摘 要

在当前，食品加工、石油纺织、皮革等产业排放的含油废水增多，含乳化油废水对环境保护和生态平衡危害极大，含油废水主要成分是水和黏着的油性物质，并且还包含了不同浓度的对人体有害的化学品，对生物的生存环境具有负面的影响。膜分离技术可以有效的处理含乳化油废水问题，长时间的使用必然造成膜污染问题。

超声波清洗技术被证实在膜分离过程中有良好的抗污染效果，为避免引入额外的超声设备，研究者开发了一种以压电材料制备的分离膜，利用压电材料可以将电能转换为机械能的特性，使膜材料在过滤过程中产生原位高频振动和超声波，从而达到抗污染的效果，而PZT压电陶瓷具有很好的压电效果。本文以Al₂O₃-PZT压电陶瓷膜处理含油乳化液废水为研究对象，以验证压电陶瓷膜的抗污染性能为目标，考察了过滤过程中，污染方式，跨膜压差，膜面流速，乳化液pH值以及乳化液的浓度对压电陶瓷膜抗污染性能的影响。研究的内容主要分为以下几个方面：

利用商业化生产的PZT陶瓷粉体为原料，通过干压成型的方法制备陶瓷膜支撑体，在空气气氛下烧结制备压电陶瓷膜支撑体，并通过浸渍提拉法再进行烧结制备Al₂O₃-PZT压电陶瓷膜。压电陶瓷支撑体的平均孔径约为1 μm，孔隙率为22.4 ％，纯水渗透率为814 L·m^-2·h^-1·bar^-1，三点抗弯强度为69.7 MPa，压电性能为385 mV。Al₂O₃分离层的平均孔径100 nm，纯水渗透率为230 L·m^-2·h^-1·bar^-1，压电性能为320 mV。

将制备的Al₂O₃-PZT压电陶瓷膜在200 ppm、2000 ppm以及酸性和碱性2000 ppm含油乳化液进行过滤实验，考察其原位超声作用。结果表明，压电陶瓷膜的原位超声作用对于膜表面有明显的的清洁作用。当外加交流电频率为210 kHz时，降低乳化油的浓度，较小的跨膜压差，增大膜面流速和输入电压可以使Al₂0₃-PZT压电陶瓷膜获得更高的稳定通量，但原位超声作用在重度污染及低表面流速下更加显著。膜表面性质可以与原位超声协同作用使Al₂O₃-PZT压电陶瓷膜具有更优异的抗污染性能。

本文制备的Al₂O₃-PZT压电陶瓷膜中包含了对人体有害的铅成分，后续实验可以研究在长时间使用Al₂O₃-PZT压电陶瓷膜过滤实验时，是否会有铅逸出情况。同时，在100 nm分离精度的Al₂O₃-PZT压电陶瓷膜基础上，可以继续制备具有原位超声作用的非对称超滤以及纳滤陶瓷膜，研究在更小尺度下原位超声的抗污染作用。由于研究条件有限，本文制备的压电分离膜仅为片状结构，无法满足工业大规模的要求，出于实际考虑，可以制备平板或管式压电陶瓷膜进行研究。

关键词：Al₂O₃-PZT压电陶瓷膜 原位超声 抗污染 含油乳化液

ABSTRACT

At present, oil-containing wastewater discharged from food processing, petroleum textile, leather and other industries is increasing. Emulsified oil-containing wastewater is harmful to environmental protection and ecological balance. The main components of oil-containing wastewater are water and adhering oily substances. It also contains chemicals harmful to human body at different concentrations, which has a negative impact on the living environment of organisms. Membrane separation technology can effectively treat wastewater containing emulsified oil, and long-term use will inevitably lead to membrane fouling.

Ultrasound cleaning technology has been proved to have good anti-fouling effect in membrane separation process. To avoid introducing additional ultrasonic equipment, researchers developed a separation membrane made of piezoelectric materials. The characteristics of piezoelectric materials can convert electrical energy into mechanical energy, which can make membrane materials produce in-situ high frequency vibration and ultrasound in the filtration process, thus achieving anti-fouling effect. PZT piezoelectric ceramics have good piezoelectric effect. In this paper, Al₂O₃-PZT piezoelectric ceramic membrane was used to treat oil-containing emulsion wastewater. In order to verify the anti-fouling performance of piezoelectric ceramic membrane, the effects of fouling mode, transmembrane pressure difference, membrane surface velocity, emulsion pH value and emulsion concentration on the anti-fouling performance of piezoelectric ceramic membrane were investigated. The contents of the study are mainly divided into the following aspects:

Using commercialized PZT ceramic powders as raw materials, ceramic film supports were prepared by dry pressing method, and piezoelectric ceramic film supports were prepared by sintering in air. Al₂O₃-PZT piezoelectric ceramic films were prepared by dipping and pulling method and then sintering. The average pore size of piezoelectric ceramic support is about 1 micron, the porosity is 22.4%, the water permeability is 814 L·m^-2·h^-1·bar^-1, the three-point bending strength is 69.7 MPa, and the piezoelectric performance is 385 mV. The average pore size of Al₂O₃ separation layer is 100 nm, the permeability of pure water is 230 L·m^-2·h^-1·bar^-1, and the piezoelectric property is 320 mV.

Al₂O₃-PZT piezoelectric ceramic membranes were filtered at 200 ppm, 2000 ppm and acidic and alkaline 2000 ppm oil-containing emulsifiers, and their in-situ ultrasound effects were investigated. The results show that the in-situ ultrasonic treatment of piezoelectric ceramic film has obvious cleaning effect on the surface of the film. When the applied AC frequency is 210 kHz, the stable flux of Al₂O₃-PZT piezoelectric ceramic film can be increased by reducing the concentration of emulsified oil, decreasing the transmembrane pressure difference, increasing the flow rate and input voltage, but the in-situ ultrasound effect is more significant under the condition of severe pollution and low surface flow rate. Al₂O₃-PZT piezoelectric ceramic membranes have excellent anti-fouling properties because of their surface properties and in situ ultrasound.

The Al₂O₃-PZT piezoelectric ceramic membrane prepared in this paper contains lead which is harmful to human body. Follow-up experiments can be carried out to study whether there will be lead escaping during long-term filtration experiments using Al₂O₃-PZT piezoelectric ceramic membrane. At the same time, on the basis of Al₂O₃-PZT piezoelectric ceramic membrane with separation accuracy of 100 nm, asymmetric ultrafiltration and nanofiltration ceramic membranes with in-situ ultrasound can be further prepared to study the anti-pollution effect of in-situ ultrasound at a smaller scale. Because of the limited research conditions, the piezoelectric separation membranes prepared in this paper are only sheet structure, which can not meet the large-scale industrial requirements. For practical consideration, flat or tubular piezoelectric ceramic membranes can be prepared for research.

KEYWORDS：Al₂O₃-PZT piezoelectric ceramic; ultrasound; anti-fouling; oil emulsion

目录

摘要 I

ABSTRACT III

目录 V

第一章 文献综述 1

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