硅酸盐复合基微滤膜的制备及其用于水处理除污染的研究
发布时间：2018-08-25 20:26
【摘要】：面对日益严重的水环境污染,常规的饮用水处理工艺某些时候已难以满足要求。以膜过滤技术和高级氧化技术为代表的新型饮用水处理技术开始受到人们的关注。膜过滤技术和高级氧化技术均因成本过高而难以大规模应用。其中,膜过滤技术中的膜成本和高级氧化技术中的催化剂成本是制约技术发展的关键。因此需要开发出廉价而高效的膜和催化剂。本文以廉价的硅酸盐水泥和石英微粉为原料,在室温环境下制备出一种低成本、平板型硅酸盐复合基微滤膜。考察了制膜过程中各工艺参数对膜的影响,进而优选出制膜的最佳工艺条件。通过扫描电镜分析、孔径分析、能量色散X射线光谱分析等手段,研究了硅酸盐复合基微滤膜的膜孔形成机制,并对膜的结构、组成和应用性能等进行了深入的表征和分析。本文还将制备的硅酸盐复合基微滤膜作为一种新型催化剂来催化臭氧降解水中有机污染物。考察了臭氧-膜联用工艺去除水中对氯硝基苯(p-CNB,p-chloronitrobenzene)的效能和机理。通过对膜制备过程中成型压力、颗粒粒径、水与硅酸盐水泥比例(w/c)、造孔剂和熟化方式等的考察,确定了制膜的各工艺参数为:成型压力6 MPa,石英粒径40.6-50.0μm,硅酸盐水泥粒径14.6μm,w/c 0.4,20℃、95%相对湿度的空气中熟化12天。依此条件制备的硅酸盐复合基微滤膜可以实现2.3μm的平均孔径,34%的孔隙率,13 m3?m-2?h-1?bar-1的纯水通量和4 MPa的抗弯强度。该条件下膜的孔径只呈现出双峰分布的特点。通过降低制膜所用石英与硅酸盐水泥的比例(q/c)至2.0,成功将膜的孔径分布由双峰分布改善为单峰分布。并依据该过程中膜孔的变化情况,分析出膜内微米级通透孔的形成机制。硅酸盐复合基微滤膜内的通透孔按成因大体可概括为三类。第一类是孔径7-8μm的膜孔,主要通过膜内石英颗粒的堆积作用而形成;第二类膜孔的孔径大体分布在1-3μm,是膜内占最大比例的膜孔,这类孔主要来源于硅酸盐水泥颗粒的堆积作用。第三类膜孔的尺寸大多在1μm以下,其孔的形成主要来源于膜内大量生长的针状钙矾石对大孔径膜孔的切割作用。通过将膜内q/c的值控制在2.0,不仅优化了膜的孔径分布,还使膜的抗弯强度提升到5-6 MPa,此时膜的平均孔径仅为1μm,膜孔隙率和纯水通量的结果也能满足要求。以筛选出的制膜条件制备硅酸盐复合基微滤膜,并对膜的结构和性能进行了深入的研究。对膜的结构表征发现,膜内的硅酸盐水泥在发生水化反应后,主要的水化产物为水合硅酸钙聚合物,在膜内呈胶凝状分布。其他产物还包括平板状的氢氧化钙,针状或薄片状的钙矾石等。硅酸盐复合基微滤膜的膜孔包含微米级孔和介孔两部分,其中微米级膜孔的孔体积在膜内占绝对优势。膜内微米级膜孔的平均孔径为1μm,介孔的平均孔径为13.5 nm。对膜性能的研究发现,硅酸盐复合基微滤膜具有与传统陶瓷膜相近的气液通量,对5×107个/L浓度的小球藻和10 NTU浊度的无机颗粒均可实现80%以上的去除。其中对小球藻的去除更有优势。但在膜污染方面,膜的藻类污染却比无机污染更难被清除。进一步的性能表征发现,硅酸盐复合基微滤膜可以承受500℃的热处理和0.01mol/L的碱腐蚀,在水环境中使用可保证水质的安全和膜的稳定。将制备的硅酸盐复合基微滤膜用于催化臭氧降解水中的有机污染物p-CNB。结果发现,在连续流实验中,臭氧-膜联用工艺可以有效去除水中p-CNB。与单独臭氧氧化工艺相比,在联用工艺中超过1.5 mg/L的溶解态臭氧被分解,致使p-CNB的去除率提高了50个百分点,而膜本身对p-CNB的吸附去除却可以忽略不计。电子顺磁共振波谱(EPR)实验和叔丁醇影响实验证明,臭氧-膜联用工艺对单独臭氧氧化过程的强化源于体系内羟基自由基的产生,膜孔表面存在的碱性水化产物和金属氧化物可能是促进羟基自由基生成和提升p-CNB去除率的关键因素。臭氧-膜联用工艺可以在多种水质条件下保证p-CNB的有效降解,且降解产物的毒性均小于p-CNB,这说明本文制备的硅酸盐复合基微滤膜除了具备截留能力外,还是一种廉价、高效的臭氧催化剂。此臭氧-膜联用工艺可作为一种应对水体突发有机污染的廉价应急处理技术。
[Abstract]:In the face of increasingly serious water environmental pollution, the conventional drinking water treatment process is sometimes difficult to meet the requirements. New drinking water treatment technologies, such as membrane filtration technology and advanced oxidation technology, have attracted people's attention. Membrane cost in filtration technology and catalyst cost in advanced oxidation technology are the keys to restrict the development of technology.So it is necessary to develop cheap and efficient membranes and catalysts.In this paper,a low cost,flat silicate composite microfiltration membrane was prepared by using cheap silicate cement and quartz powder as raw materials at room temperature. The effect of technological parameters on the membrane was studied and the optimum technological conditions were optimized. The pore formation mechanism of silicate composite microfiltration membrane was studied by means of scanning electron microscopy, pore size analysis and energy dispersive X-ray spectroscopy. In this paper, the silicate composite microfiltration membrane was used as a new catalyst to catalyze ozone degradation of organic pollutants in water. The removal efficiency and mechanism of p-chloronitrobenzene (p-CNB, p-chloronitrobenzene) in water by ozone-membrane process were investigated. The sludge ratio (w/c), pore-forming agent and curing method were investigated. The technological parameters were determined as follows: molding pressure 6 MPa, quartz particle size 40.6-50.0 micron, silicate cement particle size 14.6 micron, w/c 0.4, 20 C, 95% relative humidity curing in air for 12 days. The porosities of the membranes under this condition show only a bimodal distribution. By reducing the ratio of quartz to Portland cement (q/c) to 2.0, the pore size distribution of the membranes is successfully improved from bimodal distribution to unimodal distribution. The formation mechanism of the micropore in the membrane is analyzed. The pore in the silicate composite microfiltration membrane can be divided into three types according to its origin. The first type is the pore with a pore diameter of 7-8 micron, which is mainly formed by the accumulation of quartz particles in the membrane; the second type is the membrane with a pore diameter of 1-3 micron, which is the largest proportion in the membrane. The pore size of the third kind of pore is mostly less than 1 micron. The formation of the pore is mainly due to the cutting effect of acicular ettringite on the large pore size of the membrane. The average pore size of the membrane is only 1 micron when the strength is increased to 5-6 MPa. The results of membrane porosity and pure water flux can also meet the requirements. The main hydration product is calcium silicate hydrate polymer, which is gelled in the membrane. Other products include flat calcium hydroxide, acicular or flaky ettringite and so on. The average pore size of the microporous membrane was 1 micron, and the average pore size of the mesoporous membrane was 13.5 nm. It was found that the silicate-based microfiltration membrane had similar gas-liquid flux to the traditional ceramic membrane, and could remove more than 80% of the Chlorella and 10 NTU turbidity inorganic particles with the concentration of 5 *107/L. However, the algae contamination is more difficult to remove than the inorganic contamination in membrane fouling. Further characterization shows that the silicate composite microfiltration membrane can withstand 500 C heat treatment and 0.01 mol/L alkali corrosion. The use of silicate composite microfiltration membrane in water environment can ensure the safety of water quality and membrane stability. The results showed that the combined process of ozone and membrane could effectively remove p-CNB in water. Compared with the single ozonation process, the dissolved ozone over 1.5 mg/L was decomposed in the combined process, resulting in an increase of 50 percentage points in the removal rate of p-CNB, while the membrane itself could effectively remove p-CNB. Electron paramagnetic resonance spectroscopy (EPR) and tert-butanol effect experiments show that the enhancement of Ozonation by ozone-membrane process is due to the generation of hydroxyl radicals in the system, and the existence of alkaline hydration products and metal oxides on the pore surface of the membrane may promote the formation of hydroxyl radicals. Ozone-membrane process can ensure the effective degradation of p-CNB under various water quality conditions, and the toxicity of the degradation products is less than that of p-CNB. This indicates that the silicate composite microfiltration membrane prepared in this paper is a cheap and efficient ozone catalyst besides its interception ability. Art can be used as a cheap emergency treatment technology to deal with sudden organic pollution of water bodies.
【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】：2015
【分类号】：TU991.2
本文编号：2204007
[Abstract]:In the face of increasingly serious water environmental pollution, the conventional drinking water treatment process is sometimes difficult to meet the requirements. New drinking water treatment technologies, such as membrane filtration technology and advanced oxidation technology, have attracted people's attention. Membrane cost in filtration technology and catalyst cost in advanced oxidation technology are the keys to restrict the development of technology.So it is necessary to develop cheap and efficient membranes and catalysts.In this paper,a low cost,flat silicate composite microfiltration membrane was prepared by using cheap silicate cement and quartz powder as raw materials at room temperature. The effect of technological parameters on the membrane was studied and the optimum technological conditions were optimized. The pore formation mechanism of silicate composite microfiltration membrane was studied by means of scanning electron microscopy, pore size analysis and energy dispersive X-ray spectroscopy. In this paper, the silicate composite microfiltration membrane was used as a new catalyst to catalyze ozone degradation of organic pollutants in water. The removal efficiency and mechanism of p-chloronitrobenzene (p-CNB, p-chloronitrobenzene) in water by ozone-membrane process were investigated. The sludge ratio (w/c), pore-forming agent and curing method were investigated. The technological parameters were determined as follows: molding pressure 6 MPa, quartz particle size 40.6-50.0 micron, silicate cement particle size 14.6 micron, w/c 0.4, 20 C, 95% relative humidity curing in air for 12 days. The porosities of the membranes under this condition show only a bimodal distribution. By reducing the ratio of quartz to Portland cement (q/c) to 2.0, the pore size distribution of the membranes is successfully improved from bimodal distribution to unimodal distribution. The formation mechanism of the micropore in the membrane is analyzed. The pore in the silicate composite microfiltration membrane can be divided into three types according to its origin. The first type is the pore with a pore diameter of 7-8 micron, which is mainly formed by the accumulation of quartz particles in the membrane; the second type is the membrane with a pore diameter of 1-3 micron, which is the largest proportion in the membrane. The pore size of the third kind of pore is mostly less than 1 micron. The formation of the pore is mainly due to the cutting effect of acicular ettringite on the large pore size of the membrane. The average pore size of the membrane is only 1 micron when the strength is increased to 5-6 MPa. The results of membrane porosity and pure water flux can also meet the requirements. The main hydration product is calcium silicate hydrate polymer, which is gelled in the membrane. Other products include flat calcium hydroxide, acicular or flaky ettringite and so on. The average pore size of the microporous membrane was 1 micron, and the average pore size of the mesoporous membrane was 13.5 nm. It was found that the silicate-based microfiltration membrane had similar gas-liquid flux to the traditional ceramic membrane, and could remove more than 80% of the Chlorella and 10 NTU turbidity inorganic particles with the concentration of 5 *107/L. However, the algae contamination is more difficult to remove than the inorganic contamination in membrane fouling. Further characterization shows that the silicate composite microfiltration membrane can withstand 500 C heat treatment and 0.01 mol/L alkali corrosion. The use of silicate composite microfiltration membrane in water environment can ensure the safety of water quality and membrane stability. The results showed that the combined process of ozone and membrane could effectively remove p-CNB in water. Compared with the single ozonation process, the dissolved ozone over 1.5 mg/L was decomposed in the combined process, resulting in an increase of 50 percentage points in the removal rate of p-CNB, while the membrane itself could effectively remove p-CNB. Electron paramagnetic resonance spectroscopy (EPR) and tert-butanol effect experiments show that the enhancement of Ozonation by ozone-membrane process is due to the generation of hydroxyl radicals in the system, and the existence of alkaline hydration products and metal oxides on the pore surface of the membrane may promote the formation of hydroxyl radicals. Ozone-membrane process can ensure the effective degradation of p-CNB under various water quality conditions, and the toxicity of the degradation products is less than that of p-CNB. This indicates that the silicate composite microfiltration membrane prepared in this paper is a cheap and efficient ozone catalyst besides its interception ability. Art can be used as a cheap emergency treatment technology to deal with sudden organic pollution of water bodies.
【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】：2015
【分类号】：TU991.2
【参考文献】
相关期刊论文 前1条
1 崔素萍;郭红霞;王辰;王子明;;纳米无定形C-S-H凝胶颗粒及其结构表征[J];硅酸盐通报;2012年03期
相关博士学位论文 前1条
1 王永红;新型陶瓷分离膜制备科学基础和性能研究[D];中国科学技术大学;2006年
相关硕士学位论文 前1条
1 张芳;多孔氧化铝陶瓷支撑体及其微滤膜的制备与表征[D];中北大学;2005年
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