TWI664148B - Method and device for treating vanadium-containing aqueous solution - Google Patents

Abstract

The invention provides a method and a device for treating a vanadium-containing aqueous solution, which can effectively remove vanadium, and at the same time can suppress the degradation of the ion exchange resin. The invention is a treatment method for an aqueous solution containing vanadium, which comprises the steps of performing a dissolved oxygen removal treatment on the vanadium-containing aqueous solution; and contacting the water after the dissolved oxygen removal treatment with at least an H-type cation exchange resin to remove vanadium ions. The steps. The invention is a treatment method for an aqueous solution containing vanadium, which comprises the steps of: performing an anionic vanadium ion removal treatment on the vanadium-containing aqueous solution; and contacting the water after the anionic vanadium ion removal treatment with at least an H-type cation exchange resin, Step of removing vanadium ions.

Description

Method and device for treating vanadium-containing aqueous solution

The invention relates to a vanadium-containing aqueous solution treatment method and device for removing vanadium from an vanadium-containing aqueous solution. The invention particularly relates to a treatment method and device for removing vanadium-containing aqueous solution by using an ion exchange resin.

Vanadium has been widely used as a catalyst. In addition to vanadium in ash from coal and petroleum, groundwater in volcanic areas also contains vanadium. The vanadium-containing aqueous solution may contain various forms of vanadium depending on its source. Vanadium can form various compounds according to different valences of -I to + V. Among the vanadium compounds, a compound in which vanadium dissociates into a cation and a compound in which vanadium dissociates into an anion is included. When a vanadium is contained in an ionized or ionizable state like a soluble salt, vanadium can be removed by ion exchange.

The groundwater of volcanic ash and the like, and vanadium-containing aqueous solutions containing vanadium compounds dissociated into cations can be removed by exchange-adsorption of vanadium dissociated into cations with a cation exchange resin.

When a vanadium-containing aqueous solution is treated with a cation exchange resin, vanadium is concentrated in the resin due to exchange adsorption.

Depending on the valence of vanadium or the type of compound, the activity will vary, and many The vanadium compound has catalytic activity. If the catalytically active vanadium is concentrated in the cation exchange resin, the cation exchange resin will be oxidized due to its catalyst action, and the decomposition product of the exchange group containing the cation exchange resin (such as polystyrene sulfonic acid) will flow out, and the cations will Exchange activity is liable to decrease. The decomposition products of higher molecules such as polystyrene sulfonic acid flowing from the cation exchange resin will deteriorate the quality of the treated water, and if an anion exchange resin is provided in the latter stage, it will cause a load and the anion exchange resin will be regenerated. Problems such as short loops.

In Japanese Patent Application Laid-Open No. 2002-346559 (Japanese Patent No. 4721554), it is described that a cation exchange resin having a high degree of crosslinking is used to suppress the deterioration of the cation exchange resin to make it resistant to oxidation.

In Japanese Patent Application Laid-Open No. 2003-190947 (Japanese Patent No. 3963100), it is described that a vanadium-containing aqueous solution is brought into contact with a mixed bed of H-type strongly acidic cation exchange resin and Cl-type strongly basic anion exchange resin in the front stage to exchange vanadium for adsorption The cation exchange resin is removed. At the same time, the inside of the mixed bed is made acidic by the released H ions to improve the exchange adsorption efficiency of vanadium. Due to the concentration of vanadium, the decomposition products of the resin flowing out are adsorbed on the anion exchange resin. A treatment method in which the treated water is brought into contact with a cation exchange resin and an anion exchange resin in a subsequent stage to remove residual ions and a vanadium-containing aqueous solution. Vanadium can be effectively removed by this method. However, in this method, the mixed bed in the front stage becomes an acidic environment, and therefore the cationic resin in the mixed bed and the rear stage is easily deteriorated.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-346559

Patent Document 2: Japanese Patent Application Laid-Open No. 2003-190947

The object of the present invention is to provide a method and a device for treating an aqueous solution containing vanadium, which can effectively remove vanadium, at the same time can suppress the degradation of the ion exchange resin, and can obtain treated water stably for a long time.

The treatment method of the vanadium-containing aqueous solution of the first invention includes the steps of subjecting the vanadium-containing aqueous solution to a dissolved oxygen removal treatment; and the step of contacting the water after the dissolved oxygen removal treatment with at least an H-type cation exchange resin to remove vanadium ions.

The method for treating a vanadium-containing aqueous solution according to the second invention comprises the steps of contacting the vanadium-containing aqueous solution with a salt-type anion exchange resin to remove an anionic vanadium ion; and exchanging the water after the anionic vanadium ion removal treatment with at least an H-type cation Resin contacting to remove vanadium ions.

In the second invention, the step of contacting the vanadium-containing aqueous solution with a salt-type anion exchange resin to remove an anionic vanadium ion is preferably a contact of the vanadium-containing aqueous solution with a Cl-type anion exchange resin or a Na-type cation exchange resin with Cl. Step of contacting a mixed bed of type anion exchange resin.

The treatment device for a vanadium-containing aqueous solution according to the third invention is an ion exchange resin tower having a dissolved oxygen removal treatment means for the vanadium-containing aqueous solution; and a water exchanged with the dissolved oxygen removal treatment and filled with at least an H-type cation exchange resin.

The treatment device of the vanadium-containing aqueous solution of the fourth invention has a salt-type anion exchange tree for removing anionic vanadium ions from the vanadium-containing aqueous solution. Lipid means; and an ion exchange resin column that circulates the water after removing the anionic vanadium ions and at least fills an H-type cation exchange resin.

In the fourth invention, the salt-type anion exchange resin means is preferably a Cl-type anion exchange resin or a mixed bed of a Na-type cation exchange resin and a Cl-type anion exchange resin.

The present inventors have obtained the following findings from various research results.

When an anionic vanadium ion is present in the vanadium-containing aqueous solution, OH radicals are generated, and the substance causes oxidative degradation of the ion exchange resin.

By removing or reducing anionic vanadium ions in the vanadium-containing aqueous solution, deterioration of the cation exchange resin can be prevented.

The vanadium-containing aqueous solution that is completely or almost free of anionic vanadium ions can be prevented from deteriorating even if it is contacted with the H-type cation exchange resin in the subsequent step.

It is speculated that cationic vanadium does not directly generate OH radicals.

The present invention is based on such findings.

In the first and third inventions, after the dissolved oxygen removal treatment is performed on the vanadium-containing aqueous solution, it is brought into contact with at least an H-type cation exchange resin to remove cationic vanadium ions. If dissolved oxygen is removed from an aqueous solution containing vanadium, anionic vanadium ions in the vanadium-containing water will be reduced to cationic vanadium ions according to the equilibrium reaction. In addition, the cationic vanadium ions in the vanadium-containing aqueous solution will not be oxidized to anionic vanadium ions. And make the anion in the vanadium-containing aqueous solution The vanadium ion concentration is low. It is estimated that the generation of OH radicals in the vanadium-containing aqueous solution is thereby suppressed, and the deterioration of the cation exchange resin can be suppressed.

In the second and fourth inventions, after contacting the vanadium-containing aqueous solution with the Cl-type anion exchange resin, or contacting the vanadium-containing aqueous solution with the mixed bed of the Na-type cation exchange resin and the Cl-type anion exchange resin, at least the H-type cation is exchanged. The resin is contacted to remove cationic vanadium ions. If a vanadium-containing aqueous solution is brought into contact with a Cl-type anion exchange resin or a mixed bed of Na-type cation-exchange resin and Cl-type anion-exchange resin in this way, anionic vanadium ions can be removed without generating OH radicals. The degradation of the cation exchange resin is suppressed.

Figure 1 shows a graph of experimental results.

Fig. 2 is a graph showing experimental results.

Examples of the vanadium-containing aqueous solution to be treated in the present invention include water containing vanadium in a state capable of ion exchange, and water containing vanadium in an ionized or dissociated state. The vanadium-containing aqueous solution may also contain vanadium compounds that do not ionize, or other impurities. In the vanadium-containing aqueous solution to be treated in the present invention, when the dissociated vanadium or the dissociable vanadium is 0.1 μg / L or more, it is suitable for the treatment. Specific examples of the vanadium-containing aqueous solution to be treated in the present invention include natural water, especially Groundwater, volcanic water, deep well water from volcanic ash, and wastewater from processes using vanadium catalysts.

As before, vanadium will form compounds with valences -I ~ + V, with + II to + V being the general case. When the oxidation numbers are II and III, salts are mainly generated in the form of cations, and when the oxidation numbers are IV, the salt combined with oxygen generates VO ²⁺ in many cases. When the oxidation number of V, formed metavanadic ions or VO ³⁺ and VO ₂ ⁺ salts of anionic state of VO ₃ ^- salts. V ₂ O ₅ , which is widely used as a catalyst, is not easily soluble in water and is amphoteric. If dissolved in acid, it will generate VO ₂ ⁺ . In alkaline aqueous solution, it will generate metavanadate ions and dissociate into Anion. As such, vanadium forms compounds of various valences. In natural water, especially in volcanic ash groundwater, flowing water, and deep well water, vanadium is often contained in the form of cations and anions. In addition, the wastewater discharged from a system using a vanadium catalyst may be dissociated into cations and dissociated into anions depending on the pH.

In one aspect of the present invention, first, a dissolved oxygen removal treatment is performed on the vanadium-containing aqueous solution. The removal of the dissolved oxygen can be performed without limitation by using a film-type degassing device, a vacuum degassing device, a nitrogen degassing device, and the like. The vanadium-containing aqueous solution should preferably be deoxidized so that the dissolved oxygen concentration becomes 2 mg / L or less, especially 10 μg / L or less.

If dissolved oxygen is removed in this way, anionic vanadium ions in the vanadium-containing aqueous solution will be reduced to cationic vanadium ions according to the equilibrium reaction. In addition, cationic vanadium ions in the vanadium-containing aqueous solution will not be oxidized to an anionic state. Vanadium ions, and vanadium-containing water with low anion vanadium ion concentration Solution. Accordingly, when the vanadium-containing aqueous solution is brought into contact with the H-type cation exchange resin in the subsequent step, generation of OH radicals is suppressed, and deterioration of the H-type cation exchange resin is suppressed. OH radicals have a strong oxidizing effect and are thought to degrade cation exchange resins.

In another aspect of the present invention, the vanadium-containing aqueous solution is contacted with a Cl-type anion exchange resin to remove anionic vanadium ions. In order to bring the vanadium-containing aqueous solution into contact with the Cl-type anion exchange resin, it is preferable to flow through the packed column column of the Cl-type anion exchange resin. At this time, the circulating SV should be about 10 ~ 60h ^-1 , especially 20 ~ 30h ^-1 .

In yet another aspect of the present invention, a vanadium-containing aqueous solution is brought into contact with a mixed bed of Na-type cation exchange resin and Cl-type anion exchange resin to remove a part of the cationic vanadium ion and the anionic vanadium ion. In order to bring the vanadium-containing aqueous solution into contact with the mixed bed of Na-type cation exchange resin and Cl-type anion exchange resin, it is preferable to flow through the packed column column of this mixed bed. At this time, the circulating SV should be about 10 ~ 60h ^-1 , especially 20 ~ 30h ^-1 .

If a vanadium-containing aqueous solution is brought into contact with a Cl-type anion exchange resin or a mixed bed of a Na-type cation exchange resin and a Cl-type anion exchange resin in this way, an anionic vanadium ion in the vanadium-containing aqueous solution can be removed. The vanadium-containing aqueous solution that is completely or almost free of anionic vanadium ions can be prevented from being deteriorated even if it is contacted with the H-type cation exchange resin in the subsequent step. This is presumably because cationic vanadium does not generate OH radicals as described above.

When a mixed bed of H-type cation exchange resin and Cl-type anion exchange resin or a mixed bed of H-type cation exchange resin and OH-type anion exchange resin is used in the previous step, the H-type cation exchange resin and the vanadium-containing aqueous solution When cationic vanadium ions are contacted, H ^{+ is} generated by ion exchange, and the treated water becomes acidic, so the generation of OH radicals cannot be suppressed.

In the case where a mixed bed of Na-type cation exchange resin and OH-type anion exchange resin is used in the previous step, when an anionic vanadium ion in a vanadium-containing aqueous solution comes into contact with an OH-type anion-exchange resin, OH ^- is produced, and this OH ^- and other Metals become hydroxides and produce precipitates, which can block the ion exchange device in the subsequent stage. In contrast, as shown in one aspect of the present invention described above, when a mixed bed of Na-type cation exchange resin and Cl-type anion exchange resin is used in the previous step, anionic vanadium ions are removed. In addition, in the ion exchange reaction at this time, OH ⁻ or H ^{+ is} not generated, metal hydroxide is not generated, and the ion exchange device is not blocked.

Even if the vanadium-containing aqueous solution is brought into contact with a Cl-type anion exchange resin to remove anionic vanadium ions, if the treated water is exposed to the atmosphere, the cationic vanadium ions will be oxidized to become anionic ions, so it should be removed in the previous step. The anionic vanadium ion is immediately subjected to a post-treatment step, or it is subjected to a post-treatment step without being in contact with the atmosphere. Therefore, it is changed to a state where a Cl-type anion exchange resin or a mixed bed of a Na-type cation exchange resin and a Cl-type anion exchange resin is packed in a packed column column, and the H-type cation exchange resin layer packed in the H-type cation exchange resin column is filled. On the upstream side, a Cl-type anion exchange resin layer or a mixed bed of a Na-type cation exchange resin and a Cl-type anion exchange resin may be laminated.

In addition, the foregoing is a case where a Cl-type anion exchange resin or a Na-type cation exchange resin is used. As long as the selection coefficient of the vanadium and the salt-type ion exchange resin in the treated water is confirmed and then used, the vanadium removal property can be predicted. That is, since the influence on deterioration can be predicted, the salt-type ion exchange resin is not limited to the Cl-type or Na-type. That is, Br type, I type, NO ₃ type, SO ₄ type anion exchange resin can be used like Cl type, and NH ₄ type, K type, Ca type cation exchange resin can be used like Na type, and it is particularly suitable for use. Monovalent salt type resin. The same applies to the case where the dissolved oxygen removal treatment is performed in the previous step.

In the present invention, as described above, the vanadium-containing aqueous solution subjected to the first-stage treatment of the dissolved oxygen removal treatment or the anionic vanadium ion removal treatment is brought into contact with the H-type cation exchange resin or the H-type cation exchange resin and OH in the subsequent step. Type or salt-shaped anion exchange resin is contacted with the mixed bed, and the cationic vanadium ion dissociated into cations is adsorbed and removed on the cation exchange resin. The circulating SV at this time should be 10 ~ 60h ^-1 , especially about 20 ~ 30h ^-1 .

In the present invention, a vanadium-containing aqueous solution is circulated to a packed column (column) filled with a mixed bed of a Cl-type anion exchange resin or a Na-type cation exchange resin and a Cl-type anion exchange resin, and then to a H-type cation exchange resin packed column. Next, it can flow to the OH type anion exchange resin packed tower, or it can flow to the mixed bed of H type cation exchange resin and OH type anion exchange resin.

In the present invention, a vanadium-containing aqueous solution is circulated to the Cl-type anion exchange resin layer or Na on the upstream side of the H-type cation exchange resin layer. A packed bed of a mixed bed of a type cation exchange resin and a Cl type anion exchange resin may then flow to a packed column of an OH type anion exchange resin. In addition, in order to prevent an unexpected change in the vanadium concentration, it is also effective to use an H-type cation exchange resin having a high degree of crosslinking, such as a degree of crosslinking of 12 to 16%, to impart oxidation resistance.

In the present invention, any of a strongly acidic cation exchange resin having a fluorene group as a cation exchange group, a weakly acidic cation exchange resin having a carboxyl group, or the like can be used. As the anion exchange resin, any of a strongly basic anion exchange resin having a fourth ammonium group as an anion exchange group, a weakly basic anion exchange resin having a first to a third ammonium group, and the like can be used. These ion exchange resins are all recyclable and reused.

[Example]

Examples and comparative examples are described below. In the following Examples and Comparative Examples 1 and 2, the water to be treated was a vanadium-containing aqueous solution (aqueous solution having a vanadium equivalent concentration of 10 μg / L) obtained by dissolving ammonium vanadate in ultrapure water. In Comparative Example 3, a vanadium-containing aqueous solution (aqueous solution having a vanadium-based concentration of 10 μg / L) obtained by dissolving ammonium vanadate in industrial water was used.

[Comparative Example 1]

A strong acidic cation exchange resin (DIAION SK1B: registered trademark, manufactured by Mitsubishi Chemical Corporation, cross-linking degree: 8%) adjusted to H-shape was filled into a column with an inner diameter of 15 mm by 75 mL-R to constitute a supervisor. column.

The above-mentioned water to be treated was stored in an open-air container without any pretreatment, and was flowed to the main column at a flow rate of 50 mL / min to remove vanadium.

The measurement results of the dissolved oxygen (DO) concentration of the treated water supplied from the container to the main column and the UV absorbance of the treated water at a wavelength of 225 nm are shown in FIG. 1. This UV absorption is caused by the absorption of polystyrene sulfonic acid (PSA) in the treated water, and represents the PSA concentration in the treated water.

As shown in Figure 1, the dissolved oxygen concentration in the treated water will rise over time. The UV absorbance of the treated water began to rise rapidly after about 50 hours of circulation, and deterioration of the resin was confirmed.

[Example 1]

Except that the dissolved oxygen concentration (DO) of the water to be treated was kept at 2.0 mg / L or less by thin film degassing, it was passed through a main column in the same manner as in Comparative Example 1 and the same measurement was performed. The results are shown in FIG. 1. As shown in FIG. 1, it was observed that even after approximately 300 hours of circulation, the increase in UV absorbance caused by PSA in the treated water was suppressed.

[Example 2]

The treated water was flowed through an ion exchange column filled with 20 mL-R of Cl-type anion exchange resin, and then flowed through the main column. The flow test and measurement were performed in the same manner as in Comparative Example 1, and the results are shown in FIG. 2. this The results of Comparative Example 1 are also shown in FIG. 2. As shown in FIG. 2, it was observed that the increase in UV absorbance caused by PSA in the treated water was suppressed even after about 200 hours of circulation.

[Example 3]

The treated water was passed through an ion exchange column mixed with 10 mL-R of Cl-type anion exchange resin and Na-type cation exchange resin, and then flowed to the main column, except that the same flow test as in Comparative Example 1 and Determination. As a result, it was observed that even after 200 hours of circulation, the increase in UV absorbance caused by PSA in the treated water was suppressed.

[Comparative Example 2]

The treated water was passed through an ion exchange column mixed with 10 mL-R of H-type cation exchange resin and Cl-type anion exchange resin, and then flowed to the main column. The same flow test as in Comparative Example 1 and Determination. As a result, it was observed that the PSA in the treated water caused a significant increase in UV absorbance after about 50 hours of circulation.

[Comparative Example 3]

The treated water was passed through an ion exchange column mixed with 10 mL-R of Na-type cation exchange resin and OH-type anion exchange resin, and then flowed to the main column. Except that, the same flow test as in Comparative Example 1 and Determination. As a result, it was observed that the increase in UV absorbance caused by PSA in the treated water was suppressed, but magnesium became a hydroxide, and the main column was observed. Blockage occurred in about 60 hours.

As can be seen from the above examples and comparative examples, according to the present invention, the treatment of the vanadium-containing aqueous solution can be performed stably for a long time without deteriorating the H-type cation exchange resin.

The present invention has been described in detail using specific aspects, but those skilled in the art can understand that various changes can be made without departing from the intention and scope of the present invention.

This application is based on Japanese Patent Application No. 2014-068903 filed on March 28, 2014, and it is hereby incorporated by reference as a whole.

Claims (8)

A method for treating a vanadium-containing aqueous solution includes the steps of: performing a dissolved oxygen removal treatment on the vanadium-containing aqueous solution; and contacting the water after the dissolved oxygen removal treatment with at least an H-type cation exchange resin to remove vanadium ions. A treatment method for an aqueous solution containing vanadium, which comprises the steps of contacting an aqueous solution containing vanadium with a salt-type anion exchange resin to remove anionic vanadium ions; and removing the treated water from the anionic vanadium ion with at least an H-type cation exchange resin The step of contacting and removing vanadium ions. For example, the treatment method of the vanadium-containing aqueous solution in the second item of the patent application, wherein the step of contacting the vanadium-containing aqueous solution with a salt-type anion exchange resin and removing the anionic vanadium ion is to contact the vanadium-containing aqueous solution with a Cl-type anion exchange resin A step of contacting a mixed bed of a Na-type cation exchange resin and a Cl-type anion exchange resin. For example, the method for treating a vanadium-containing aqueous solution according to item 2 or 3 of the patent application scope, wherein the step of removing dissolved oxygen from the vanadium-containing aqueous solution is performed before the step of removing anionic vanadium ions. A treatment device for an aqueous solution containing vanadium, which comprises a means for removing dissolved oxygen from an aqueous solution containing vanadium, and an ion exchange resin tower that circulates the water after the dissolved oxygen removal treatment and is filled with at least an H-type cation exchange resin. A treatment device for an aqueous solution containing vanadium, comprising: a salt-type anion exchange resin means for removing anionic vanadium ions from the vanadium-containing aqueous solution; and circulating water for removing the anionic vanadium ions and filling at least an H-type cation exchange resin Ion exchange resin tower. For example, the treatment device for an aqueous solution containing vanadium according to item 6 of the patent application, wherein the aforementioned salt-type anion exchange resin means is a mixed bed of a Cl-type anion exchange resin or a Na-type cation exchange resin and a Cl-type anion exchange resin. For example, a treatment device for an aqueous solution containing vanadium according to item 6 or 7 of the scope of patent application, wherein a means for removing dissolved oxygen is provided in the front stage of the salt-type anion exchange resin means.