含酚废水的正渗透-膜蒸馏分离过程研究
文献类型：学位论文
| 作者 | 李权耕 |
| 学位类别 | 硕士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 王军 |
| 关键词 | 正渗透，膜蒸馏，微波，酚，传质强化，煤气化废水，Forward osmosis, Membrane distillation, Microwave, Phenolic compounds, Enhancement of mass transfer, Coal gasification wastewater |
| 其他题名 | The study on the separation of phenolic wastewater by forward osmosis – membrane distillation (FO-MD) integrated process |
| 学位专业 | 环境工程 |
| 中文摘要 | 本文针对煤气化废水中的酚类污染物处理及资源化关键问题，构建“正渗透-微波辅助膜蒸馏”组合工艺，重点探讨运行工艺条件对代表性酚类污染物正渗透、膜蒸馏跨膜传质的影响，探索微波辅助对含酚高盐汲取液膜蒸馏过程的影响。本研究可为煤气化废水达标排放和资源化处理提供技术支持。研究取得创新性研究成果如下： 1．研究考察组合工艺中运行工艺参数对代表性酚类物质（目标污染物）正渗透分离过程的影响规律，并探讨影响机理。与醋酸纤维正渗透膜相比，聚酰胺复合正渗透膜具有较高的产水通量和酚类物质截留率；正渗透过程对目标污染物的截留受电荷排斥效应和空间阻隔效应的共同作用，提高原料液 pH值可减小苯酚和间苯二酚的渗透通量，但是，4-正丙基苯酚渗透通量、正渗透的产水通量和反向盐通量未受 pH值的影响；随NaCl汲取液浓度的升高，正渗透产水通量呈对数变化，而目标污染物渗透通量、比反向盐通量没有发生明显变化。因此，高原料液 pH值和NaCl汲取液浓度有利于正渗透过程对酚类物质的截留。此外，研究还考察模拟煤气化废水正渗透工艺处理效果，研究表明，正渗透工艺对模拟废水中TOC的去除率达到 80%以上，随着正渗透过程的进行，截留率略有上升，可能是由于正渗透膜表面污染导致其表面负电性增强所致。 2．采用优化后的溶解扩散模型对正渗透过程中目标污染物渗透通量和产水通量进行理论预测。理论计算值与实验测定值对比发现，理论计算可以很好预测目标污染物的渗透通量和产水通量。且理论公式计算表明，正渗透膜支撑层内严重的浓差极化现象是实际产水通量远低于理论产水通量的主要原因，理论计算可为运行条件的优化、正渗透膜的研发提供技术指导。 3．系统的考察了运行工艺参数对含酚高盐汲取液微波膜蒸馏过程的影响，并分析微波强化传质机理。研究结果表明微波辅助明显强化和稳定膜蒸馏的传质过程，在适当条件下，微波辅助对传质通量强化率可达 25.4%。在高 pH值条件下，微波辅助可有效缓解膜蒸馏膜表面的膜污染现象。微波辅助对膜蒸馏膜特性影响的研究表明，微波辅助并没有对膜的各项性能造成显著影响。 |
| 英文摘要 | In this study, a forward osmosis-membrane distillation (FO-MD) integrated membrane process was investigated for the treatment and reuse of phenolic pollutants in the coal pressurized gasification wastewater. The effect of operation parameters on the mass transfer mechanism of typical phenolic contaminants on the FO and MD membrane surfaces in FO-MD combined process will be mainly investigated. Then the microwave assisted technology was introduced for the study of the MD desalination process of high salt concentration draw solution. All these can offer technical support for the treatment and the reuse of coal pressurized gasification wastewater. This research has obtained the following innovative results: 1. The effects of operation parameters on the FO separation process of representative phenolic contaminants (target contaminants) were investigated. Compared with CTA FO membrane, the TFC-ES FO membrane had smaller pore size, higher porosity, lower pore tortuosity and thickness, it was of benefit to reduce the internal concentration polarization phenomenon of FO membrane, so the TFC-ES FO membrane had a higher water permeation flux and a higher phenol rejection than the commercial CTA FO membrane. The mass transfer of organic contaminants was dependent on both steric hindrance and electrostatic repulsion between the negatively charged active layer of FO membrane and also negatively charged phenolic compounds. As a result, the permeation fluxes of phenol and resorcinol at high pH were remarkable lower than fluxes at low pH values. In addition, the permeation flux of 4-propylphenol, water permeation flux and reverse salt flux of FO process remained almost constant over the entire range of pH values. The water flux appeared a logarithm increase with the increase of the concentration of NaCl draw solution, while the concentration of NaCl draw solution didn’t obviously affect the target contaminants fluxes and specific reverse salt flux. Therefore, it was beneficial to the rejection of target contaminations in high pH of feed solution and high concentration of NaCl draw solution. Besides, the treatment of simulated coal pressurized gasification wastewater by FO process was also investigated. Results showed that the TOC rejection rate of simulated coal pressurized gasification wastewater by FO process was beyond 80%. With the FO test running, the rejection performance became even better which may result from the improvement of the negative charge property of membrane surface caused by membrane fouling. 2. In this study, optimized solution-diffusion model were used to predict the target contaminants permeation fluxes and water permeation flux in FO processes. It was found that the modeling results fitted well with the experimental results. The results showed that the severe internal concentration polarization hugely reduced mass transfer driving force and water permeation flux. The optimized model in this study could provide technical support for the optimization of operation parameters and the preparation of FO membrane. 3. The effects of operation parameters on microwave-assisted membrane distillation process of phenolic draw solution of high salt concentration and the mechanism of mass transfer enhancement by microwave assistance were nvestigated. It was found that microwave assistance significantly improved the mass transfer of membrane distillation. The maximum mass transfer coefficient increasing rate in this study was about 25.4% under optimal conditions. When the pH of draw solution increased above 10, the microwave assistance could ease the membrane fouling. The test results of membrane properties indicated that microwave irradiation had no significant influence on the characteristics of membrane materials. |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34341]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 李权耕. 含酚废水的正渗透-膜蒸馏分离过程研究[D]. 北京. 中国科学院研究生院. 2015. |
入库方式： OAI收割
来源：生态环境研究中心
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