磁性微球的改性及其固定化铁还原菌的性能

以油酸、聚乙二醇、柠檬酸钠和3-氨丙基三乙氧基硅烷(APTES)为改性剂,采用化学共沉淀法制备4种改性磁性微球.通过粒度测定(PSD)、X射线衍射分析(XRD)、傅里叶红外光谱分析(FTIR)、热重分析(TGA)、磁强度测定(VSM)对各种磁性微球进行表征,并对比各微球固定化铁还原菌后还原Fe(Ⅲ)EDTA的性能,最终确定最佳的磁性微球改性条件.结果表明:APTES改性的Fe₃O₄磁性微球固定化铁还原菌效果优于其他改性微球,其最佳条件为APTES投加量8 mL,1 mg铁还原菌需1.5 g磁性微球进行固定化;APTES-Fe₃O₄固定化铁还原菌后连续使用5次,其Fe(Ⅲ)EDTA还原效率仍可保持在90%以上.

Modification of Magnetic Microspheres and Its Performance ofImmobilized Iron Reducing Bacteria

The modifiers of oleic acid, polyethylene glycol, sodiumcitrate and 3-ammonia propyl triethoxy silane(APTES)were applied to modify the Fe₃O₄ magnetic microspheres by chemical co-precipitation method. The magnetic microspheres were characterized by PSD, XRD, FTIR, TGA and VSM, and reduction rates of Fe(Ⅲ)EDTA by different magnetic microsphere immobilized iron reducing bacteria were compared, to determine the optimal preparation conditions. The results showed that the Fe(Ⅲ)EDTA reduction rate of the iron-reducing bacterium immobilized on the APTES-Fe₃O₄ microspheres was higher than that of the other microspheres. The optimal preparation conditions for the APTES-Fe₃O₄ microspheres were determined as follows: 8 mL of APTES, and 1.5 g magnetic microspheres for immobilization of 1 mg iron-reducing bacteria. More importantly, the reduction efficiency still maintained 90% of its initial reduction ability after the 5th reused cycle.