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Ozone-water contacting by ceramic membranes

机译：臭氧水与陶瓷膜的接触

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A comon process in water treatment is the wet oxidation for the removal fo certain orgnaic and inorgnic pollutanrts. The strogest oxidant technically aplied in this proces is ozone, which is an unstable gas under normal conditions, and therefore is produced from oxygen on site, usually by elecrical discharege. After that the oxone has to be transferred from that gas inot the water to be treated. conventionally ozone transfer is achieved by bringing the gas and water in direct contact by means of buble columns, conjectors or other similar devices. under unfavorable conditions, however, these methods suffer from excessive formation of foam requiring an extra treatment and a high-energy demand for pumping gas or water. this project's approach was to improve the transfer by better control of gaseous and aqueous phase's conditions at the contact surface. This was achieved by means of a membrane both separating the two phases and allowing for an ozone transfer between them. Due to ozone's high oxidation potential, chemically inert ceramic membranes were chosen for that purpose. In experiments, it was found that the transfer of the unstable ozone molecules is not obstructured by ceramic membrane matrial. Transfer rates between gaseous ozone and model water were measured for conventional ceramic membranes, as well as specially designed ones. They are comparable to conentional methods ro better on the base of mass transfte per reactor volume. In conventional oxide membranes, water enters the pores because ofcapillary effects in the hydrophilic material [Burggraaf, A.J. and Cot, L., 1996, Fundamentals of inorganic Membrane Science and technology Elsevier science, the Netherlands]. The water in the pores raises the diffusion resistance for the ozone thus decreasing the transfer itself. Consequently, the modification of the hydrophilic material features into a hydrophobic behavior was one promising approach for the optimization of the process. It was achieved through the application of a hydrophobic coating to the membrane surface, which greatly improved the transfer efficiency.
机译：水处理的常见方法是湿法氧化去除某些有机和无机污染物。从技术上讲，这种最严格的氧化剂是臭氧，它在正常条件下是不稳定的气体，因此通常是通过电放电从现场的氧气中产生的。在那之后，必须从该气体中转移氧杂环丁烷，以处理水。通常，臭氧的转移是通过气泡塔，喷射器或其他类似装置使气体和水直接接触来实现的。然而，在不利的条件下，这些方法会产生过多的泡沫，需要额外的处理，并且需要大量的能量来泵送气体或水。该项目的方法是通过更好地控制接触表面的气相和水相条件来改善转移。这是通过将两相分离并允许臭氧在两相之间转移的膜来实现的。由于臭氧的高氧化电位，因此选择了化学惰性的陶瓷膜。在实验中，发现不稳定的臭氧分子的转移不受陶瓷膜材料的阻碍。测量了传统陶瓷膜以及专门设计的膜在气态臭氧与模型水之间的传输速率。在每反应器体积传质的基础上，它们可与常规方法媲美。在传统的氧化膜中，由于亲水性材料中的毛细作用，水会进入孔中[Burggraaf，A.J.和Cot，L.，1996，《无机膜科学与技术的基础知识》，Elsevier科学，荷兰]。孔中的水提高了臭氧的扩散阻力，从而降低了转移本身。因此，将亲水材料的特征改性为疏水行为是优化工艺的一种有前途的方法。这是通过在膜表面上应用疏水涂层实现的，大大提高了转移效率。

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