Gore-Tex membranes

Back-pulse Filtration using GORE-TEX Membrane Filter Cloths... 

The soluble ions of iron and aluminium are usually reduced to a minimum by adjusting the electrolyte pH. For the removal of solid iron hydroxide and aluminium hydroxide Bayer decided to use a new pre-coat-free brine purification technology -back-pulse filtration using GORE-TEX membrane filter cloths. 

Since the installation of the retrofit, the brine quality has been monitored using different types of analysis (MS, ICP, EDX, etc.). The filtration efficiency of the GORE-TEX membranes has always met the Bayer specifications, which are significantly less than 100 ppb iron and aluminium. The filter membranes were put into operation in August 1998 and continue in service at this time. 

Fig. 22.2 Sealing arrangement of the GORE-TEX membrane filter cloths on the support element.

Filling the vessel is an obvious necessity, but because of the fine pore structure of the GORE-TEX membrane (described below), air trapped in the vessel does not pass... 

The filtrate that is back-pulsed from the dome first expands the filter socks thereby cracking the cake. The movement of the socks and the subsequent liquid flow through them serves to dislodge the filter cake solids from the GORE-TEX membrane surface. Because of the expanded PTFE material of the membrane, the cake releases from... 

The final principles of back-pulse filter technology are the nature and properties of the GORE-TEX membrane. The membrane is composed of expanded polytetra-fluoroethylene, or e-PTFE. The membrane traces its roots to the invention of e-PTFE by Robert W. Gore in 1969. Since that time, e-PTFE has found application in many areas including medical devices, electronics, fabrics and fuel cells to name a few. In the filtration area, e-PTFE is used in the form of a membrane to capture and remove particles from both gaseous and liquid streams. 

The success of this and the other operations derives from the correct application of back-pulse filtration principles, in particular the back-pulse step itself in which the filter cloths are cleaned and made ready for further filtration. The properties of the GORE-TEX membrane, composed of expanded polytetrafluoroethylene, give rise to the desirable results of these brine filtrations, in particular ... 

Another potential material for cell construction purposes is nickel. For instance, Eka Chemicals has employed nickel cartridges with standard GORE-TEX membranes to remove graphite particles directly from a caustic decomposer. The result was promising. Not only was the graphite removed but the quantities of mercury were reduced to levels of <10 pg. Aside from the cleaner caustic, the volume of sludge was drastically reduced since no pre-coat was required in this procedure. 

Liu, C. and Martin, C. R. 1990. Ion transporting membranes II. Ion transport mechanism in Nafion-rmpregnated Gore-Tex membranes. Journal of the Electrochemical Society 137 510-515. 

Fig. 2.17. Lyoguard tray for special applica- ble, transparent thin-film bottom (W.L. Gore, tions. 1, Gore-Tex membrane barrier 2, fill D-85636 Putzbrunn, Germany),...

For the FTIR investigations, GORE-TEX is an ideal substrate membrane on which to deposit the LB films. However, the GORE-TEX membrane is readily deformed which leads to cracks in the LB film during handling and mounting into the diffusion cell. This problem... 

Gore, D.W. Gore-Tex membrane distillation. Proceedings of the Tenth Annual Convection of the Water Supply Improvement Association, Honolulu III USA, 1982. 

Major polymer applications wear reduction, friction reduction, film, tubes, gaskets, valve and pump parts, tank lining, laboratory equipment, filtration membranes, bearings, piston rings, seals, non stick coating, electric insulation applications, Gore-Tex membranes... 

Fig. 2.4 Electron microscope photography of PTFE microporous film (GORE-TEX membrane) (accessed from http //www.evo.com/waterproof-ratings-and-breathability-guide.aspx).

Zhang et al [66] produced a superhydrophobic surface by the simple mechanical extension of a poly(tetrafluoroethylene) (PTFE) film. The fibriUar structure, a consequence of cavitation during deformation, resulted in contact angles larger than 150°. This structure, which is similar to the well-known Gore-Tex membrane, is best known for its use as a textile that is permeable to water vapor but not liquid water. However, these membranes are essentially fibrillar networks that are fundamentally different from the nonwoven fibrous textiles such as those formed by electrospinning. 

M. J. Raimer, Back-Pulse Filtration using Gore-Tex Membrane Filter Cloths. In J. Moorhouse (ed.). Modem Chlor-Alkali Technology, vol. 8, Blackwell Science, Oxford (2001), p. 272. 

In another study a Gore-Tex membrane impregnated with Nafion was coated onto a working electrode used for the electrochemical polymerization of pyrrole. In this case the electrolyte was an acetonitrile solution of a tetrafluorborate salt [145]. According to the authors, by this method it is possible to obtain membranes conducting only on one face, conducting in the bulk or conducting on both faces but not in the bulk. 

Penner RM, Martin CR (1985) Ion-transporting composite membranes. I. Nafion-impregnated Gore-Tex membranes. J Electrochem Soc 132 514-515... 

---