Ceramic membranes liquid filtration

Microfiltration and ultrafiltration are the two main filtration techniques for which ceramic membranes have been widely used to date. As described in Section 6.2.1.2, MF and UF ceramic membranes exhibit macro- and mesoporous structure, respectively, which result from packing and sintering of ceramic particles. Liquid flow in such porous media is convective in nature and the simplest description of permeation flux, J, is given by the Darcy s equation [20] ... 

Compared to modules based on cylindrical elements, flat ceramic membrane modules are not developed in a large extent and are limited to date to small liquid volume treatment [27]. Flat ceramic membranes are generally implemented as disks in laboratory scaled cells, offering a limited filtration surface area. Indeed a diameter of 90 mm that is one of the largest available dimensions for these membrane disks results in a filtration surface of -56 cm. Anopore alumina membranes supplied by Whatman or ATZ ceramic membrane disks with zirconia or titania top-layers from Sterlitech are typical examples of these commercially available flat ceramic membranes. Sterlitech ATZ ceramic membrane disks and the corresponding membrane holder are shown in Figure 6.16. 

In a general way, most of ceramic membrane modules operate in a cross-flow filtration mode [28] as shown in Figure 6.18. However, as discussed hereafter, a dead-end filtration mode may be used in some specific applications. Membrane modules constitute basic units from which all sorts of filtration plants can be designed not only for current liquid applications but also for gas and vapor separation, membrane reactors, and contactors, which represent the future applications of ceramic membranes. In liquid filtration, hydrodynamics in each module can be described as one incoming flow on the feed side gf, which results in two... 

As the newest development of the liquid filtration family, nanofiltration (NF) is capable of retaining small molecules from 200 to 1000 Da, and multivalent ions. The main current applications of NF polymeric membranes are dealing with the production of drinking and process water, the sulphate removal of seawater or the desalination of cheese whey. Ceramic nanofilters were... 

A typical example of the application of ceramic membranes in chemical industry is the cleaning of mono ethanol amine. Mono ethanol amine (MEA) is used for the absorption of H2S from acid gasses but is polluted during this process by various organic compounds. Filtration of the MEA over 0.2 pm HIC ceramic membranes at an average flux of 32 1/m h produces a clean, transparent yellow liquid, free of solids. Filtration temperature is 37°C, pH is about 11.5. Tests lasted successfully for over 700 h. Another example is the filtration of Ti02 from a waste stream in the so-called sulphuric acid process... 

Siskens CAM. Applications of ceramic membranes in liquid filtration. In Bmggraaf AT and Cot L (eds.). Fundamentals oflrwrganic Membrane Science and Technology. Amsterdam, the Netherlands Elsevier, 1996, pp. 619—639. 

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