JP4344842B2 - Regeneration method of chelate adsorbent - Google Patents

Description

  The present invention uses a chelate adsorbent, and is contained in, for example, industrial wastewater and industrial water (hereinafter, collectively referred to as a liquid to be treated), for example, heavy metals such as copper, zinc, nickel, cobalt, For example, after treating metals such as boron, germanium, arsenic, antimony, selenium, etc., the adsorbed metal or metals are eluted from the chelate adsorbent using acid or alkali solution in an adsorption tower etc. It is related with the method of reproducing | regenerating.

  If the regeneration method of the present invention is adopted, the chelate adsorbent can be efficiently regenerated, for example, purification of various industrial effluents discharged from glass factories, plating factories, power plants, etc., desalination of seawater, hot spring water, etc. It can be widely used for the purification of the above, and the recovery of the metal and the like metal components as valuable resources.

  Various industrial effluents as described above may contain various toxic metals. From the viewpoint of preventing environmental pollution, these toxic metals need to be sufficiently removed by effluent treatment. In addition, heavy metal components contained in rivers and groundwater have a negative effect on the human body. Therefore, sufficient consideration must be given when using them as drinking water.

  In addition, many of the similar metals have an adverse effect on the human body, and their environmental standards have been set in recent years. More specifically, boron and boron compounds, which are one type of similar metals, are widely used in the glass industry, plating industry, rust preventives and cosmetics fields, etc., and the effluent discharged from their manufacturing processes. Some contain boron. In addition, wastewater from various power plants, flue gas desulfurization wastewater, and seawater also contain boron. It has been pointed out that boron can cause health problems. Environmental standards for water pollution, environmental standards for groundwater pollution, environmental standards for soil pollution, and standard values are set as additional items in tap water quality standards. In addition, in the field of treatment of boron-containing wastewater, and further in the field of producing drinking water by seawater desalination, removal and separation of boron are important issues.

  These boron-containing water treatment methods include a coagulation precipitation method using aluminum sulfate, slaked lime, etc. (Patent Document 1, etc.), a solvent extraction method using alcohols (Patent Document 2, etc.), an adsorption method using an ion exchange resin, etc. Patent Document 3 and the like) are known. Among these conventional methods, in the coagulation precipitation method disclosed in Patent Document 1 and the like, a large amount of coagulation precipitation agent must be used to increase the removal efficiency of boron, and a large amount of sludge is generated accordingly. Problems are pointed out. In addition, the solvent extraction method disclosed in Patent Document 2 and the like has a low boron extraction rate, so that a large amount of solvent must be used, which causes an increase in the COD value of waste water. Furthermore, the adsorption method using an ion exchange resin disclosed in Patent Document 3 has a problem in terms of removal efficiency due to a poor selective adsorption effect on low-concentration boron.

  As an alternative to these treatment methods, an adsorption method using a chelate adsorbent, particularly an adsorption method using a chelate-forming fiber having a chelate-forming functional group introduced into the fiber molecule as disclosed in Patent Document 4, It is expected to be effectively used as an extremely excellent method in terms of processing efficiency, such as having high selective adsorptivity for low concentrations of boron and having a very high adsorption rate.

However, for example, when boron is drained from a chelate adsorbent adsorbed with boron after being treated by passing the boron-containing wastewater through the cylindrical container filled with the chelate adsorbent, the acid or alkali solution is simply used. In a general method of charging the liquid into a cylindrical container, a large amount of acid or alkali solution must be used, and a large amount of eluent with a low boron concentration is discharged accordingly. In addition, the processing cost of the eluent increases.
JP 7-323292 A Japanese Patent Laid-Open No. 11-652 Japanese Patent Laid-Open No. 57-197040 Japanese Patent Laid-Open No. WO98 / 42910

  The present invention has been made paying attention to the above-mentioned circumstances, and its purpose is to perform chelate adsorption by a simple method when treating metals and / or similar metals contained in waste water with chelate adsorbents. An object of the present invention is to provide a method capable of efficiently regenerating a material.

  The regeneration method of the present invention that was able to solve the above-mentioned problem is to use an acid solution or an alkali solution as a regenerant when regenerating a chelate adsorbent adsorbing a metal and / or a similar metal in a cylindrical container. The residual liquid in the cylindrical container filled with the chelate adsorbent that adsorbs the metal and / or the like metal is drained, and then the regenerant is put into the drained cylindrical container to thereby form a chelate. The gist of the present invention is to elute the metal and / or similar metal adsorbed on the adsorbent.

  When carrying out the present invention, it is preferable to repeat the above-mentioned liquid removal and the introduction of the regenerant multiple times, since elution and regeneration can be performed more smoothly and efficiently.

  Examples of the metal and / or metal to be treated in carrying out this method include iron, copper, nickel, aluminum, cobalt, cadmium, mercury, lead, zinc, calcium, magnesium, barium, manganese, boron, germanium. , Arsenic, selenium, antimony, etc., which can be effectively applied to a liquid to be treated containing these alone or containing two or more thereof.

  In addition, as the chelate adsorbent used in carrying out this method, those having any shape including bead-like or granular chelate resins can be used. Particularly preferred are chelate-forming fibers such as fabrics such as knitted fabrics, or yarns, powders, and granules. These can be used alone or in combination of two or more appropriately considering the chelate capture efficiency and pressure loss of metals and similar metals by liquid passage.

  Examples of the fiber base material constituting the chelate-forming fiber include cellulose-based, polyolefin-based, nylon-based, and polyester-based materials. Among these, cellulose-based fibers are particularly preferable.

  As those chelate-forming fibers, when applied to a liquid to be treated containing a metal, it is particularly desirable to use those having iminodiacetic acid groups introduced into the fiber molecules as chelate-capturing functional groups. In the case of applying to a treatment liquid containing the same, it is particularly desirable to use a chelate-trapping functional group having an N-methylglucamine group introduced into the fiber molecule.

  When the residual liquid in the cylindrical container filled with the chelate adsorbent is drained, for example, a method of extruding the residual liquid by sending gas into the cylindrical container from the upper part of the cylindrical container, It is preferable to employ a method in which the residual liquid is extracted from the lower part of the cylindrical container using a pump installed on the downstream side because the liquid removal can be performed efficiently in a shorter time. In this liquid removal step, the moisture content of the chelate adsorbent filled in the cylindrical container [= {residual liquid mass in the cylindrical container / chelate adsorbent solid mass} × 100 (%)] is 80 to 80. It is desirable to perform liquid removal so that it may become 300%.

  According to the method for regenerating a chelate adsorbent according to the present invention, when regenerating the chelate adsorbent adsorbing a metal and / or a similar metal in a cylindrical container, an acid solution or an alkali solution as a regenerant is used, After draining the residual liquid in the cylindrical container filled with the chelate adsorbent, the operation of charging the regenerant into the cylindrical container is preferably repeated from the chelate adsorbent by repeating the operation multiple times. In addition to being able to elute metals and / or similar metals with high efficiency and reducing the amount of used and discharged eluents after drainage treatment, the recovery rate can be improved when recovering metals and similar metals as valuable substances. Can be increased.

  In the regeneration method of the present invention, when a chelate adsorbent adsorbing a metal and / or a similar metal is regenerated in a cylindrical container, an acid solution or an alkali solution as a regenerant is charged into the cylindrical container. A major feature is that the residual liquid in the cylindrical container filled with the chelate adsorbent is once drained. That is, when a cylindrical container filled with a chelate adsorbent is treated by passing wastewater containing boron, for example, and then eluting boron from the chelate adsorbent adsorbing boron using an acid solution as an eluent, In a normal method in which an acid solution is poured into a cylindrical container without removing the residual liquid in the cylindrical container, the acid solution is diluted with the residual liquid in the cylindrical container, so that the acid concentration at the initial stage of liquid passing is reduced. The elution performance for boron is lowered. As a result, a large amount of acid solution is required to quantitatively recover boron, and the boron concentration in the eluent is inevitably lowered and the absolute amount of the eluent is increased.

  Therefore, in the present invention, for example, before putting an acid solution into the cylindrical container as a regenerant, the residual liquid in the cylindrical container is once drained, and then the acid solution is charged. Then, dilution (concentration reduction) of the acid solution in the cylindrical container at the initial stage of regeneration (elution) can be prevented, and the elution efficiency of boron can be greatly increased.

  It is of course possible to carry out such a regeneration operation by draining and adding a regenerant, but if this operation is repeated a plurality of times, the regeneration efficiency can be further improved. For example, when treating a boron-containing liquid, when the acid solution is brought into contact with the chelate adsorbent adsorbing boron, the time until the acid diffuses into the moisture inside the chelate adsorbent and the boron eluted from the chelate adsorbent Takes time to diffuse to the surface of the chelate adsorbent, and further, it takes time for the boron diffused to the surface of the chelate adsorbent to diffuse throughout the packed bed of chelate adsorbent. It is difficult to collect and elute completely in one regeneration operation. However, if the above elution and regeneration operations are continuously repeated a plurality of times, the elution regeneration efficiency can be remarkably improved.

In the repetitive operation, the amount of regenerant introduced at one time and the number of repetitions are preferably 0.5 Bed volume or less, more preferably 0.3 Bed volume or less (Bed volume means adsorption). This refers to the volume ratio of the liquid input to the filling volume of the material (hereinafter sometimes abbreviated as BV).
The number of repetitions is preferably 2 times or more, more preferably 4 times or more, including the introduction of washing water for extruding the regenerant. If the above-mentioned input amount and the number of repetitions are out of the desired ranges, the boron recovery rate tends to decrease or the eluted boron concentration tends to decrease. In addition, the holding time from the introduction of the regenerant to the draining is preferably 20 seconds or longer, and preferably 1 minute or longer.

  The regenerating agent used in the regenerating method of the present invention is an aqueous solution such as sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid as the acid solution, and an aqueous solution such as sodium hydroxide, potassium hydroxide or lithium hydroxide as the alkaline solution. Preferably used. The concentration of these regenerants is not particularly limited, but is preferably in the range of 1 to 6N. If the concentration is less than 1N, a tendency to reduce the regeneration efficiency tends to be caused by the dilution effect in the cylindrical container, Conversely, if the concentration exceeds 6N and the concentration becomes excessively high, the viscosity of the regenerant increases, the contact efficiency with the chelate adsorbent decreases, and the regeneration efficiency decreases, and the deterioration of the chelate adsorbent due to acid or alkali is promoted. Therefore, it is not desirable.

  Examples of metals and / or similar metals to which the regeneration method of the present invention is applied include various elements present in a solution. Examples of elements that can effectively exhibit the characteristics of the present invention include iron. , Copper, nickel, aluminum, cobalt, cadmium, mercury, lead, zinc, calcium, magnesium, barium, manganese, boron, germanium, arsenic, selenium, antimony and the like.

  As the chelate adsorbent used in the regeneration method of the present invention, those having any shape including a bead-like or granular chelate resin can be used, but in order to further increase the elution efficiency after adsorption, the surface area is large and As described above, it is desirable to use a fibrous chelate adsorbent, that is, a chelate-forming fiber, having a shape characteristic in which diffusion into the chelate adsorbent such as a regenerant is likely to proceed rapidly. A chelate-forming fiber is a fiber in which a group capable of forming a chelate with a metal or a similar metal is introduced into a fiber molecule, and there is no particular limitation on the shape, but short fiber powder, or granulating them. It may be any of the above-mentioned granular, long-fiber monofilaments and multifilaments, short-fiber spun yarns, fabrics knitted or knitted into woven or knitted fabrics, and non-woven fabrics. It is also effective to adjust the chelate capture efficiency and the liquid flow resistance during the treatment by combining two or more types of fibers having different properties.

  In addition, the kind of fiber material into which the group having chelate-forming ability is introduced is not particularly limited, for example, various vegetable fibers such as cotton and hemp; various animal fibers such as silk and wool Various kinds of recycled fibers such as viscose rayon; various synthetic fibers such as polyamide, acrylic and polyester can be used, and these fibers have various modifications as required. It does not matter. However, in consideration of ease of introduction of chelate-forming functional groups, wettability with water to be treated, strength, stability, etc., the most preferable natural fiber has a large number of hydrophilic hydroxyl groups in the molecule. Among these, vegetable cellulosic fibers are used.

  In addition, the chelate-forming group introduced into the fiber includes all functional groups capable of forming a chelate with a metal or a similar metal, but is easy to introduce into the fiber molecule, chelate-forming ability, etc. Considering these, an iminodiacetic acid group and an N-methylglucamine group are particularly preferable. More specific examples include chelate-forming fibers as disclosed in JP 2000-248467 and WO 98/42910.

  As a specific method for draining the residual liquid in the cylindrical container, for example, an air pump or an air compressor is installed on the upstream side of the cylindrical container, and the residual liquid in the cylindrical container is cylindrical by air (air). The method of extruding below a container is mentioned. It is also possible to employ a method in which a liquid feed pump, a suction pump or the like is installed downstream of the cylindrical container, and the residual liquid in the cylindrical container is extracted from below the cylindrical container. At this time, if necessary, a non-oxidizing gas such as nitrogen or an inert gas is used as the blowing gas instead of the air used for liquid removal. It is also possible to suppress this.

  Regarding the degree of liquid removal when the residual liquid in the cylindrical container filled with the chelate adsorbent is drained, the water content of the chelate adsorbent in the cylindrical container [moisture content (%) = in the cylindrical container Residual liquid mass / chelate adsorbent solid content mass × 100] is preferably 80 to 300%, more preferably 100 to 250%. Reducing the water content as much as possible is a favorable condition for improving the regeneration efficiency. However, if the moisture content is less than the above-mentioned appropriate range, a substantial improvement in the regeneration efficiency is not recognized, and the capacity of the pump to be used In view of the drainage time and the like, it is not practical to make the moisture content lower than the appropriate range. Moreover, when the moisture content exceeds the above appropriate range, the dilution rate of the regenerant (acid solution or alkali solution) in the cylindrical container increases, and a tendency for the regeneration efficiency to decrease is recognized.

  However, if adjusted so as to be within the above appropriate moisture content range, the regeneration of the chelate adsorbent can be carried out more efficiently, and the eluent containing a high concentration of metal or similar metal with a small amount of regenerant from the chelate adsorbent. Can be obtained, that is, high regeneration efficiency can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following Examples, and may be appropriately changed within a range that can meet the purpose described above and below. Of course, the present invention can be carried out in addition to those described above, and both are included in the technical scope of the present invention.

Example 40 g of chelate-forming fiber (introduction amount of chelate group: 0.8 mmol / g) in which N-methylglucamine was immobilized on 17 dtex rayon yarn cut to 1 mm in length was applied to an industry with a boron concentration of 117 ppm. After adding to 2000 ml of wastewater, the mixture was stirred at 20 ° C. for 1 hour, and the boron concentration in the wastewater was 7 ppm. The chelate-forming fiber (boron adsorption amount: 5.5 mg-B / g-chelate-forming fiber) obtained by this treatment is packed into a polypropylene column having a diameter of 5 cm, and the residual liquid in the column is removed using a suction pump. I let it flow out from the bottom. Next, as a regenerant, sulfuric acid and water having a predetermined concentration were repeatedly supplied a predetermined number of times, and each time sulfuric acid and water were added, the residual liquid in the column was collected from the lower part of the column using a suction pump. The time from adding the regenerant to draining was 1 minute.

  As shown in Tables 1 to 3 below, run 1 (water content at each drainage: 110%, regenerant: 2N-sulfuric acid aqueous solution), run 2 (water content at each drainage: 134%, regenerant) : 4N-sulfuric acid aqueous solution and ion-exchanged water), Run 3 (water content at the time of each liquid removal: 152%, regenerant: 6N-sulfuric acid aqueous solution and ion-exchanged water). Indicated. In addition, FIGS. 1 and 2 show changes in the boron concentration and boron recovery rate of the effluent with respect to BV of the regenerant and washing water charged.

Comparative Example The operation of removing the residual liquid in the column using a suction pump was not performed, and 2N of the regenerating liquid was regenerated at a flow rate of 20 ml / min while the chelate adsorbent was completely filled in the residual liquid in the column. A test was conducted in the same manner as in the above example except that an aqueous sulfuric acid solution was passed, and the results are shown in FIGS.

  As is clear from the comparison between the example shown in FIGS. 1 and 2 and the comparative example, the boron concentration in the eluent is increased depending on whether or not the residual liquid in the cylindrical container (column) is drained in advance. The regenerative efficiency of the chelate adsorbent is remarkably changed, and when the residual liquid in the column is drained, the boron recovery rate is extremely high compared to the case where the liquid removal treatment is not performed, and the boron concentration in the eluent It is remarkably high, and it can be confirmed that excellent reproduction efficiency can be obtained.

It is a graph which compares and shows the relationship of the boron density | concentration in the effluent at the time of reproduction | regeneration obtained by the Example and the comparative example, and regeneration agent input BV. It is a graph which compares and shows the relationship of the collection | recovery rate of boron obtained by the Example and the comparative example, and regenerant input BV.

Claims (8)

In a method for regenerating a chelate adsorbent adsorbing a metal and / or a similar metal in a cylindrical container, an acid solution or an alkaline solution is used as a regenerant, and the chelate adsorbent adsorbing the metal and / or the similar metal is filled. The residual liquid in the cylindrical container is drained, and then the chelating adsorption is repeated four or more times by adding the regenerant or washing water for extruding the regenerant into the drained cylindrical container. A method for regenerating a chelate adsorbent characterized by eluting a metal and / or a similar metal adsorbed on the material. When the residual liquid in the cylindrical container filled with the chelate adsorbent is drained, the moisture content of the chelate adsorbent [moisture content (%) = residual liquid mass in the cylindrical container / chelate adsorbent solid mass × reproduction method according to claim 1, 100] performs drainer as a 80 to 300%.   The metal and / or metal is selected from the group consisting of iron, copper, nickel, aluminum, cobalt, cadmium, mercury, lead, zinc, calcium, magnesium, barium, manganese, boron, germanium, arsenic, selenium, and antimony. The regeneration method according to claim 1, wherein the regeneration method is at least one kind.   The regeneration method according to any one of claims 1 to 3, wherein the chelate adsorbent is a chelate-forming fiber having at least one shape selected from the group consisting of cloth, thread, powder, and granules.   The regeneration method according to claim 4, wherein the base material of the chelate-forming fiber is a cellulosic fiber.   The regeneration method according to claim 4 or 5, wherein the chelate-forming fiber has an iminodiacetic acid group or an N-methylglucamine group introduced into a fiber molecule.   2. The liquid is removed by feeding gas into the cylindrical container from the upper part of the cylindrical container and pushing out the residual liquid in the cylindrical container filled with the chelate adsorbent to the lower part of the cylindrical container. The regeneration method in any one of -6.   8. The chelate according to claim 7, wherein a pump is disposed downstream of the cylindrical container, and the liquid is removed by extracting the residual liquid in the cylindrical container filled with the chelate adsorbent from the lower part of the cylindrical container by the pump. Adsorbent regeneration method.