xDLVO理论解析天然有机物存在下纳米颗粒膜污染行为
发布时间：2018-10-15 14:09
【摘要】：近年来,纳米技术已广泛用于许多工业产品中,导致工程纳米颗粒在水环境中的浓度升高。在纳米颗粒中,二氧化钛(TiO_2)纳米颗粒被制造用作许多和工业产品中的颜料,防晒剂,光催化剂和半导体,对微生物,植物和动物有毒性作用,并且可能对生态系统造成损害。因此,纳米颗粒如何被废水处理系统去除并如何影响其性能已经受到学者们广泛的关注。超滤被认为是废水处理中去除纳米颗粒的有效方法。然而,由于膜污染会导致膜处理技术维护和操作成本的增加,膜污染仍然是限制超滤技术的广泛应用的桎梏因素。目前关于从膜分离技术中去除纳米颗粒的研究很少。当纳米颗粒排入水中时,环境因素例如天然有机物质和水中的溶液条件将影响纳米颗粒的行为。以前的研究只集中在单个纳米颗粒的膜污染,还未对在天然有机物存在下纳米颗粒膜污染的机理的进行定量分析。本研究利用 extended Derjaguin-Laudau-Verwey-Overbeek(xDLVO)理论对腐殖酸与纳米TiO_2混合物膜污染过程中的界面作用力进行定量解析,评价不同界面作用能(范德华力作用能、双电层力作用能以及极性力作用能)对膜污染的贡献程度,探究腐植酸浓度及溶液条件影响HA-TiO_2混合物膜污染的主控机制。在对界面作用力进行定量解析的基础上,分别对不同污染条件下HA-TiO_2混合物膜污染趋势与界面作用能进行线性拟合,从而更为全面、系统的对xDLVO理论描述HA-TiO_2混合物膜污染行为的适用性作出评价。研究结果表明,极性力作用能对总界面作用能的贡献最大,污染条件的影响主要是通过改变极性力作用能来实现。腐植酸浓度对于HA-TiO_2混合物的表面特性及界面作用能的大小具有显著影响,腐植酸浓度的升高使HA-TiO_2混合物疏水性增加,从而减小膜与HA-TiO_2混合物间及污染物之间的作用能,导致更严重的膜污染。对于HA-TiO_2混合物,pH值的升高或离子强度的降低会减弱界面作用力的吸引性或增强界面作用力的排斥性,从而减缓HA-TiO_2混合物的膜污染。不同溶液条件下HA-TiO_2混合物膜污染趋势与界面作用能具有良好的线性相关性,故xDLVO理论可以较好地预测HA-TiO_2混合物的膜污染。
[Abstract]:In recent years, nanotechnology has been widely used in many industrial products, resulting in the concentration of engineering nanoparticles in the water environment increased. Among nanoparticles, titanium dioxide (TiO_2) nanoparticles are manufactured as pigments, sunscreens, photocatalysts and semiconductors in many and industrial products, toxic to microorganisms, plants and animals, and may damage ecosystems. Therefore, how nanoparticles are removed by wastewater treatment system and how to affect their performance have been widely concerned by scholars. Ultrafiltration is considered to be an effective method to remove nanoparticles in wastewater treatment. However, because membrane fouling will lead to the increase of maintenance and operation cost of membrane treatment technology, membrane fouling is still the shackle factor that limits the wide application of ultrafiltration technology. At present, there is little research on the removal of nanoparticles from membrane separation technology. When nanoparticles are discharged into water, environmental factors such as natural organic matter and solution conditions in water will affect the behavior of nanoparticles. Previous studies focused on membrane fouling of a single nanoparticle, but not on the mechanism of membrane fouling in the presence of natural organic matter. In this study, extended Derjaguin-Laudau-Verwey-Overbeek (xDLVO) theory was used to quantitatively analyze the interfacial forces in the process of membrane fouling of the mixture of humic acid and nanometer TiO_2, and to evaluate the different interaction energies (van der Waals force). The contribution of double layer force energy and polar force energy to membrane fouling was investigated. The main control mechanism of HA-TiO_2 mixture membrane fouling influenced by humic acid concentration and solution conditions was explored. On the basis of quantitative analysis of interfacial forces, the membrane fouling trend of HA-TiO_2 mixture under different pollution conditions and the interaction energy of the interface were fitted linearly respectively, so that it was more comprehensive. The applicability of xDLVO theory to describe membrane fouling behavior of HA-TiO_2 mixtures is systematically evaluated. The results show that the interaction energy of polar force has the greatest contribution to the total interaction energy of the interface, and the influence of pollution conditions is mainly realized by changing the action energy of polar force. The concentration of humic acid has a significant effect on the surface characteristics and interfacial interaction energy of HA-TiO_2 mixture. The increase of humic acid concentration increases the hydrophobicity of HA-TiO_2 mixture, thus reducing the interaction energy between the membrane and HA-TiO_2 mixture and between pollutants. Leading to more serious membrane fouling. For HA-TiO_2 mixtures, the increase of pH value or the decrease of ionic strength will reduce the attraction of interfacial forces or the repellency of interfacial forces, thus reducing the membrane fouling of HA-TiO_2 mixtures. There is a good linear correlation between membrane fouling trend and interfacial interaction of HA-TiO_2 mixtures under different solution conditions, so xDLVO theory can better predict membrane fouling of HA-TiO_2 mixtures.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
本文编号：2272787
[Abstract]:In recent years, nanotechnology has been widely used in many industrial products, resulting in the concentration of engineering nanoparticles in the water environment increased. Among nanoparticles, titanium dioxide (TiO_2) nanoparticles are manufactured as pigments, sunscreens, photocatalysts and semiconductors in many and industrial products, toxic to microorganisms, plants and animals, and may damage ecosystems. Therefore, how nanoparticles are removed by wastewater treatment system and how to affect their performance have been widely concerned by scholars. Ultrafiltration is considered to be an effective method to remove nanoparticles in wastewater treatment. However, because membrane fouling will lead to the increase of maintenance and operation cost of membrane treatment technology, membrane fouling is still the shackle factor that limits the wide application of ultrafiltration technology. At present, there is little research on the removal of nanoparticles from membrane separation technology. When nanoparticles are discharged into water, environmental factors such as natural organic matter and solution conditions in water will affect the behavior of nanoparticles. Previous studies focused on membrane fouling of a single nanoparticle, but not on the mechanism of membrane fouling in the presence of natural organic matter. In this study, extended Derjaguin-Laudau-Verwey-Overbeek (xDLVO) theory was used to quantitatively analyze the interfacial forces in the process of membrane fouling of the mixture of humic acid and nanometer TiO_2, and to evaluate the different interaction energies (van der Waals force). The contribution of double layer force energy and polar force energy to membrane fouling was investigated. The main control mechanism of HA-TiO_2 mixture membrane fouling influenced by humic acid concentration and solution conditions was explored. On the basis of quantitative analysis of interfacial forces, the membrane fouling trend of HA-TiO_2 mixture under different pollution conditions and the interaction energy of the interface were fitted linearly respectively, so that it was more comprehensive. The applicability of xDLVO theory to describe membrane fouling behavior of HA-TiO_2 mixtures is systematically evaluated. The results show that the interaction energy of polar force has the greatest contribution to the total interaction energy of the interface, and the influence of pollution conditions is mainly realized by changing the action energy of polar force. The concentration of humic acid has a significant effect on the surface characteristics and interfacial interaction energy of HA-TiO_2 mixture. The increase of humic acid concentration increases the hydrophobicity of HA-TiO_2 mixture, thus reducing the interaction energy between the membrane and HA-TiO_2 mixture and between pollutants. Leading to more serious membrane fouling. For HA-TiO_2 mixtures, the increase of pH value or the decrease of ionic strength will reduce the attraction of interfacial forces or the repellency of interfacial forces, thus reducing the membrane fouling of HA-TiO_2 mixtures. There is a good linear correlation between membrane fouling trend and interfacial interaction of HA-TiO_2 mixtures under different solution conditions, so xDLVO theory can better predict membrane fouling of HA-TiO_2 mixtures.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
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1 田琳;xDLVO理论解析天然有机物存在下纳米颗粒膜污染行为[D];山东大学;2017年
2 陈德坤;xDLVO理论解析混凝预处理对葡聚糖超滤膜污染的影响机理[D];山东大学;2017年
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