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OP-10改性PVDF超滤膜的制备及性能研究

Preparation And Properties of OP-10 Modified PVDF Ultrafiltration Membranes

作者: 专业:化学 导师:芦艳 年度:2015 学位:硕士  院校: 东北石油大学

Keywords

PVDF ultrafiltration membrane, hydrophilic, OP-10, nanometer metal particles, modified membrane

        聚偏氟乙烯(PVDF)是一种兼具氟树脂和通用树脂特性的高分子有机聚合物。以其优良的耐温、耐氧、耐侯、耐辐射、耐化学腐蚀和易成膜等特性而倍受青睐。但PVDF表面自由能低,制备出来的分离膜表面疏水性较高,在分离膜应用过程中,易受到污染从而使膜的水通量下降。对膜材料进行改性,增强分离膜的亲水性是解决膜污染问题的有效途径。为提高PVDF超滤膜的亲水性,增强其水通量,从而改善膜的抗污染能力,实验利用具有极强亲水性的非离子型表面活性剂OP-10与PVDF溶液共混,采用相转化法流延成膜,制备OP-10改性PVDF高分子板式超滤膜。通过杯式超滤装置考察表活剂OP-10的含量对改性膜水通量、截留率、孔隙率等性能的影响;利用W-56强度测定仪对膜拉伸强度和断裂伸张率进行测量;采用接触角测定仪测得膜与纯水的接触角用以表征膜的亲水性的变化;使用傅立叶红外光谱仪(FT-IR)分析了OP-10组分加入对PVDF晶型的影响;应用扫描电镜(SEM)和原子力显微镜(AFM)观察了膜的表面孔分布及断面结构和表面粗糙程度。结果表明,表面活性剂OP-10的加入没有改变有机膜的微观结构,改性膜在保持了PVDF超滤膜原有特性的基础上,纯水通量最高增加368.2%,改性膜PVDF5的纯水接触角由改性前的83.52°降至54.67°,亲水性明显提高,孔隙率增加9.28%,改性膜韧性略有提高。改性膜中OP-10的加入量w(OP-10)为1.67%时,膜的性能最好,改性效果最佳。OP-10的加入在改善改性膜的通量和亲水性的同时,使其截留率和机械强度都稍有下降。为改进添加OP-10改性效果不足之处,在此基础上添加纳米氧化铝(Al2O3)、纳米二氧化硅(SiO2)和纳米二氧化钛(TiO2),同样采取相转化法方法制备表面活性剂和纳米金属粒子共同改性PVDF膜。实验表明:三种纳米金属粒子的添加都不同程度的提高了改性膜的水通量;其中纳米氧化铝粒子的添加与OP-10共同改性的效果最好,PVDF8的纯水通量增加至1410.96 L·m-2·h-1,接触角降至53.14o,截留率提高至97.6%,机械拉伸强度20.5123N,断裂伸长率7.18%,有效的弥补了因添加表面活性剂OP-10所导致机械强度和截留率的缺陷。为考察改性膜的抗污染能力,实验采用管式改性膜对油田含油污水进行超滤,并对污染膜进行清洗,结果表明:经超滤膜处理的水中油类含量均小于0.6mg/L,TOC(Total Organic Carbon)去除率均超过95%,COD(Chemical Oxygen Demand)和浊度的去除率均在90%以上,固体悬浮物含量小于0.5mg/L且固体颗粒的粒径中值小于2μm。改性膜的出水指标均高于未改性膜,并且出水的水质达到了油田回注水标准。为考察污染膜经清洗后的通量恢复情况,实验采取几种不同类型的化学药剂对膜进行清洗。实验表明:碱性药剂对膜的清洗效果最好,膜的通量恢复最明显,其中以含量为2%的十二烷基苯磺酸钠溶液的清洗能力最优,PVDF8膜的通量恢复率达95.7%。表面活性剂OP-10和纳米金属粒子共同对PVDF膜改性效果明显,大幅度提高了改性膜的亲水性,提高了PVDF膜的抗污染能力。
    Polyvinylidene fluoride(PVDF) is a macromolecular organic polymer which owns the feature of both fluorine resin and common resin. PVDF is widely preferred due to its excellent temperature, oxygen, weather, radiation, chemical corrosion resistance property, as well as the approachable film formation characteristic. However, because of the lower free energy on the surface of PVDF, the hydrophobicity of this separation membrane is relatively high and is easy to be contaminated, which would decrease the water flux during its application. Enhance the hydrophilicity of the membrane by modification is an effective way to solve its fouling problem.To improve the contamination resistance of PVDF ultrafiltration by increasing its hydrophilicity and then enhance its water flux, nonionic surfactant OP-10 with extremely high hydrophilicity was mixed with PVDF for the fabrication of PVDF macromolecular plate ultrafiltration membrane by using phase transformation method. By using cup ultrafiltration device, the influence of OP-10 amount on the water flux, retention, porosity and other properties of modified membrane was investigated. The tensile strength and the fracture elongation rate of the film was measured by W-56 strength tester. The hydrophilic change was characterized by testing the contact angle between the film and pure water with contact angle measurement. The impact of OP-10 on PVDF polymorphs was analyzed by Fourier transform infrared spectroscopy(FT-IR) and the pore distribution, film section structure and surface roughness observed by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results showed that the microscopic structure wasn’t altered by the adding of OP-10 and the pure water flux increased 368.2% maximumly on the base of retaining its original properties. The contact angle descended from 83.52° to 54.67°, which indicated the ascendance of hydrophilic. At the meantime, the porosity increased 9.28% and the toughness of the modified film was improved. The performance of the film, as well as the modification effect was obtained with 1.67% w(OP-10) adding amount of OP-10.The flux and hydrophilic was improved by the adding of OP-10, while also decreased its retention rate and mechanical strengthen slightly. In order to improve these deficiencies, nano-alumina(Al2O3), nano silicon dioxide(SiO2) and titanium dioxide(TiO2) were appended for the modification of PVDF membrane along with surfactant in terms of phase transformation method. The results proved that three kinds of nano particles increased the water flux in different degrees, among which the nano-alumina exhibited the best modification effects combined with OP-10. The pure water flux reached to 1410.96 L·m-2·h-1 and the contact angle decreased into 53.14o. What’s more, the retention rate increased into 97.6% while the mechanical tensile obtained at 20.5123 N, along with 7.18% breaking elongation rate. These results all showed that the drawbacks caused by adding OP-10 in strength tensile and retention rate were improved.In order to investigate the pollution resistance ability of modified membrane, oil contained wastewater from oil filed was ultrafiltrated by tubular modified membrane, and then the contaminated membrane was cleaned. The result revealed that the oil amounts in the water after ultrafiltration were less than 0.6 mg/L, and the removal rate of TOC(Total Organic Carbon) was more than 95%. Furthermore, the removal rate of COD(Chemical Oxygen Demand) and turbidity were more than 90% similarly. The particle size of suspended solids content was less than 0.5 mg/L with its size less than 2μm. The effluent index of modified membrane were all higher than the unmodified membrane, and the water quality of effluents has reached the re-injected water standards of oil field. Several different types of chemicals for membrane cleaning have been used to testify the recovery extent of the contaminated membrane. The results indicated that alkali chemicals shows the best cleaning effects with the most obvious flux recovery. The content of 2% sodium dodecyl benzene sulfonate solution exhibited the best cleaning capability among all those alkali chemicals with 95.7% flux recovery rate. In a word, the hydrophilicity of PVDF, as well as its contamination persistence were improved by the effect of surfactant OP-10 and nano metal particles.
        

OP-10改性PVDF超滤膜的制备及性能研究

摘要4-6
Abstract6-7
创新点摘要8-11
第一章 绪论11-22
    1.1 课题研究背景11-13
        1.1.1 膜分离技术简介12-13
    1.2 膜技术在含油污水处理中的应用13-16
        1.2.1 含油污水简介13-14
        1.2.2 含油污水的传统处理技术及其存在的问题14-15
        1.2.3 含油污水处理膜的选择15-16
    1.3 聚偏氟乙烯(PVDF)膜的改性研究进展16-20
        1.3.1 PVDF膜的表面改性16-18
        1.3.2 PVDF膜的材料改性18-20
    1.4 研究OP-10改性PVDF超滤膜的目的、意义及主要内容20-22
        1.4.1 课题研究的目的和意义20-21
        1.4.2 课题研究的主要内容21-22
第二章 OP-10改性超滤膜的制备及性能表征22-32
    2.1 实验主要材料和仪器设备22-23
    2.2 改性PVDF超滤膜的制备23
    2.3 超滤膜性能测试23-26
        2.3.1 纯水通量的测定23-24
        2.3.2 接触角的测定24
        2.3.3 孔隙率的测定24
        2.3.4 截留率的测定24-26
        2.3.5 机械性能的测定26
    2.4 超滤膜的微观结构观察26-27
        2.4.1 扫描电子显微镜(SEM)26
        2.4.2 傅立叶红外(FI-IR)光谱26-27
    2.5 结果与讨论27-31
        2.5.1 OP-10加入量对PVDF改性膜通量的影响27
        2.5.2 OP-10加入量对PVDF改性膜接触角的影响27-28
        2.5.3 OP-10加入量对PVDF改性膜孔隙率和截留率的影响28
        2.5.4 OP-10加入量对PVDF改性膜机械性能的影响28-29
        2.5.5 扫描电子显微镜(SEM)分析29-30
        2.5.6 傅立叶红外(FT-IR)光谱分析30-31
    2.6 本章小结31-32
第三章 OP-10与纳米Al_2O_3/SiO_2/TiO_2共混改性PVDF膜的制备与表征32-41
    3.1 引言32
    3.2 改性超滤膜制备32-33
    3.3 改性膜性能表征33
        3.3.1 改性膜通量的测定33
        3.3.2 改性膜机械强度的测定33
        3.3.3 改性膜接触角的测定33
        3.3.4 改性膜截留率和孔隙率的测定33
    3.4 改性膜结构表征33-34
        3.4.1 改性膜的傅立叶红外观测33
        3.4.2 改性膜的AFM观测33-34
        3.4.3 改性膜的SEM观测34
    3.5 结果与讨论34-40
        3.5.1 改性膜组份对膜通量的影响34-35
        3.5.2 改性膜机械强度的分析35
        3.5.3 改性膜接触角的分析35-36
        3.5.4 改性膜孔隙率与截留率的分析36
        3.5.5 改性膜傅立叶红外光谱图分析36-38
        3.5.6 改性膜原子力显微镜(AFM)分析38-39
        3.5.7 改性膜表面SEM分析39-40
    3.6 本章小结40-41
第四章 改性PVDF超滤膜抗污染性试验41-47
    4.1 引言41-42
    4.2 实验材料与设备及工艺流程42
        4.2.1 实验水样42
        4.2.2 实验药剂及设备42
    4.3 实验工艺流程42-43
    4.4 实验结果与分析43-46
        4.4.1 含油污水各项污染物去除率43-44
        4.4.2 PVDF超滤膜的通量衰减率44-45
        4.4.3 清洗后膜的通量恢复率45-46
    4.5 本章小结46-47
结论47-48
参考文献48-53
发表文章目录53-54
致谢54-55
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