Reverse osmosis apparatus

Pressure resistance of polymer films prepared under various reaction conditions were examined by using a batch-wise reverse osmosis apparatus. Hydrostatic pressure was applied by using a mixture of toluene/methanol as a pressure medium. 

The must ultrafiltered with high flux membranes has also been treated with membranes having intermediate or very high rejection for electrolytes.Cellulose acetate and polyamide membranes were used. The Reverse Osmosis apparatus shown in fig.4 was used. 

A small reverse-osmosis apparatus allows a person to obtain drinkable fresh water from seawater. 

Assume that a portable reverse-osmosis apparatus operates on seawater, whose concentrations of constituent ions are listed in Table 18.5, and that the desalinated water output has an effective molarity of about 0.02 M. What minimum pressure must be applied by hand pumping at 297 K to cause reverse... 

Grade 2 water to reverse osmosis or de-ionisation, followed by filtration through a membrane filter of pore size 0.2 jum to remove particulate matter. Alternatively, Grade 2 water may be redistilled in an apparatus constructed from fused silica. 

Extraction of Surfactant. The influence of surfactant on the physical properties of the fiber require its removal prior to the establishment of the reverse osmosis rejection membrane. Surfactant is removed in a pressure extraction apparatus by the recirculation of hot aqueous alcohol. Surfactant is removed to concentrations less than 2% on the weight of dry fiber. 

Research effort at Albany International Research Co. has developed unit processes necessary for pilot scale production of several species of reverse osmosis hollow fiber composite membranes. These processes include spin-dope preparation, a proprietary apparatus for dry-jet wet-spinning of microporous polysul-fone hollow fibers, coating of these fibers with a variety of permselective materials, bundle winding using multifilament yarns and module assembly. Modules of the membrane identified as Quantro II are in field trial against brackish and seawater feeds. Brackish water rejections of 94+% at a flux of 5-7 gfd at 400 psi have been measured. Seawater rejections of 99+% at 1-2 gfd at 1000 psi have been measured. Membrane use requires sealing of some portion of the fiber bundle for installation in a pressure shell. Much effort has been devoted to identification of potting materials which exhibit satisfactory adhesion to the fiber while... 

In bioprocesses, a variety of apparatus that incorporate artificial (usually polymeric) membranes are often used for both separations and bioreactions. In this chapter, we shall briefly review the general principles of several membrane processes, namely, dialysis, ultrafiltration (UF), microfiltration (MF), and reverse osmosis (RO). 

D.T. Bray, Reverse Osmosis Purification Apparatus, US Patent 3,417,870 (December, 1968). 

First multi-leaf spiral wound membrane module developed by Don Bray and others at Gulf General Atomic, under US Patent no. 3,417,870, "Reverse Osmosis Purification Apparatus," December, 1968. A multi-leaf spiral configuration improves the flow characteristics of the RO module by minimizing the pressure drop encountered by permeate as it spirals into the central collection tube. 

A process called reverse osmosis is used to remove salts from seawater to make drinking water for human consumption. If a pressure greater than the osmotic pressure is applied to the solution side of an apparatus such as shown in Figure 15.6, water is forced from the solution (the seawater) to the pure solvent (water) side. This process is used industrially for water purification. 

Prepare an instraction sheet for a portable, reverse-osmosis desalination apparatus that can be used for camping. Research and include information on how efficient the apparatus is, how much pressure must be used, and how much drinking water can be produced in a given amount of time. 

Suppose we place a semipermeable membrane between a saline (salt) solution and pure water. If the saline solution is pressurized under a greater pressure than its osmotic pressure, the direction of flow can be reversed. That is, the net flow of water molecules will be from the saline solution through the membrane into the pure water. This process is called reverse osmosis. The membrane usually consists of cellulose acetate or hollow fibers of a material structurally similar to nylon. This method has been used for the purification of brackish (mildly saline) water. It has the economic advantages of low cost, ease of apparatus construction, and simplicity of operation. Because this method of water purification requires no heat, it has a great advantage over distillation. 

Studies of the plasma polymerization of tetrafluoroethylene in such a capacltively coupled system are described in another paper presented at this symposium [ 9]. The apparatus has been used to coat polysulfone hollow fibers with pyridine and acetylene + nitrogen plasma polymer to form a composite reverse osmosis desalination membrane. Salt rejections of 90-93% have been achieved at fluxes of 1.5-2.0 g.f.d with a fiber take up rate of 50-100 cm/min. 

Most importantly non-porous membranes such as ion exchange membranes, membranes for reverse osmosis, pervaporation, etc. should not be used in systems in which insoluble compounds precipitate on and in the membranes because this will destroy them and their functionality will be lost. Secondly all separation membranes, including ion exchange membranes, can achieve excellent performance by use of an appropriate apparatus and under optimum operation. For example, because solute and solvent transport speeds in the membrane phase are different from those in the solution, membrane-solution interfaces play an important role in separation, which depends on the structure of the apparatus and its operation. In this chapter, many examples of applications of ion exchange membranes are explained together with the principles on which they rely to achieve separation. 

FIGURE 11.10 Osmosis (a, b) and reverse osmosis (c). (a) In normal osmosis, water molecules pass through the semipermeable membrane from the less-concentrated into the moreconcentrated solution, in this case from pure water into the brine (salt water), (b) At a certain height of the brine solution in this apparatus, the pressure of the column of water is equal to the osmotic pressure and the flow stops, (c) In reverse osmosis, the application of external pressure greater than the osmotic pressure forces water molecules from the salty side to the pure water side. 

The water softening process removes most calcium and magnesium ions from tap water. By doing so a downstream placed apparatus, such as reverse osmosis, electrodeionisation or distillation apparatus, is protected against the deposit of calcium and magnesium salts (Timescale ). 

Apparatus for reverse osmosis can function for a Iraig time without much maintenance. The semi-permeable membrane should be replaced periodically because of ageing. The average lifetime of a membrane is 2-3 years. 

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