粉煤灰粘土膨润土等对Cd^(2+)吸附性能的比较研究  

Effects of Fly Ash,Clay and Bentonite on the Sorption of Cd^(2+)

作　　者：席永慧[1] 胡中雄[2] 

机构地区：[1]同济大学建筑工程系,上海200092 [2]同济大学地下建筑与工程系,上海200092

出　　处：《农业环境科学学报》2004年第5期930-934,共5页Journal of Agro-Environment Science

基　　金：上海市科技发展基金(022312202)

摘　　要：采用室内试验方法,研究了粉煤灰、粘土、膨润土等从溶液中去除有毒金属离子Cd2+的吸附过程。结果表明,粉煤灰、膨润土对Cd2+的吸附能力远大于粘土、粉质粘土,且粉煤灰大于膨润土。平衡吸附模型充分说明在高浓度下,Cd2+在粘土、粉质粘土上的吸附最符合Langmuir等温线。试验结果还表明,随着吸附剂中Cd2+浓度的增加,粉煤灰等吸附剂对Cd2+吸附的百分率均呈减小的趋势。Sorption of heavy metal Cd2+from aqueous solutions by fly ash, cla y and bentonite was investigated. The results of kinetic experiments at 20 ℃± 2 ℃showed that the sorption process of Cd 2+was rapid. The time of reachin g sorption equilibrium of Cd2+on clay, silty clay and bentonite was about 2 h, while that on fly ash was about 24 h. The equilibrium uptake of Cd2+on clay, silty clay,fly ash and bentonite at an initial concentration was obtained thro ugh the hyperbola regression of (C0-C)/C0 ～t curves. Sorption capacity of Cd2+on fly ash and bentonite was much larger than those of clay and silty cla y (about 10～20 times), and that on fly ash was larger than that on bentonite. At high concentration, the sorption of Cd2+on clay, silty clay was fitted to a Langmuir isotherm, and the Cd2+saturation sorption capacity on clay and silty clay were 8.81 mg·g-1 and l4.04 mg·g-1respectively. Although the Cd2+ sorption on fly ash were not fitted to a Linear isotherm, Langmuir isotherm or F reundlich isotherm, the Cd2+sorption capacity on fly ash was about 50～70 mg ·g-1under 100～1 100 mg·L-1equilibrium concentration. The larger sorp tion capacity of Cd2+on fly ash could attribute to the high pH of fly ash (11. 8) and major oxides constituents that were ideal adsorbents for metals. When Cd2 +loading in adsorbents such as clay, silty clay, fly ash increased,the perce ntage of Cd2+sorption by these adsorbents decreased, which indicated that the metal loading was an important factor that can significantly affect the Cd2+so rption results on soil and fly ash. Fly ash was demonstrated an effective adsorb ent for Cd2+in environmental administering.

关 键 词：粉煤灰 CD^2+ 吸附 等温线 

分 类 号：X705[环境科学与工程—环境工程]