂三乙醇胺或酒石酸钠使R下降。研究络合体系超滤浓缩行为,结果表明体积浓缩因子为10时,膜通量仅下降14.6%,R值大约为1;浓缩液用于解离研究,控制解离pH为2.5,可得:当截留液镉浓度为99.6mg·L-1时,渗透液镉浓度可达93.1mg·L-1,对应络合物解离效率为93.5%;解离液用于超滤洗涤,当洗涤液体积为原料液体积4倍时,截留液镉浓度从洗涤前99.6mg·L-1降低至洗涤结束时3.87mg·L-1,镉洗脱率为96.1%,洗涤后聚电解质纯度高。
The kinetics of complexation reaction of poly （acrylic acid） sodium salt （PAASS） with cadmium ions was investigated by using a simulated wastewater. It was found that, when pH value and the concentrations of cadmium ion and PAASS are 6, 10 mg.L^-1 and 5000 mg.L^-1, respectively, the reaction kinetics of complexation can be described by a pseudo-first-order equation. In order to determine the cadmium binding capacity of PAASS, the change of cadmium ion rejection coefficient （R） of PAASS with its loading ratio was studied, and the result shows that the cadmium binding capacity of PAASS is 0.033 g Cd.（g PAASS）^-1. The effects of pH and competitive complexing agents on R were investigated, and it was found that R increases rapidly when pH increases from 5 to 6 and decreases when the competitive complexing agent （triethanolamine or tartrate sodium） is present. In the ultrafiltration concentration process of the complexation system, it was found that, when the volume concentration factor reaches 10, the membrane flux only declines 14.6% and the R is about equal to 1. The final concentrated solution was used to study the behavior of decomplexation, and it was found that, controlling the pH at 2.5 and then when the cadmium concentrations in the retentate is 99.6 mg.L^-1, the cadmium concentration in the permeate can reach 93.1 mg.L^-1, it corresponds to the decomplexation ratio of 93.5%. The washing experiment of the decomplexation solution was carried out further; and it was found that, with the washing liquid volume four times larger than the feed volume, the cadmium concentration in the retentate decreases from its beginning value of 99.6 mg.L^-1 to 3.87 mg.L^-1. It means that the removal ratio of cadmium reaches 96.1% and a high purified PAASS can be obtained after washing.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2008年第5期883-888,共6页
Journal of Chemical Engineering of Chinese Universities
基金
湖南省自然科学基金资助项目(05JJ40020)
湖南省教育厅基金资助项目(05C170)
关键词
络合
超滤
聚丙烯酸钠
含镉模拟废水
complexation
ultrafiltration
poly （acrylic acid） sodium salt
simulated wastewater containing cadmium ion
