JP2014064968A - Method for treating brine including phenols and heavy metals by using adsorbent and method for regenerating adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treating method capable of simultaneously removing, from a brine such as a body of water accompanying an oil field, etc., phenols and heavy metals through a singular operation and a method for regenerating an adsorbent used in the water treating method.SOLUTION: The method of one embodiment for treating a brine including phenols and heavy metals by using an adsorbent comprises a step of preparing an adsorbent including a resin having a polyamine structure and a step of immersing the adsorbent within a brine including phenols and heavy metals and then adsorbing and removing the phenols and heavy metals.

Description

  Embodiments of the present invention relate to a method for treating brine containing phenols and heavy metals using an adsorbent, and a method for regenerating the adsorbent.

  In recent years, effective use of water resources is required due to industrial development and population growth. For that purpose, reuse of brine such as industrial brine is very important. To achieve this, it is necessary to purify the water, ie to separate other substances from the water. In particular, with the increase in oil production from oil fields, the oil field accompanying water accompanying oil production has increased. Until now, the oil accompanying water in the oil field has a high salinity and contains oil, solids, volatile organic substances, water-soluble organic substances, etc., and is released to the environment in addition to the return disposal to the oil fields.

  A heavy metal can be mentioned as a typical solid content contained in oilfield-associated water, and a phenol can be mentioned as a typical volatile organic substance.

  As a method for removing phenols, removal using an ion exchange resin has been performed. For example, it is often performed using a strongly basic resin, and a resin having a functional group such as quaternary ammonium has been used (see Patent Document 1).

  On the other hand, as a method for removing heavy metals, for example, it is often removed using an ion exchange resin having a chelating group such as iminodiacetic acid or using a dithiocarbamic acid chelating agent. Different methods have been adopted (see Patent Document 2). Therefore, in order to remove phenols and heavy metals from the oilfield-associated water, it is necessary to combine the two methods as described above, resulting in a need for a two-stage treatment process. For this reason, there existed a fault that processing time increased and the processing cost increased.

  In addition, the oil associated with the oil field is brine and has low acidity, so the selectivity of phenol is low, and ions containing higher acidity than phenol, such as contained salts such as chloride ions, are first adsorbed to the strongly basic resin. As a result, the amount of adsorption depends on the salt concentration in the oil-field associated water, which is the treated water.

JP 2004-160356 A JP 2003-53343 A

  The present invention provides a water treatment method capable of simultaneously removing phenols and heavy metals from brine such as oilfield-associated water by a single operation, and a method for regenerating an adsorbent used in the water treatment method. With the goal.

  The method for treating brine containing phenol and heavy metal using the adsorbent according to the embodiment includes the steps of preparing an adsorbent containing a resin having a polyamine structure, and immersing the adsorbent in brine containing phenols and heavy metal. A step of adsorbing and removing the phenols and the heavy metal.

(Adsorbent)
First, the adsorbent used in the water treatment method for brine containing phenols and heavy metals according to the embodiment will be described.

  The adsorbent needs to contain a resin having a polyamine structure, and is not particularly limited as long as this requirement is satisfied. For example, a substance having a structure in which a functional group having a polyamine structure is added to a poorly water-soluble resin such as a crosslinked polystyrene, a crosslinked poly (meth) acrylic resin, or a crosslinked phenol resin can be used.

  The “polyamine structure” in the present embodiment means an aliphatic hydrocarbon in which two or more amino groups are bonded. In this embodiment, examples of such a polyamine structure include aliphatic amines, aromatic amines, quaternary ammonium salts, and aminophosphoric acids. Particularly, polyethylene polyamines represented by the general formula (1) A structure is preferred.

（ｎは１から２０までの整数）

(N is an integer from 1 to 20)

  As is clear from the general formula (1), the polyethyleneamine structure is an aliphatic hydrocarbon having a simple structure in which two or more amino groups are added, and based on the adsorption principle described below, the coordination to the amino group of the heavy metal. There is no functional group that interferes with the position, and the selectivity of coordination of heavy metal to the amino group is increased, so that the adsorption property of heavy metal by the adsorbent is increased.

  In the general formula (1), n is 1 or more and 20 or less. When n is larger than 20, in the production method described below, the reactivity of the polyethyleneamine structure to the above-mentioned poorly water-soluble resin is lowered, and the addition ratio of the polyethyleneamine structure to the resin is reduced. Therefore, the adsorption characteristics of the adsorbent with respect to heavy metals are deteriorated.

  Further, the shape of the adsorbent is not particularly limited, and if necessary, spherical, granular, angular, fibrous, thread-like, rod-like, tubular, sheet-like, membrane-like Any shape such as a plate-like material can be used. However, it is preferably a spherical object. In this case, for example, when the adsorbent is packed in the column and the brine is passed through, an appropriate gap is generated between the adsorbents, and the brine does not cause a large pressure loss before and after passing through the gap. It can flow smoothly and the contact efficiency with the adsorbent can be improved, so that phenols and heavy metals in the brine can be efficiently recovered.

  When the adsorbent is packed in a column to adsorb phenols and heavy metals in brine, for example, the average diameter of the adsorbent is desirably 100 μm or more and 5000 μm or less. When the average particle diameter of the particles is 100 μm or more and 5000 μm or less, both the high packing ratio of the column and the ease of water flow can be achieved. When the average particle size is 100 μm or less, the filling rate of the adsorbent to the column becomes high, and it becomes difficult for water to flow. When the average particle size is 5000 μm or more, the packing rate of the column becomes low and water can be easily passed, but the amount of adsorbent adsorbed per unit volume decreases.

The average particle diameter can be measured by a sieving method. Specifically, it can be measured by sieving using a plurality of sieves having an opening of 100 μm to 5000 μm according to JISZ8901 _{: 2006} “Test Powder and Test Particles”.

  In addition, the range of the preferable average diameter of an adsorbent is 100 micrometers or more and 2 mm or less, More preferably, they are 300 micrometers or more and 1 mm or less.

Further, the bulk density of the adsorbent is preferably in the range of 0.2 g / cm ³ or more and 2 g / cm ³ or less regardless of the method of adsorbing and removing phenols and heavy metals in brine. If the bulk density is less than 0.2 g / cm ³ , the proportion of pores occupying the volume is too large, and it may be difficult to maintain the strength of the adsorbent. When the bulk density is 2 g / cm ³ or more, the proportion of pores occupying the volume is too small, and the surface area of the adsorbent is decreased, which may deteriorate the performance as the adsorbent.

  The bulk density in this case can be measured, for example, by putting resin particles from a certain height such as 10 cm into a container having a certain capacity, filling the container, and measuring the weight. For example, it can be measured using a bulk density measuring device (As One, KAM-01).

(Method for producing adsorbent)
The adsorbent first produces a resin such as, for example, a poorly water-soluble crosslinked polystyrene, a crosslinked poly (meth) acrylic resin, or a crosslinked phenolic resin for adding a functional group having a polyamine structure.

  Cross-linked polystyrene resins include alkyl-substituted styrenes such as styrene, methylstyrene, and ethylstyrene, polycyclic aromatic monovinyl monomers such as monovinylbiphenyl, benzylstyrene, monovinylvinylnaphthalene, and monovinylanthracene, and halogen-substituted styrenes such as bromostyrene. This monomer can be polymerized and then crosslinked using a crosslinking agent containing a vinyl group.

  Examples of the cross-linked acrylic resin include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate. ) Acrylates; non-crosslinkable (meth) acrylic acid ester monomers such as hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, glycidyl methacrylate, methoxypolyethylene glycol (meth) acrylate, etc. And those obtained by crosslinking polymerization of these monomers. Moreover, the crosslinking agent containing a vinyl group can be used as needed.

  Furthermore, examples of the phenolic resin include those obtained by crosslinking phenolic monomers such as phenol, cresol, phenol, cresol, xylenol, p-alkylphenol, p-phenylphenol, chlorophenol, bisphenol (resol type phenol resin). . Moreover, what was bridge | crosslinked using the crosslinking agent containing aldehydes, such as formaldehyde (novolak-type phenol resin) can also be used as needed.

  Examples of the crosslinking agent containing a vinyl group include polyvinyl monomers such as divinylbenzene, divinylnaphthalene, divinyltoluene, divinylxylene, trivinylbenzene, 1,3,5-triacryloylhexahydro-1,3,5-triazine. And aromatic polyvinyl monomers such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, butylene glycol diacrylate, butylene glycol dimethacrylate, and the like. You may use these in mixture of 2 or more types. Among these, it is preferable to use an aromatic polyvinyl monomer, particularly divinylbenzene.

  The amount of the crosslinking agent containing a vinyl group can be arbitrarily added depending on the characteristics of the resin particles, and is not particularly limited, but is usually 0.5 to 90% by mass with respect to the total monomer weight. It can be.

  In addition, when the above-described monomer is polymerized, a polymerization initiator can be appropriately used. As such a polymerization initiator, a known oil-soluble radical generator is used, such as a peroxide catalyst such as benzoyl peroxide, lauroyl peroxide, tertiary butylhydroxyperoxide, azobisisobutyronitrile, etc. And an azo catalyst.

  The usage-amount of a polymerization initiator is 500-30,000 ppm normally with respect to a monomer component, Preferably it is 500-10,000 ppm. In the polymerization, an organic solvent or an inorganic salt may be added to the reaction system as a porous agent to form a large number of pores in the particles.

  These particle monomers contain groups capable of reacting with polyamines, such as chloromethyl groups and epoxy groups. Specifically, in the monomer of the above-mentioned crosslinked polystyrene resin or crosslinked acrylic ester resin, vinyl benzyl halide such as chloromethylstyrene, bromomethylstyrene, iodomethylstyrene, glycidyl acrylate, epoxy such as 3,4-epoxycyclohexyl methacrylate, etc. This can be achieved by adding a group-containing (meth) acrylate and carrying out a polymerization reaction, or in the case of having a hydroxyl group such as a phenol resin, by introducing an epoxy group by reacting the hydroxyl group with epichlorohydrin or the like.

  The reaction between the crosslinked resin as described above and the polyamine structure is performed by polymerizing the monomer and using the obtained granular polymer and polyamine. The temperature is preferably 50 ° C. to 150 ° C., and the solvent is an aprotic solvent such as N, N-dimethylformamide, dimethyl sulfoxide, acetonitrile, ketones such as acetone and methyl ethyl ketone, and other alcohols such as methanol, ethanol and propanol. Water, etc. can be used, and these mixed solvents can also be used.

(Water treatment method with adsorbent)
After preparing the adsorbent as described above, the adsorbent and brine are brought into contact with each other to adsorb and remove phenols and heavy metals in the brine.

  The means for bringing the adsorbent into the brine is not particularly limited. For example, the adsorbent is introduced into the brine, and if necessary, the phenols and heavy metals are collected by stirring and then settled. A method is mentioned. This method is effective when treating a relatively large amount of brine. According to this method, there is a concern that the water purification equipment becomes relatively large, but there is an advantage that a large amount of brine can be treated at one time.

  In addition, as described above, the adsorbent can be packed in a column and brought into contact by introducing brine into the column to recover phenols and heavy metals in the brine. This method is suitable for treating a small amount of brine since the treatment apparatus is relatively small but the amount of brine is limited.

  Although the adsorption principle of phenols by the adsorbent is not clear, it is considered that the amino group in the polyamine structure causes some interaction with the phenols, and the phenols are adsorbed by the adsorbent based on this interaction. .

  Further, the adsorption of heavy metals by the adsorbent is caused by coordination of the heavy metal to the nitrogen atom portion, which is an electron donor element of polyamine, as shown in the general formula (2) to form the following chelate. (M represents a heavy metal). Furthermore, since the adsorbent has a polyamine structure, it is considered that the selection of amino groups to which heavy metals in the brine are coordinated increases and the adsorption characteristics of heavy metals in the brine are increased.

Incidentally, salinity in brine (Na ⁺ and Cl ^-, etc.) is also attached e.g. electrostatically to said adsorbent, the adsorbent comprising a resin having a polyamine structure as described above, the heavy metal described above Since chelate formation by coordination bonds and adsorption of phenols become dominant, adsorption of phenols and heavy metals in the target brine can be performed regardless of the salt concentration in the brine.

  In the present embodiment, the pH value of the brine is 8 or less, preferably 7 or less, more preferably 6 or less. When the pH value of the brine is higher than 8, the brine may contain strongly basic substances such as hydroxyl groups, and phenols derived from weakly basic amino groups of the polyamine structure in the adsorbent described above. In addition, the adsorption characteristics of heavy metals may deteriorate.

  In order to adjust the pH of the brine within the above range, for example, a mineral acid such as sulfuric acid or hydrochloric acid is appropriately added.

  Moreover, the lower limit of the pH value of the brine can be set to pH = 1, for example. Even if the pH value is made smaller than this, there is a problem that not only the adsorption property of the adsorbent is improved, but also the amount of mineral acid used is increased and the water treatment cost is increased.

  In the present embodiment, the temperature of the brine is preferably 100 ° C. or less, more preferably 60 ° C. or less, and particularly preferably 50 ° C. or less. Since the adsorption of phenols and heavy metals by the adsorbent as described above is an endothermic reaction, if the temperature of the brine is high, the adsorption reaction does not proceed, and the adsorption characteristics of the adsorbent for phenols and heavy metals may deteriorate. is there.

  In addition, the lower limit of the temperature of brine can be 0 degreeC, for example. Even if the temperature is lower than this, there is a problem that not only the adsorption property of the adsorbent is improved, but also the energy cost required for cooling is increased and the water treatment cost is increased.

  The brine in the present embodiment includes, for example, factory brine containing seawater and salts, agricultural brine, and particularly oilfield associated water containing a relatively large amount of brine, petroleum-derived phenols and heavy metals.

  In addition, when the brine is associated with oil fields, remove suspended solids by the pressurized flotation method or coagulation sedimentation method, remove phenols and metal ions using this treatment method, and finally perform biological treatment. As a result, the accompanying water can be purified.

  Moreover, the phenols in this embodiment mean the compound of the form which substituted the hydrogen atom of the benzene ring by hydroxyl group -OH, For example, phenol, cresol, xylenol, trimethylphenol, chlorophenol etc. can be mentioned.

  Furthermore, the heavy metal in the present embodiment means a metal having a specific gravity of 4 or more, and examples thereof include mercury, silver, lead, copper, iron, chromium, manganese, cobalt, and nickel.

(Adsorbent regeneration process)
The adsorbent subjected to the water treatment can be regenerated and reused. In order to regenerate, it is necessary to remove the adsorbed phenols and heavy metals from the particle surface. In order to remove such an adsorbing component, a method of washing with an alkaline solution can be used. If there is still room for heavy metal adsorption, it is possible to remove only phenols by heating and use it again in the adsorption treatment.

  In the regeneration treatment with an alkaline solution, adsorbed phenols and heavy metals can be removed. As the alkaline solution, for example, a solution having a pH of 8 or more is required. Examples of the alkaline solution include an aqueous sodium hydroxide solution and an aqueous potassium hydroxide solution. In addition, removal of phenols and heavy metals from the adsorbent when such an alkaline solution is used means that the hydroxyl group in the alkaline solution weakens the interaction between the amino group of the polyamine structure and the phenol. Based on For example, in the case of heavy metals, it is considered that the coordinate bond between the amino group of the polyamine structure and the heavy metal is attacked by a hydroxide ion or the like, and the coordinate bond is broken.

  The regeneration process by heating can be performed when only the adsorbed phenol is targeted for removal and the metal adsorption is not saturated, but only the phenol adsorption is saturated. It is simple because it does not use chemicals, and only phenol can be recovered, so that two compounds can be recovered separately while adsorbing two compounds to one adsorbent, and each can be recovered as a valuable resource after recovery. Is possible.

  As a heating method, there are a method of circulating a heated gas through the adsorbent or a method of heating a container containing the adsorbent, and any method may be used. The gas to be circulated must be one that does not react with the functional groups present on the surface of the adsorbent. Moreover, in order to remove the salt adhering to the adsorbent, it is desirable to heat in the presence of water vapor.

  The heating temperature is preferably 60 ° C. or higher and 200 ° C. or lower. This is because if the temperature is 60 ° C. or lower, the volatilization of phenols is slow, and if the temperature is 200 ° C. or higher, the organic adsorbent is denatured by heat. A more preferred temperature is between 80 ° C and 150 ° C.

  In addition, the phenols and heavy metals adsorbed on the adsorbent can be removed in sequence by performing the regeneration treatment using an alkaline solution after the regeneration treatment by heating, so that the phenols and heavy metals can be collected separately. Can do.

[Test solution adsorption test]
<Preparation of test solution>
Prepare 2% by mass and 10% by mass sodium chloride aqueous solution, add phenol so that it becomes 20 ppm, add FeCl ₃ or ZnCl ₂ so that the iron concentration becomes 10 ppm or zinc concentration becomes 10 ppm, and the pH is 6. A test solution was obtained. Further, the following adsorption test was performed using 5 ml of the test solution and 50 mg of the adsorbent. In addition, the test solution was stirred for 1 hour after the adsorbent of the test solution was added.

  The phenol concentration in the test solution was determined by gas chromatography after extracting the supernatant of the test solution with chloroform. The iron concentration and the zinc concentration were quantified using ICP (Inductively coupled plasma) emission spectrometry.

Example 1
An adsorption test was performed using a crosslinked polystyrene having a polyethylene polyamine group represented by the formula (1).

(Example 2)
An adsorption test was performed using a crosslinked glycidyl methacrylate having a polyethylene polyamine group represented by the formula (1).

(Comparative Example 1)
An adsorption test was performed using A368S manufactured by Sumitomo Chemtech, which is a quaternary ammonium type strongly basic ion exchange resin.

(Comparative Example 2)
An adsorption test was performed using A378D manufactured by Sumitomo Chemtech, which is a tertiary ammonium type strongly basic ion exchange resin.

  Tables 1 and 2 show the phenol concentration and iron ion concentration remaining in the test solution after adsorbing (supernatant), and Tables 3 and 4 also show the test solution after adsorbing (supernatant). The remaining phenol concentration and zinc ion concentration are shown, and the lower concentration in the table indicates that the adsorbent can be efficiently removed.

  As is apparent from Tables 1 to 4, it can be said that the adsorbent having a polyamine group can adsorb phenol simultaneously with metal ions even in brine. That is, it is understood that phenol can be adsorbed and removed simultaneously with metal ions by a single operation using the adsorbent.

[Adsorption test of oilfield associated water]
An adsorption test was performed by adding 50 mg of polyamine group-containing cross-linkable polystyrene to 5 ml of oil field-associated water from which suspended solids and the like were removed, and stirring for 1 hour.

  The concentration of the phenol resin in the test solution was quantified by gas chromatography after extracting the supernatant of the test solution with chloroform. The iron concentration was quantified using ICP emission spectrometry.

  As is apparent from Table 5, it can be said that the adsorbent having a polyamine group can adsorb phenol simultaneously with metal ions even in brine such as oilfield-associated water. That is, it is understood that phenol can be adsorbed and removed simultaneously with metal ions by a single operation using the adsorbent. Moreover, it turns out that adsorption | suction of various phenolic compounds is also possible.

[Adsorbent regeneration test]
<Alkali regeneration>
The adsorbents after the phenol and iron adsorption tests shown in Tables 1 and 2 were added to a 1N sodium hydroxide solution, stirred for 2 hours, washed with pure water, and dried at room temperature and normal pressure. did.

<Heating regeneration>
The adsorbents after the phenol and iron adsorption tests as shown in Tables 1 and 2 were put in an oven at 150 ° C., heated in an air atmosphere for 1 hour, and air-cooled until the temperature returned to room temperature.

  Using the adsorbent after alkali regeneration and heat regeneration, an adsorption test for phenol and iron was performed again to yield a regeneration rate. The regeneration rate is defined as a value obtained by dividing the amount of adsorption in the adsorption test performed after regeneration by the amount of adsorption in the adsorption test before regeneration.

  As can be seen from Table 6, in both adsorbent regeneration methods of alkali regeneration and heat regeneration, the regeneration rate of phenol and iron ions is high, and the adsorbent can be repeatedly used for brackish water. It was found that ions can be adsorbed.

  In addition, iron can be adsorbed by adsorbing only phenol with the adsorbent obtained by heat regeneration and then performing alkali regeneration, so that only phenol is desorbed from the adsorbent by heat regeneration and subsequent alkali regeneration. It can be seen that iron ions can be eliminated. That is, it can be seen that phenol and iron can be recovered separately by regenerating the adsorbent in this order.

  As mentioned above, although several embodiment of this invention was described, these embodiment was posted as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims (7)

Providing an adsorbent comprising a resin having a polyamine structure;
Immersing the adsorbent in brine containing phenols and heavy metals to adsorb and remove the phenols and heavy metals;
A method for treating brine containing phenol and heavy metals using an adsorbent. The method for treating brine containing phenols and heavy metals using an adsorbent according to claim 1, wherein the polyamine structure comprises a functional group represented by the general formula (1).

(N is an integer from 1 to 20).   The method for treating brine containing phenols and heavy metals using an adsorbent according to claim 1, comprising adjusting the pH value of the brine to 8 or less.   The method for treating brine containing phenols and heavy metals using the adsorbent according to any one of claims 1 to 3, wherein the brine is water associated with an oil field discharged during crude oil production. Providing an adsorbent comprising a resin having a polyamine structure;
Immersing the adsorbent in brine containing phenols and heavy metals to adsorb and remove the phenols and heavy metals;
Contacting the adsorbent with an alkaline aqueous solution having a pH value of 8 or more to remove the phenols and heavy metals adsorbed on the adsorbent;
A method for regenerating an adsorbent for phenols and heavy metals, comprising: Providing an adsorbent comprising a resin having a polyamine structure;
Immersing the adsorbent in brine containing phenols and heavy metals to adsorb and remove the phenols and heavy metals;
Removing the phenols adsorbed on the adsorbent by heating the adsorbent to 60 ° C. or higher;
A method for regenerating an adsorbent for phenols and heavy metals, comprising: Providing an adsorbent comprising a resin having a polyamine structure;
Immersing the adsorbent in brine containing phenols and heavy metals to adsorb and remove the phenols and heavy metals;
Removing the phenols adsorbed on the adsorbent by heating the adsorbent to 60 ° C. or higher;
Contacting the adsorbent with an alkaline aqueous solution having a pH value of 8 or more to remove the heavy metal adsorbed on the adsorbent;
A method for regenerating an adsorbent for phenols and heavy metals, comprising: