JP2010100875A - Methods for oxidizing hypophosphoric acid ion and phosphorous acid ion, method for cleaning electroless nickel plating waste liquid, and method for recycling phosphate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning an electroless nickel plating waste liquid and a method for recovering nickel and a phosphate and recycling them using simple apparatus by a low-cost and effective process by eliminating a problem in the conventional oxidation method for cleaning the electroless nickel plating waste liquid. <P>SOLUTION: The method for cleaning an electroless nickel plating waste liquid comprises: a first step where nickel ions are separated from an electroless nickel plating waste liquid; a second step where hypophosphoric acid ions in a separate liquid obtained in the first step are oxidized into phosphorous acid ions by an oxidation catalyst; a third step where the phosphorous acid ions obtained in the second step are oxidized into orthophosphoric acid ions by an oxidation catalyst; and a fourth step where the orthophosphoric acid ions obtained in the third step are converted into a phosphate, which is subjected to filtering/separating, thus is cleaned into a waste liquid having a phosphorous concentration of ≤16 mg//l, and the phosphoric acid is recovered as a phosphate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for purifying electroless nickel plating waste liquor, and more specifically, separates nickel ions remaining in electroless nickel plating waste liquor and recovers resources, and the separation liquor is used to remove hypophosphite ions from phosphorous acid. Phosphorus ion by oxidizing phosphorous acid ion into positive phosphate ion using an oxidation catalyst, and then precipitating the normal phosphate ion as phosphate using alkaline earth metal compound and separating by filtration. The present invention relates to a method of purifying waste liquid of 16 mg / l or less and recovering the precipitate as phosphorus resources.

  As is well known, hypophosphorous acid and phosphite ions are contained in large amounts in electroless nickel plating wastewater, but phosphorus compounds contribute to environmental eutrophication such as lakes and closed waters. Therefore, the outflow of phosphorus from the plating process is strictly regulated year by year (in accordance with the ministerial ordinance for establishing drainage standards (Prime Ministerial Ordinance No. 35 on June 21, 1971)) ) Has been established, and the development of a high-performance purification method is awaited.

  On the other hand, since phosphorus is a precious resource, effective utilization of phosphorus-containing waste liquid is required, and a method of recycling resources by oxidizing hypophosphorous acid and phosphite ions into normal phosphate ions is also considered. It has been.

  For example, Patent Document 1 describes a method in which a copper salt is added to a plating waste solution containing hypophosphite ions and heated to oxidize them to phosphite ions. Patent Document 2 describes a method in which a boron-nickel compound is brought into contact with an aqueous solution containing hypophosphite ions and oxidized to phosphite ions. Patent Document 3 describes a method in which metal palladium is brought into contact with an aqueous solution containing hypophosphite ions to oxidize them to phosphite ions. Patent Document 4 describes a method for producing phosphoric acid by reacting a waste liquid containing phosphonic acid and / or phosphinic acid with hydrogen peroxide in the presence of tungstate ion and / or molybdate ion. . Patent Document 5 discloses that after adding hydrogen peroxide to a plating waste solution containing phosphorous acid and / or hypophosphorous acid, ultraviolet light is irradiated to convert phosphorous acid and / or hypophosphorous acid into normal phosphoric acid. Is described. Patent Document 6 discloses a hydrothermal reaction treatment in a pressure-resistant sealed container in the presence of at least one metal ion selected from nickel ions, cobalt ions, and copper ions, and hypophosphite ions and phosphite ions. A method is described in which is oxidized to normal phosphate ions. In Patent Document 7, an electroless nickel plating waste solution is brought into contact with a chelate resin to adsorb and separate nickel from the nickel complex. The adsorbed and separated nickel is eluted and recovered with an acid, and the waste solution after nickel separation is in the presence of ozone. A method is described in which an organic acid is decomposed into water and carbon dioxide gas by ultraviolet irradiation with a high-pressure mercury lamp, hypophosphorous acid and phosphorous acid are oxidized, and then a precipitant is added and recovered as a phosphate. Patent Document 8 discloses that a metal salt and sodium hypophosphite in a high-concentration plating waste liquid are decomposed using a catalyst selected from the group consisting of metals of Group 8 of the Periodic Table of Elements and compounds thereof. Next, a method of oxidizing and decomposing organic acid and sodium phosphite in a high concentration waste liquid using a sodium hypochlorite-based oxidizing agent is described. Patent Document 9 discloses that an electroless plating reaction is caused by contact between an electroless nickel plating aging solution and nickel powder, nickel ions in the aging solution are separated and recovered as nickel metal, and gypsum or mineral acid is separated into the separated mother liquor. And slaked lime are used to separate and recover the phosphite as calcium phosphite.

JP 58-119389 A JP-A-6-263414 Japanese Patent Application Laid-Open No. 6-279209 JP-A-1-310793 JP-A-4-338284 JP-A-10-85769 Japanese Patent Laid-Open No. 11-226596 JP 61-120688 A Japanese Patent Laid-Open No. 9-176861

  However, in the conventional method described above, it has been difficult to efficiently generate normal phosphate ions in a short time and at low cost by oxidizing a waste liquid containing high concentration hypophosphorous acid or phosphite ions. . In addition, the conventional method has a large cost burden on chemicals and electric power to be used, and has a problem that a special reactor is required, so that it is difficult to say that the method is satisfactory.

  That is, Patent Document 1 (Japanese Patent Laid-Open No. 58-119389) using a copper salt as an oxidizing agent, Patent Document 2 (Japanese Patent Laid-Open No. 6-263414) using a boron-nickel compound catalyst, and a metal palladium catalyst. In the above-mentioned Patent Document 3 (Japanese Patent Laid-Open No. Hei 6-279209) using phosphite, hypophosphite ions can be oxidized to phosphite ions, but oxidation to regular phosphate ions is difficult.

  In Patent Document 4 (Japanese Patent Laid-Open No. 1-310793), it is necessary to add a large amount of hydrogen peroxide as an oxidizing agent and tungstate and / or molybdate ions as a catalyst, which only increases the processing cost. Rather, oxidation from phosphorous acid and / or hypophosphite ions to positive phosphate ions is not sufficient.

  In the above-mentioned patent document 5 (Japanese Patent Laid-Open No. 4-338284), not only hydrogen peroxide as an oxidizing agent but also ultraviolet irradiation is performed, not only the apparatus and the processing cost are increased, but also phosphorous acid and / or Oxidation from hypophosphite ions to positive phosphate ions is not sufficient.

  In Patent Document 6 (Japanese Patent Laid-Open No. 10-85769), hypophosphorous acid and phosphite ions can be oxidized into normal phosphate ions, but in a heat-resistant sealed container in the presence of metal ions such as nickel. Since the hydrothermal reaction is performed at a high temperature, the initial cost of the apparatus is high, and the reaction time is long, which is not economical.

  In Patent Document 7 (Japanese Patent Laid-Open No. 11-226596), the waste liquid containing hypophosphorous acid, phosphite ions and organic acid after nickel separation is treated by ultraviolet irradiation with a high-pressure mercury lamp in the presence of ozone. For this reason, the running cost such as the initial cost of the apparatus and the ultraviolet power becomes high, which is not economical.

  In Patent Document 8 (Japanese Patent Laid-Open No. 61-120688), a catalyst selected from the group consisting of metals of Group 8 of the periodic table and compounds thereof and a sodium hypochlorite-based oxidizing agent are used. In addition to high drug costs, oxidation to phosphorous acid and positive phosphate ions is not sufficient, and processing time is long.

  In Patent Document 9 (Japanese Patent Laid-Open No. 9-176661), electroless plating reaction is caused by contact with an electroless nickel plating aging solution and nickel powder to separate and recover nickel ions as nickel metal, and hypophosphorous acid. Ions can be oxidized to phosphite ions, but oxidation to phosphite ions is not sufficient, and oxidation to normal phosphate is difficult.

  As a result of various experiments on the treatment of electroless nickel plating waste liquid using hypophosphite as a reducing agent, the present inventors are composed of boron and nickel in the waste liquid containing hypophosphorous acid and phosphite ions. The present invention has been completed by discovering that the coexistence of colloidal particles of an amorphous compound can effectively oxidize normal phosphate ions.

  The present invention solves the problems such as oxidation of hypophosphorous acid and phosphite ions of the conventional method, purifies the electroless nickel plating waste liquid by a low-cost and effective method using a simple apparatus, The purpose is to provide a method for recycling.

  The technical problem can be achieved by the present invention as follows.

  That is, the present invention provides an aqueous solution containing hypophosphite ions in an amorphous state composed of boron and nickel under the conditions that the pH value of the aqueous solution is 7.0 to 11.0 and the temperature is 15 to 80 ° C. This is a method for oxidizing hypophosphite ions in which hypophosphite ions are oxidized to phosphite ions by contacting with colloidal particles of the compound (Invention 1).

  Further, the present invention provides an aqueous solution containing phosphite ions, an amorphous compound comprising boron and nickel under the conditions that the pH value of the aqueous solution is 2.0 to 5.0 and the temperature is 80 to 100 ° C. This is a method for oxidizing phosphite ions, wherein the phosphite ions are oxidized into normal phosphate ions by contacting with the colloidal particles (present invention 2).

  The present invention also provides a first step of separating nickel ions from the electroless nickel plating waste liquid, and a step of oxidizing hypophosphite ions in the separated liquid obtained in the first step to phosphite ions using an oxidation catalyst. The second step, the third step of oxidizing the phosphite ion obtained in the second step to the normal phosphate ion by the oxidation catalyst, and the conversion of the normal phosphate ion obtained in the third step to phosphate It is a purification method of electroless nickel plating waste liquid characterized by comprising a fourth step of purifying the wastewater having a phosphorous concentration of 16 mg / l or less by filtration separation and recovering phosphoric acid as a phosphate ( Invention 3).

  Further, according to the present invention, there is provided an electroless nickel plating waste solution according to the present invention in which the nickel ion separation method in the first step uses a selective heavy metal chelate resin to adsorb and separate nickel ions and elute the adsorbed nickel ions. (Invention 4).

  Further, the present invention is a method in which the hypophosphite ion oxidation method in the second step is a method in which the aqueous solution is brought into contact with an oxidation catalyst at a pH value of 7.0 to 11.0 and a temperature of 15 to 80 ° C. 3. A method for purifying an electroless nickel plating waste liquid according to 3 or 4 (Invention 5).

  In addition, the present invention is a method in which the oxidation method of phosphite ions in the third step is a method in which the aqueous solution is brought into contact with an oxidation catalyst at a pH value of 2.0 to 5.0 and a temperature of 80 to 100 ° C. (5) A method for purifying an electroless nickel plating waste liquid according to (5) to (5).

  In the present invention, the method of converting to phosphate in the fourth step is a method in which phosphate is precipitated using an alkaline earth metal compound and the solid-liquid separated phosphate is recycled. It is the purification method of the electroless nickel plating waste liquid of the invention 3-6 (this invention 7).

  Moreover, this invention is the purification method of the electroless nickel plating waste liquid of this invention 3-7 used by making the support | carrier carry | support the oxidation catalyst used in a 2nd process and a 3rd process (this invention 8).

  Moreover, this invention is the purification method of the electroless nickel plating waste liquid of this invention 3-8 whose oxidation catalyst is a colloidal particle of the amorphous compound which consists of boron and nickel (this invention 9).

  In the present invention, the addition amount of colloidal particles of amorphous compound composed of boron and nickel used in the second and third steps is 0.04 to 1.0 mol / l in terms of Ni. 9 is a method for purifying an electroless nickel plating waste liquid according to 9 (Invention 10).

  Moreover, this invention is a method of using the phosphate collect | recovered by the purification method of the electroless nickel plating waste liquid in any one of this invention 3-10 as a recycled resource (this invention 11).

  According to the method of the present invention, it is possible to easily oxidize hypophosphite ions and phosphite ions of the electroless nickel plating waste liquid, which has heretofore been difficult, into normal phosphate ions. The phosphorus-containing waste liquid from can be highly purified. In addition, the method of the present invention contributes to the recovery of nickel and phosphorus from plating waste liquid that was a source of environmental pollution.

  The configuration of the present invention will be described in more detail as follows.

  First, the oxidation catalyst for hypophosphite ions and phosphite ions according to the present invention will be described.

The oxidation catalyst used in the present invention is prepared by precipitating colloidal particles obtained by allowing a reducing agent such as dimethylamine borane or NaBH ₄ to act on an aqueous solution containing nickel ions, sufficiently washed with water, and filtered to obtain boron. A colloidal particle of an amorphous compound composed of nickel.
Since the amorphous compound composed of boron and nickel is amorphous, a diffraction peak does not appear in X-ray diffraction measurement, but a broad peak (latent crystal) of metallic nickel may be detected. Further, when a peak of a nickel compound such as highly crystalline nickel hydroxide, nickel carbonate, or basic nickel carbonate appears, the catalytic activity is significantly reduced.
The molar ratio of boron to nickel (B / Ni) when the amorphous compound composed of boron and nickel is acid-dissolved and elemental determination is performed using atomic absorption spectrometry or ICP emission spectroscopy is 0.4 to It is preferable to be 0.6.

  The amorphous compound colloidal particles comprising boron and nickel are preferably used in the form of a paste containing moisture. When dried, the surface of the colloidal particles is oxidized to form a hydroxide or carbonate, and the catalytic activity is deactivated.

  In producing colloidal particles of an amorphous compound composed of boron and nickel, a soluble salt such as nickel sulfate or nickel chloride can be used as the nickel raw material used in the aqueous solution containing nickel ions.

  In producing colloidal particles of an amorphous compound composed of boron and nickel, nickel is prepared so that the Ni concentration of the colloidal aqueous solution obtained by mixing and contacting the nickel ion aqueous solution and the reducing agent is 0.25 to 1.0 mol / l. It is preferable to adjust the concentration of the ionic aqueous solution. When the amount is less than 0.25 mol / l, amorphous colloidal particles are hardly obtained. When the amount exceeds 1.0 mol / l, the catalytic activity is lowered due to secondary aggregation of the colloidal particles. A more preferable Ni concentration is 0.30 to 1.0 mol / l.

  In producing colloidal particles of an amorphous compound composed of boron and nickel, the amount of the reducing agent added to the aqueous solution containing nickel ions is preferably 0.5 to 2.5 mol with respect to 1 mol of nickel. When the amount is less than 0.5 mol, nickel ions are not sufficiently reduced. When the amount exceeds 2.5 mol, an amorphous compound composed of boron and nickel cannot be obtained. The reducing agent can be added in the form of powder and aqueous solution.

  Next, the purification method of the electroless nickel plating waste liquid according to the present invention 3 to 10 will be described.

  In the electroless nickel plating waste liquid purification method according to the present invention 3 to 10, the target electroless nickel plating waste liquid is an electroless nickel plating liquid using a hypophosphite such as sodium hypophosphite as a reducing agent. Waste liquid. That is, as electroless nickel plating proceeds, hypophosphite, which is a reducing agent in the electroless nickel plating solution that has been built, is oxidized to phosphite, and when this phosphite ion gradually increases, plating occurs. Since the function is deteriorated, it is a waste liquid to be discarded despite containing a considerable amount of nickel ions.

  In the method of purifying electroless nickel plating waste liquid according to the present invention, the first step is a step of separating nickel ions from the electroless nickel plating waste liquid, and the nickel ions are adsorbed and separated using a selective heavy metal chelate resin. It elutes nickel ions.

  In the first step of the present inventions 3 to 10, the nickel ion adsorption resin introduces a functional group such as an iminodiacetic acid type or an iminopropionic acid type into a chelate resin having a metal selectivity function, such as a styrene-divinylbenzene copolymer. Resin etc. which can be used can be used.

Nickel ions can be adsorbed and separated by filling the chelate resin into a column apparatus and passing the electroless nickel plating waste liquid. The conditions for passing through the column apparatus filled with the chelate resin are preferably a nickel concentration of 1 g / l or less, a pH of 3.0 to 6.0, and an SV (space flow rate) of 30 h ⁻¹ or less.

In the first step according to the present inventions 3 to 10, after nickel ions are adsorbed to the chelate resin, the chelate resin is then brought into contact with an acid solution to elute the nickel ions to be recycled. As a recycling method, it is preferable to add a step of adding oxalic acid to the eluted nickel ions to generate nickel oxalate, followed by solid-liquid separation and recovery.
A known method can be used as the treatment method in which the chelate resin having adsorbed nickel ions is brought into contact with an acid solution to elute the nickel ions and the treatment method in which oxalic acid is added to produce nickel oxalate.

  In the method for purifying electroless nickel plating waste liquid according to the present invention, the second step is a step of oxidizing hypophosphite ions in the separated liquid obtained in the first step into phosphite ions using an oxidation catalyst.

  In the second step of the present invention 3 to 10, the hypophosphite ion concentration in the separation liquid is preferably 10 to 40 g / l, more preferably 10 to 35 g / l, and still more preferably 10 to 30 g / l. . What is necessary is just to dilute or concentrate so that it may become a desired density | concentration as needed.

In order to oxidize hypophosphite ions in the second step of the present invention 3 to 10 to phosphite ions, the pH value of an aqueous solution containing hypophosphite ions using an alkali metal hydroxide such as sodium hydroxide Is adjusted to 7.0 to 11.0, and the aqueous solution temperature is set to 15 to 80 ° C. Then, colloidal particles of an amorphous compound composed of boron and nickel may be added and mixed by stirring. When the pH value of the aqueous solution is less than 7.0 or exceeds 11.0, it is difficult to proceed with the oxidation reaction of hypophosphite ions. A preferable pH value range is 7.0 to 10.0.
If the aqueous solution temperature is 15 ° C. or higher, an oxidation reaction of hypophosphite ions occurs. It is not necessary to perform the oxidation reaction at a temperature exceeding 80 ° C., and a preferable temperature range is 20 to 50 ° C.

  The conditions of the hypophosphite ion oxidation method according to the present invention 1 are the same as the treatment conditions of the second step in the electroless nickel plating waste liquid purification method according to the present invention.

  In the method for purifying electroless nickel plating waste liquid according to the present invention, the third step is a step of oxidizing the phosphite ions obtained in the second step into normal phosphate ions by an oxidation catalyst.

  In the third step of the present invention 3 to 10, the phosphite ion concentration in the aqueous solution is preferably 20 to 120 g / l, more preferably 30 to 100 g / l, and further preferably 30 to 80 g / l. What is necessary is just to dilute or concentrate so that it may become a desired density | concentration as needed.

  In order to oxidize phosphite ions to normal phosphate ions in the third step of the present invention 3 to 10, the pH value of an aqueous solution containing phosphite ions using mineral acid such as sulfuric acid is set to 2.0 to 5. The colloidal particles of an amorphous compound composed of boron and nickel may be added and stirred and mixed while adjusting the temperature to 0 and heating the aqueous solution temperature to 80 to 100 ° C. When the pH value of the aqueous solution is less than 2.0, the colloidal particles of the amorphous compound composed of boron and nickel dissolve and lose catalytic activity. When the pH value exceeds 5.0, the oxidation reaction of phosphite ions proceeds It becomes difficult. A preferable pH value range of the aqueous solution is 2.5 to 4.5. Further, if the heating temperature is less than 80 ° C., the oxidation rate is slow, and it is not preferable to perform the oxidation reaction at a temperature exceeding 100 ° C. because a special oxidizer is required. A preferable heating temperature range is 90 to 100 ° C.

  The conditions for the phosphite ion oxidation method according to the second aspect of the present invention are the same as the treatment conditions for the third step in the electroless nickel plating waste liquid purification method according to the present invention.

  The oxidation catalyst used in the second step and the third step of the present inventions 3 to 10 uses colloidal particles of an amorphous compound composed of boron and nickel of the aforementioned inventions 1 and 2.

  The amount of colloidal particles of amorphous compound composed of boron and nickel used in the second step and the third step is 0.04 to 1.0 mol / in colloidal particle of amorphous compound composed of boron and nickel. What is necessary is just to add so that it may become l. When the amount of the colloidal particles of the amorphous compound composed of boron and nickel is less than 0.04 mol / l, the oxidation reaction hardly occurs. In the case of exceeding 1.0 mol / l, the catalytic activity decreases. A more preferable range of the addition amount is 0.08 to 0.80 mol / l.

  The colloidal particles of the amorphous compound composed of boron and nickel can be reused by filtration separation and recovery from the aqueous solution in which the production of normal phosphate ions is completed in the third step.

  In addition, it is convenient to use colloidal particles of an amorphous compound composed of boron and nickel supported on a support such as activated carbon, alumina, diatomaceous earth, or ferrite because filtration and separation can be facilitated during recycling.

  In the purification method of electroless nickel plating waste liquid according to the present invention, the fourth step is a step of converting the normal phosphate ion obtained in the third step into a phosphate and filtering and separating the alkaline earth metal compound. It is used for precipitation of phosphate, solid-liquid separation and recovery of phosphate for recycling.

As the alkaline earth metal compound used in the fourth steps of the present inventions 3 to 10, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide are used. As a method of using the alkaline earth metal compound, it may be added to an aqueous solution containing normal phosphate ions, mixed with stirring, and then solid-liquid separated.
The addition amount of the alkaline earth metal compound used in the fourth step is preferably 1 to 2 molar equivalents relative to phosphorus.

  The waste liquid that has undergone the fourth step can make phosphate ions in the solution 16 mg / l or less in terms of P.

  After the obtained phosphate precipitate is solid-liquid separated by a known method, the phosphate can be recovered as a resource simultaneously with the purified waste liquid.

<Action>
The important point in the present invention is that the amorphous (amorphous) compound colloidal particles composed of boron and nickel are brought into contact with an aqueous solution containing hypophosphite ions and phosphite ions under specific conditions. These are the fact that they can be efficiently oxidized to phosphite ions and phosphate ions, respectively.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, it cannot be overemphasized that the scope of the present invention is not limited to these Examples.

  The concentrations of hypophosphite ion, phosphite ion and phosphate ion in the solution were analyzed by “Ion Chromatography ICA-2000 (Toago DKK Co., Ltd.)”.

The contents of nickel and boron in the oxidation catalyst were determined by dissolving the oxidation catalyst powder with hydrochloric acid and measuring with “Plasma emission spectroscopic analyzer iCAP6500 (Thermo Electron Co., Ltd.)”.
Identification of the crystal phase of the oxidation catalyst was performed using an “X-ray diffractometer RINT2500 (manufactured by Rigaku Corporation)” (tube: Cu).

  In the practical test, a four-necked flask with a volume of 300 ml or 1000 ml was used, a reflux condenser was attached to condense the evaporated water vapor, the aqueous solution was stirred with a magnetic stirrer, and the heating was equipped with a temperature control device. A water bath was used.

  Colloidal particles of an amorphous compound composed of boron and nickel were prepared in advance as described below and subjected to an implementation test. Water used was ion exchange water.

<Preparation of Amorphous Compound Colloidal Particles 1 Consisting of Boron and Nickel>
A colloidal solution was prepared by adding 50 ml of an aqueous solution containing 0.14 mol of sodium borohydride to 200 ml of an aqueous solution containing 0.076 mol of reagent-grade nickel chloride hexahydrate while stirring. At this time, the molar ratio of the reducing agent to the nickel salt (reducing agent / Ni) was 1.8. The produced colloidal solution is allowed to settle, and centrifuged using a centrifuge at a rotational speed of 2000 rpm for 5 minutes. Then, the supernatant is discarded, and ion-exchanged water is added to the washed product, which is centrifuged again and pasted. Shaped colloidal particles were obtained.
As a result of X-ray diffraction measurement of the colloidal particles in an undried state, a broad peak corresponding to metallic nickel as shown in FIG. 1 was confirmed. As a result of element quantification by ICP, the molar ratio of B / Ni was 0.50. From the above results, it was confirmed to be colloidal particles of an amorphous (amorphous) compound composed of boron and nickel.

<Preparation of colloidal particles 2 to 7 of amorphous compound composed of boron and nickel>
Colloidal particles 1 composed of the amorphous nickel compound, except that the raw material nickel salt type and concentration, the reducing agent type and concentration, and the resulting colloidal particles were dried or not (paste, powder) were changed. Colloidal particles were prepared under the same conditions.

  Table 1 shows the preparation conditions at this time and the properties of the obtained colloidal particles. Moreover, the X-ray-diffraction measurement result of the colloidal particle 6 is shown in FIG. The colloidal particles 6 were confirmed to have broad peaks corresponding to metallic nickel and basic nickel carbonate peaks.

<Preparation of aqueous solution containing hypophosphite ions>
A reagent-grade sodium hypophosphite monohydrate was dissolved in ion-exchanged water to prepare a 3% PO ₂ aqueous solution.

<Example 1>
100 ml of a 3% PO ₂ aqueous solution was weighed into a 200 ml beaker, and sodium hydroxide was added to this aqueous solution to adjust the pH to 7.0, and then the solution was put into a four-necked flask. While stirring with a magnetic stirrer at a liquid temperature of 25 ° C., 1 g (corresponding to 0.17 mol / l) of colloidal particles 1 of an amorphous compound composed of boron and nickel was added in terms of nickel. Bubbles were generated immediately after the addition and the reaction proceeded.
The bubbles were collected by the water displacement method and analyzed by gas chromatography. As a result, the generated gas was hydrogen gas. Gas generation decreased with the passage of time, and gas generation stopped when 60 minutes passed.

On the other hand, PO ₂ was analyzed by ion chromatography by sampling every elapsed time. The results are shown in Table 2. Table 2 shows that PO ₂ decreased with the passage of time and the oxidation reaction was completed after 60 minutes. Since this coincided with the time when the generation of hydrogen gas was stopped, the colloidal particles 1 of an amorphous compound composed of boron and nickel have a catalytic action to decompose water in the presence of hypophosphorous acid. found.
The aqueous solution after completion of the oxidation reaction was separated and recovered into an amorphous compound colloidal particle 1 composed of boron and nickel and an aqueous phosphorous acid solution using a centrifugal separator.

<Example 2>
An oxidation reaction of a hypophosphite ion aqueous solution was carried out in the same manner as in Example 1, except that the amorphous compound colloidal particles 1 composed of boron and nickel collected in Example 1 were added as an oxidation catalyst. Similar to the result of Example 1, the oxidation reaction was completed in 60 minutes. Thereby, the catalytic action of the additive was confirmed.

<Examples 3 and 4, Comparative Examples 1 and 2>
An oxidation reaction of a hypophosphite ion aqueous solution was performed under the same conditions as in Example 1 except that the type of colloidal particles of the amorphous compound composed of boron and nickel was changed. The results are shown in Table 3.

<Examples 5 to 9, Comparative Examples 3 and 4>
An oxidation reaction of the hypophosphite ion-containing aqueous solution was performed under the same conditions as in Example 1 except that the pH value was changed. The results of the oxidation reaction are shown in Table 4. From Table 4, it was confirmed that the pH range for rapid reaction was 7.0 to 10.

<Examples 10 to 12>
An oxidation reaction of the hypophosphite ion-containing aqueous solution was performed under the same conditions as in Example 1 except that the addition amount of the colloidal particles 1 of the amorphous compound composed of boron and nickel was changed. The results of the oxidation reaction are shown in Table 5. From Table 5, as shown in Example 11, the oxidation reaction has occurred sufficiently when the added amount of the colloidal particles 1 of the amorphous compound composed of boron and nickel is 0.4 mol / l in terms of Ni. Is shown. Further, according to Example 10, the reaction sufficiently proceeded even at 0.04 mol / l. It has been shown that adding 0.80 mol / l or more is not economical.

<Preparation of aqueous solution containing phosphite ions>
A 3% PO ₃ aqueous solution was prepared by dissolving reagent-grade disodium phosphite pentahydrate in ion-exchanged water.

<Example 13>
100 ml of a 3% PO ₃ aqueous solution was weighed in a 200 ml beaker, sulfuric acid was added to the aqueous solution to adjust the pH to 4.5, and then the solution was put into a four-necked flask. The flask was placed in a water bath, and the aqueous solution temperature was heated to 90 ° C. while stirring with a magnetic stirrer. The generated water vapor was condensed using a reflux condenser. When the heating temperature reached 90 ° C., 1.0 g (corresponding to 0.17 mol / l) of colloidal particles 2 of an amorphous compound composed of boron and nickel was added in terms of Ni. Bubbles were generated immediately after the addition and the reaction proceeded.
The bubbles were collected by the water displacement method and analyzed by gas chromatography. As a result, the generated gas was hydrogen gas. Gas generation decreased with the passage of time, and gas generation stopped when 360 minutes passed.
On the other hand, the amount of phosphite ions was sampled at each elapsed time and analyzed by ion chromatography. The results are shown in Table 6. Table 6 shows that phosphite ions decreased with the passage of time, and that the oxidation reaction was completed after 360 minutes. Since this coincided with when the generation of hydrogen gas stopped, the colloidal particles 2 of the amorphous compound composed of boron and nickel have a catalytic action of decomposing water in the presence of phosphite ions. found.
The aqueous solution after completion of the oxidation reaction was recovered by separating it into a colloidal particle 2 of amorphous compound composed of boron and nickel and a normal phosphate ion aqueous solution by a centrifugal separator.

<Example 14>
The phosphite ion aqueous solution was oxidized under the same conditions as in Example 13, except that the amorphous compound colloidal particles 2 composed of boron and nickel collected in Example 13 were added. Similar to the result of Example 13, the oxidation reaction was completed in 360 minutes. The catalytic action of the additive was confirmed.

<Examples 15 and 16, Comparative Examples 5 and 6>
The phosphite ion aqueous solution was oxidized under the same conditions as in Example 13 except that the type of colloidal particles of the amorphous compound composed of boron and nickel was changed. The results are shown in Table 7.

<Example 17>
The aqueous solution of normal phosphate ions recovered in Example 13 was collected in a 300 ml beaker, 1 equivalent of calcium chloride was added to phosphorus PO _{4 in} this aqueous solution, and the pH value was adjusted to 10.0 with an aqueous calcium hydroxide solution. The mixture was adjusted and stirred for 30 minutes to obtain a white precipitate. Next, this white precipitate was subjected to suction filtration with Nutsche using an analytical filter paper (5C). The filtrate was clear and the phosphorus concentration was 5 mg / l. The result of chemical analysis after drying the white precipitate was calcium phosphate. From this, it was confirmed that the normal phosphate ion aqueous solution was recovered as a solid phosphate, and the wastewater could be purified to a phosphorus concentration of 10 mg / l or less.

<Examples 18 to 20>
The phosphite ion-containing aqueous solution was oxidized under the same conditions as in Example 13 except that the pH value of the aqueous solution was changed. The results of the oxidation reaction are shown in Table 8. As Table 8 shows, the reaction proceeds rapidly at pH values of 2.5 and 4.0, but when the pH value reaches 5.0, the oxidation reaction takes time. Therefore, it was shown that increasing the pH value beyond 5.0 is not preferable because the reaction time becomes longer.

<Examples 21 to 23>
The phosphite ion-containing aqueous solution was oxidized under the same conditions as in Example 13 except that the addition amount of the colloidal particles 2 of the amorphous compound composed of boron and nickel was changed. The results of the oxidation reaction are shown in Table 9. As shown in Example 9 from Table 9, the oxidation reaction was confirmed to occur sufficiently when the added amount of the colloidal particles 2 of the amorphous compound composed of boron and nickel was 0.4 mol / l in terms of Ni. Show. Further, according to Example 21, the reaction was sufficiently advanced even at 0.04 mol / l. Even when 0.80 mol / l was added, the reaction time was about the same as in Example 22, indicating that adding over 0.80 mol / l was not economical.

<Comparative Example 7>
The aqueous solution containing hypophosphite ions under the same conditions as in Example 1 except that the amount of colloidal particles 1 of amorphous compound composed of boron and nickel was 0.06 g (equivalent to 0.01 mol / l) in terms of Ni. An oxidation reaction was performed. The solution after 60 minutes was sampled and analyzed for phosphorus concentration. As a result, the hypophosphite ion concentration was 21300 mg / l.
This was about 70% of the stock solution concentration, indicating that the oxidation reaction was slow.

<Comparative Example 8>
The phosphite ion-containing aqueous solution was oxidized under the same conditions as in Example 13 except that the heating temperature was 50 ° C. When the heating temperature reached 50 ° C., colloidal particles 2 of amorphous compound composed of boron and nickel were added, but no foaming phenomenon occurred. Foaming occurred slightly after 120 minutes. The liquid after 240 minutes was sampled to analyze phosphorus. As a result, 29000 mg / l of phosphite ion still remained. Since this value is not much different from the stock solution concentration (30000 mg / l), it was shown that the oxidation reaction does not proceed at a heating temperature of 50 ° C.

<Comparative Example 9>
An oxidation reaction of the aqueous solution containing phosphite ions was performed under the same conditions as in Example 13 except that the pH value was 7.0. The solution after 360 minutes was sampled and analyzed for phosphorus concentration. As a result, the phosphite ion was 22000 mg / l, which is about 75% of the stock solution concentration. A pH value of 7.0 indicated that the oxidation reaction proceeded very slowly.

<Comparative Example 10>
Oxidation of an aqueous solution containing phosphite ions under the same conditions as in Example 13 except that the amount of colloidal particles 2 of amorphous compound composed of boron and nickel was 0.06 g (equivalent to 0.01 mol / l) in terms of Ni. Reaction was performed. The solution after 360 minutes was sampled and analyzed for phosphorus concentration. As a result, the phosphite ion concentration was 25500 mg / l. This was 85% of the concentration of the stock solution, indicating that the oxidation reaction was not progressing.

<Example 24> An example waste liquid composition using an electroless nickel plating waste liquid is as follows.
PO ₂ : 24800 mg / l
PO ₃ : 42200 mg / l
Ni: 1770 mg / l
Lactic acid: 9400 mg / l
Malic acid: 8900mg / l

First step:
Chelating resin regeneration process (A)
1 l of selective heavy metal chelate resin (brand: Lebatit TP207, manufactured by Bayer (base: polystyrene, exchange group: iminodiacetic acid)) is packed in a column (diameter: 7.5 cm, height: 25 cm), and 10% by weight of sulfuric acid is added. The water flow rate was 5 l / hr, and the water was regenerated to H type by passing 2 l. Next, the extruded water was washed with 7 l of pure water, and it was confirmed that the passing liquid was neutral. Next, using sodium hydroxide having a concentration of 4% by weight, the water flow rate was 5 l / hr, and 1 l was passed through to replace 50% of the H-type resin with Na-type. Next, after extruding and washing with 5 l of pure water, both regenerated resins were stirred and mixed to form an HNa mixed bed type, and a selective heavy metal chelate resin tower was prepared.

Electroless nickel plating waste liquid adjustment process (B)
Collect 5 liters of the waste liquid having the above composition, dilute 3 times with pure water, adjust the pH value to 5.5 with 5 wt% sodium hydroxide solution, and add 15 liters of diluted aqueous solution of electroless nickel plating waste liquid. Got ready.

Nickel ion adsorption process (C)
Using the selective heavy metal chelate resin tower created in step (A), the diluted waste solution of the electroless nickel plating waste solution prepared in step (B) is passed at a rate of 5 l / hr and passes through the selective heavy metal chelate resin. The subsequent nickel concentration was kept below 1 mg / l. The entire amount of the liquid to be treated (diluted aqueous solution of electroless nickel plating waste liquid) was passed through, and then 7 l of pure water was passed through to extrude the liquid to be treated and wash the resin. The treated liquid after passing water and the extrusion liquid were combined to form nickel-treated water.

Second step: A step of oxidizing PO ₂ to PO ₃ using nickel-treated water in the first step.
Sodium hydroxide is added to 1 liter of nickel-treated water obtained in the first step to adjust the pH to 7.0, the temperature is 25 ° C., and the amount of colloidal particles 3 of amorphous compound composed of boron and nickel is changed to Ni. 10 g in terms of conversion was added to carry out an oxidation reaction.

  The results are shown in Table 10.

Third step: A step of continuously oxidizing PO ₃ to PO ₄ using the liquid after the treatment in the second step.
The pH of the liquid 1l after the treatment through the second step was adjusted to 4.5 using sulfuric acid, and an oxidation reaction was performed at a temperature of 90 ° C.
The aqueous solution after completion of the oxidation reaction was allowed to stand, and after removing the supernatant, it was separated into a colloidal particle 3 of amorphous compound composed of boron and nickel and an aqueous solution of normal phosphate ions using a centrifugal separator.

  The results are shown in Table 11.

Fourth step: Waste liquid purification and recovery step 150 ml of the orthophosphate ion aqueous solution recovered in the third step is taken into a 300 ml beaker, and 1 equivalent of calcium chloride is added to PO _{4 in} this aqueous solution, followed by hydroxylation. The pH value was adjusted to 10.0 using an aqueous calcium solution and stirred for 30 minutes to obtain a white precipitate. Next, this white precipitate was subjected to suction filtration with Nutsche using an analytical filter paper (5C). The filtrate was clear and the phosphorus concentration was 8 mg / l. The result of chemical analysis after drying the white precipitate was calcium phosphate. From this, it was confirmed that the electroless nickel plating waste liquid can be purified to a phosphorus concentration of 16 mg / l or less, and that the normal phosphate ion aqueous solution can be recovered as a solid phosphate.

<Comparative Example 11>
Based on Example 24, it carried out on the conditions of Example 24 except that the third step was omitted and calcium chloride was added to the solution after the treatment in the second step. The obtained aqueous solution was analyzed by solid-liquid separation. As a result, the produced precipitate was calcium phosphite, and the residual concentration of phosphorous acid (PO ₃ ) ions in the aqueous solution was 120 mg / l (47 mg / l in terms of P). Therefore, the electroless nickel plating waste liquid could not be purified to a phosphorus concentration of 16 mg / l or less. In addition, the phosphorous acid aqueous solution could not be recovered as a solid normal phosphate.

<Comparative Example 12>
Based on Example 24, in place of the amorphous compound colloidal particles 3 composed of boron and nickel in the third step, nickel powder (average particle size 3 μm, crystallinity) was used to oxidize phosphite ions. Was carried out under the conditions of Example 24. As a result of analyzing the obtained aqueous solution, the phosphite ion concentration did not change from the concentration before the nickel powder was introduced. This indicates that ordinary nickel powder has no ability to oxidize phosphite ions to normal phosphate ions.

It is an X-ray-diffraction pattern of the colloidal particle 1 of the amorphous compound which consists of boron and nickel. It is an X-ray-diffraction pattern of the colloidal particle 6 of the amorphous compound which consists of boron and nickel.

Claims (11)

Contacting an aqueous solution containing hypophosphite ions with colloidal particles of an amorphous compound composed of boron and nickel under the conditions that the pH value of the aqueous solution is 7.0 to 11.0 and the temperature is 15 to 80 ° C. A method of oxidizing hypophosphite ions, wherein hypophosphite ions are oxidized to phosphite ions. An aqueous solution containing phosphite ions is brought into contact with colloidal particles of an amorphous compound composed of boron and nickel under conditions where the aqueous solution has a pH value of 2.0 to 5.0 and a temperature of 80 to 100 ° C. A method of oxidizing phosphite ions, which oxidizes phosphite ions to regular phosphate ions. A first step of separating nickel ions from the electroless nickel plating waste solution, a second step of oxidizing hypophosphite ions in the separated solution obtained in the first step to phosphite ions by an oxidation catalyst, and a second step By oxidizing the phosphite ion obtained in the step into a positive phosphate ion by an oxidation catalyst, and converting the normal phosphate ion obtained in the third step into a phosphate salt and separating by filtration, A method for purifying electroless nickel plating waste liquid, comprising a fourth step of purifying wastewater having a phosphorus concentration of 16 mg / l or less and recovering phosphoric acid as a phosphate. The method for purifying electroless nickel plating waste liquid according to claim 3, wherein the nickel ion separation method in the first step uses a selective heavy metal chelate resin to adsorb and separate nickel ions and elute the adsorbed nickel ions. The method for oxidizing hypophosphite ions in the second step is a method in which the aqueous solution is brought into contact with an oxidation catalyst at a pH value of 7.0 to 11.0 and a temperature of 15 to 80 ° C. Purification method of electroless nickel plating waste liquid. The oxidation method of phosphite ions in the third step is a method of bringing the aqueous solution into contact with an oxidation catalyst at a pH value of 2.0 to 5.0 and a temperature of 80 to 100 ° C. The electroless nickel plating waste liquid purification method of description. The method for converting normal phosphate ions into phosphate in the fourth step is a method for precipitating phosphate using an alkaline earth metal compound and recycling the solid-liquid separated phosphate. The purification method of the electroless nickel plating waste liquid in any one of 3-6. The method for purifying electroless nickel plating waste liquid according to any one of claims 3 to 7, wherein an oxidation catalyst used in the second step and the third step is supported on a carrier. The method for purifying an electroless nickel plating waste liquid according to any one of claims 3 to 8, wherein the oxidation catalyst is colloidal particles of an amorphous compound composed of boron and nickel. The addition amount of the colloidal particle of the amorphous compound consisting of boron and nickel used in the second step and the third step is 0.04 to 1.0 mol / l in terms of Ni. Of electroless nickel plating waste liquid. The method of utilizing the phosphate collect | recovered by the purification method of the electroless nickel plating waste liquid in any one of Claims 3-10 as a resource.

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