柠檬酸缓释膜与质构量化净水菌胶囊的制备及其性能研究

发布时间：2018-08-08 10:58

【摘要】：我国环境污染问题凸显,水资源的保护和合理利用迫在眉睫,江浙地区由于地表水占比较大,其治理的需求也更为迫切。氮素污染会导致水体富营养化,对水产养殖、工业发展和生活用水造成严重危害,水体中氨态氮的治理难度最大。本研究采用微生物对水体污染进行修复,主要目的为降低水体中氨氮。研究从微生物固定化技术入手,以载净水菌胶囊的体系研究为主体,利用海藻酸钠、聚乙烯醇为壁材,结合质构量化分析探究出合理的微生物固定化体系,同时利用壳聚糖、聚乙烯醇等高聚物制备柠檬酸缓释膜,并进行净水效果的评估。主要的研究内容及结果如下:(1)柠檬酸检测体系的建立和优化。Fe3+和柠檬酸根离子于酸性条件下在紫外照射下会形成紫色络合物,试验采用分光光度法构建检测体系,对检测波长、Fe3+浓度、光照和静置时长等条件进行优化,最终确立最适的检测体系为:混合体系总体积200μL,其中Fe3+和硝酸混合体系50μL(Fe3+浓度0.5 mol/L、HNO3浓度0.5mol/L),柠檬酸和dd H2O混合体积150μL。检测波长为440 nm,柠檬酸的检测范围为:0.5×10-3 mol/L~0.5×10-1 mol/L。经HPLC法柠檬酸检测结果对比显示,该检测方法稳定有效,可用于柠檬酸的检测。(2)对壳聚糖-柠檬酸交联体系的研究。通过对交联体系包封率和柠檬酸载药量的分析,确立了较优壳聚糖-柠檬酸交联体系为:0.1 mol/L柠檬酸钠40 m L+20mg/m L壳聚糖溶液50 m L。将该交联体系用不同体积的10%聚乙烯醇溶液进行包覆,经烘干后制备出聚乙烯醇包覆的柠檬酸缓释膜。对缓释膜体进行水体释放实验表明:柠檬酸的释放速率会随着膜体中聚乙烯醇使用比例的减少而增加,各实验组中柠檬酸陆续在16 h~3 d内释放率均达到90%以上,研究表明聚乙烯醇在一定程度上能延缓柠檬酸的释放。(3)基于质构量化的净水菌胶囊制备。通过质构量化指标的引入,对固定化壁材、辅料添加量、固化液浓度、固化时长等因素进行优化分析,确立较优的微生物固定化体系为:微胶囊壁材配方为V(4%海藻酸钠):V(10%聚乙烯醇)=1:9;较佳固化液配方为4%Ca Cl2和4%H3BO3的混合溶液;辅料竹炭、硅藻土和沸石的适宜添加量(w/v)分别为20%~60%、20%~30%和20%~60%。对较优配方下的微胶囊进行空隙率分析和内部结构扫描电子显微镜观察表明:在微胶囊内部存在大量的孔隙,这利于胶囊内部和外界的物质交换。同时水体释放实验表明该微胶囊内有部分微生物能释放到水体环境中。(4)实验室模拟净水实验。摇瓶净水实验结果表明:该载菌微胶囊能去除水体中的氨氮,20 h后各实验组中NH4+-N浓度从1 h时39.3 mg/L~44.7 mg/L均降低到0.1 mg/L以下,氨氮去除率99%以上。24 h后各实验组中的总氮值也出现不同程度的下降;微胶囊片状膜于自制模拟河道,进行开放水体净水实验结果表明:各实验组中氨氮值随着水力停留时间(HRT)增加而降低,当HRT为30 h时氨氮值由进水的6.2 mg/L~6.4 mg/L下降到1.2 mg/L~1.7 mg/L、总氮值由11.4 mg/L下降到2.1mg/L~2.6 mg/L;投加柠檬酸缓释膜实验组的净水效果略好于未投加组。适宜碳源的投加有利于增强微生物水体修复的效果。
[Abstract]:The problem of environmental pollution in China is prominent, the protection and rational utilization of water resources is imminent. In Jiangsu and Zhejiang areas, because of the large amount of surface water, the demand for its treatment is more urgent. Nitrogen pollution will lead to eutrophication of water body, cause severe harm to aquaculture, industrial development and living water, and the difficulty of treatment of ammonia nitrogen in water body is the most difficult. The main purpose of remediation of water pollution by microorganism is to reduce the ammonia nitrogen in water. From the technology of microbial immobilization, the main body of the study is to study the system of the capsule of water carrying bacteria, using sodium alginate and polyvinyl alcohol as the wall material, and combining the qualitative and quantitative analysis to explore the rational microbial immobilization system, and the use of chitosan, Citric acid sustained-release membranes were prepared by polyvinyl alcohol and other polymers. The main contents and results were as follows: (1) the establishment and optimization of citric acid detection system and optimization of.Fe3+ and citrate ions under acidic conditions would form purple complexes under UV irradiation, and the test system was constructed by spectrophotometry. The measurement wavelength, Fe3+ concentration, light and static time length were optimized. Finally, the optimum detection system was established as follows: the total volume of the mixed system was 200 mu L, of which the mixture of Fe3+ and nitric acid was 50 L (Fe3+ concentration 0.5 mol/L, HNO3 concentration 0.5mol/L), and the mixed volume of citric acid and DD H2O was 440 nm, and the detection range of citric acid was 0.5 x 1. The comparison of 0-3 mol/L~0.5 x 10-1 mol/L. by HPLC method of citric acid detection shows that the method is stable and effective and can be used for the detection of citric acid. (2) the study of chitosan citric acid crosslinking system. Through the analysis of the encapsulation efficiency of the crosslinking system and the drug loading of citric acid, a better chitosan citric acid crosslinking system is established as: 0.1 mol/L lemon Sodium acid 40 m L+20mg/m L chitosan solution 50 m L. coated the crosslinking system with different volume 10% polyvinyl alcohol solution and prepared the citric acid sustained-release membrane coated with polyvinyl alcohol. The release experiment of the slow-release membrane body showed that the release rate of citric acid decreased with the use of polyvinyl alcohol in the membrane body. The release rate of citric acid in 16 h~3 D was up to 90% in each experiment group. The study showed that polyvinyl alcohol could delay the release of citric acid to a certain extent. (3) preparation of water purification capsule based on quantitative texture. The optimum microorganism immobilization system is as follows: the microcapsule wall material is V (4% sodium alginate): V (10% polyvinyl alcohol) =1:9, and the better cure solution is a mixed solution of 4%Ca Cl2 and 4%H3BO3; the suitable addition amount of the auxiliary bamboo charcoal, diatomite and zeolite (w/v) is 20%~60%, 20%~30% and 20%~60%. to the better formula. The gap rate analysis and the internal structure scanning electron microscope (SEM) show that there are plenty of pores inside the microcapsule, which is beneficial to the exchange of material inside and outside of the capsule. At the same time, the release experiment of water body shows that some microbes in the microcapsule can be released into the environment of the water body. (4) the laboratory simulated water purification experiment in the laboratory. The experimental results showed that the microcapsule was able to remove ammonia nitrogen in water. After 20 h, the concentration of NH4+-N decreased to less than 0.1 mg/L from 39.3 mg/L~44.7 mg/L from 1 h, and the total nitrogen value in the experimental groups decreased with the removal rate of ammonia nitrogen above 99%.24 H. The experimental results showed that the ammonia nitrogen value in the experimental group decreased with the increase of hydraulic retention time (HRT). When HRT was 30 h, the value of ammonia nitrogen decreased from 6.2 mg/L~6.4 mg/L to 1.2 mg/L~1.7 mg/L, the total nitrogen value decreased from 11.4 mg/L to 2.1mg/L~2.6 mg/L, and the water purification effect of the experimental group adding citric acid slow release membrane was better than that of the unadded group. The addition of suitable carbon sources is conducive to enhancing the effect of microbial water restoration.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52;X172

【参考文献】