纤维基镧复合材料高效除磷控菌方法的研究

发布时间：2018-06-08 20:09

本文选题：吸附除磷 + 控菌　；参考：《哈尔滨工业大学》2017年博士论文

【摘要】：随着我国经济的腾飞,国民生活水平也得到了大幅提升,与人民生活息息相关的《生活饮用水卫生标准》也日益严苛,作为基础建设的城镇饮用水水质得到了很大的改善。尤其近十年随着给水处理工艺的发展和更新,饮用水品质在经过给水处理的各个环节后得到了很大程度的改善。但是优质的水质却往往受到供水管网带来的生物安全隐患的威胁,因此如何保持给水输配途中的水质成为了人们极度重视的问题。原水有机物残留量为管网中的微生物提供了生长的条件,水体呈现生物不稳定,同时残余有机物会快速消耗水中余氯严重地削弱了水体保证生物安全性的能力。针对给水生物安全问题,许多研究尝试通过强化消毒等常规手段控制微生物生长,但是这往往会带来消毒副产物生成,增加微生物抗药性等一系列隐患。除此之外,限于给水水质的严格要求,新开发的消毒剂还有待毒性测试。因此,给水生物安全问题仍待进一步研究。与以往研究不同,本课题直接选择关注生物稳定性以控制饮用水生物安全,并且课题另辟蹊径不采用常规控制可同化有机碳(AOC)而是采用除磷的方法控制生物稳定性,为实现生物稳定性提供了多重通道和选择,这种“磷断粮”的思路不仅仅是一种生物安全的保障方法,也为打破仅从碳源考量生物稳定性的定势思维,构建新思路做出深入研究。为了解决给水中低浓度磷去除困难的实际问题,课题筛选不同种类的除磷吸附剂,最终确定了能与磷酸根具有超强结合能力的镧基化合物作为功能组分。在此基础上,通过静电纺丝以及后续共沉淀等制备手段,得到了可以稳定固着在聚丙烯腈高分子纳米纤维中均匀分散的氢氧化镧纳米棒以及氧化镧纳米颗粒两种材料。并且为了保证镧基纤维优秀的磷吸附能力,通过调整静电纺丝的参数(电压15-20 k V,环境湿度HR 30-50,电压参数18-20 k V,PAN溶液浓度参数5 wt%-7 wt%,电纺速度参数0.1-1.0 m L/h),降低纤维直径至100-200 nm,并且纤维直径分布集中,最终得到了纤维结构稳定,形貌一致,直径细小的基于氢氧化镧纳米棒以及氧化镧纳米颗粒的最优纺丝材料。同时,通过研究La(OH)_3/PAN纤维的制备过程,得到静电纺丝过程可以保证金属盐活性位点负载具有优异的分散性,并且电纺和共沉淀一起对金属盐的生长有很好的调控作用,保证材料的一体性和吸附功能的最大化。聚丙烯腈在上述制备过程中,一方面作为支撑结构为镧离子和氢氧化钠的作用提供接触位点,另一方面也控制了氢氧化镧的成核与生长,使得氢氧化镧的生长由于位点的固定和限制而避免了大量纳米棒的沉积,使得单分散式各向异性生长的氢氧化镧纳米棒得以生成。La_2O_3/PAN纤维和La(OH)_3/PAN纤维对磷酸根优异的吸附能力验证了镧基化合物与磷酸根的超强作用能力。La_2O_3/PAN纤维的饱和吸附量为77.76 mg P/g(La),而与之相比,La(OH)_3/PAN纤维因为组分中高分散性La(OH)_3纳米棒增加了反应接触的活性位点被证明具有更高的吸附能力,饱和吸附量达172.2 mg P/g(La)。并且La(OH)_3/PAN纤维具有超高效的吸附速率和对低浓度磷的超强捕捉能力,当初始浓度为2 mg P/L时,20 min即可迅速去除,去除率达到98.9%,这种突出的吸附性能保证了缺磷环境的实现,解决了控菌目标的瓶颈问题。除此之外,La(OH)_3/PAN纤维的稳定性阻止了负载成分的泄漏,保证了功能组分La(OH)_3纳米棒的使用安全,证明了这种纳米材料在给水中应用的安全性。在通过镧进行有效除磷的水体中,观察典型阳性与阴性菌的生长,证明缺乏磷元素的水体,对菌种的生长有很好的控制效果,磷浓度在一定阈值下会抑制大肠杆菌和金黄色葡萄球菌的生长。并通过自来水水体的实验,证明通过“磷断粮”的方法能够很好的保证水质生物安全稳定性,经过二次接触污染的水体菌落个数并没有增长,缺磷环境减少了微生物二次生长的风险。最后,通过控制纺丝湿度,对静电纺丝材料进行改进,制备出能够兼具过滤除菌和长效控菌的镧基滤膜。La(OH)_3/PAN滤膜在静电纺丝中添加了镧基盐类,使得电纺纤维的平均直径由140 nm降至110 nm,进而降低了滤膜的孔径,最大孔径由0.90μm降至0.20μm。并且在后续共沉淀的过程中La(OH)_3纳米棒的生长提高了纤维的机械性能,同时滤膜表面由于镧基盐类负载得到的正电性也提高了菌体与膜表面的静电引力作用,这些滤膜改进增加了滤膜对菌体的截留能力。除此之外,由于La(OH)_3/PAN滤膜中功能组分镧的添加,增加了对水中磷酸根的去除,厚度100μm以上的滤膜对磷的截留能力超过了97%,并且能够完全截留浓度为107 CFU/m L的大肠杆菌。强化了滤出水的生物安全稳定性,相比同样具有过滤效果的滤膜,La(OH)_3/PAN滤膜能够明显控制微生物的二次生长使得水体具有长效的控菌能力。
[Abstract]:With the development of our country's economy, the national living standard has also been greatly improved. The sanitary standard for drinking water which is closely related to the people's life is also increasingly harsh. The water quality of urban drinking water has been greatly improved as a basic construction. In recent ten years, with the development and renewal of water treatment technology, the quality of drinking water has been given to the people. Every link of water treatment has been greatly improved, but the quality water quality is often threatened by the hidden danger of biological safety caused by the water supply network. So how to keep the water quality in the water supply and distribution has become a serious problem. The residual amount of organic matter in the original water provides the conditions for the growth of the microorganism in the pipe network. The water body presents biological instability, while residual organic substances will rapidly consume the residual chlorine in water to seriously weaken the water body's ability to ensure biological safety. In order to control the biological safety of water, many studies try to control microbial growth by means of intensive disinfection, but this will bring the production of disinfection by-products and increase the resistance of microorganisms. In addition to the strict requirements of water quality, the newly developed disinfectant still remains to be tested for toxicity. Therefore, the problem of biological safety in water supply remains to be further studied. Unlike previous studies, the subject has chosen to pay attention to biological stability to control the biological safety of drinking water. The regulation of assimilable organic carbon (AOC) is to control biological stability by means of phosphorus removal, and provides multiple channels and choices for the realization of biological stability. The idea of "phosphorus cutting" is not only a safeguard method for biological safety, but also a new way of thinking to break down a new thinking for the stability of the raw material only from the carbon source. In order to solve the practical problem of the difficulty in removing the low concentration of phosphorus in the water supply, we select different kinds of phosphorus removal adsorbents, and finally determine the functional component of the lanthanum compound, which can have super strong binding capacity with the phosphate root. On this basis, it can be stabilized by the means of electrostatic spinning and subsequent coprecipitation. Two materials are fixed in the polyacrylonitrile polymer nanofibers, which are evenly dispersed lanthanum hydroxide nanorods and two lanthanum oxide nanoparticles. In order to ensure the excellent phosphorus adsorption capacity of the lanthanum fiber, the parameters of the electrostatic spinning are adjusted (voltage 15-20 K V, ambient humidity HR 30-50, voltage parameter 18-20 K V, PAN solution concentration parameter 5 wt%-7 w) T%, the electrospinning speed parameter 0.1-1.0 m L/h), reduce the fiber diameter to 100-200 nm, and the fiber diameter distribution is concentrated. Finally, the fiber structure is stable, the morphology is consistent, and the diameter of the lanthanum oxide nanorods and lanthanum oxide nanoparticles are the best spinning materials. In the same time, the preparation process of La (OH) _3/PAN fiber was obtained and the static was obtained. The electrospinning process can ensure the excellent dispersibility of the metal salt active site load, and the electrospinning and co precipitation have a good control effect on the growth of metal salts, ensuring the integration of the materials and maximizing the adsorption function. In the preparation process, polyacrylonitrile is used as the supporting structure for lanthanum and sodium hydroxide on the one hand. The action provides contact sites, on the other hand, the nucleation and growth of lanthanum hydroxide is controlled. The growth of lanthanum hydroxide is prevented by the deposition of a large number of nanorods due to the fixed and restricted loci of lanthanum hydroxide. The monodisperse lanthanum hydroxide nanorods with monodisperse anisotropic growth are able to produce.La_2O_3/PAN fiber and La (OH) _3/PAN fiber to phosphoric acid. The excellent adsorption capacity of the root showed that the saturated adsorption capacity of.La_2O_3/PAN fiber was 77.76 mg P/g (La), and compared to that, the La (OH) _3/PAN fiber increased the reactive site of the reaction contact with the highly dispersed La (OH) _3 nanorods in the component and proved to have a higher adsorption capacity and saturated absorption. The attachment amounts to 172.2 mg P/g (La). And La (OH) _3/PAN fiber has super efficient adsorption rate and super strong capture ability to low concentration of phosphorus. When the initial concentration is 2 mg P/L, 20 min can be quickly removed and the removal rate reaches 98.9%. This outstanding adsorption performance ensures the realization of the phosphorus deficiency environment and solves the bottleneck problem of the target control. In addition, the stability of La (OH) _3/PAN fibers prevented the leakage of the load components and ensured the safety of the functional component La (OH) _3 nanorods. The safety of the nanomaterials used in water supply was proved. The growth of typical positive and negative bacteria was observed in the water body of effective phosphorus removal through lanthanum, and the water body lacking phosphorus was proved to be a water body. The growth of bacteria has a good control effect. Under a certain threshold, the concentration of phosphorus inhibits the growth of Escherichia coli and Staphylococcus aureus. Through the experiment of water body water, it is proved that the method of "phosphorus grain breaking" can guarantee the safety and stability of the water quality, and the number of colonies that have been contaminated by two times has not increased. Long, phosphorus deficient environment reduced the risk of two growth of microbes. Finally, by improving the spinning humidity and improving the electrospinning material, the lanthanum.La (OH) _3/PAN filter membrane, which could have both filtrating and long effect bacteria, was prepared to add lanthanum base salts in the electrospinning, and the average diameter of the electrospun fiber was reduced from 140 nm to 110 nm. The pore size of the filter membrane was reduced, the maximum aperture was reduced from 0.90 to 0.20 m to 0.20 Mu and the growth of La (OH) _3 nanorods during the subsequent coprecipitation improved the mechanical properties of the fiber. Meanwhile, the positive electricity of the membrane surface due to the lanthanide base salt load increased the electrostatic force of the bacteria and the membrane surface, and the filter membranes were improved. In addition to the addition of the functional component lanthanum in the La (OH) _3/PAN filter membrane, the removal of phosphate was increased by the addition of the functional component lanthanum in the filter membrane of the La (OH). The ability to intercept the phosphorus by the filter film above 100 mu m was more than 97%, and it could completely intercept the Escherichia coli with a concentration of 107 CFU/m L. The biological safety stability of the filtered effluent was enhanced. Compared with the same filtration membrane, the La (OH) _3/PAN membrane can control the two growth of microorganisms obviously, so that the water body has a long-term ability to control bacteria.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU991.2

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