不同pH下有机酸对针铁矿和膨润土吸附Cd^(2+)、Pb^(2+)的影响  

EFFECTS OF ORGANIC ACIDS ON Cd^(2+) AND Pb^(2+) ADSORPTION ON GOETHITE AND BENTONITE AT DIFFERENT pH

作　　者：黄丽[1] 刘畅[1] 胡红青[1] 刘凡[1] 李学垣[1] 

机构地区：[1]华中农业大学农业部亚热带农业资源与环境重点实验室,武汉430070

出　　处：《土壤学报》2007年第4期643-649,共7页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(No.40371065);湖北省自然科学基金(No.2005ABA139)资助

摘　　要：用平衡吸附法研究了不同pH下,三种有机酸(乙酸、酒石酸和柠檬酸)对针铁矿和膨润土等温吸附Cd2+、Pb2+的影响。结果表明:在加入的Cd2+、Pb2+浓度分别小于0.2 mmol L-1和4.0 mmol L-1时,针铁矿和膨润土吸附平衡体系的pH随加入重金属浓度的增加而降低,膨润土体系的pH降低更明显。在有机酸作用下,pH对针铁矿和膨润土吸附Cd2+、Pb2+的影响差异显著。3<pH<4.5时,针铁矿Cd2+的吸附率很小;4.5<pH<8时,Cd2+吸附率明显上升,并趋向饱和吸附。针铁矿Pb2+的吸附率从pH3时开始上升,pH5.5时其吸附率基本稳定于95%。三种有机酸作用下,膨润土Cd2+的吸附率均从40%(pH3时)缓慢地上升;pH8时吸附率近90%。pH3时,加入各有机酸的膨润土Pb2+吸附率均在60%左右;pH6时,加入柠檬酸的上升至80%,其他处理均上升至95%。不同pH下,膨润土Cd2+、Pb2+吸附率的变幅为40%~90%,而针铁矿的为3%~90%;有机酸对促进针铁矿吸附Cd2+和Pb2+的影响大小顺序均为:柠檬酸>酒石酸>乙酸,其对膨润土吸附的影响差异不明显。Effects of organic acids （acetic acid,tartaric acid and citric acid） on Cd^2＋、Pb^2＋ adsorption on goethite and bentonite were studied with the batch method. Results show that pH decreased with the increase in concentration of Cd^2＋ and Pb^2 ＋ in the goethite and bentonite isothermal systems when the concentration of Cd^2＋、Pb^2＋ was lower than 0.2 mmol L^-1 and 4.0 mmol L^- 1, respectively. The decrease of pH in bentonite system was more obvious than in goethite system. The effect of pH on Cd^2＋、Pb^2＋ adsorption of goethite and bentonite varied sharply with organic acids added. Cd^2＋ sorption rate was small with goethite when pH was in the range from 3 to 4.5, but it went upward sharply when pH was higher （4.5 〈 pH 〈 8）, and tended toward saturation at pH 8. Pb^2＋ sorption rate began to increase when pH was 3 with goethite, and it leveled off to 95 % at pH 5.5. Affected by three organic acids, Cd^2＋ sorption rate increased slowly from 40% at pH 3 with bentonite, and approached close to 90% at pH 8 .Pb^2＋ sorption rates were around 60% in bentonite systems added with different organic acid. They increased to 80% when citric acid was added and 95% when other organic acid added. Cd^2＋、Pb^2＋ sorption rates varied from 40% to 90% with bentonite at different pH,but from 3% to 90% with goethite. In terms of effect of organic acids on Cd^2＋、Pb^2＋ adsorption of goethite, the three acids were in the order of citric acid 〉 tartaric acid 〉 acetic acid, but the effect was not clear with bentonite.

关 键 词：PH 有机酸 针铁矿 膨润土 CD^2+ Pb^2+吸附 

分 类 号：S153[农业科学—土壤学]