Showing papers on "Reverse osmosis published in 1973"

Preparation of reverse osmosis membranes by plasma polymerization of organic compounds

Abstract: The plasma polymerization of organic compounds was used to prepare a composite reverse osmosis membrane which consists of an ultrathin semipermeable membrane formed by plasma polymerization of an organic compound or compounds and a porous substrate. Many nitrogen-containing compounds (aromatic amines, heteroaromatic compounds, aliphatic amines, and nitriles) were found to yield excellent reverse osmosis membranes by plasma polymerization directly onto porous substrates such as Millipore filters, porous polysulfone filters, and porous glass tubes. Factors involved in the preparation of reverse osmosis membranes by plasma polymerization were investigated and discussed. The plasma polymerized membranes have the following unique features: (1) very stable performance independent of salt concentration and applied pressure (practically no water flux decline was observed with many membranes): (2) salt rejection and water flux both increase with time in the initial stage of reverse osmosis (consequently, the performance of the membrane improves with time of operation); (3) very high salt rejection (over 99%) with high water flux (up to 38 gfd) can be obtained with 3.5% NaCl at 1500 psi (membranes perform equally well under conditions of sea water conversion and brakish water treatment).

Membrane method and product

Abstract: There is disclosed a method of forming membranes on the order of 10-200A (0.001 to 0.01 Mu ) thick, particularly for use in reverse osmosis processes where solvents are caused to flow from a more concentrated solution to a more dilute solution through the membrane. The membrane is formed from a plurality of monomolecular layers of a polymer material alone, and in mixtures, which can be crosslinked, if desired.

Aromatic polyamides for reverse osmosis and methods of their permselective polymeric membranes

Abstract: Permselective membranes are prepared from novel synthetic organic aromatic polyamides of the formula The membranes are useful in separating components of fluid mixtures or solution such as water containing dissolved salts or lactam. D R A W I N G

Hollow fiber reverse osmosis systems analysis and design

Abstract: A predictive model of hollow fiber reverse osmosis systems is developed using the equivalent annulus assumption. The fraction of feed recovered Φ depends on five parameters. Optimum values exist for the ratio of the inside to outside fiber radius ri/ro and for the outside fiber radius ro. For dilute systems, a simple closed form expression is obtained for Φ which enables one to determine optimum values easily. The effects of pressure, temperature, flow rate, concentration, viscosity of the feed, system length, membrane rejection parameter, and number of fibers are studied. Countercurrent is superior to concurrent operation.

Synthesis of Reverse Osmosis Membranes by Plasma Polymerization of Allylamine

Abstract: The polymerization of allylamine in a radio-frequency electrodeless plasma to form thin polymer films on microporous filter media provides very effective dry composite membranes for reverse osmosis. Salt and urea rejections as high as 98 percent and 46 percent, respectively, have been achieved from a solution containing 10 grams of sodium chloride per liter and 10 grams of urea per liter. The plasma conditions and polymerization technique are discussed.

Apparatus for monitoring water purification system

Abstract: An apparatus for precisely monitoring the effectiveness of a reverse osmosis water purification system is disclosed which continuously measures and compares the electrical conductivities of the impure aqueous solution and the purified water on the inlet and outlet sides, respectively, of the semipermeable membrane of the reverse osmosis system. A meter provides a visual indication of the comparison which is preferably related to the ratio of the outlet side conductivity to the inlet side conductivity and a fail-safe alarm signals when this ratio exceeds a selected level. The meter may be scaled so that during a normal operating mode of the apparatus it indicates the actual ratio of the impurity levels of the outlet and inlet sides and during a test mode it indicates a selectable alarm point.

Method for drying water-wet membranes

Abstract: A water-wet cellulose ester membrane, such as the asymmetric cellulose acetate membrane in sheet or tubular forms used for water desalination by reverse osmosis, is dried by: (1) immersing it in water-soluble alcohol at low temperatures until the water is replaced by alcohol; (2) immersing the alcohol-wet membrane in an alcohol-soluble organic liquid at low temperatures until the alcohol is replaced by the liquid; and (3) drying the product at ambient temperature. In this manner, the membrane is quickly dried without collapsing the walls of its pores. Upon rewetting, the membrane will regain most of its original reverse osmosis properties. For gas permeation the separation capabilities of dried membrane may be improved by heat treatment.

Precoat for permeability separation systems

Abstract: Procedures are disclosed for preventing fouling of reverse osmosis and ultrafiltration membranes by relatively large molecules and particulate matter. In particular, absorbents are used, with and without finely divided activated carbon, to form a "precoat" on the membrane. The "precoat" is laid down on the membrane at the beginning of a reverse osmosis or ultrafiltration cycle. It is removed at the end of a cycle by flushing, preferably followed by a cleaning. The "precoat" process is applied to the ultrafiltration of raw sewage as a preferred example.

Preparation of reverse osmosis membranes by complete evaporation of the solvent system

Abstract: A method for preparing asymmetric reverse osmosis membranes by preparing a dilute solution of cellulose acetate in a solvent system consisting of a solvent and at least one pore-forming material selected from the nonsolvents for cellulose acetate, casting the solution to form a thin film, and allowing the solvent system to evaporate completely. The dry membranes so formed can be stored in the absence of water and rewet when necessary for use in reverse osmosis separations. The membranes can be repeatedly dried and rewet without any special treatment steps and without harm to the membrane.

Water purification means

Abstract: A FILTER SYSTEM IS PROVIDED FOR THE PURIFICATION OF WATER, WHEREBY PARTICULATES AND VIRUSES MAY BE ECONOMICALLY AND RELIABLY REMOVED. THE SYSTEM COMPRISES A FILTER MEANS FOR REMOVAL OF SILTS AND COLLOIDAL MATERIALS, A TREATED CARBON VIRUS FILTER, AND A SPECIALLY TREATED HONEYCOMB CARTRIDGE FOR REMOVAL OF MICROBIOLOGICAL FLOR, E.G., BBACTERIA, FUNGI, MOLDS, AND ALGE ONE MICRON OR LARGER. OPTIONALLY, THE SYSTEM MAY INCLUDE REVERSE OSMOSIS MEANS, AN ION EXCHNGE DEMINERALIZER, AND AN ULTRAFINE MEMBRANE FILTER.

Formalized poly(vinyl alcohol) membranes for reverse osmosis

Abstract: The permeation properties of formalized poly(vinyl alcohol) membranes are described. The interest of this work is centered on the properties relevant to desalination by reverse osmosis. These membranes, when properly prepared, showed reasonably high water permeability, high salt rejection, and stability in the presence of acids and alkalies.

Production of semipermeable polybenzimidazole membranes

Abstract: A process is provided for forming an improved reverse osmosis membrane of unusually high physical durability and chemical stability. The membrane is formed of the specific polybenzimidazole chemical structure indicated in the claims. In a preferred embodiment the membrane is formed of poly-2,2''-(mphenylene)-5,5''-bibenzimidazole. The membrane is formed by (a) providing a solution of the polybenzimidazole polymer of the formula indicated, (b) depositing a film of the solution upon a support, (c) evaporating an amount of solvent from the film sufficient to allow the formation of a thin solid layer on the exposed surface of the film having a density which is substantially greater than that of the remaining portion of the film on which the solid layer of increased density is formed, and (d) washing the resulting film with a non-solvent for the polymer to remove residual solvent. The reverse osmosis membranes exhibit performance characteristics which are more highly resistant to deterioration upon the passage of time, are capable of operation at high pressures (e.g., 1,000 psi and up), are capable of operation at elevated temperatures (e.g., 100*C), and exhibit outstanding chemical stability.

Reverse osmosis membrane module

Abstract: A spiral-wound membrane module for separating a solvent from a solution such as water from an impure solution by means of a reverse osmosis process and a method for making such membrane module. An elongated sheet of semi-permeable membrane material has disposed in juxtaposition to its opposite surfaces, respectively, a sheet of porous product water spacer material and a sheet of a feed water spacer material to provide a three-ply membrane composite which is wrapped around a hollow tubular mandrel. The membrane composite wound around the tubular mandrel is disposed in an outer cover in which at least one opening is provided having its end sealed and extending through a radial axis of the spirally wound membrane composite and a wall of the tubular mandrel. Thus, the porous product water spacer material is in direct fluid communication with the tubular mandrel and the product water collected in the product water spacer material is required only to traverse a maximum of one-half revolution thereof to drain into the hollow tubular mandrel.

Reducing alcohol content in wine or similar drinks - by reverse osmosis through membrane permeable to alcohol and water only

Abstract: Low-alcohol wine, sparkling wine or win-like drink (e.g. cider) is prepd. by withdrawing a part of the alcohol by reverse osmosis through a membrane permeable to alcohol and water only, the membrane being made of cellulose acetate, a polyamide or a polyvinyl acetate from which 98% is of the acetyl gps., are removed by hydrolysis. The alcohol content is reduced without affecting the aroma of the drink.

Process for removing pollutants from liquids

Abstract: The treatment of waste water by the application of polyelectrolytes to the waste water to remove dispersed and dissolved waste particles and then subjecting the resultant treated or clarified solution to reverse osmosis to further remove dissolved particles therefrom.

System for concentrating solutions by low pressure recycling

Abstract: A FLUID CONCENTRATION SYSTEM IS OPERATED BY (1) PUMPING A FEED SOLUTION OF LOW CONCENTRATION, HAVING AN OSMOTIC PRESSURE BELOW ABOUT 600 P.S.I., INTO A FIRST STAGE REVERSE OSMOSIS MEMBRANE SEPARATION APPARATUS OPERATING AT A DRIVING PRESSURE OF UP TO ABOUT 800 P.S.I., TO PROVIDE A FIRST LOWER CONCENTRATE SOLUTION AND A FIRST HIGH CONCENTRATE SOLUTION; (2) PUMPING THE HIGH CONCENTRATE SOLUTION INTO A SECOND STAGE REVERSE OSMOSIS MEMBRANE SEPARATION APPARATUS, OPERATING AT A DRIVING PRESSURE OF UP TO ABOUT 800 P.S.I., TO PROVIDE AN INTERMEDIATE LOW CONCENTRATE SOLUTION AND A SECOND HIGH CONCENTRATE SOLUTION, HAVING AN OSMOTIC PRESSURE OF BETWEEN ABOUT 800 TO 3000 P.S.I.; AND (3) RECYCLING AT LEAST ONE OF THE CONCENTRATE SOLUTIONS BACK THROUGH AT LEAST ONE OF THE REVERSE OSMOSIS MEMBRANE SEPARATION APPARATUS.

Integral reverse osmosis membrane with highly pressed woven fabric support member

Abstract: An integral cellulosic reverse osmosis membrane having a permeable fabric support is made by a process which comprises casting a concentrated membrane-forming dope and forming a reverse osmosis membrane on a smooth surface of a permeable casting and membrane support fabric comprising substantially unsized continuous multiple warp and fill strands of fiber-forming crystalline organic thermoplastic resin, which fabric has been highly pressed at temperatures and pressures sufficient to smooth the surfaces of the fabric to a high degree of smoothness and sufficient to substantially completely close permanently the interstices at the strand intersections while leaving the pressed fabric permeable to the flow of a fluid such as desalinated water.

Reverse osmosis system adaptable for manual operation

Abstract: A reverse osmosis system comprising a pressure resistant container in which a rotatable membrane element-carrying assembly is mounted. Means for rotating the membrane element-carrying assembly and means for actuating a pump for pressurizing feed liquor introduced into the pressure resistant container are operated by human effort, and these means are preferably interconnected.

Semi-permeable polyvinyl alcohol membranes

Abstract: Polyvinyl alcohol material, having good handleability and porosity making it suitable for use in reverse osmosis, is provided by a process which comprises subjecting the material, successively, to I. A DRY HEAT TREATMENT WITHIN CAREFULLY DEFINED LIMITS OF TEMPERATURE, TIME AND VISCOSITY, AND II. A HOT WATER TREATMENT.

Pretreatment for reverse osmosis process

Abstract: A PRETREATMENT PROCESS FOR INCREASING THE USEFUL LIFE OF A REVERSE OSMOSIS MEMBRANE COMPRISING PASSING AT LEAST A PORTION OF A REVERSE OSMOSIS MOLDULE INFLUENT THROUGH A STRONG BASIC TYPE II AMION EXCHANGE RESIN UNTIL CARBONATE IONS ARE DETECTED IN THE EXCHANGE RESIN EFFLUENT. A REVERSE OSMOSIS MODULE INFLUENT IS THUS CONTROLLED TO CONTINUOUSLY HAVE A PH VALUE BELOW 8, WHICH GREATLY INCREASE THE LIFE OF A CELLULOSE ACETATE REVERSE OSMOSIS MEMBRANE. THE CAPACITY OF THE ANION EXCHANGE RESIN IS EXTENDED BEYOND THE CONVENTIONAL END POINT FOR SUCH RESIN.

Reverse osmosis water purifying system for household use

Abstract: A household water purifying system employs a reverse osmosis purifying unit in which a porous, semipermeable membrane-covered support, or preferably a frame carrying a plurality of membrane elements having semipermeable membrane outer surfaces, is rotated within a pressure resistant container. Water under household pressure is introduced into the purifying unit and water more concentrated in salts originally present is released from the purifying unit by an automatically actuated on-off valve. Purified water produced by the purifying unit is delivered to an unpressurized water storage tank so that no back pressure can be applied to the membrane from its product water side. Purified water is dispensed from the water storage tank by a submerged pump and a valve; and water is maintained not above a predetermined level in the water storage tank by a float actuating a release valve.

Method of sterilizing reverse osmosis water treatment units

Abstract: The semi-permeable membrane of a reverse osmosis water treatment unit is treated during periods of "down time" with a solution having a pH preferably in the range of 4.5 and 6.0 and tending both to sterilize the membrane as well as to retard bacterial and fungal growth thereon. The method comprises: passing an aqueous solution of the desired pH and containing formaldehyde and an acid selected from the group consisting of acetic, formic, citric, fumaric and boric, into the water treatment unit and through the membrane thereof and maintaining said aqueous solution in the unit and in contact with the membrane during extended periods of unit "down time" to both sterilize the unit and extend the life of its membrane.

Evaluation and development of physical-chemical techniques for the separation of emulsified oil from water

Abstract: Various methods for separating emulsified oil from water were surveyed and investigated. A state-of-the-art review of physical-chemical processes for oil-water separation included conventional flotation, precipitate flotation, adsorption, flotation, magnetization, coalescence, chromatography, layer filtration, reverse osmosis, absorption filtration, hydrocyclone treatment, centrifugation, settling, chemical coagulation, evaporation-distillation, freezing, biological oxidation, clarification-flotation, and solvent extraction. Promising physico-chemical processes for oil-water separation include granular C adsorption, powdered C adsorption followed by polyelectrolyte coagulation and final polishing, and powdered C adsorption followed by direct filtration. Greater than 99% oil removal can be achieved with these processes.