改性Fe_3O_4纳米粒子的定性及对功能菌固定化与脱氮特性

Characteristics of modified Fe_3O_4 nanoparticles and application for immobilization of functioning bacterium and denitrification in water

为解决水体富营养化所导致的恶臭现象,用Si O2和壳聚糖（CS）对Fe3O4纳米粒子进行改性,再运用纳米粒子与微胶囊吸附-包埋的方法固定化功能性菌株,进而对该体系的脱氮特性进行了研究。通过扫描电镜（SEM）、透射电镜（TEM）、X射线衍射仪（XRD）、热重分析（TGA）及振动样品磁强计（VSM）等手段对材料的形貌、结构、磁学性能等进行表征。研究结果表明,Si O2与CS在Fe3O4微球表面形成的包覆层具有产物结晶度高、形态规则、磁性能优良等特点。磁性微球在20min时对菌株的吸附率达85.00%,吸附的活菌数达（2.1-2.2）×106cfu/m L。在对水体脱氮的研究中,游离态菌株对氨氮和硝氮的去除率分别为54.13%和59.17%,固定化菌株对氨氮和硝氮的去除率分别达到72.26%和74.56%。实验结果表明,改性Fe3O4磁性微球对菌株吸附能力强,微胶囊结构使固定化菌株比游离态菌株具有更强的脱氮性能,且能延长Fe3O4磁性微球的生命周期。

In order to solve the water pollution caused by eutrophication,Fe3O4 nanoparticles modified with Si O2 and chitosan（CS）was used for immobilizing functional strain,so that the strain can denitrify the contamination in water more efficiently. The morphology,structure and magnetic properties of Fe3O4 nanoparticles were characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）,thermogravimetric analysis（TGA） and vibrating sample magnetometer（VSM）,and the functions for removing ammonia nitrogen and nitrate nitrogen from water were investigated. The results showed that Fe3O4 nanoparticles exhibited highly ordered crystallinity,regular crystalline morphologies and excellent magnetism. The adsorption rate for the bacteria was up to 85.00% and the numbers of adsorption strain achieved（2.1—2.2）×106cfu/m L at 20 min during the adsorption process. Furthermore,when the non-immobilized strain was added into the media（liquid）,the removal rate of ammonia nitrogen and nitrate nitrogen was 54.13% and 59.17%,respectively. However,when the immobilized strain was added into the media,the removal rate of ammonia nitrogen and nitrate nitrogen increase to 72.26% and 74.56%. Experimental resultsshowed that the modified Fe3O4 nanoparticles had strong adsorption capacity for the strain. In the mean time,the microcapsule structure could make the immobilized strain have better performance and longer life cycle of Fe3O4 nanoparticles compared with the non-immobilized strain.