改性沸石和铁粉的复合材料处理水中六价铬的研究

利用海藻酸盐的凝胶化将零价铁粉固定于改性沸石表面,制得复合材料,以期在保留改性沸石的吸附性的同时增加铁粉的还原性.复合材料的扫描电镜图片可以看出铁粉分散嵌于海藻酸钙薄层,同时海藻酸钙不会阻碍Cr(VI)与改性沸石的接触.实验考察材料去除水中Cr(VI)性能,结果表明:复合材料,改性沸石,铁粉的除Cr(VI)效率分别为:74.1%,38.4%,9.1%,这得益于改性沸石和铁粉相互的协同作用. 对反应后复合材料进行XPS检测,其表面含有Cr3+,Cr6+表明了材料吸附能力同时还具有还原性.并且对Cr(VI)去除的现象能用伪二级吸附动力学方程描述.平衡吸附量qe和反应速率常数k呈相反的变化趋势.铁粉含量为5.4%的材料性能较好:qe为0.96mg/g, k为0.011g/(mg×h);在Cr(VI)浓度为70mg/L时,上述铁含量的复合材料仍具有较高的处理性能,其qe和k分别为 1.29mg/g, 0.0094g/(mg×h).

Kinetic study for removal of soluble Cr(VI) by prepared surfactant-modified zeolites supported zero-valent iron composite

Based on the sol-gel transition property of sodium alginate, a kind of composite that: zero valent iron (ZVI) powder was immobilized on the surface of SMZ was prepared so that the composite would have both the adsorption capacity of SMZ and the reducibility of ZVI. The composite was scanned by scanning electron microscope, which indicated that iron powder was uniformly entrapped in a thin calcium-alginate film on the SMZ surface, besides the film did not impede the contact between Cr (VI) and SMZ. The batch experiments aimed to test the capability of removing soluble Cr (VI) by the composite and showed that: removal efficiency of composite, SMZ, ZVI was74.1%,38.4%,9.1%, respectively. The reacted composites was also scanned by X-Ray photoelectron spectrometer (XPS), it revealed that Cr3+, Cr6+ were both on the surface of the composite, which verified the composite owned the adsorption and the reducing ability. The reaction between the composites and Cr (VI) can be expressed by pseudo-second order kinetic model. The changing trend of qe and k was opposite. The composite with a 5.4% iron content showed better performance: its qe was 0.96mg/g, and k was 0.011g/(mg×h). And it still showed good performance when the concentration of Cr (VI) was 70mg/L. It has a qe of 1.29mg/g, and a k of 0.0094g/(mg×h).