JP5733853B2 - Method for recovering hydroiodic acid from waste liquid - Google Patents

Description

  The present invention relates to a method for recovering hydroiodic acid from waste liquid to obtain hydroiodic acid from waste liquid containing iodine ions.

  Hydroiodic acid is a useful substance because it is used as a raw material for synthesis of various iodine compounds, a medical intermediate synthesis reagent, a reducing agent, and the like. This hydroiodic acid is usually produced by industrially adding a reducing agent to a mixed solution or suspension of iodine and water.

  Iodine has many uses such as, for example, X-ray contrast agents, bactericides, fungicides, herbicides, pharmaceuticals, industrial catalysts, polarizing films for liquid crystal displays, photographic drugs, and electrolytes. Various iodine compounds such as hydrofluoric acid, iodic acid, and potassium iodide are used as raw materials, catalysts, and intermediate synthesis reagents.

  As described above, iodine and iodine compounds used in many applications are often contained in waste liquids generated in various treatment processes according to each application and discharged out of the process.

  Therefore, since iodine is a rare substance and an extremely valuable resource, it is economical to recover hydroiodic acid from a waste solution containing iodine ions discharged out of the process as described above. Is also extremely important and beneficial from the standpoint of the natural environment.

  And as a method of recovering hydroiodic acid from the waste liquid, hydrogen iodide is produced from the waste liquid containing inorganic substances and water-soluble organic substances such as iodine, iodine ions, boric acid, potassium ions generated in the manufacturing process of the liquid crystal display polarizing film. A method for recovering an acid is known (for example, see Patent Document 1). In this method, a waste liquid containing iodine, iodine ions, potassium ions, etc. is subjected to normal electrodialysis, so that iodine is once recovered as an aqueous potassium iodide solution, and then this aqueous potassium iodide solution is electrically converted using a bipolar membrane. By subjecting to a dialysis method, an aqueous potassium hydroxide solution and hydroiodic acid are separated and recovered.

  Moreover, as a method for recovering iodine from the waste liquid, a method for recovering iodine from the waste liquid containing an organic iodine compound generated in the manufacturing process of the organic compound such as an X-ray contrast medium is known. In this method, once the waste liquid is burned at a high temperature to break the bond between iodine and organic matter, iodine is absorbed into the reducing agent aqueous solution to form an iodine absorbing liquid, and then iodine is recovered from the iodine absorbing liquid by a conventional method. (For example, refer to Patent Documents 2 and 3.)

JP 2009-23847 A (page 3-4, FIG. 1) Japanese Examined Patent Publication No. 54-13234 (page 1-3) JP-A-6-157005 (page 2-4, FIG. 1)

  However, since the method of Patent Document 1 requires two-stage electrodialysis, the number of steps is increased and a special bipolar membrane is required. Therefore, there is a problem that hydroiodic acid cannot be easily recovered. It is done.

  In addition, in order to recover hydroiodic acid from the waste liquid generated in the manufacturing process of the organic compound such as the X-ray contrast agent by the methods of Patent Documents 2 and 3 described above, the iodine recovered from the waste liquid is further added with hydrogen iodide. Since a step for converting to an acid is required and the number of steps increases, there may be a problem that hydroiodic acid cannot be easily recovered.

  This invention is made | formed in view of such a point, and it aims at providing the collection | recovery method of the hydroiodic acid from the waste liquid which can collect | recover hydroiodic acid from a waste liquid easily.

The method for recovering hydroiodic acid from the waste liquid according to claim 1 is an inorganic anion other than iodine ion, borate ion and borate ion, which is produced in a process using at least one of iodine and iodine compound, and A concentration separation step for concentrating and separating hydroiodic acid from waste liquid containing at least one of organic anions by double displacement electrodialysis using an electrodialysis tank incorporating four sample chambers as a set ; And a purification step of purifying the separated hydroiodic acid by distillation .

According to the invention described in claim 1, by using a double displacement electrodialysis method in which four sample chambers are incorporated as a set , iodine is produced in a process using at least one of iodine and an iodine compound. Hydroiodic acid can be easily concentrated and separated from waste liquid containing ions, borate ions and / or inorganic anions other than borate ions and / or organic anions. it can.

In addition, hydroiodic acid can be easily concentrated and separated from the waste solution containing iodine ions and borate ions produced in a process using at least one of iodine and iodine compounds. By purifying, high purity hydroiodic acid can be easily recovered from the waste liquid.

It is explanatory drawing which shows the structure of the electrodialysis tank used for the collection method of the hydroiodic acid from the waste liquid which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the electrodialysis tank used for the collection method of the hydroiodic acid from the waste liquid which concerns on the 2nd Embodiment of this invention.

Hereinafter, the configuration of the base technology of the present invention will be described in detail with reference to FIG.

  In FIG. 1, 1 is an electrodialysis tank as an electrodialysis apparatus, and this electrodialysis tank 1 concentrates hydroiodic acid (HI) from a stock solution D as a waste liquid which is a raw material containing iodine ions. It is a concentration separator.

  The electrodialysis tank 1 uses a two-chamber method in which one set of two chambers is configured by being alternately partitioned into two sample chambers. Specifically, a pair of electrodes 2a and 2b are disposed on both sides of the electrodialysis tank 1. One of the pair of electrodes 2a and 2b, that is, the electrode 2a is used as an anode as a positive electrode. The other of the pair of electrodes 2a and 2b, that is, the electrode 2b is used as a cathode as a negative electrode.

Furthermore, the electrodialysis tank 1 is provided with a chamber frame 3 as a frame having a notch (not shown), and electrodes 2a and 2b are attached to the inside of both end portions along the longitudinal direction of the chamber frame 3. In the chamber frame 3, the cation exchange membrane K partitioning the polar liquid P supplied to the electrode chamber 4 a on the positive electrode side from the positive electrode side where the electrode 2 a of the chamber frame 3 is disposed, One anion exchange membrane A ₁ and the first cation exchange membrane K ₁ are alternately and repeatedly arranged in a state of being spaced apart at equal intervals. Therefore, the electrodes 2a and 2b in the electrodialysis tank 1 are alternately partitioned by the first anion exchange membrane A ₁ and the first cation exchange membrane K ₁ .

Each of the cation exchange membranes K, the first anion exchange membranes A ₁ and the first cation exchange membranes K ₁ is stretched along the longitudinal direction in order to give tension. Both ends of each cation exchange membrane K, first anion exchange membrane A ₁ and first cation exchange membrane K ₁ are fastened and fixed to both side surfaces of the chamber frame 3.

The first anion-exchange membrane A _1, for example, typical strongly basic styrene - divinylbenzene based homogeneous anion exchange membrane is used. In addition, when the stock solution D contains divalent ions such as sulfate ions (SO ₄ ²⁻ ) or trivalent ions such as borate ions (BO ₃ ³⁻ ) as impurities, the first negative The use of a monovalent anion selective permeation membrane with enhanced monovalent anion selective permeability as the ion exchange membrane A ₁ is effective because the selective permeability of iodine ions (I ⁻ ) can be further improved. Further, as the monovalent anion selective permeable membrane, for example, Selemion ASV manufactured by Asahi Glass Co., Ltd. (Selemion is a registered trademark), Aciplex A-192 manufactured by Asahi Kasei Co., Ltd. (Aciplex is a registered trademark), or the like is used.

As the cation exchange membrane K ₁ of the cation exchange membrane K, and the first, for example, strongly acidic styrene - divinylbenzene based homogeneous cation exchange membrane is used. Further, when sodium ions (Na ⁺ ), calcium ions (Ca ²⁺ ), and the like are contained as impurities in the stock solution D, hydrogen is used as the cation exchange membrane K and the first cation exchange membrane K _1. Use of an ion selective permeable membrane or a monovalent cation selective permeable membrane is effective because the selective permeability of hydrogen ions (H ⁺ ) can be further improved. Furthermore, as these hydrogen ion selective permeable membranes or monovalent cation selective permeable membranes, for example, Selemion HSV manufactured by Asahi Glass Co., Ltd. (Selemion is a registered trademark) and Aciplex K-192 manufactured by Asahi Kasei Co., Ltd. (Aciplex is registered). Trademark).

On the other hand, the electrode 2a of the electrodialysis cell 1, 2b is accommodated in the interior, electrodes of both polarities side cation exchange membrane K or first cation exchange membrane K ₁ at partitioned compartment frame 3 is as electrode liquid chamber It becomes room 4a, 4b. These electrodes chamber 4a, a first anion exchange membrane A ₁ between 4b, the first cation exchange membrane K located on the anode side of the cation exchange membrane K or first anion-exchange membrane A _{1 The} inside of the chamber frame 3 partitioned by ₁ is a concentration chamber 5 which is a generation tank as a sample chamber. Further, the first anion exchange membrane A ₁ between the electrode chambers 4a and 4b is partitioned by a _first cation exchange membrane K ₁ located on the cathode side of the first anion exchange membrane A ₁ . The inside of the chamber frame 3 becomes a stock solution chamber 6 which is a desalination chamber as a sample chamber.

In other words, the stock chamber 6, a pair of electrodes 2a, an anode side by 2b is partitioned by a first anion exchange membrane A _1, the cathode side is partitioned by the first cation exchange membrane K _1. Further, concentrating chamber 5, a pair of electrodes 2a, an anode side by 2b is partitioned by a cation exchange membrane K or first cation exchange membrane K _1, partition the cathode side in the first anion-exchange membrane A ₁ It has been. These stock solution chambers 6 and concentration chambers 5 are alternately formed. Furthermore, the electrode chambers 4a and 4b are located on both sides in the width direction of the stock solution chamber 6 and the concentration chamber 5 formed alternately.

The anode-side electrode chamber 4a is partitioned by a cation exchange membrane K. Furthermore, the electrode chambers 4b of the cathode side is partitioned by a cation exchange membrane K _n is a first cation exchange membrane K ₁ of the last group counted from the anode side.

Further, the liquid supply port and the liquid discharge port located on both side surfaces of the chamber frame 3 along the longitudinal direction of the electrode chambers 4a and 4b are, for example, an inlet and an outlet of an extreme liquid P such as an aqueous solution of sodium hydrogen sulfate (NaHSO ₄ ). The polar liquid inlet and the polar liquid outlet.

Furthermore, the liquid supply port and the liquid discharge port located on both side surfaces of the chamber frame 3 along the longitudinal direction of the stock solution chamber 6 are a stock solution inlet and a stock solution outlet that serve as an inlet and an outlet for the stock solution D, respectively. Therefore, the stock solution D is supplied to the stock solution chamber 6 between the first anion exchange membrane A ₁ and the first cation exchange membrane K ₁ . Here, the stock solution D is a waste solution containing iodine ions and borate ions. The stock solution D contains impurities such as inorganic anions and organic anions other than iodine ions and borate ions. Impurities contained in the stock solution D are not particularly limited. For example, inorganic anions include chlorine ions, bromine ions, sulfate ions, nitrate ions, phosphate ions, and the like, and organic anions include acetate ions, Examples include formate ion and oxalate ion.

  Further, the liquid supply port and the liquid discharge port located on both side surfaces of the chamber frame 3 along the longitudinal direction of the concentration chamber 5 are an inlet of the concentrated solution serving as an inlet and an outlet of the concentrated solution C as a hydroiodic acid concentrated solution, and It is considered as the concentrate outlet. Here, the concentrated liquid C is a hydroiodic acid aqueous solution containing at least water and hydroiodic acid, and the hydroiodic acid being concentrated.

  Therefore, the stock solution D is supplied to the stock solution chamber 6 from the stock solution inlet. Further, the concentrate C is supplied to the concentration chamber 5 from the concentrate inlet. Further, the electrode solution 4a, 4b located on both sides of the stock solution chamber 6 and the concentration chamber 5 in the width direction and in contact with the electrodes 2a, 2b is supplied with an anolyte and a catholyte polar solution P from the polar solution inlet. Is done.

Here, number of repetitions n of the sequence of the electrodialysis cell first anion-exchange membrane A ₁ in one of the compartment frame 3 and the first cation exchange membrane K ₁ can be appropriately selected depending on the purpose, preferably Is the number of repetitions of about 10 or more and 1000 or less. In addition, each supply of the polar solution P, the undiluted solution D, and the concentrated solution C to the electrode chambers 4a and 4b, the undiluted solution chamber 6, and the concentrating chamber 5 of the electrodialysis tank 1 can be continuously performed.

  Further, the concentration of hydroiodic acid in the stock solution D in the stock solution chamber 6 is lowered by continuing electrodialysis in the stock solution chamber 6. For this reason, the stock solution D in which the concentration of hydroiodic acid is sufficiently reduced is appropriately extracted as a processing solution, and a new stock solution D is replenished. In addition, the processing liquid can be continuously extracted and continuously replenished.

Further, the concentrated liquid C in the concentration chamber 5 is subjected to electrodialysis, whereby the hydrogen ions (H ⁺ ) and the first anion exchange that have permeated through the cation exchange membrane K and the first cation exchange membrane K _1. The concentration of hydroiodic acid in the concentrate C increases due to iodine ions (I ⁻ ) that have permeated through the membrane A ₁ . For this reason, a concentrated hydroiodic acid concentrated liquid can be obtained by extracting the concentrated liquid C having an increased concentration of hydroiodic acid as many times as necessary or continuously.

  Next, a method for recovering hydroiodic acid from the waste liquid according to the first embodiment will be described.

  First, a current equal to or lower than the limit current density measured in advance is supplied between the electrodes 2a and 2b of the electrode chambers 4a and 4b of the electrodialysis tank 1.

Then, as shown in FIG. 1, the hydrogen ions (H ⁺ ) in the positive electrode chamber 4a pass through the cation exchange membrane K, and the hydrogen ions in the stock solution chamber 6 pass through the first cation exchange membrane K. ₁ is transmitted. At the same time, iodine ions (I ⁻ ) in each stock solution chamber 6 permeate the _first anion exchange membrane A ₁ .

In this case, an iodine ion and other anions can not transmit cation exchange membrane K ₁ of cation exchange membranes K and the first. The hydrogen ions can not pass through the first anion exchange membrane A _1.

  For this reason, the concentration of hydroiodic acid in the concentrate C in the concentration chamber 5 increases, and the concentration of hydroiodic acid in the concentrate D in the stock solution chamber 6 decreases. Thereafter, the treatment liquid in which the concentration of hydroiodic acid in the concentration chamber 5 is increased, that is, the concentrated liquid C is extracted from the concentration chamber 5 to obtain a hydroiodic acid concentrated liquid which is a high-concentration hydroiodic acid aqueous solution. Can be obtained.

Then, according to the base technology, supplies the stock D in stock chamber 6 between the first anion-exchange membrane A ₁ of the electrodialysis cell 1 and the first cation exchange membrane K1, cation-exchange After supplying the concentrate C to the concentrating chamber 5 between the membrane K or the first cation exchange membrane K ₁ and the first anion exchange membrane A ₁ , between the electrodes 2 a and 2 b of the electrodialysis tank 1 By supplying an electric current, hydroiodic acid in the stock solution D is separated into the concentrate C in the concentration chamber 5 by electrodialysis. As a result, the concentration of hydroiodic acid in the concentrate C in the concentration chamber 5 increases, so that hydroiodic acid can be easily concentrated and separated from the stock solution D.

  Therefore, hydroiodic acid can be easily concentrated and separated from the waste liquid containing iodine ions by using the electrodialysis method, so that hydroiodic acid can be easily recovered from the waste liquid.

  Further, since electrodialysis is performed using a normal ion exchange membrane without using a special ion exchange membrane such as a bipolar membrane, hydroiodic acid can be concentrated and separated from the stock solution D with a simple configuration.

The stock solution D is a waste liquid produced in a process using at least one of iodine and an iodine compound and containing at least one of iodine ions , borate ions, inorganic anions other than borate ions, and organic anions. As long as it exists, it may be obtained by any manufacturing process, and the concentration of iodine ions and borate ions, and the type and content of other impurities are not particularly limited.

  Moreover, when insoluble matter exists in the waste liquid, electrodialysis may be performed using the waste liquid directly or after removing the insoluble matter after pH adjustment as the stock solution D.

  When performing electrodialysis, the stock solution D is preferably an aqueous solution. In particular, when the stock solution D is a waste solution discharged from the organic compound production process, most of it may be an organic solvent.

  As an ion exchange membrane used in electrodialysis, a styrene-divinylbenzene polymer is usually used as a material. Even if the organic material is contained in the stock solution D, it can be used as it is as a raw material as long as the organic material does not damage the film. For example, oxygen-containing organic compounds such as acetic acid, propionic acid, ethanol, and acetone can be used as they are even if they are contained in an amount of about 20% by mass. Depending on the type of organic solvent, the ion exchange membrane may be damaged. In such a case, the iodine component can be extracted into an aqueous layer by mixing with water, and the aqueous layer can be used as a raw material.

  Here, in addition to iodine ions in the waste liquid used as the stock solution D, inorganic ions such as borate ions, chlorine ions, bromine ions, sulfate ions, phosphate ions and nitrate ions, acetate ions, formate ions and oxalic acid When organic anions such as ions are included, it is considered that anions other than iodine ions may also permeate the anion exchange membrane, but a strong basic styrene-divinylbenzene-based ordinary homogeneous anion exchange membrane Is used, the permeation selectivity of iodine ions is very good, and borate ions other than iodine ions and other anions are difficult to permeate until the iodine ion concentration in the waste liquid becomes very low. I found it. Accordingly, iodine ions are concentrated in the concentrated liquid C, the contamination of other anions can be extremely reduced, and hydroiodic acid can be effectively concentrated and separated.

  In addition, if the hydroiodic acid concentrate obtained by concentrating hydroiodic acid from the stock solution D, which is a waste liquid by electrodialysis, contains trace amounts of inorganic anions and organic anions other than hydroiodic acid, distillation is performed. The hydroiodic acid concentrate may be purified by distillation using a distillation apparatus such as a magnetic Raschig packed tower equipped with a flask, and hydroiodic acid can be efficiently recovered with high purity by distillation purification.

  Therefore, by using the electrodialysis method, the hydroiodic acid concentrate can be easily concentrated and separated from the waste liquid containing iodine ions and borate ions. By distilling and purifying this hydroiodic acid concentrate, High purity hydroiodic acid can be easily recovered.

  However, when sulfate ion is contained in the hydroiodic acid concentrate, there is a method in which barium hydroxide or barium salt other than sulfuric acid is added to the hydroiodic acid concentrate and the sulfuric acid is precipitated as a barium salt and separated. .

  The method for removing inorganic anions other than iodine ions and organic anions from the hydroiodic acid concentrate is not limited to the above method, and a known method that can remove inorganic ions and organic anions other than iodine ions. If so, it is applicable.

Next, an embodiment of the present invention will be described with reference to FIG. In addition, about the structure and effect | action same as the said base technology , the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The electrodialysis tank 1 shown in FIG. 2 is basically the same as the configuration of the electrodialysis tank 1 shown in FIG. 1, but the electrodes 2a and 2b disposed at both ends of the electrodialysis tank 1 are connected to the positive electrode side. Subsequently to the cation exchange membrane K that partitions the polar liquid P from the first cation exchange membrane A ₁ , the first cation exchange membrane K ₁ , the second anion exchange membrane A ₂ , and the second cation exchange membrane A ₁ by partitioning alternately with ion exchange membrane K _2, 4 four-chamber pair which are formed are separated alternately sample chamber of the sample chamber, a plurality are selected according to the purpose, preferably 5 to 500 The number of repetitions of n is provided.

The electrodialysis tank 1 is provided with a stock solution chamber 6 adjacent to the electrode chamber 4b on the cathode side. In the stock solution chamber 6, the cathode side is partitioned by the _second cation exchange membrane K ₂ , and the anode side is partitioned by the second anion exchange membrane A ₂ .

Further, a concentrating chamber 5 adjacent to the stock solution chamber 6 is provided on the anode side of the stock solution chamber 6 via the _second anion exchange membrane A2. The concentration chamber 5 is partitioned on the cathode side by the second anion exchange membrane A ₂ and on the anode side by the first cation exchange membrane K ₁ .

Furthermore, an acid chamber 7 as a sample chamber adjacent to the concentration chamber 5 is provided on the anode side of the concentration chamber 5 via the _first cation exchange membrane K1. The acid compartment 7, the cathode side is partitioned by the first cation exchange membrane K _1, the anode side is partitioned by a first anion exchange membrane A _1. The acid chamber 7 is supplied with an acid solution A that is an aqueous solution of a strong acid such as sulfuric acid. Here, the liquid supply port and the liquid discharge port located on both side surfaces of the chamber frame 3 along the longitudinal direction of the acid chamber 7 are an acid inlet and an acid outlet that serve as an inlet and an outlet for the acid solution A, respectively. The acid chamber 7 is supplied with the acid solution A from the acid inlet, and the acid solution A is led out from the acid outlet.

On the anode side of the acid chamber 7, there is provided a salt chamber 8 which is a solution chamber as a sample chamber adjacent to the acid chamber 7 via the _first anion exchange membrane A ₁ . The salt chamber 8, the cathode side is partitioned by a first anion exchange membrane A _1, a second cation anode is positioned on the anode side of the cation exchange membrane K or first anion-exchange membrane A ₁ It is partitioned by exchange membrane K _2. The salt chamber 8 is supplied with an aqueous solution of acid or salt by-produced corresponding to the acid solution A supplied to the acid chamber 7, for example, a salt solution S such as an aqueous solution of sodium hydrogen sulfate (NaHSO ₄ ). The

  Here, the liquid supply port and the liquid discharge port located on both side surfaces of the chamber frame 3 along the longitudinal direction of the salt chamber 8 are a salt inlet and a salt outlet that serve as an inlet and an outlet for the salt solution S, respectively. The salt chamber 8 is supplied with the salt solution S from the salt inlet, and the salt solution S is led out from the salt outlet.

As a result, iodine ions (I ⁻ ) in the stock solution D supplied into the stock solution chamber 6 and hydrogen ions in the acid solution A supplied into the acid chamber 7 by electrodialysis in a batch method using the electrodialysis tank 1. From (H ⁺ ), hydroiodic acid is generated by the double displacement dialysis reaction, the concentration of hydroiodic acid in the concentrate C in the concentration chamber 5 increases, and the salt solution S in the salt chamber 8 increases. The concentration of the acid or salt in it, for example the concentration of sodium hydrogen sulfate, increases.

  Further, the concentration of hydroiodic acid in the stock solution D in the stock solution chamber 6 of the raw material system and the concentration of the acid in the acid solution A in the acid chamber 7 are gradually reduced, and the current value is accompanied by the decrease in this concentration. Decreases.

  After the current value is sufficiently reduced, the electrodialysis in the electrodialysis tank 1 is temporarily stopped, and appropriate amounts of the stock solution D and the acid solution A in the raw material stock solution chamber 6 and the acid chamber 7 are extracted as treatment solutions. The chamber 6 and the acid chamber 7 are filled again with the stock solution D and the acid solution A which are raw material solutions.

  The concentrated solution C and the salt solution S in the production system concentration chamber 5 and the salt chamber 8 are left for use as raw materials for the next electrodialysis, and the remainder is extracted as a product solution. Further, each of the polar solution P, the stock solution D, the concentrated solution C, the acid solution A, and the salt solution S is continuously fed into the electrode chambers 4a, 4b, the stock solution chamber 6, the concentration chamber 5, the acid chamber 7, and the salt chamber 8. Continuous operation is also possible by supplying and extracting.

  Therefore, by repeating the above-described steps, a high concentration aqueous solution of hydroiodic acid can be obtained.

In addition, when it is set as the structure which collect | recovers hydroiodic acid from waste liquid by a double displacement electrodialysis method in this way, the electrodialysis tank 1 should just be the structure integrated as 4 sets of sample chambers, and is concentrated. The chamber 5, the stock solution chamber 6, the acid chamber 7, and the salt chamber 8 are not limited to the configuration provided as described above. That is, for example, a first anion exchange membrane A _1, between the second cation exchange membrane K ₂ located on the anode side of the cation exchange membrane K or first anion-exchange membrane A ₁ concentration A chamber 5 is defined as a stock solution chamber 6 between the anion exchange membrane A ₁ and the first cation exchange membrane K _1, and between the first cation exchange membrane K ₁ and the second anion exchange membrane A ₂ . The space between the second anion exchange membrane A ₂ and the second cation exchange membrane K ₂ may be the acid chamber 7.

Next, examples and reference examples of the present invention will be described.
[Reference Example 1]
Using the electrodialysis tank 1 shown in FIG. 2 (G4 type electrodialysis tank manufactured by Asahi Kasei Co., Ltd., 4 chambers / set, 5 sets of incorporated membranes, effective membrane area 0.02 m ² / sheet) Electrodialysis was performed in order to concentrate and separate hydroiodic acid from the waste liquid containing ions, chloride ions and acetate ions.

As a first cation exchange membrane K ₁ and the second cation exchange membrane K _2, it was used Selemion CMV manufactured by Asahi Glass Co., Ltd.. Further, using a general anionic permselective membrane in which Asahi Glass Selemion AMV Co., Ltd. first as an anion-exchange membrane A _1, 1 dianion permselective membrane as the second anion-exchange membrane of Asahi Glass Selemion ASV manufactured by Co., Ltd. was used.

  Then, 1384 g of the adjusted model waste liquid (composition: iodine ion 8.7% by mass, acetate ion 0.8% by mass, chloride ion 0.2%) is supplied to the stock solution chamber 6 as a stock solution D, and 1% by weight of iodination 713 g of an aqueous hydrogen acid solution was supplied to the concentration chamber 5 as a concentrate C. At the same time, 1782 g of a 3.3% by mass sulfuric acid aqueous solution was supplied to the acid chamber 7 as an acid solution A, and 1000 g of a 1.7% by mass sodium hydrogen sulfate aqueous solution was supplied to the salt chamber 8 as a salt solution S. Further, 1000 g of a 5% by mass aqueous sodium hydrogen sulfate solution was supplied as the polar liquid P to each electrode chamber 4a, 4b.

  In this state, after electrodialysis for 1.7 hours at a constant voltage of 8.5 V, the liquid volume in each chamber was measured, and the liquid composition in each chamber was measured by ion chromatography.

  The amount of liquid in each chamber is 1083 g of stock solution D in stock solution chamber 6, 942 g of concentrate C in concentration chamber 5, 1572 g of acid solution A in acid chamber 7, 1198 g of salt solution S in salt chamber 8, The extreme liquid P in the electrode chambers 4a and 4b was 992g.

  The ion concentration of each chamber is such that the ion concentration of the stock solution D in the stock solution chamber 6 is 0.5 mass% iodine ion, 0.9 mass% acetate ion, and 0.2 mass% chloride ion. The concentration of ion C in the concentrated solution C is 12.9% by mass of iodine ions, less than 0.1% by mass of acetate ions, and less than 0.1% by mass of chloride ions, and the ion concentration of the acid solution A in the acid chamber 7 is sulfate ions. The ion concentration of the salt solution S in the salt chamber 8 was 0.2% by mass, and the sulfate ion was 5.4% by mass.

As a result, the iodine ion permeability from the stock solution D to the concentrate C was 95%, and the acetate ion removal rate was 93%.
[Example 1]
The same electrodialysis tank 1, cation exchange membrane K, first anion exchange membrane A ₁ , first cation exchange membrane K ₁ , second anion exchange membrane A ₂ , and second as in Reference Example 1 electrodialysis was carried out using a cation exchange membrane K _2. Further, as the stock solution D, a waste solution containing iodine ions, sulfate ions and borate ions was used.

  Then, 1416 g of the adjusted model waste solution (composition: iodine ion 8.6% by mass, sulfate ion 3.1% by mass, boron 0.34% by mass) is supplied to the stock solution chamber 6 as a stock solution D, and 1% by weight of iodination 720 g of an aqueous hydrogen acid solution was supplied as a concentrate C to the concentration chamber 5. At the same time, 1782 g of a 3.3% by mass sulfuric acid aqueous solution was supplied to the acid chamber 7 as an acid solution A, and 1000 g of a 1.7% by mass sodium hydrogen sulfate aqueous solution was supplied to the salt chamber 8 as a salt solution S. Further, 1000 g of a 5% by mass aqueous sodium hydrogen sulfate solution was supplied as the polar liquid P to each electrode chamber 4a, 4b.

  In this state, after performing electrodialysis treatment at 8.5 V constant voltage for 2.6 hours, the liquid volume in each chamber is measured, and the liquid composition in each chamber is measured by ion chromatography and an ICP emission spectrometer. did.

  The amount of liquid in each chamber is 1156 g for stock solution D in stock solution chamber 6, 923 g for concentrate C in concentration chamber 5, 1571 g for acid solution A in acid chamber 7, 1203 g for salt solution S in salt chamber 8, and electrode chamber The polar liquid P in 4a and 4b was 976 g.

  The ion concentration in each chamber is such that the ion concentration of the stock solution D in the stock solution chamber 6 is 0.8 mass% iodine ion and 3.8 mass% in sulfate ions, and the ion concentration of the concentrate C in the concentration chamber 5 is Iodine ions are 13.2% by mass, sulfate ions are 0.2% by mass, the ion concentration of the acid solution A in the acid chamber 7 is less than 0.1% by mass of sulfate ions, and the salt solution S in the salt chamber 8 is The ion concentration was 3.8% by mass of sulfate ion. Furthermore, the boron of the stock solution D was 0.4 mass%, and the boron of the concentrated liquid C was less than 0.01 mass%.

As a result, the iodine ion permeability from the stock solution D to the concentrate C was 94%, and the boron removal rate was 98%.
[Reference Example 2]
The same electrodialysis tank 1, cation exchange membrane K, first anion exchange membrane A ₁ , first cation exchange membrane K ₁ , second anion exchange membrane A ₂ , and second as in Reference Example 1 electrodialysis was carried out using a cation exchange membrane K _2. Further, as the stock solution D, a waste solution containing iodine ions, chlorine ions, nitrate ions, and bromine ions was used.

  Then, 1086 g of the adjusted model waste liquid (composition: iodine ion 9.0% by mass, chlorine ion 1.6% by mass, nitrate ion 0.7% by mass, bromine ion 0.6% by mass) is used as the stock solution D in the stock solution chamber 6. Then, 721 g of a 1% by mass hydroiodic acid aqueous solution was supplied as a concentrate C to the concentration chamber 5. At the same time, 1903 g of a 3.3% by mass sulfuric acid aqueous solution was supplied to the acid chamber 7 as an acid solution A, and 1004 g of a 1.7% by mass sodium hydrogen sulfate aqueous solution was supplied to the salt chamber 8 as a salt solution S. Further, 1000 g of a 5% by mass aqueous sodium hydrogen sulfate solution was supplied as the polar liquid P to each electrode chamber 4a, 4b.

  In this state, after performing electrodialysis treatment at a constant voltage of 8.5 V for 2 hours, the liquid volume in each chamber was measured, and the liquid composition in each chamber was measured by ion chromatography.

  The amount of liquid in each chamber is 881 g of stock solution D in stock solution chamber 6, 777 g of concentrate C in concentration chamber 5, 1794 g of acid solution A in acid chamber 7, 1194 g of salt solution S in salt chamber 8, and electrode chamber. The polar liquid P in 4a and 4b was 984 g.

  The ion concentration in each chamber is such that the ion concentration of the stock solution D in the stock solution chamber 6 is 1.0 mass% iodine ion, 1.9 mass% chlorine ion, 0.6 mass% nitrate ion, and 0.6 mass% bromine ion. And the ion concentration of the concentrate C in the concentration chamber 5 is 12.2% by mass of iodine ions, 0.2% by mass of chloride ions, 0.2% by mass of nitrate ions, and 0.2% by mass of bromine ions, The ion concentration of the acid solution A in the acid chamber 7 was 0.1% by mass of sulfate ions, and the ion concentration of the salt solution S in the salt chamber 8 was 5.7% by mass of sulfate ions.

As a result, the transmittance from the stock solution D to the concentrated solution C was 90% for iodine ions, 24% for bromine ions, 20% for nitrate ions, and 9% for chlorine ions.
[Reference Example 3]
The same electrodialysis tank 1, cation exchange membrane K, first anion exchange membrane A ₁ , first cation exchange membrane K ₁ , second anion exchange membrane A ₂ , and second as in Reference Example 1 electrodialysis was carried out using a cation exchange membrane K _2. Further, a diiodide compound was produced by iodination reaction using hydroiodic acid and 1,10-diiododecane as the stock solution D, and further obtained by reacting with acetone in the presence of a potassium compound. The product, potassium iodide-containing waste liquid, was used.

  1500 g of potassium iodide-containing waste liquid (including 11% by mass of potassium iodide and 1.7% by mass of potassium sulfate) is supplied as the stock solution D to the stock solution chamber 6, and 700 g of a 1% by weight hydroiodic acid aqueous solution is added to the concentrate C. To the concentrating chamber 5. At the same time, 1000 g of a 5% by mass sulfuric acid aqueous solution was supplied to the acid chamber 7 as the acid solution A, and 500 g of a 1% by mass sodium hydrogen sulfate aqueous solution was supplied to the salt chamber 8 as the salt solution S. Further, 1000 g of a 5% by mass aqueous sodium hydrogen sulfate solution was supplied as the polar liquid P to each electrode chamber 4a, 4b.

  In this state, after performing electrodialysis treatment at a constant voltage of 8.5 V for 2 hours, the liquid volume in each chamber was measured, and the liquid composition in each chamber was measured by ion chromatography.

  The stock solution D in the stock solution chamber 6 had a liquid volume of 1180 g, and ion concentrations of 0.5% by mass of iodine ions and 1.0% by mass of sulfate ions.

  Concentrated liquid C in the concentration chamber 5 had a liquid volume of 940 g, and ion concentrations of 13.2% by mass of iodine ions and 0.2% by mass of sulfate ions.

As a result, the transmittance of iodine ions from the stock solution D to the concentrate C was 93%.
[Example 2]
923 g of hydroiodic acid concentrate (concentration: iodine ion 12% by mass, sulfate ion 0.2% by mass) obtained by concentrating and separating hydroiodic acid from the waste solution by electrodialysis was collected in a three-necked flask, and a nitrogen stream, room temperature And 4.6 g of barium carbonate under stirring.

After stirring for 30 minutes, the precipitated crystals were filtered and washed with a small amount of water to obtain 983 g of filtrate. As a result of analyzing the composition of the filtrate by ion chromatography, iodine ion was 11.3% by mass, and sulfate ion was not detected at all.
[Example 3]
942 g of hydroiodic acid concentrate (composition: 12.3% by mass of iodine ions, 0.1% by mass of chloride ions) obtained by concentrating and separating hydroiodic acid from the waste solution by electrodialysis was transferred to a distillation flask. Distillation after addition of 1.4 g of hypophosphorous acid (H ₃ PO ₂ ), concentration under reduced pressure under a nitrogen stream using a magnetic Raschig packed tower having an inner diameter of 18 mm and a tower height of 1 m did. After separating the first fraction, 170 g of a fraction of 65 ° C. or higher and 66 ° C. or lower was obtained at 50 mmHg. Further, when the obtained fraction was analyzed, the hydroiodic acid concentration was 58% by mass, and no other inorganic salt was found in the analysis by ion chromatography.
[Example 4]
The same electrodialysis tank 1, cation exchange membrane K, first anion exchange membrane A ₁ , first cation exchange membrane K ₁ , second anion exchange membrane A ₂ , and second as in Reference Example 1 electrodialysis was carried out using a cation exchange membrane K _2. Further, as the stock solution D, a waste solution containing iodine ions, sulfate ions and borate ions was used.

  Then, 1300 g of the adjusted model waste liquid (composition: iodine ion 12.6% by mass, sulfate ion 2.0% by mass, chlorine ion 1.0% by mass, boron 1.0% by mass) is supplied to the stock solution chamber 6 as a stock solution D. Then, 720 g of a 1% by mass hydroiodic acid aqueous solution was supplied as a concentrate C to the concentration chamber 5. At the same time, 2294 g of 3.3 mass% sulfuric acid aqueous solution was supplied to the acid chamber 7 as the acid solution A, and 1287 g of 1.7 mass% sodium hydrogen sulfate aqueous solution was supplied to the salt chamber 8 as the salt solution S. Further, 1000 g of a 5% by mass aqueous sodium hydrogen sulfate solution was supplied as the polar liquid P to each electrode chamber 4a, 4b.

  In this state, after performing electrodialysis for 3.3 hours at a constant voltage of 8.5 V, the liquid volume in each chamber is measured, and the liquid composition in each chamber is measured by ion chromatography and an ICP emission spectrometer. did.

  The amount of liquid in each chamber is 1089 g for stock solution D in stock solution chamber 6, 1205 g for concentrate C in concentration chamber 5, 2105 g for acid solution A in acid chamber 7, 1612 g for salt solution S in salt chamber 8, and electrode chamber The extreme liquid P in 4a and 4b was 978 g.

  The ion concentration in each chamber is such that the ion concentration of the stock solution D in the stock solution chamber 6 is 0.9 mass% iodine ion, 2.0 mass% sulfate ion, 0.78 mass% chlorine ion, and 1.2 mass% boron. And the concentration of ions in the concentrate C in the concentration chamber 5 is 13.1% by mass of iodine ions, 0.32% by mass of sulfate ions, 0.38% by mass of chlorine ions, and less than 0.01% by mass of boron. The ion concentration of the acid solution A in the chamber 7 was less than 0.1% by mass of sulfate ions, and the ion concentration of the salt solution S in the salt chamber 8 was 3.8% by mass of sulfate ions.

  As a result, the iodine ion permeability from the stock solution D to the concentrate C was 92%, and the boron removal rate was 99%.

  Next, concentrate C, which is a hydroiodic acid concentrate, was transferred to an Erlenmeyer flask, and 29.8 g of barium carbonate was added at room temperature and with stirring. After stirring for 30 minutes, the solution was allowed to stand overnight to precipitate insolubles. 1003 g of supernatant was obtained.

  As a result of analyzing the composition of the supernatant by ion chromatography, no sulfate ions were detected.

Further, the supernatant was transferred to a distillation flask, 1.0 g of 30% by mass hypophosphorous acid (H ₃ PO ₂ ) was added, and a magnetic Raschig packed tower having an inner diameter of 18 mm and a tower height of 1 m was added. And distilled under reduced pressure under a nitrogen stream and then distilled. After separating the first fraction, 195 g of a fraction of 60 mmHg and 68 ° C. or higher and 70 ° C. or lower was obtained. Further, when the obtained fraction was analyzed, the hydroiodic acid concentration was 58% by mass, and no other inorganic salts were found by ion chromatography analysis .

  The present invention can be used, for example, to recover hydroiodic acid, which is a useful substance because it is used as a raw material for synthesis of various iodine compounds, a reagent for synthesis of medical intermediates, a reducing agent, and the like from a waste liquid.

C Hydroiodic acid D Stock solution as waste

Claims (1)

Four sample chambers from a waste solution produced in a process using at least one of iodine and iodine compound and containing at least one of iodine ions, borate ions, and inorganic anions other than borate ions and organic anions A concentration and separation step of concentration and separation as hydroiodic acid by a double displacement electrodialysis method using an electrodialysis tank incorporated as a set ;
A method for recovering hydroiodic acid from waste liquid, comprising a purification step of purifying the concentrated hydroiodic acid by distillation .

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