摘要
以油页岩渣及其二氧化钛改性材料为吸附剂,探究它们去除水溶液中亚甲基蓝和六价铬的能力.通过实验,控制溶液的pH值、温度、初始浓度和接触时间,观察吸附效果变化特征,研究其动力学和热力学性能.实验表明,改性油页岩渣吸附亚甲基蓝和六价铬的吸附率是未改性的2—3倍,且改性油页岩渣对亚甲基蓝的吸附率可达97%,对六价铬的吸附率不到25%.吸附亚甲基蓝时,pH值越大,吸附效果越好;而吸附六价铬时,最适pH值为4.改性油页岩渣吸附亚甲基蓝实验符合准二阶动力学方程,计算得反应活化能为13.29 kJ.mol-1,表明此过程主要是物理吸附.在热力学方面,由范特霍夫方程计算得ΔG<0、ΔH>0,表明此过程自发吸热,可见此过程还伴有化学吸附.Langmuir和Freundlich等温模型拟合结果表明,Langmuir模型数据拟合甚佳,R2=0.9999,说明改性油页岩渣吸附亚甲基蓝是单分子层吸附.二氧化钛改性油页岩渣经7次回收利用后,对亚甲基蓝的吸附效果仅减少约1.5%.
Oil shale ash and its TiO2 modified material were used as adsorbents to explore their abilities of removing methylene blue and Cr （ VI ） in solutions. In these experiments, by varying the pH value of the solution, temperature, initial concentration and contact time, the characters of the adsorption were observed and the kinetic and thermodynamic properties were studied. The experiments showed that the adsorption capacity of the modified oil shale ash was twice to three times as much as that of the untreated one. The adsorption rate of methylene blue on the modified oil shale ash was up to 97%, while the adsorption of Cr（ VI ） was less than 25%. For the adsorption of methylene blue, the higher the pH value, the larger the adsorption＇capacity. And for the adsorption of Cr（ VI ）, the optimal pH value was 4. The adsorption of methylene blue on the modified oil shale ash fitted the Pseudo-second-order dynamic equations. The calculated activation energy was 13.29 kJ·mo1-1, indicating that this process was physical adsorption. The calculation according to the Van＇t Hoff equation showed that AG 〈 0 and AH 〉 0, indicating that this process was spontaneous and endothermic, and it also suggests that this process involved chemical adsorption. The experimental data was fitted with the Langmuir and Freundlich isotherm models. The results show that the Langmuir model fitted the model data well, R2 = 0. 9999, indicating that the adsorption of methylene blue on modified oil shale ash was monolayer adsorption. After recycling 7 times, the adsorption capacity of methylene blue on the modified oil shale ash decreased by only about 1.5%.
出处
《环境化学》
CAS
CSCD
北大核心
2012年第11期1683-1690,共8页
Environmental Chemistry
基金
中国中央大学基础研究基金(2010ZY38)
中国地质大学(北京)"科技立项"
实验室开放基金资助
关键词
油页岩渣
改性
吸附
亚甲基蓝
含铬废水
oil shale ash, modified, adsorption, methylene blue, Cr（VI）.
