斜发沸石的改性及吸附机理及其对高氟水的去除

Modification and adsorption mechanism of clinoptilolite and its fluoride removal from high fluoride water

对斜发沸石不同条件(烘干、焙烧、微波、酸淬、碱淬和盐淬)改性后吸附水中氟离子的性能进行了对比。结果表明,焙烧、酸淬处理沸石较其他改性沸石对F-的吸附效果良好,吸附量分别提高了0.23 mg/g和0.44 mg/g。进一步研究了焙烧/酸淬沸石对F-的吸附,吸附量达到了0.72 mg/g。进而探讨了斜发沸石改性机理。借助BET孔径分析可知,焙烧/酸淬后沸石孔径由原样的22.30 nm增大到32.32 nm,吸附F-后孔径为19.75 nm。焙烧主要是去除沸石孔道中的有机杂质,增大孔道体积和比表面积;而FTIR红外光谱分析表明,酸浸渍对Si—O或Al—O键(1 581 cm-1)的影响较大,产生了新的弯曲振动峰,极大促进了斜发沸石对F-的吸附。F-吸附等温线与Langmuir等温式拟合最佳,斜发沸石对F-的吸附主要为双分子层吸附。

The capacities of clinoptilolite to adsorb fluoride from wastewater were compared after modification under different conditions such as drying,roasting,microwave disposal,pickling,alkali leaching and salt quenching.The results showed that the adsorption capacities of clinoptilolite disposed by roasting and pickling were better than that of clinoptilolite disposed by others,under which the adsorption capacities were enhanced by0.23 mg/g and 0.44 mg/g,respectively.Further study indicated that the fluoride adsorption capacity could reach0.72 mg/g after the clinoptilolite disposed by roasting/pickling.Then the modification mechanisms of clinoptilolite was explored.The BET analysis showed that the average pore diameter of clinoptilolite increased from 22.30 nm to 32.32 nm after modification by roasting/pickling,and turned to 19.75 nm after the adsorption of fluoride.Roasting could increase the pore volume and the specific surface area of clinoptilolite by removing the organic impurities in the pore channels.Moreover,the FTIR analysis showed that pickling had a great influence on Si—O or Al—O bond（1 581 cm-1） with new bending vibration peaks,which greatly promoted the capacity of clinoptilolite to adsorb fluoride.The adsorption model was mainly double molecule layer with adsorption isotherm fitting best with the Freundlich isotherm.