JPS6112758B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the regeneration of adsorbents, and more particularly to a method for desorbing an adsorbent from an adsorbent by eluting the adsorbent into an inert solvent maintained at supercritical conditions. and devices.

A number of inorganic adsorbents have become well known over time, the most commonly used of which are activated carbon, alumina, silica and silicates.

Although activated carbon and various inorganic adsorbents are still widely used for many purposes, the development of synthetic polymer adsorbents in recent years has extended industrial applications to a much wider range of applications than previously associated with activated carbon. The use of adsorbents in processes has been widespread. In some cases, polymeric adsorbents have been replaced with activated carbon, silica, alumina, and the like. One of the primary reasons for the rapid spread of the use of polymeric adsorbents lies in the fact that liquids can be used to remove adsorbed substances from the polymers by solvation or reaction mechanisms. Because this fluid removal is normally performed under ambient conditions, many of the disadvantages associated with, for example, activated carbon regeneration can be avoided.

Organic solvents such as methanol or isopropanol can be used in regenerating the polymer adsorbent. If the adsorbent is a weak acid, a base can be used to react with it and remove it;
Acids can be used as reaction components. or,
Water can be used if the adsorbent is from an ionic solution; and hot water or a stream can be used if the adsorbent is a volatile substance.

By far the most widely used technique for polymer sorbent regeneration is solvent extraction. After loading the adsorbent material to the leakage point with respect to the adsorbed species, a suitable organic solvent is passed through the bed of polymeric adsorbent to dissolve and extract the adsorbent material. Due to the cost of the solvent used to regenerate the polymer adsorbent, it is necessary to recover a high percentage of that solvent. Additionally, many such solvents pose problematic contamination problems whenever they are disposed of, whether in large or small quantities. In addition to such recovery costs, there are operational factors to consider in recovering and purifying such solvents for reuse.

In solvent regeneration, a solvent is used to drain water (or other liquid from which impurities have been removed) from a bed of adsorbent material. This means that a solvent-water mixture is obtained which has to be separated in the solvent recovery step. Some of the most effective, common, and less expensive solvents for regeneration of polymer adsorbents form azeotropes with water, and such azeotropes must be handled during solvent recovery. In the distillation of a mixture forming an azeotrope, one column is used to recover one component and the azeotrope. In order to recover the other component in purified form, the azeotrope must then be sent to a second column operating either at higher or lower pressure. Each such column requires a large number of theoretical plates. Therefore, although the use of solvents for the adsorbed species in the regeneration of polymer adsorbents does not represent any new technology, it is clear that it poses significant economic problems. In fact, due to the difficulty of solvent recovery problems, the use of synthetic polymer resin adsorption unless the crude regeneration solvent stream can be recycled or otherwise used economically in an adjacent process. are often excluded.

Alternatively, it is desirable to have a process by which adsorbed substances can be effectively removed or efficiently extracted from polymeric adsorbents and the solvent can also be purified for recycling more economically than is currently possible. is desirable.

Accordingly, it is a primary object of the present invention to provide an improved method for regenerating polymer adsorbents. Another object is to provide a process of the above character which is based on an efficient and economical recovery of the used solvent and optionally the adsorbed material. Yet another object may be to provide the above method which can be applied to a wide range of polymer adsorbent-adsorbent combinations.

A further object is to provide a method of the above character in which unavoidable solvent losses do not pose additional contamination problems.

Another main object of the invention is to use a polymeric adsorbent to remove organic impurities and an inert solvent in the form of a supercritical fluid to desorb the adsorbed material from the adsorbent and regenerate it. use. An object of the present invention is to provide an improved wastewater purification method and apparatus.

Other objects of the invention will be partly apparent and partly apparent from the following description.

In the method of the invention, a polymer adsorbent is regenerated by desorbing the adsorbent from the polymer adsorbent by eluting the adsorbent into a chemically inert solvent in the form of a supercritical fluid. After the adsorbent is fixed, the adsorbent is brought into contact with a suitable supercritical fluid, and the supercritical fluid containing the eluted adsorbent is subjected to a physical treatment to make it a non-solvent for at least a portion of the adsorbent. , thus separating the adsorbate and the supercritical fluid into two phases. After separating the adsorbate from the supercritical fluid,
The supercritical fluid, which can be said to be in a non-solvent state, can be subjected to other physical treatments to restore it to a state in which it is a solvent for the adsorbed substance, and in this way it can be circulated. It can therefore be said to be in a solvent state before being recycled. The physical treatment can consist of changing the temperature or pressure or both of the supercritical fluid. As an optional step,
The adsorbent can be reacted with the reactant while being dissolved in or mixed with the supercritical fluid.

In the detailed description that follows, the term "non-solvent state" is applied to a supercritical fluid to indicate that it has a relatively low solubility for one or more adsorbed substances, while the term "non-solvent state" is applied to a supercritical fluid to indicate that it has a relatively low solubility for one or more adsorbed substances; '' is applied to supercritical fluids to indicate that they have a relatively high solubility for one or more adsorbent substances. That is, these words are not used in an absolute sense, but in a relative sense.

Accordingly, the invention consists of a number of steps and the relationship of one or more of those steps to each other and is illustrated in the method disclosed below, and the scope of the invention is indicated in the following claims. has been done.

In order to fully understand the nature and objects of the present invention, the following detailed description is provided with reference to the accompanying drawings.

Commercially available polymer adsorbents can be described as hard, insoluble, high surface area, porous polymers. Typically, they are provided in spherical form of nominally about 16 to 50 mesh. They are available with a variety of polarities and surface properties and can be used as adsorbents in a wide variety of applications. The polymer adsorbent may be, for example, a polymer of styrene, a copolymer of styrene and divinylbenzene, or a polymer containing an acrylic acid ester, trimethylolpropane trimethacrylate or trimethylolpropane dimethacrylate. [For example, on April 13, 1972, the International Institute of Advanced Hygiene Research
RMSimpson, “The Separation of Organic Chemicals from Water”, presented at the 3rd Symposium (Sanitation Research), where typical chemical structures of polymer adsorbents were presented.
From Water). German Publication No. 1943807
See also issue].

This polymeric adsorbent has found many different uses in wastewater treatment. For example, they are used to decolorize kraft pulp mill bleach effluents and dye wastewater as well as remove pesticides from wastewater streams.
have been used to remove alkylbenzene sulfonate or linear alkyl sulfonate type surfactants from wastewater and explosives such as TNT and DNT from effluent streams. These polymeric adsorbents are used to remove trace (ppb) organic contaminants in water or in chemical processes, enzymes and protein isolation, as well as vitamin B-12, tetracycline, oxytetracycline and oleandomycin. It has also been used in methods for analyzing other biological materials.

Typical examples of pesticides that can be removed from wastewater streams by adsorption onto polymeric adsorbents are pesticide components such as Lindane, DDT, Malathion and endrin, heptachlor and other chlorinated hydrocarbon intermediates. be.

Examples of organics that can be removed from wastewater streams using polymeric adsorbents include Junk et al., Journal of Chroma.
Table 1 reported by lograpny.99 745-762 (1974). The resins used had helium porosity of 42% and 51%, surface area of 330 and
750 m ² /g, average pore diameters of 90 and 50 Å, skeletal densities of 1.08 and 0.09 g/cc, and nominal mesh sizes of 20 to 50. XAD-2 sold by Rohm and Haas Company
and XAD-4).

Table 1 Organic substances that can be removed from water streams by adsorption on polymeric adsorbents Alcohol, hexyl, 2-ethylhexanol, 2-octanol, decyl, dodecyl, benzyl, cinnamyl, 2-phenoxyethanol, aldehydes and ketones, 2 , 6-dimethyl-4-heptanone, 2-undecanone, acetophenone, benzophenone, benzyl, benzaldehyde, salicylaldehyde, ester,
Benzyl acetate, dimethoxyethyl phthalate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, diethyl fumarate, dibutyl fumarate, di-2-ethylhexyl fumarate, diethyl malonate, methyl benzoate, methyl decanoate , methyl octanoate, methyl palmitate, methyl salicylate, methyl methacrylate polynuclear aromatic, naphthalene, 2-methylnaphthalene, 1-methylnaphthalene, biphenyl, fluorene, anthracene, acenaphthene, tetrahydronaphthalene, alkylbenzene, ethylbenzene, cumene, p-cymene, acid (acidified), octanoic acid, decanoic acid, palmitic acid, oleic acid, benzoic acid, phenol, phenol, o-cresol, 3,5-xylenol, o-chlorophenol, p-chlorophenol , 2,4,6-trichlorophenol, 1
- Naphthol, ether, hexyl, benzyl, anilyl, 2-methoxynaphthalene, phenyl, halogen compound, benzyl chloride, chlorobenzene, iodobenzene, o-dichlorobenzene, m-dichlorobenzene, 1,2,4,
5-tetrachlorobenzene, α-o dichlorotoluene, m-chlorotoluene, 2,4-dichlorotoluene, 1,2,4-trichlorobenzene nitrogen compound, hexadecylamine, nitrobenzene, indole, o-nitrotoluene, N-
methylaniline, benzothiazole, quinoline, isoquinoline, benzonitrile, benzoxazole. The polymer adsorbent is regenerated by eluting the adsorbent material when the adsorbent bed reaches a predetermined saturation point defined as a point. Also, as noted above, this removal of adsorbed material has heretofore been accomplished by using organic liquid solvents such as methanol or isopropanol at ambient temperature and pressure and involves costly solvent recovery steps. Ta.

According to the method of the present invention, supercritical fluids are used for adsorbent regeneration, and the method does not require a phase change of the solvent and therefore requires minimal energy consumption. This method also offers the possibility of achieving efficient adsorbate recovery if desired.

It is known that a certain gas reaches a supercritical state when it is kept at a certain pressure and above a certain temperature. Broadly speaking, the term supercritical state may be defined herein as a temperature and pressure range above the critical temperature and pressure of the compound. Although the term "supercritical" generally applies to any temperature above the critical state, in the following description it refers to any temperature above the critical pressure and up to about 1.3 times the critical temperature. Used to refer to gas. However, in most cases, approximately 1.1 of the unit critical temperature
It is preferred to use temperatures no higher than 2 times.

In the process of the invention, carbon dioxide has been found to be particularly suitable for removing organic adsorbate from polymer adsorbents. The critical temperature of carbon dioxide is 304.2〓 (31.0℃) and the critical pressure is 72.9 atmospheres. The most advantageous conditions used for the practice of this invention are temperatures between about 1.01 times its critical temperature and
1.1 times, i.e. approximately 308〓 to 335〓 (34℃ to 62℃)
between. This temperature range is slightly above room temperature. Additionally, carbon dioxide has several other advantages, among which it does not pollute the atmosphere and is inexpensive.

In selecting a supercritical fluid for regeneration of a polymer adsorbent adsorbing one or more organic species, the supercritical fluid must be a solvent for the species to be removed. , and it must be a fluid that does not react with the surface of the adsorbent.

For any adsorbent/supercritical fluid system, the supercritical fluid is first made a solvent for the adsorbent;
The physical changes that the supercritical fluid must undergo in order to become a non-solvent for the adsorbent will, of course, depend on the solubility of the adsorbent in the supercritical fluid at various temperatures and pressures. A typical example of such a system is naphthalene/supercritical carbon dioxide. Figure 1 is a graph of naphthalene solubility in carbon dioxide over a temperature range of 35°C to 55°C for selected pressures (Yu.V.
Tsekha−nskaya.M, B.Iomtev and EV
(Taken from Muskina, Zh.Fiz, Khim.38, 2166 (1964)). According to this graph in Figure 1, a dissolved organic compound, such as naphthalene, is (a) subjected to a temperature cycle at constant pressure (e.g.
Absorb at 35°C and precipitate at 35°C; or 80°C.
(b) subjected to a pressure cycle at a constant temperature (e.g. 55°C, adsorbed at 300 atm and precipitated at 80 atm); or (c) at temperature /pressure cycling; can be separated from the supercritical carbon dioxide solvent.

The method and apparatus of the invention are schematically shown in FIG. In this case CO ₂ is used as a supercritical fluid to remove hydrocarbon impurities adsorbed onto the polymer adsorbent. The spent polymer adsorbent to be regenerated in the apparatus of FIG. 3 is introduced from an adsorbent storage tank (see FIG. 6) by line 11 at substantially ambient pressure and temperature to a desorption column 10 (as a fluid contacting device). action). The flow of spent polymer adsorbent is controlled by a high pressure on/off valve 12. The desorption column 10 must be constructed to withstand the maximum pressures applied to the supercritical fluid. Any pressure vessel suitably designed to withstand such pressures can be used as a desorption column. Although the process shown in FIG. 3 is a batch method, it is of course within the scope of the present invention to use a continuous method if necessary. In such a batch method, the consumed adsorbent is packed into a desorption column 10 in batches, pressurized, and desorbed by circulating a supercritical fluid.

The desorption column 10 also has a regenerated adsorbent take-off line 13 with a high-pressure valve 14 , a gas introduction line 15 with a high-pressure valve 16 , and a gas take-off line 17 with a high-pressure valve 18 .

A high pressure line 2 in which a supercritical fluid for regeneration, e.g. carbon dioxide at 300 atmospheres and 35° C., is stored in a storage tank 20 and has a high pressure fluid flow control valve 22.
1 into the desorption column 10 periodically.
After contacting the adsorbent in the desorption column 10, the supercritical fluid in which the adsorbent material, e.g. a hydrocarbon, is dissolved is removed from the column 10 through a high pressure line 23;
The flow rate is controlled by a high pressure on/off valve 24.

In the embodiment of the invention shown in FIG. 3, the physical process that renders the supercritical fluid non-solvating for the adsorbate is to reduce the pressure. This transfers the supercritical fluid to a suitable expander, such as a turbo expander 25.
This is done by expanding it in the 300
In this example using CO ₂ at atmospheric pressure and 35° C., this expansion typically reduces the pressure to about 80 atmospheres. In the case of the example shown in FIG. 3, the temperature also decreases due to expansion. In any case, before circulating the supercritical fluid, it is necessary to adjust the temperature of the fluid so that it has a minimum solubility for the adsorbate. 3, heat exchangers 26 and 38 are shown in the fluid lines to provide temperature control.

The reduction in pressure of the supercritical fluid caused by expansion in the expander 25 and the temperature fluctuations in the heat exchanger 26 cause the supercritical fluid to become a non-solvent for the adsorbate. In effect, the adsorbed material precipitates, resulting in a two-phase fluid which is taken to a phase separator 29. This separator can be, for example, a cyclone separator 29 or a holding tank. Adsorbent material is removed from phase separator 29 through adsorbent removal line 30 having valve 31 and supercritical fluid is removed from separator 29 through removal line 32 and valve 33. In this particular embodiment using CO ₂ , the temperature of the CO ₂ is raised to about 35° C. in heat exchanger 26 . However, since the pressure is only 80 atmospheres,
In order to return this CO ₂ to a supercritical fluid in a solvent state for the adsorbent, it is necessary to compress it.
This is done by returning the pressure to 300 atmospheres in the compressor 35 and bringing the temperature to about 95°C.
Since this temperature is significantly higher than the desired temperature for supercritical conditions of CO ₂ in this example, it is used in heat exchanger 26 to heat the fluid exiting expander 25 . That is, one side of the heat exchanger 26 forms part of a supercritical fluid line 37 that connects the storage tank 20 and the compressor 35. In this embodiment using _CO2 , the temperature of the supercritical fluid leaving the heat exchanger 26 is still higher than the desired 35°C, so a second heat exchanger 38 is installed to separate the supercritical fluid and the external supply. Heat exchange is performed with the coolant, for example water passing through the coil 40. The supercritical fluid thus reaches the storage tank 20 and is circulated under solvent conditions.

Supercritical fluids can be used as solvents for adsorbed materials above their critical pressures and temperatures. It is preferred to keep the temperature no more than 50°C above the supercritical temperature, and in some cases it is preferred to keep the temperature during solvation no more than about 10°C above the critical temperature. The maximum pressure is determined by the high pressure capability of the equipment used. In general, higher pressure is preferable in order to increase the ability to dissolve adsorbed substances. When selecting physical conditions to render the supercritical fluid a non-solvent for the adsorbent, it is desirable not to change the pressure and/or temperature of the supercritical fluid more than is necessary to separate the adsorbent.

In some cases, it is desirable to change the chemical and therefore physical properties of the adsorbent after it has been removed from the adsorbent. This is accomplished by reacting the adsorbent material with a suitable reactant while it is dissolved or mixed in the supercritical fluid. Specifically, in FIG. 4, a reaction chamber 45 is shown into which a reactant for the adsorbate (eg, oxygen for hydrocarbons) is introduced through line 46 and valve 47. In FIG. 4, the same elements as in FIG. 3 are given the same numbers. The supercritical fluid is then removed from line 23a, which is an extension of line 23, and valve 48. If reactants are introduced into the supercritical fluid while it is in a solvent state, as shown in FIG. 4, reaction chamber 45 and all lines and valves must be capable of handling high pressures. Alternatively, a reaction chamber may be connected to line 28 in a manner similar to that shown in FIG. The reaction can be carried out in

FIG. 5 shows another embodiment of the method and apparatus for treating a supercritical fluid to make it a non-solvent for the adsorbed substance and then converting it into a solvent by processing it again and circulating it as a solvent. In the embodiment of FIG. 5, this process step is limited to changing the temperature of the supercritical fluid to effect phase separation, and for the purpose of illustration, the adsorbent is comprised of at least two species, and Assume that they exhibit different solubilities in a supercritical fluid. In FIG. 5, reference numbers are given to the same elements as in FIG. 3.

The apparatus of FIG. 5 is for a multi-step separation process that involves two sequential increases (or decreases) in temperature. Although two steps are shown, any number can be used. The supercritical fluid containing all the dissolved adsorbent material is introduced through line 23 into a first heat exchanger 50, which exchanges indirect heat with an externally supplied heat exchange fluid in line 51. heating (cooling) to a first high (low) temperature sufficient to separate a first portion of adsorbent material using In effect, the supercritical fluid is turned into a non-solvent state for a first portion of adsorbent material, but remains in a solvent state for a subsequent portion of adsorbent material. This first two-phase liquid is transferred to a first phase separator 5 through a line 52.
3, from which a portion of the first adsorbent material is removed via line 54 and valve 55. The supercritical fluid containing the second adsorbate portion is then directed through line 58 to a second heat exchanger 57 and further heated (cooled) by an externally supplied heat exchange fluid in line 58 with a screw. . This heating further separates the second adsorbent material, and the resulting two-phase fluid is conveyed via line 59 to a second phase separator 60, from which a portion of the second adsorbent material is transferred to line 61 and a valve. 62. The high temperature supercritical fluid is sent to a heat exchanger 64 through a line 63, and is cooled (or heated) by indirectly exchanging heat with a coolant (or heating fluid) supplied from the outside through a line 65. . The supercritical fluid at the desired temperature and pressure (ie, solvent conditions for all adsorbate) is then passed through line 66 to storage tank 20.

If only temperature is used to make the supercritical fluid a non-solvent state for the adsorbate, a high pressure device is used throughout. In the embodiment shown in FIG. 5, it is preferable that the supercritical pressure is relatively low and the solubility of the adsorbate is relatively sensitive to temperature.

Of course, the second heat exchange step shown in FIG. 5 is removed,
It is also within the scope of the invention to perform a single separation step by temperature change alone. Further, as shown in FIG. 3, it is also within the scope of the present invention to perform depressurization of the supercritical fluid in two or more steps to separate two or more types of adsorbed substances. Furthermore, it is within the scope of the present invention to incorporate the reaction steps shown in FIG. 4 into FIG. 5.

FIG. 6 schematically shows the state in which the adsorbent regeneration method and apparatus of the present invention are incorporated into a wastewater purification system. The apparatus shown in Figure 3 is used. Since the same elements are given reference numbers, the description of the supercritical fluid circulation will not be repeated.

Figure 6 shows two adsorption columns 70 used alternately.
and 71 to show a device that regenerates one when the other is in use. This is, of course, a known arrangement and any suitable number of adsorption columns can be used in parallel or in series. The wastewater to be purified is introduced from line 72 into column 70 or 71 depending on whether valve 73 or 74 is open.
Let us assume that we are passing fluid through column 70 and that valve 73 is open and valve 74 is closed. Column 7
0 is filled with an adsorbent that adsorbs impurities,
Treated water is removed through line 75 and valve 76. Since no fluid is flowing into the column 71 and it is on standby ready for immediate use,
Valve 77 of water withdrawal line 78 is closed. Under these conditions, the valve 80 of the spent polymer adsorbent line 79 and its associated column 70 is closed. Meanwhile, the valve 82 of the spent polymer adsorbent line 81 and its associated column 71 is opened, and the spent adsorbent as well as the adsorbed material stuck to its surface is removed from the spent adsorbent supply tank 84.
It can be transported by pump 83 to the reactor and periodically introduced into the contact column 10 for regeneration as described above and as described in FIG. Slurry pumps or drainers that act as pump 83 are known.

Typically, the polymer adsorbent will not be dried before desorption. This is because water can be removed by the solvent supercritical carbon dioxide and then separated from the carbon dioxide by appropriate changes in temperature and/or pressure. However, in some cases it may be desirable to remove residual water from the adsorbent prior to regeneration with supercritical fluid. In that case, before extracting the adsorbate from the adsorbent in the contact column 10, valves 22 and 24 are closed and valve 16 is closed.
and 18 are opened to allow a drying gas, such as hot air, to pass over the consumable adsorber to remove residual water. Carbon dioxide at atmospheric pressure is then passed upward through the dry, depleted adsorbent to remove any air remaining in the pores of the depleted adsorbent. Then valve 16
and 18 and open valves 22 and 24; and regeneration occurs as described above. Valves 12, 22, 23, 16 are then closed, valve 14 is opened, and the regenerated polymer adsorbent is transferred via line 13 into an adsorbent storage tank 85;
It can then be transferred by pump 86 to column 71 which is free of fluid flow. The regenerated adsorbent is then connected to line 87 controlled by valve 88.
into column 71. When no fluid is flowing through column 70, regenerated adsorbent is admitted to column 70 through line 89 and controlled by valve 90.

FIG. 2 shows an improvement to the device shown in FIG.
In the arrangement of FIG. 2, the separate desorption column 10 is removed, along with conduit means for delivering the depleted adsorbent and removing the regenerated adsorbent therefrom. Instead, desorption is accomplished directly in columns 70 and 71, where these columns are vessels capable of withstanding the pressure necessary to maintain the supercritical fluid supplied from storage tank 20 in its solvent state. be. Fluid conduits 23 for alternately removing supercritical fluid containing adsorbate from columns 70 and 71 are conduits 2 with valves 24a and 24b, respectively.
It is branched into 3a and 23b. Similarly, fluid conduits 21 supplying supercritical fluid alternately to columns 70 and 71 are provided with valves 22a and 22b, respectively.
It branches into conduits 21a and 21b having .

The method of the invention will be further explained with reference to the schematic diagram of FIG. 6, using phenol and 2,4,6-trichlorophenol as adsorbents, a polymeric resin as adsorbent and supercritical carbon dioxide as solvent. I can do it. A typical example of such a resin is pore melt
51%, true wet density 1.02g/cc, surface area 780m ² /
g, an average pore diameter of 50 Å, a skeletal density of 1.08 g/cc, and a nominal mesh size of 20-50. At a water flow rate of 0.5 gallons per minute per cubic foot, this polymer adsorbent adsorbs approximately 0.78 pounds per cubic foot of phenol with 0% leakage from a concentration of 250 ppm in the feed water. This adsorbent also adsorbs 12 lb/ft3 of trichlorophenol at the same flow rate and 0% leakage. Regeneration of the adsorbent can be carried out by using supercritical fluid under the conditions described above when a leak point is detected in the adsorption. Supercritical carbon dioxide can be used at 35°C and 300 atm to dissolve phenol and trichlorophenol from the polymer adsorbent, and then by reducing the pressure to 80 atm and/or increasing the temperature to 45°C. Carbon dioxide can be converted to a non-solvent state for the adsorbate. The presence of phenol in the carbon dioxide can be detected by means of a plasma radiation detection means. The resulting reactivated adsorbent can then be contacted again with additional aqueous phenol/trichlorophenol solution.

By dissolving the adsorbed material from the polymeric adsorbent using a supercritical fluid, the adsorbent is free from any appreciable thermal or chemical degradation and the adsorbed species can be recovered if desired. can.
Additionally, it is possible to use supercritical fluids such as carbon dioxide, ethane or ethylene, which require temperatures and pressures well within the capabilities of existing equipment. Finally, these fluids (particularly carbon dioxide) are cheap, which greatly contributes to the economics of industrial processes and wastewater purification.

Trace amounts of organic impurities in wastewater can be detected and quantities as small as PPb can be measured. After removing impurities from a water stream by adsorption onto a polymer adsorbent, they are dissolved in a supercritical fluid according to the method of the invention. Complete separation of adsorbate impurities from supercritical fluids is easily achieved without any chemical or physical changes in the adsorbate, making it difficult to accurately determine the amount of impurities in a given sample. Well-known analytical techniques can be used.

[Additional relationship]

The invention of original patent number 1247631 (Japanese Patent Publication No. 1247631 (Japanese Patent Publication No. 59-24854) is by bringing an adsorbent, such as activated carbon, to which an adsorbent is fixed, into contact with a supercritical fluid that is a solvent for the adsorbent. The adsorbed substance eluted in the fluid can be removed by separating the fluid from the adsorbent and subjecting the fluid to a physical treatment that makes it a non-solvent for the adsorbed substance. The adsorbent is separated from the adsorbent by precipitating the adsorbent, and then subjected to a physical treatment such that the precipitated adsorbent and the separated fluid are again used as a solvent for the adsorbent, and then reused as an extraction solvent. The present invention relates to an extraction method and an apparatus for extracting organic substances present in water as impurities to be removed.
Polymer adsorption is carried out in the same manner as above using a supercritical fluid that is fixed on a polymer adsorbent and can take either a solvent or a non-solvent state for the organic matter through appropriate physical treatment. This invention relates to a method and apparatus for extracting adsorbed organic substances from the body, and is an invention in which the main part of the original invention is an essential part of its structure, and which achieves the same purpose as the original invention. It is an invention that

[Brief explanation of the drawing]

FIG. 1 is a graph showing the solubility of naphthalene in carbon dioxide over a temperature range of 35 DEG C. to 55 DEG C. for selected pressures. FIG. 2 is a schematic diagram of one embodiment of the apparatus used to practice the invention. FIG. 3 is a flow diagram for explaining a specific example of the method of the present invention. FIG. 4 is a schematic diagram of a variation of the method of FIG. 3 that involves reacting the chemically reactant and the adsorbent while dissolved in a supercritical fluid. FIG. 5 is a flow diagram for explaining another embodiment of the method of the present invention. FIG. 6 is a flow diagram of a wastewater purification system incorporating the method of the present invention.

Claims (1)

[Scope of Claims] 1. A water treatment method for removing at least one organic substance from water, comprising: (a) treating a synthetic organic polymer adsorbent with a synthetic organic polymer adsorbent; (b) directing the synthetic organic polymer adsorbent adsorbing the organic material onto the organic material under conditions such that the organic material is adsorbed as an adsorbent; contacting a supercritical fluid as a solvent to desorb and elute the organic material into the supercritical fluid, thereby enabling the adsorbent to adsorb an additional amount of the organic material; During the contact, the supercritical fluid has a temperature of about 1.01 to 1.3 of its critical temperature (〓).
(c) separating the supercritical fluid containing the dissolved organic material from the adsorbent; and (d) separating the supercritical fluid containing the organic material from the fluid. (e) subjecting the organic substance to a physical treatment to make it a non-solvent, thereby creating a two-phase system consisting of the fluid in a non-solvent state and the organic substance; separating a two-phase system into a fluid in a non-solvent state and the organic substance; (f) following the separation step, subjecting the fluid in a non-solvent state to a physical treatment that converts it into a supercritical fluid in a solvent state; A method as described above, characterized in that it consists of the steps of, in particular, rendering it a solvent for the organic substance. 2. The synthetic organic polymer adsorbent is a styrene polymer, a copolymer of styrene and divinylbenzene,
or a polymer containing acrylic acid ester, trimethylolpropane trimethacrylate, or trimethylolpropane dimethacrylate. 3. The method according to claim 1, wherein the supercritical fluid is carbon dioxide. 4. The method according to claim 1, wherein the supercritical fluid used in step (b) is at a temperature between about 1.01 and 1.1 times the critical temperature (〓) of the fluid. 5. The method of claim 1, wherein the supercritical fluid is carbon dioxide at a temperature between about 34°C and 65°C. 6. The method of claim 1, wherein the physical treatment of step (d) comprises reducing the pressure of the supercritical fluid. 7. The method of claim 1, wherein the physical treatment of step (f) comprises compressing the non-solvent fluid to a pressure greater than its critical pressure. 8. The method of claim 6, wherein said pressure reduction is achieved by expanding said supercritical fluid and simultaneously reducing its temperature. 9. The physical treatment of step (f) compresses the fluid in the non-solvent state, thereby heating the fluid and pressurizing it to a pressure above its critical pressure, and compressing the fluid in the non-solvent state. 9. A method according to claim 8, comprising indirectly performing heat exchange with the compressed fluid obtained, thereby lowering the temperature of the compressed fluid and creating the supercritical fluid in the solvent state. 10 The physical treatment of step (d) includes changing the temperature of the supercritical fluid in one direction, and the physical treatment of step (f) includes changing the temperature of the non-solvent fluid in the direction of step (d). 2. A method according to claim 1, comprising changing in the opposite direction. 11. The method according to claim 1, wherein the physical treatment of step (d) and the separation of step (e) are carried out in a multi-step process, thereby effecting the separation of more than one fraction of the adsorbed substance. Method. 12. The method of claim 1, comprising chemically reacting the adsorbent in the supercritical fluid with a reactive component for the adsorbent introduced into the fluid. 13. The method of claim 1, wherein the water comprises bleaching effluent from a pulp mill and the organic material comprises a pigment material. 14. The method of claim 1, wherein said water comprises a stream containing waste dye as said organic material. 15. The method of claim 1, wherein the water is an agricultural wastewater stream containing agricultural, pesticides, detergents, or explosives as the organic material. 16. The method of claim 1, wherein the water contains biological material as the organic material. 17 The synthetic organic polymer adsorbent adsorbing the adsorbed substance is brought into contact with a supercritical fluid that is a solvent for the adsorbed substance to desorb the adsorbed substance from the synthetic organic polymer adsorbent and to remove the adsorbed substance from the supercritical fluid. dissolving into a critical fluid, thereby enabling the adsorbent to adsorb an additional amount of the adsorbent, the temperature of the supercritical fluid being reduced to the critical temperature of the fluid (〓).
1. A method for desorbing an adsorbed substance from a synthetic organic polymer adsorbent, characterized in that the pressure is in the range of about 1.01 to 1.3 times the critical pressure of the fluid and the pressure is greater than the critical pressure of the fluid. 18. The method of claim 17, wherein the supercritical fluid is carbon dioxide. 19. The method of claim 17, wherein the supercritical fluid is at a temperature between about 1.01 and 1.1 times the critical temperature of the fluid. 20. The method of claim 19, wherein the supercritical fluid is carbon dioxide. 21 (a) a container device for effecting contact between a wastewater containing organic matter and a polymeric adsorbent contained therein; (b) a container device for circulating the wastewater through the container device, thereby an apparatus for adsorbing an organic substance onto the adsorbent; (c) a temperature and pressure that causes the adsorbent adsorbing the organic substance and a supercritical fluid to be brought together so that the supercritical fluid serves as a solvent for the organic substance; (d) a pressure vessel apparatus for contacting the organic material under conditions of, thereby desorbing the organic material from the adsorbent and dissolving it in the supercritical fluid; (d) altering the physical conditions of the supercritical fluid to (e) a first physical treatment device for converting the organic material into a non-solvent for the organic material, thereby forming a two-phase system consisting of the organic material and the supercritical fluid in the non-solvent state; a fluid conduit device connecting the pressure vessel device and the first physical processing device, the fluid conduit device being arranged to direct the supercritical fluid containing the non-solvent to the first physical processing device; (g) a phase separation device for separating the supercritical fluid in the non-solvent state and the organic material; (g) a phase separation device for converting the non-solvent supercritical fluid into its solvent state for recycling into the pressure vessel device; A wastewater treatment device for removing organic substances from wastewater, comprising a combination of two physical treatment devices. 22. The device of claim 21, wherein the container device also acts as the pressure vessel device. 23 the first physical processing device includes a device for unidirectionally changing the temperature of the supercritical fluid;
22. The apparatus of claim 21, wherein the second physical treatment device includes a device for varying the temperature of the fluid in a direction opposite to that provided by the first physical treatment device. 24. The first physical treatment device comprises at least two stages, the physical treatment in each stage increasing in size, and the phase separation device comprises at least two stages; 22. Apparatus according to claim 21, comprising a phase separator following each stage of , by means of which the adsorbed material is removed as a fraction. 25. The apparatus of claim 21, wherein the first physical processing device comprises a fluid expansion device and the second physical processing device comprises a fluid compression device. 26. The apparatus of claim 25, including a heat exchanger suitable for effecting heat exchange between fluid removed from the fluid expansion device and fluid removed from the fluid compression device.