磁性硅藻土的制备及其性能

Preparation and performance of magnetic diatomite

针对现有硅藻土吸附容量小和固液分离难的问题,采用共沉淀法制备2种磁改性硅藻土:Ⅰ和Ⅱ,通过扫描电镜(SEM)、比表面积测定(BET)、X射线衍射(XRD)等对制备的磁性硅藻土进行结构分析,并采用磁滞回线评估其磁性;考察了溶液pH、吸附剂用量和吸附时间对其吸附硝基苯的影响以及吸附饱和后的固液分离性能。结果表明:2种磁改性样品的饱和磁化强度分别为26.28 emu/g和4.8 emu/g,比表面积分别为39.242 m^2/g和60.588 m^2/g,为原土的1.3倍和2倍;对硝基苯的去除率分别达74.95%和95.2%,为原土的1.8倍和2.3倍;吸附饱和的磁改性样品在外加磁场作用下可迅速实现固液分离,且分离后2种磁改性样品溶液的悬浮物浓度分别为8.6 mg/L和9.8 mg/L。

In view of the low adsorption capacity and difficult solid-liquid separation of existing diatomites,two kinds of magnetic diatomite,viz,I and II,were prepared by a common precipitation method. Scanning electron microscopy（ SEM）,Brunauer-Emmett-Teller（ BET） surface area analysis,and X-ray diffraction（ XRD）were used to characterize the magnetic diatomites,and their magnetic hysteresis loops were evaluated. The adsorption of nitrobenzene by the two samples was investigated by changing the p H,adsorbent amount,and adsorption time,and the performance during solid-liquid separation after saturated adsorption was also discussed. The results showed that the saturated magnetizations of the two samples were 26. 28 and 4. 8 emu / g,while the specific surface areas were 39. 242 and 60. 588 m^2/ g,which were 1. 3 and 2 times that of the raw diatomite. The nitrobenzene removal rates reached 74. 95% and 95. 2%,which were 1. 8 and 2. 3 times that of the raw diatomite. The magnetic samples could be separated quickly under magnetic fields,and the concentration SS were 8. 6and 9. 8 mg / L in two modified sample solutions after separation.