Silicone membranes coating

VOCs can also be removed by applying vacuum and using composite membranes as, for example, in the VaporSep process commercialized by the MTR, where a porous support is used for a silicone membrane coating in a spiral wound configuration. Hydrophobic polypropylene hollow fibers with an ultrathin and highly VQC-permeable plasma-polymerized nonporous silicone skin on the outer surface can be also effective [31-33]. 

Membranes comprising silicone rubber coated onto polyimides, polyacrylonitrile or other microporous supports membranes are widely used [12,27]. Other rubbers such as ethylene-propylene terpolymers have been reported to have good properties also [28]. Polyamide-polyether block copolymers have also been used for pervaporation of some polar VOCs [29,30]... 

Table 34.3 H2 Permeation Rates and Permeability Ratio of H2/CH4 for Plasma Polymers of Butyronitrile Deposited on Silicone-Carbonate-Coated Polysulfone Porous Membranes...

MTR, Inc. has also developed another commercial PV application using silicon rubber coated on microporous poly-imide support membranes for the separation of dissolved volatile organic compound (VOC) from water, achieving very high separation factors for toluene, benzene, chlorinated solvents, esters, and ethers. 

Figure 1.5 Microreactor with permeable porous silicon membrane (squares of 350-750pm, thickness 70pm) coated with Pd (via immersion) with heating filament and temperature sensor for CO measurements up to 140°C. Reprinted from [37], Copyright 2002, with permission from Elsevier.

Ikegami, T., Negishi, H., Yanase, H., Sakaki, K., Okamoto, M., Koura, N., et al. (2007). Stabilized production of highly concentrated bioethanol from fermentation broths by Zymomonas mobilis by pervaporation using silicone rubber-coated silicalite membranes. Journal of Chemical Technology and Biotechnology, 82, 745—751. 

Example 7.2.2 We wish to estimate the membrane area required to produce nitrogen-enriched air having xti.fiL = 0.95 using a silicone rubber-coated hollow fiber membrane, with (QN m/ m) at 25 °C = 4.6 x 10 gmol/s-cm -cm Hg and =2.1. The feed air is introduced at... 

Both MMMpEG and gly-MMMpEG were tested for the separation of gases such as SO2, NH3, H2S, CO2, H2, N2, CH4, C2H4, and C2H6. The gas to be tested was passed through the membrane under a pressure of 5-50 psig at ambient temperature. The permeation rate and selectivity for each pure gas, both polar and nonpolar, was measured and calculated. For comparison purposes, a reference membrane composed of silicone mbber coated on a porous polysulfone (SR-PS) was also prepared and tested. The results are summarized in Tables 30.2-30.6. 

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