Ceramic membranes flux performance

A study was carried out into the potential recovery of plasticiser and solvent from waste PVC plastisols using a ceramic multi-bore crossflow tube filter. The procedure employed to perform the test sequence involved clean water flux measurement, media acclimatisation, optimisation trial, concentration run, cleaning trial and final water flux measurement. Permeate samples were analysed using gas chromatography and compared with standards of diisononylphthalate(DINP)/white spirit mixtures. The ceramic membrane successfully recovered a clear mixture of DINP and white spirit. 

We reported our recent developed membranes called carbon whisker membrane (CWM) and c on-coated coamic membrane. The CWM performed a better permeant flux in the filtration process in comparison with the membrane without whiskers. Also, CWMs have a self-cleaning function which can increase the separation efficiency during die filtration and increase die lift-time of the membrane. The carbon-coated ceramic membranes with various pore sizes can be made for the puipose of nanofiltration. 

Normally when one of the two performance indicators of a porous ceramic membrane for gas separation (i.e., separation factor and permeability) is high, the other is low. It is, therefore, necessary to m e a compromise that offers the most economic benefit Often it is desirable to slightly sacrifice the separation factor for a substantial increase in the permeation flux. This has been found to be feasible with a 5% doping of silica in an alumina membrane [GaBui et al., 1992]. 

Microriltraticiii and ultraTiltratiop of lees or crude wines. More specifically, crossflow micro- and ultra-filtration ceramic membranes have the potential for replacing all the above separation steps except cold treatment [Castelas and Serrano, 1989]. When using inorganic membranes for removing bacterias, yeasts or suspended particles, the choice of the pore size is very important in determining the filtrate flux and the rejection performance of these materials from wines. 

Most inorganic membrane supports exhibit a tubular shape. This is a well-adapted geometry for cross-flow filtration in which the feed stream is circulated across the surface of the membrane and the permeated flux passes through the membrane in a perpendicular direction. Stainless steel, carbon, and ceramic are the most frequently used materials in the preparation of supports. As shown in Fig. 2, tubes or multichannel substrates can act as membrane supports. A well-designed support must be mechanically strong, and its resistance to fluid flow must be very low. Aiming at enhancing flux performances, multilayered substrates have been prepared that exhibit an asymmetric structure... 

Basso et al. [79] performed an efficient cleaning process for alumina ceramic membrane, used in degumming by the UF of crnde soybean oil on a pilot scale in order to restore the levels of permeate flux. In this cleaning method, which nsed only hexane, the best results were obtained by... 

The conventional membrane architecture (CA), the one where the catalyst is placed within the wall of the membrane, is the most studied on the laboratory scale and most frequently reported in the literature. However, the application of the conventional architecture to H2S decomposition is limited by the current ceramic membrane thermal stability [72] and a mismatch between the membrane performance, in terms of flow through and the heat flux, which could be applied to the catalytic tubes. Such imbalance would, from an engineering point of view, require a large and impractical heat transfer surface. 

A composite ceramic membrane was formed [77] by the graft polymerisation of a hydrophilic polymer, PVP, onto the surface of silica membranes (pore size = 3.0 pm). The flux of an unmodified UF membrane of an oil/water emulsion (4.7%) decreased with time as compared to the flux of the composite membrane. The dechne in flux was caused by fouling and/or the immediate formation of an oil gel layer on the surface of the unmodified membrane. The modified membrane, in contrast, was not only more resistant to adsorption of oil, but also had a higher oil rejection. The performance of the modified ceramic membrane depends upon the configuration of the grafted chains in response to solvent—polymer interactions. Thus, the hydrophific PVP polymer chains tend to expand or extend away from the surface in aqueous solutions, preventing oil adsorption on the membrane surface. Simultaneously, the hydrophific polymer allows the passage of water molecules preferentially over oil. 

Luo, H.X., Wei, Y.Y., Jiang, H.Q. et al. (2010) Performance of a ceramic membrane reactor with high oxygen flux Ta-containing perovskite for the partial oxidation of methane to syngas. Journal of Membrane Science, 350, 154-160. 

Mikulasek, P. and Dolecek, P., Use of a Rotating Filter to Enhance Membrane Filtration Performance of Latex Dispersions , Sep. Sci. Technol., 29,1943 (1994) Mikulasek, P. and Hrdy, J., Permeate Flux Enhancement Using a Fluidized Bed in Microfiltration with Ceramic Membranes , Chem. Biochem. Eng. Q.. 13, 133 (1999)... 

Effluent treatment may be carried out using ceramic membrane bioreactors. However, equipment remains expensive compared to conventional activated sludge treatment methods. However, where tubular membranes are used, the performance can be improved by using tube inserts, which are effective turbulence promoters. It was found (Xu et al., 2002) that the permeate flux was increased by a factor of 2.5 without any detrimental effect on the effluent quality. Other formats for membrane bioreactors include fully stirred tanks, packed-bed columns and jet loop columns. 

Liithi and Luisi [44] have used a hoUow fiber membrane reactor for peptide synthesis catalyzed by a-chymotrypsin in microemulsion. Chang et al. [110] described the immobilization of lipase on liposomes, which, in turn, were solubilized in AOT/isooctane reversed micelles and used for the continuous glycerolysis of olive oil in an ultrafiltration cell. The half-Ufe of the Chromo. viscosum lipase was 7 weeks. The development of an ultrafiltration ceramic membrane bioreactor for the simultaneous lipolysis of olive oil and product separation in AOT/isooctane reversed micellar media has been also reported [106,107], Cutinase performance was also evaluated in a ceramic membrane reactor [9]. An attempt to minimize the surfactant contamination problem was based on the use of an electro-ultrafiltration method which can decrease the gel formation in the membrane surface, improving the filtration flux, achieving the separation of the AOT reverse micelles [187],... 

Performance of a ceramic membrane reactor with high oxygen flux Ta-containing perovskite for the partial oxidation of methane to syngas. 

Luo, H., Wei, Y., Jiang, H., et al. (2010). Performance of a Ceramic Membrane Reactor with High Oxygen Flux Ta-Containing Perovskite for the Partial Oxidation of Methane to Syngas, J. Membrane Sci., 350, pp. 154—160. 

The performance of porous ceramic membranes is typically expressed by the permeate flux (throughput) and the selectivity (separation ability), which in turn are governed by the pore size distribution, porosity and intrinsic membrane surface properties, and as such there are a variety of direct and indirect characterisation techniques used to evaluate the potential of a membrane and predict its performance. In this way new membranes can be efficiently and effectively screened and later optimised without the need for lengthy permeation experiments, reducing overall development time. Similarly, these techniques can be used to understand and/or verify a new membrane s transport and separation mechanisms. 

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