渗透汽化法-电渗析技术去除费托合成废水中含氧有机物的研究

Removal of organic compounds from Fischer-Tropsch synthesis wastewater by pervaporation and electrodialysis

费托合成废水是煤液化合成油过程中产生的反应水,主要成分包括醇、酸、醛、酮等含氧有机物.将费托合成废水中的有机物回收,降低其中的有机物含量,对煤制油成为集成优化的清洁生产过程具有重要意义.本研究通过筛选对醇类具有分离能力的膜材料,采用渗透汽化技术分离并回收费托合成废水中的含氧有机物,考察了多种复合膜对于不同二元体系和多元体系的渗透汽化性能.结果表明,当进料液中各组分的质量比为乙醇∶丙醇∶丁醇∶乙酸:水=2.5∶1∶1∶1∶94.5时,经过二级渗透汽化分离,透过液中的各组分质量分数分别为乙醇19.01%,丙醇14.71%,丁醇24%,乙酸0.38%,水41.9%,有机物的总质量分数可达到58.1%,从而可以直接作为燃料进行燃烧.此外,采用电渗析技术对废水中的乙酸进行去除,并考察了其去除乙酸的效果.采用渗透汽化-电渗析组合技术去除费托合成废水中的含氧有机物,可以有效提高费托合成废水的可生化性、经济性,对实现大规模煤间接液化合成油的清洁生产具有重要意义.

The Fischer-Tropsch reaction wastwater which is produced in the process of coal liquefaction synthetic oil, includes organic compounds, such as alcohols, acids, aldehydes, and ketones. It should be significant to improve the cleaner production process if the organic compounds can be reused from the wastewater. In this study, pervaporation was used in recovery of oxygen-containing organic compounds from Fischer-Tropsch synthesis wastewater. Three different membrane materials were compared for separating alcohol from water. Separation performance of composite membranes for different binary and multiple mixtures were investigated. When the feed solution composed by ethanol ＂ propyl alcohol .＂ butanol ： acetic acid ： water（mass ratio） = 2. 5 ： 1 ： 1 ： 1 ： 94. 5, the content of each component in permeating liquid was （mass fraction） ethanol 19. 01%, propanol 14. 71%, butanol 2.4%, acetic acid 0. 38%and water 41.9%, after two-stage pervaporation separation. The tatal content of oxygen-containing organic compounds reached 58. 1%. Moreover, acetic acid was removed from water by electrodialysis and the separation performance was investigated. The removal of organic compounds from Fischer-Tropsch synthesis wastewater by pervaporation and electrodialysis can not only improve the biodegradability, hut also improve the economic performance. Therefore, it is a potential application for recovering oxygen- containing organic compounds from Fischer-Tropsch synthesis wastewater.