JPS6130603B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for separating oil from water.

The invention comprises passing a water stream containing preferably no more than 1000 ppm of oil by weight through an oil-absorbent bed, the absorbent bed having at least a perforated body through which water passes, the perforated body having a surface thereof. has an oil-absorbing coating, the oil-absorbing coating consisting of a generally deposit of oil-absorbing latex particles, the latex particles being oil-swellable and oil-insoluble; swells in oil from 2 to 50 times its unswollen volume, and the amount of the oil-swellable latex particle coating is sufficient such that, when swollen with oil, its volume closes the internal pores within the porous body and prevents the passage of water flow. It is characterized in that it is a quantity that has a certain volume.

The present invention also provides a conduit through which water flows and an initial system which is transverse to the conduit and is permeable to water but in sealed connection with the conduit so that water flowing within the conduit is forced to pass through it. A device for removing oil from a water stream containing not more than 1000 ppm of oil, based on the weight of the water stream, consisting of an absorbent bed of pores, having a latex coating of an oil-absorbing polymer on the surface of the porous body, the coating being in contact with the oil. The object of the present invention is to provide an improved device which swells to 2 to 50 times the volume of the unswollen film when applied, and the swelling amount is sufficient to block the porous body and prevent water flow from passing through. “Oil” is generally immiscible with water or 2% by weight in water at 25°C and atmospheric pressure.
Refers to oils or organic liquids that do not dissolve Such oils include, for example, petroleum oils such as kerosene, lubricating oils, gasoline, jet fuels, and fuel oils. Other oils include benzene, toluene, xylene, ethylbenzene; aliphatic hydrocarbons such as hexane, octane, dodecane, eicosane and their positional isomers; cyclic hydrocarbons such as cyclohexane, ethylcyclohexane; ketones such as 2- Octenone, 4-dodecenone; and chlorinated solvents such as 1,1,1-trichloroethane and o-dichlorobenzene.

The features and advantages of the invention will become more apparent from the accompanying drawings and the associated specification.

FIG. 1 is a schematic diagram of a filter device according to the invention.

FIG. 2 is a partial cross-sectional view of a perforated body used in the apparatus of FIG.

FIG. 1 shows a device 10 according to the invention.
The device 10 has an integral waterway or means 11 for delimiting the waterway. The conduit 11 has a vertically extending branch or means 12 exhibiting a pressure drop open to the atmosphere and a thickened overbed retainer 13. A water flow 14 flowing in the direction of the arrow passes through the water conduit 11 . Water stream 14 preferably contains less than 1000 parts by weight of oil or organic compound per million parts by volume of water. Headrace waterway 11
has an outlet 15 located far from the branch pipe 12 and adjacent to the enlarged portion 13. A number of perforated passage elements 17 are within the enlarged portion 13 of the headrace 11 and are generally in sealing relationship with adjacent portions of the enlarged portion 13 of the headrace 11 . Branch pipe 1
2, there is a perforated over-bed holding net 18 like a wire mesh. The second support net 19 is generally adjacent to the outlet section 15. As shown in FIG. 1, perforated filter element 17 is generally disc-shaped to allow water to flow therethrough.
Each perforated element 17 has a surface coating (not shown) of oil-absorbing latex, which is oil-swellable, oil-insoluble, and which covers the unswollen coating volume. It swells 2 to 50 times.

FIG. 2 shows a partial cross-section of the over-element 25. As shown in FIG. The filter element 25 consists of a perforated body 26 having a large number of cell walls 27 and a large number of internal gaps 28 . element 25
generally consists of a porous matrix 29 that is insoluble in water. Substrate 29 has an oil-absorbing coating 31 on its surface. The oil-absorbing coating film 31 is the oil-swellable latex coating film having oil-swelling properties as described above. In operation of the device and in carrying out the method of the invention, a water stream containing a small amount of oil passes through the water conduit 11, as indicated by the arrow in FIG. The water flow passes through the filter element 17 and exits through the outlet 15 of the headrace. Small amounts of oil in the water stream are absorbed by latex coatings, such as coating 31. The coating 31 swells when oil is added thereto, resulting in a large number of swollen latex particles, which aggregate into viscous droplets and are passed downstream of the coating 17 into contact with the unswollen coating. When the unswollen coating comes into contact with the highly swollen particles, it picks up some of the oil from it and becomes agglomerated droplets or globules of viscous oil-swollen latex particles that are large enough to fill the excess element, i.e., the internal voids. be sufficiently closed to prevent water from passing through. When the overflow element 17 is clogged and the water head in the branch pipe 12 rises and reaches a certain height, the water flow head is closed or the overflow element 17 is replaced with an element having an unswollen latex coating in another similar flow machine. . A wide variety of materials can be used as substrates for supporting oil-absorbing latex coatings in the practice of this invention. Particularly preferred materials are flexible synthetic resin foams, such as open-cell polyurethane foams; open-cell foams such as polyethylene foams, polypropylene foams, polybutene foams, polyvinyl chloride foams, polybutadiene foams, and polyisoprene foams. polyolefin foams and other rubber foams. Other useful materials as substrates for coating with oil-absorbing latexes include sand, vermiculite, bagasse, straw, sawdust, granulated petroleum and charcoal, coke, crushed automobile and truck tires,
There are metal grains, glass grains and glass forms. Woven or non-woven fabrics of natural or synthetic fibers are also suitable as substrates. For many applications, a substrate that is not affected by oil or organic liquids contained within the water stream is desirable. This is especially true if the absorbent bed is exposed to a contaminated water stream for a relatively long period of time. However, in many cases it is also possible to use substrates that are gradually disturbed by organic matter in the water stream. A typical example of this application is an overfill, which constantly monitors the pressure drop across the overfill and quickly replaces it if it becomes clogged. It is generally important that the rate of swelling of the latex polymer coating is substantially greater than the rate of swelling or dissolution of the substrate. For applications where substrates sensitive to organic liquids are used, it is generally desirable that the swellable latex polymer swell at least twice the rate of swelling or dissolution of the substrate.

Latex polymers useful in the practice of this invention are any polymeric latexes that swell upon contact with oil. Convenient latex polymers swell upon contact with water. However, further swelling is required when it comes into contact with the oil or organic material to be removed. The choice of polymer for use in the oil or organic liquid can be easily determined by comparing the swelling index in the particular liquid in which the latex polymer particles are immersed or absorbed. This swelling index can be conveniently determined by immersing the latex polymer in the desired oil or organic liquid and measuring the volume per unit polymerization of the latex polymer after 30 minutes in water and oil. The volume ratio per unit weight with organic liquid and without oil or organic liquid is the swelling index. If the polymer dissolves, the swelling index becomes infinite. Polymer particles are suitable for use in the present invention if their swelling index is greater than 1.2. A swell index of at least 1.5, preferably 3 or more is desirable for most applications. It is important in the practice of this invention to use crosslinked polymers that swell but do not dissolve.
Polymers are suitable for use in the present invention if they swell in the presence of organic liquids and water. However, in most cases it is desirable to use polymers that are sufficiently cross-linked to exhibit a swelling index of 1.5 to 50, preferably 3 to 50. A variety of polymeric materials are conveniently used. These polymers include styrene and substituted styrenic polymers; polyvinyl chloride copolymers of vinyl chloride, such as a copolymer of 60% vinyl chloride and 40% vinyl acetate; 75% vinylidene chloride and 25% acrylonitrile. Polymers and copolymers of vinylidene chloride, including copolymers of acrylic polymers such as methyl methacrylate, ethyl acrylate, and the like. Generally the chemical composition of the polymer is not critical. Polymers must exhibit significant swelling properties, i.e. at least in the organic liquid to which the polymer must adapt under the desired operating temperature and pressure conditions.
The volume should increase by at least 20% in 10 minutes. Particularly good materials that are compatible with a wide variety of organic liquids are styrenic polymers, such as polystyrene and polymers of styrene and up to 10% by weight divinylbenzene. Alkylstyrene polymers and copolymers are particularly advantageous for general use of aliphatic and aromatic hydrocarbons. The alkylstyrene polymers swell very quickly on contact with aliphatic and/or aromatic hydrocarbons. Generally, the faster a polymer swells, the faster it shuts off when it comes into contact with an organic liquid. Alkyl styrene polymers and copolymers typically exhibit substantial swelling within one minute when contacted with so-called No. 2 diesel oil.

Cross-linked polymers and copolymers of styrenes, especially tertiary-alkylstyrenes, are preferably used as absorbent latex polymers in the process of the invention. The alkylstyrenes that can be used to prepare these polymers are those with alkyl groups having from 4 to 20 carbon atoms, preferably from 4 to 12 carbon atoms, such as tertiary-alkylstyrenes, n-alkylstyrenes, 2-alkylstyrenes, etc. These include alkylstyrenes, isoalkylstyrenes, and copolymers thereof.

Particularly preferred for use in the practice of this invention are alkyl styrenes such as those described above and cross-linked copolymers with alkyl esters formed from C ₁ -C ₂₄ alcohols and acrylic or methacrylic acids or mixtures thereof. It is.

Suitable monomers that can be used as comonomers with alkylstyrenes include, for example, vinylnaphthalenes, styrene, vinyltoluenes, α-methylstyrenes, ring-substituted α-methylstyrenes, halostyrenes, aryl-styrenes. and alkaryl styrenes; methacrylic esters, acrylic esters, fumarate esters and half-esters, maleate esters and half-esters, itaconate esters and half-esters, vinylbiphenyls, aliphatic carboxylic acids vinyl esters, alkyl vinyl esters, alkyl vinyl ketones, α-olefins, isoolefins, butadiene, isoprene, dimethylbutadiene, acrylonitrile and methacrylonitrile.

It is desirable that the latex polymers used in the process of the invention contain a small amount of cross-linking agent, preferably from 0.01 to 2% by weight. Cross-linking agent is 1
Within 1%, the most effective absorption of oil and organic liquid impurities occurs because the polymer easily swells and absorbs a substantial amount of organic material. When water containing organic liquids is passed through an absorbent bed with a 25% by volume latex polymer coating, up to 2% cross-linking agent may be appropriate since in such operations the polymer allows for low volumes of absorbed organic matter. It is.

Cross-linking agents that can be used to prepare absorbent latex polymers suitable for use in the present invention include, for example, divinylbenzene, diethylene glycol dimethacrylate, diisopropenylbenzene, diisopropenyl diphenyl, diallyl maleate, diallyl phthalate, allyl Acrylates, allyl methacrylates, allyl fumarates, allyl itaconates, alkyd resins, butadiene or isoprene polymers, cyclooctadiene, methylenenorbornylenes, divinyl phthalates, vinylisopropenylbenzene, divinyl Polyethylenically unsaturated compounds such as biphenyl and other diene compounds known to be used as cross-linking agents in vinyl addition compositions of these polymers.
or poly-reactive compounds. Latex polymers containing cross-linkers usually swell due to the absorbed organic material. Excess cross-linking agent takes an unreasonably long time to absorb and the latex polymer cannot absorb enough organic liquid to fill the internal voids of the absorbent bed. If the absorbing polymer contains no cross-linking agent or contains too little cross-linking agent, the polymer will eventually dissolve in the organic material, e.g., as a continuous non-particulate mass of polymer-concentrated organic liquid, which effectively inhibits water flow. It will not stop.

The polymers for use in the present invention are prepared by emulsion polymerization techniques, preferably polymerized with free radical catalysis. For most applications, the latex used in the practice of this invention will have a particle size of 500 to 2000 Angstroms, although latexes with smaller and larger particle sizes may also be used.

Example Based on 30 parts by weight of a mixture of 70% by weight of tertiary butylstyrene, 20% by weight of 2-ethylhexyl acrylate, 10% by weight of mixed methacrylate esters of alcohols from cetyl to eicosyl, and the weight of the above three monomers. 0.075% by weight (active) of a 1:1 mixture of divinylbenzene and diethylbenzene (active), 0.5 parts by weight of potassium persulfate based on the weight of monomers (ROM), 1% by weight of sodium bicarbonate based on the same weight of ROM, the same weight of ROM. An oil-absorbing latex was prepared by polymerization in the presence of 70 parts by weight of water containing 2% by weight of a surfactant which was on the basis of a mixed long-chain sodium alkyl sulfate. The polymerization reaction was carried out as follows: 20% water containing potassium persulfate and sodium bicarbonate and 2% by weight of the total monomer mixture.
was added to the reactor. The reactor was stirred and heated to 80°C for 30 minutes. At this point, the remaining monomer and aqueous potassium persulfate and sodium bicarbonate solutions were added at a constant rate over 5 hours. After the addition was complete, the reaction mixture was stirred for an additional hour at 80°C. The container and contents are then heated to 35°C.
It was cooled to The reaction mixture was filtered to remove coagulum. A latex with a particle size of approximately 1000 Å and a solid content of 28.2% was obtained. This latex was used to coat a number of open-cell polyurethane plates 3 1/2 inches (8.9 cm) in diameter and 1/4 inch (0.635 cm) thick. The board was immersed in latex, the excess latex was squeezed out, and the board was dried at 80°C for 16 hours to form a coating.
Various coating weights were applied to the polyurethane foam by repeating the dipping, pressing and drying process. Polyurethane foam has a density of 1.7 pounds per cubic foot (27.23 Kg/cm ³ ) and per inch (2.54 cm).
41±5 holes and 1/2 inch (1.27 cm) water pressure
had an air flow rate of 8 cubic feet per minute (226.53 per minute) through a 4 inch square (25.8 cm ² ), 1/4 inch (0.635 cm) thick sample.
A number of experiments were conducted using urethane boards with various latex coating weights and uncoated boards. The equipment used was generally as shown in Figure 1, and the wastewater filtered was No. 2 fuel oil-containing water. The test equipment was supplied with 25 gallons of water per hour (94.64) and 25 ml of No. 2 fuel oil per hour. Before putting the water-oil mixture into a perforated filter plate, water and oil were mixed using a propeller-type stirrer so that the oil was finely dispersed in the water. Water branch pipe 12
The experiment was terminated if a height of 48 inches (121.9 cm) was raised in the branch pipe corresponding to 100 cm or if oil clearly passed through the overplate. First, a urethane foam board without a urethane coating was used. 1 out of 12 branch pipes
The water head after hours, i.e. the height is approximately 3 inches (76.2 cm)
At this point, surface oil appeared in the wastewater.
The initial water head was about 5 inches (12.7 cm) using a board with a coating weight of 23.8% of the latex described above.
Surface oil appeared after 2.5 hours at about 6 inches (15.24 cm) of water head. Three plates with membrane weights of 59.7%, 33.5% and 55.5% latex solids were then used. After 10 minutes of the third hour, a water head of 48 inches (121.9 cm) was achieved with no fuel oil passing through the latex solids 59.7 and 55.5 weight percent coated plates.
The 33.5% by weight latex solids coated urethane foam reached a head of 48 inches (121.9 cm) a little over 3 hours ago. In all cases, a small but unmeasurable amount of DuPont Oil Red A (an oil soluble dye) was added to the fuel oil to aid in determining the oil distribution within the coated foam pattern. No oil was observed in either case where the water passed through the latex-coated foam sample, i.e., the red color did not spread throughout the bed, and no oil was observed in the drain water either by odor or taste. .

Because of the wide variety of organic materials, oil-absorbing latexes, and substrates that can be separated from water using the present invention, if one wishes to test the suitability of combinations of organic materials, latexes and substrates, and latex film weights, A convenient method for determining the suitability of a combination is to create a coated bed 6 inches (15.25 cm) thick and add the organic liquid to be removed from the water stream dropwise at 24°C. It is convenient to add dyes to such experiments that readily indicate the presence of organic liquids in the bed. 6 inches (15.24cm)
The combination is suitable for the practice of the present invention, provided that the overbed does not flow the organic liquid under 6 inches (15.24 cm) of water head.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a device according to the invention. DESCRIPTION OF SYMBOLS 11... Water conduit, 12... Branch pipe, 13... Over-bed holding part, 14... Water flow, 17... Over-element, FIG. 2 shows a partial sectional view of the perforated body used in the device of the present invention. There is. 25... hyperelement, 26... porous body, 28...
Internal gap, 29... Porous substrate, 31... Oil-absorbing coating film.

Claims (1)

[Claims] 1. Since a water stream containing 1000 ppm or less of organic liquid or oil on a weight basis is passed through an oil-absorbing bed, the absorbent bed has at least a basic porous body through which water passes, and the perforated The body has an organic liquid or oil-absorbing coating on its surface, the coating consisting mainly of deposits of latex particles, the latex particles being organic liquid or oil-swellable and organic liquid or oil-absorbing. The latex particles are comprised of insoluble cross-linked polymers that are swellable in an organic liquid or oil to 2 to 50 times their unswollen volume, and the amount of the organic liquid or oil-swellable latex coating is . A method for removing organic liquid or oil from a water stream, characterized in that when swollen with the organic liquid or oil, the volume is sufficient to close the internal gap in the porous body and prevent water flow from passing through. 2. The method according to claim 1, wherein the porous body is a non-granular body. 3 Claim 1 in which the porous body is a granular body
The method described in section. 4. The method of claim 1, comprising the step of monitoring pressure drop through the porous body. 5. The method of claim 2, wherein the porous body is an open-cell plastic foam. 6 A headrace through which water flows, and a foundation hole located laterally within the waterway that is permeable to water and in sealed connection with the headrace, so that the water flowing within the waterway is forced to pass through it. The porous body constituting the absorbent bed has an organic liquid- or oil-absorbing coating film on its surface, and the coating film has an unswollen coating volume when it comes into contact with the organic liquid or oil. consisting of a latex coating of an organic liquid or oil-absorbing polymer that swells from 2 to 50 times a water flow, preferably on a weight basis, characterized by
Equipment for removing organic liquids or oils from water streams containing less than 1000 ppm of organic liquids or oils. 7. The device according to claim 6, wherein the porous body is a non-granular body. 8 Claim 6, wherein the porous body is a granular body
Apparatus described in section. 9. The device of claim 6, further comprising means for indicating the pressure drop across the perforated body. 10. The device of claim 6, wherein the porous body is plastic foam.