JP2010214336A - Boron adsorbent and method for manufacturing boron adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an novel adsorbent with high boron adsorption capacity. <P>SOLUTION: The boron adsorbent includes a carrier with a porous structure and at least one of organic compounds having the structural formulas (1) to (4) for modifying the surface of the carrier. In the formulas, R contains a primary or secondary amino group and R<SB>1</SB>to R<SB>4</SB>are each hydrogen or an aliphatic chain containing an unsaturated carbon bond, an ether bond, an ester bond, and a functional group such as hydroxyl, a carboxylic acid, or the like. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a boron adsorbent and a method for producing the boron adsorbent.

  Contamination of water due to boron content is spreading as an environmental problem. For example, if boron is contained in water in the order of several ppm, plant growth is hindered, which is a serious problem.

  As a boron removal technique, a reverse osmosis (RO) method (Patent Document 1), an ion exchange method (Patent Document 2), a coagulation precipitation method (Patent Document 3), and the like are known. Boron cannot be treated in a single treatment, and the ion exchange method has a low treatment capacity of 7-9 mg-B / g and high treatment costs. Further, the coagulation precipitation method is not suitable as a method for treating boron contained in a large amount of water because a large amount of chemicals is required and waste is increased.

JP 2001-269544 A JP 2001-179253 A JP 2007-136325 A

  In view of the above problems, an object of the present invention is to provide a novel adsorbent having a high boron adsorption capacity.

（それぞれ分子中の少なくとも一つのＲには第１級または第２級のアミノ基を含み、Ｒ₁-Ｒ₁₀は水素又は脂肪鎖であって、不飽和炭素結合、エーテル結合、エステル結合、水酸基及びカルボン酸等の官能基を含むことができる。）に関する。 One embodiment of the present invention is characterized by comprising a porous structure carrier and at least one of organic compounds having the structural formulas (1) to (4) obtained by modifying the surface of the carrier. Boron adsorbent

(At least one R in the molecule contains a primary or secondary amino group, and R _{1 to} R ₁₀ are hydrogen or an aliphatic chain, and are an unsaturated carbon bond, an ether bond, an ester bond, a hydroxyl group. And functional groups such as carboxylic acids.

  According to the present invention, a novel adsorbent having a high boron adsorption capacity can be provided.

It is a figure which shows schematic structure of the apparatus used for boron adsorption | suction in embodiment.

  Hereinafter, details of the present invention and other features and advantages will be described based on embodiments.

(Boron adsorbent)
The boron adsorbent in the present embodiment is formed by modifying the surface of a porous carrier with an organic compound shown below.

  As the carrier, silica gel, alumina, glass, kaolin, mica, talc, clay, hydrated alumina, wollastonite, iron powder, potassium titanate, titanium oxide, zinc oxide, silicon carbide, silicon nitride, calcium carbonate, carbon , Barium sulfate, boron, ferrite and the like can be used.

  Among these, if a carrier such as ferrite is used, application using magnetism is possible. For example, the boron adsorbent can be positively brought into contact with the medium to be treated by magnetically stirring the boron adsorbent itself without providing a separate stirring device. Thereby, the adsorption processing time can be shortened. Further, when recovering the boron adsorbent, it can be easily recovered using magnetism, and the system can be simplified and the maintainability can be improved.

  On the other hand, the treatment amount of the boron adsorbent varies depending on the surface area. When it is necessary to reduce the size of the system, it is preferable that the amount of adsorption per unit volume or unit weight is large, and it is recommended to use a support having a pore structure. Therefore, it is preferable to use a porous structure carrier such as silica gel.

  In addition to preparing the inorganic substance as described above as a carrier, the substance obtained by the polymerization of the silane coupling agent used in the process of producing the target boron adsorbent due to the following production method is gelled. Can also be used as a carrier.

In the present embodiment, the boron to be adsorbed is generally because they are contained in water, B (OH) ₃ or B (OH) ₄ ^- is a hydroxylated boron.

（それぞれ分子中の少なくとも一つのＲには第１級または第２級のアミノ基を含み、Ｒ₁-Ｒ₁₀は水素又は脂肪鎖であって、不飽和炭素結合、エーテル結合、エステル結合、水酸基及びカルボン酸等の官能基を含むことができる。）。 The surface of the carrier is modified with at least one organic compound having the structural formulas (1) to (4). The degree of modification of the carrier surface with the organic compound depends on, for example, the production method described below (amount of the silane coupling agent relative to the carrier), but as an example, a range of 0.5 mmol / g to 5 mmol / g. It can be.

(At least one R in the molecule contains a primary or secondary amino group, and R _{1 to} R ₁₀ are hydrogen or an aliphatic chain, and are an unsaturated carbon bond, an ether bond, an ester bond, a hydroxyl group. And functional groups such as carboxylic acids.).

The organic compound having the structural formula as described above has a carboxyl group and a hydroxyl group so as to be adjacent as functional groups. Boron compounds to be adsorbed B _{(OH) 3} or B _{(OH) 4} ^- in the form of. The reaction mechanism between boron and a carboxyl group or a hydroxyl group is not clear, but it is presumed that when the hydroxyl group of boron approaches each functional group, a bond is formed and adsorption is performed.

  In addition, when the carboxyl group and the hydroxyl group are not adjacent to each other, they are bonded only to either the carboxyl group or the hydroxyl group. Therefore, the bond with the boron becomes insufficient, and the boron cannot be sufficiently adsorbed.

  In addition, any of the above organic compounds has an amino group. Therefore, when the adsorbent containing the carrier and the organic compound is actually put into a solution containing boron, the pH in the solution can be increased, and the above-described boron adsorption reaction can be promoted. it can.

  Examples of the organic compound having the structural formula (1) include 4-amino-3-hydroxybutyric acid, serine, and threonine.

  Examples of the organic compound having the structural formula (2) include 4-amino-2-hydroxybutyric acid, isoserine, and 2-amino-3-hydroxydibutanoic acid.

  Furthermore, examples of the organic compound having the structural formula (3) include 3-aminosalicylic acid, 4-aminosalicylic acid, 5-aminosalicylic acid and the like.

  Examples of the organic compound having the structural formula (4) include 3-amino-3-hydroxyacrylic acid and 2-amino-3-hydroxyacrylic acid.

  In addition, the support | carrier and organic compound which were mentioned above originate in the manufacturing method demonstrated below, and can be combined and modified by bridge | crosslinking by Si-O bond.

(Production method of boron adsorbent)
Next, the manufacturing method of the boron adsorbent in the present embodiment will be described.

  First, a carrier such as the above-described ferrite or silica gel is prepared, and the organic compound having the structural formulas (1) to (4) described above is bonded to the carrier and modified.

  The bonding and modification of the organic compound to the carrier are not particularly limited, but a silane coupling agent is preferably used. Since the carrier is an inorganic compound, it is possible to form a strong bond with the organic compound by using a silane coupling agent. In this case, as described above, the carrier and the organic compound are bonded through a Si—O bond. As a result, the surface of the carrier is modified by the organic compound.

  Among the silane coupling agents, it is particularly preferable to use an alkoxysilane coupling agent. The alkoxysilane coupling agent is easy to obtain and rich in reactivity, and can easily form the Si—O bond as described above.

  Examples of such alkoxysilane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethylsilane, 3-glycidoxypropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, Examples include 3-aminopropyldimethylethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and the like.

  The treatment using the silane coupling agent described above can be performed as follows.

  As a first method, a silane coupling agent is added to water or ethanol, or a mixed solvent thereof, and the carrier is immersed, followed by stirring after 15 minutes to 3 hours, preferably 30 minutes to 1 hour. By washing with pure water, Si—O bonds can be formed on the surface of the carrier.

  In addition, by using dry toluene, dry tetrahydrofuran or the like instead of the above-described solvent such as water and stirring the carrier and the silane coupling agent and the solvent under reflux, Si on the surface of the carrier under anhydrous conditions. -O bonds can be formed.

  As a second method, an alkoxysilane compound such as methoxysilane and a functional group-containing alcohol compound such as 3-aminopropyl alcohol are used as raw materials, for example, by thermally reacting on the surface of the single substance by a CVD method, Si—O bonds can be formed on the surface.

  As a third method, a Si—O bond can be formed by dissolving a silane coupling agent in a predetermined solvent (for example, toluene) and adhering it to the surface of the carrier by evaporating with heating.

  From the above-described principle of boron adsorption, boron adsorption depends on the amount of the organic compound that modifies the surface of the support. In this embodiment, the amount of the organic compound depends on the amount of Si formed on the surface of the support. It depends on the proportion of —O bonds, that is, the surface coverage of the carrier by the silane coupling agent. This surface coating amount depends on the treatment amount of the silane coupling agent on the carrier.

The addition amount (g) of the silane coupling agent is
Addition amount (g) = carrier amount (g) × specific surface area (m ² / g) / minimum coating area of silane coupling agent (m ² / g)
It can be expressed as

  Since the area that one molecule can cover varies depending on the type of silane coupling agent, the minimum coverage area of each silane coupling agent is calculated as shown in the above equation when deriving the optimum amount of silane coupling agent required for processing. Apply.

  Specifically, the amount of the silane coupling agent relative to the carrier is preferably 1% by weight to 10% by weight. If it is less than 1% by weight, the coating amount of the silane coupling agent on the carrier is decreased, the amount of the organic compound bound (modification ratio) is decreased, and boron may not be sufficiently adsorbed. Moreover, when it exceeds 10 weight%, it may gelatinize by condensation of silane coupling agents.

  Next, a boron adsorbent in which the surface of the carrier is modified with the organic compound by bringing the organic compound into contact with the carrier surface-treated with the silane coupling agent as described above, for example, in an alkaline solution is provided. can do.

(Boron adsorption operation)
Next, the boron adsorption operation according to the embodiment will be described.

  FIG. 1 is a diagram showing a schematic configuration of an apparatus used for boron adsorption in the present embodiment. As shown in FIG. 1, in this apparatus, the adsorbing means T1 and T2 filled with the boron adsorbent described above are arranged in parallel, and the contact efficiency promoting means X1 and the adsorbing means T1 and T2 are disposed outside the adsorbing means T1 and T2. X2 is provided. The contact efficiency promoting means X1 and X2 can be a mechanical stirrer or a non-contact magnetic stirrer, but they are not essential components and may be omitted.

  Further, the adsorption means T1 and T2 are provided with a medium to be processed storage tank W1 in which a medium to be processed containing boron is stored through supply lines L1, L2 and L4, and discharge lines L3, L5 and L6. It is connected to the outside via Furthermore, the adsorption means T1 and T2 are connected via a supply line L11, L12 and L14 to a desorption medium storage tank D1 in which a desorption medium is stored, and via the discharge lines L13, L15 and L16, A desorption medium recovery tank R1 is connected.

  The supply lines L1, L2, L4, L12 and L14 are provided with valves V1, V2, V4, V12 and V14, respectively, and the discharge lines L3, L5, L13, L15 and L16 are provided with valves V3, respectively. , V5, V13, V15, and V16 are provided. The supply lines L1 and L11 are provided with pumps P1 and P2. Further, concentration measuring means M1, M2 and M3 are provided in the medium storage tank W1, supply line L1 and discharge line L6, respectively, and the desorption medium storage tank D1, discharge line L16 and desorption medium recovery tank R1 are Concentration measuring devices M1, M11 and M13 are provided, respectively.

  Further, the control of the valve and pump and the monitoring of the measured value in the measuring device are collectively managed by the control means C1.

  Next, an operation for adsorbing boron using the apparatus shown in FIG. 1 will be described.

  First, the medium to be treated is supplied from the tank W1 to the suction means T1 and T2 through the supply lines L1, L2, and L4 to the suction means T1 and T2. At this time, boron in the medium to be treated is adsorbed by the adsorption means T1 and T2, and the medium to be treated after adsorption is discharged to the outside through the discharge lines L3 and L6.

  At this time, if necessary, the contact efficiency promoting means X1 and X2 are driven to increase the contact area between the boron adsorbent filled in the adsorbing means T1 and T2 and the medium to be treated, and by the adsorbing means T1 and T2. The adsorption efficiency of boron can be improved.

  Here, the adsorption states of the adsorption means T1 and T2 are observed by the concentration measurement means M2 provided on the supply side and the concentration measurement means M3 provided on the discharge side of the adsorption means T1 and T2. When the adsorption is performed smoothly, the boron concentration measured by the concentration measuring means M3 is lower than the boron concentration measured by the concentration measuring means M2. However, as the adsorption of boron in the adsorption means T1 and T2 progresses gradually, the difference in boron concentration between the concentration measuring means M2 and M3 arranged on the supply side and the discharge side decreases.

  Accordingly, when the concentration measuring means M3 reaches a predetermined value set in advance and it is determined that the adsorption capacity of boron by the adsorption means T1 and T2 has reached saturation, the control is performed based on information from the concentration measuring means M2 and M3. The means C1 temporarily stops the pump P1, closes the valves V2 and V3, and stops the supply of the processing medium to the suction means T1 and T2.

  Although not shown in FIG. 1, when the pH of the medium to be treated fluctuates, or the pH is strongly acidic or strongly basic, it is out of the pH range suitable for the adsorbent according to the present invention. In this case, the pH of the medium to be treated may be measured by the concentration measuring means M1 and / or M2, and the pH of the medium to be treated may be adjusted through the control means C1.

  After the adsorption means T1 and T2 reach saturation, the desorption medium is supplied from the desorption medium storage tank D1 to the adsorption means T1 and T2 through the supply lines L11 and L12 by the pump P2. Boron adsorbed by the adsorbing means T2 is eluted (desorbed) into the desorption medium, discharged to the outside of the adsorbing means T1 and T2 through the discharge lines L13, L15, and L16, and collected in the recovery tank R1. In addition, it can also be made to discharge | emit outside, without collect | recovering to collection tank R1. The precipitated boron may be collected by filtration.

  When the desorption of boron by the desorption medium is performed smoothly from the adsorption means T1 and T2, the concentration of boron measured by the concentration measuring device M12 provided on the discharge side of the desorption medium is provided on the supply side. The value is higher than that of the concentration measuring device M11. However, as the desorption of boron in the adsorbing means T1 and T2 progresses gradually, the difference in boron concentration in the concentration measuring means M11 and M12 arranged on the supply side and the discharge side decreases.

  Therefore, when the concentration measuring means M12 reaches a predetermined value set in advance and it is determined that the boron desorption ability by the adsorption means T1 and T2 by the desorption medium has reached saturation, information from the concentration measuring means M11 and M12 The control means C1 temporarily stops the pump P2, closes the valves V12 and V14, and stops the supply of the medium to be processed to the suction means T1 and T2.

  After the desorption of boron from the adsorption means T1 and T2 is completed as described above, the medium to be treated is supplied again from the medium to be treated storage tank W1, and the boron in the medium to be treated is adsorbed by boron. Can be reduced.

  The concentration measuring device M13 is configured to appropriately measure the concentration of boron in the desorption medium recovery tank R1 as necessary.

  In the above example, boron is simultaneously adsorbed to the adsorbing means T1 and T2, and boron is desorbed. However, these operations can be alternately performed by the adsorbing means T1 and T2. For example, boron is first adsorbed by the adsorbing means T1, and after the adsorbing capacity reaches saturation, boron is desorbed as described above from the adsorbing means T1, and at the same time, boron is adsorbed by the adsorbing means T2. It can also be done.

  In this case, in the apparatus shown in FIG. 1, since boron can be always adsorbed in either the adsorbing means T1 or T2, continuous operation is possible.

  As the desorption medium, an acidic solvent such as dilute hydrochloric acid aqueous solution or dilute sulfuric acid aqueous solution having a pH of about 2 to 5 can be used. The amount of the desorption solvent is preferably 2 to 10 times the volume of the adsorption means T1 and T2. If it is less than 2 times, the desorption of boron may not be carried out sufficiently efficiently, and if it is more than 10 times, the drug cost becomes high, which is inefficient.

  Next, the present invention will be described in more detail with reference to examples.

Example 1
1 g of 4-aminosalicylic acid was dissolved in 10 ml of 1M aqueous sodium hydroxide and 1.54 g of epoxysilane was added. After stirring for 12 hours, 8 ml of a 0.1 M aqueous hydrochloric acid solution was added to obtain a brown white gel substance. The product was filtered, washed with pure water, and dried at 80 ° C. for 24 hours to obtain 0.866 g of a glassy substance (adsorbent).

100 mg of the above substances are added to 50 ml of Na ₂ B ₄ O ₇ · 10H ₂ O-containing water adjusted to a concentration of 20 ppm-B, 50 ppm-B, 100 ppm-B, and 500 ppm-B, respectively, and stirred with a NISSIN rotary mixer. (16 rpm). When the boron concentration of the water to be treated after 90 minutes was measured by ICP-MS, the adsorption amount was as shown in Table 1.

(Example 2)
1.19 g of 4-amino-3-hydroxybutyric acid was dissolved in 10 ml of 1M aqueous sodium hydroxide solution and 2.36 g of epoxysilane was added. After stirring for 12 hours, 5 ml of a 0.1 M aqueous hydrochloric acid solution was added to obtain a white gel-like substance. The product was filtered, washed with pure water, and dried at 80 ° C. for 24 hours to obtain 1.21 g of a glassy substance (adsorbent). Next, in the same manner as in Example 1, the adsorption amount after 90 minutes in the boron concentration of Na ₂ B ₄ O ₇ · 10H ₂ O-containing treated water was measured, and the results shown in Table 1 were obtained.

Example 3
1.15 g of glassy material was obtained in the same manner as in Example 2 except that 1.19 g of 4-amino-2-hydroxybutyric acid was used instead of 1.19 g of 4-amino-3-hydroxybutyric acid. . Next, in the same manner as in Example 1, the adsorption amount after 90 minutes in the boron concentration of Na ₂ B ₄ O ₇ · 10H ₂ O-containing treated water was measured, and the results shown in Table 1 were obtained.

Example 4
1 g of 4-aminosalicylic acid was dissolved in 10 ml of 1M aqueous sodium hydroxide and 1.54 g of epoxysilane was added. After stirring for 12 hours, 0.01 M aqueous hydrochloric acid solution was added until pH7 was reached. 1 g of silica gel (100-210 μm: Nacalai Tesque 60N sphere) was added thereto, stirred for 1 hour, filtered, washed with pure water, and dried at 60 ° C. for 12 hours to obtain 1.21 g of an adsorbent. Next, in the same manner as in Example 1, the adsorption amount after 90 minutes in the boron concentration of Na ₂ B ₄ O ₇ · 10H ₂ O-containing treated water was measured, and the results shown in Table 1 were obtained.

(Example 5)
1.19 g of 4-amino-3-hydroxybutyric acid was dissolved in 10 ml of 1M aqueous sodium hydroxide solution and 1.54 g of epoxysilane was added. After stirring for 12 hours, 0.01 M aqueous hydrochloric acid solution was added until pH7 was reached. 1 g of silica gel (100-210 μm: 60N sphere manufactured by Nacalai Tesque) was added thereto. After stirring for 1 hour, it was filtered, washed with pure water, and dried at 60 ° C. for 12 hours to obtain 1.10 g of an adsorbent. Next, in the same manner as in Example 1, the adsorption amount after 90 minutes in the boron concentration of Na ₂ B ₄ O ₇ · 10H ₂ O-containing treated water was measured, and the results shown in Table 1 were obtained.

(Example 6)
Instead of 1.19 g of 4-amino-3-hydroxybutyric acid, 1.12 g of an adsorbent was obtained in the same manner as in Example 5 except that 1.19 g of 4-amino-2-hydroxybutyric acid was used. Next, in the same manner as in Example 1, the adsorption amount after 90 minutes in the boron concentration of Na ₂ B ₄ O ₇ · 10H ₂ O-containing treated water was measured, and the results shown in Table 1 were obtained.

(Comparative example)
A commercially available boron adsorbent, IRA743 made by Organo was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

  As described above, as is clear from the examples and comparative examples, according to the present invention, the adsorbent obtained by modifying the surface of the carrier with the organic compound as represented by the above structural formulas (1) to (4) is used. As a result, it was found that the concentration after 90 minutes with respect to the initial concentration of boron in the treated water was greatly reduced, and the adsorbent exhibited high adsorption characteristics for boron.

  While the present invention has been described in detail based on the above specific examples, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

Claims (7)

A porous structure carrier;
At least one organic compound having the structural formulas (1) to (4) obtained by modifying the surface of the carrier;
Boron adsorbent characterized by comprising

(At least one R in the molecule contains a primary or secondary amino group, and R _{1 to} R ₁₀ are hydrogen or an aliphatic chain, and are an unsaturated carbon bond, an ether bond, an ester bond, a hydroxyl group and a carboxyl group. It can contain functional groups such as acids).   The boron adsorbent according to claim 1, wherein the carrier and the organic compound are cross-linked through a Si—O bond.   The boron adsorbent according to claim 1 or 2, wherein the carrier is a magnetic carrier.   The boron adsorbent according to claim 1 or 2, wherein the carrier is silica gel. Treating the porous carrier with a silane coupling agent;
Contacting at least one of organic compounds having the structural formulas (1) to (4) with the carrier,
A method for producing a boron adsorbent comprising obtaining a boron adsorbent obtained by modifying the surface of the carrier with at least one of the organic compounds having the structural formulas (1) to (4).

(At least one R in the molecule contains a primary or secondary amino group, and R _{1 to} R ₁₀ are hydrogen or an aliphatic chain, and are an unsaturated carbon bond, an ether bond, an ester bond, a hydroxyl group and a carboxyl group. It can contain functional groups such as acids).   6. The method for producing a boron adsorbent according to claim 5, wherein the silane coupling agent is an alkoxysilane coupling agent.   The method for producing a boron adsorbent according to claim 5 or 6, wherein a concentration of the silane coupling agent is 1% by weight to 10% by weight with respect to the carrier.

Images