JPS6023873B2 - Processing method for waste liquid containing hypophosphite ions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating a waste liquid containing hypophosphite ions, for example, a waste liquid of an electroless nickel plating solution using sodium hypophosphite as a reducing agent.

Conventionally, waste liquid (aging waste liquid, washing waste liquid, etc.) of electroless nickel plating solution using subbox sodium phosphate as a reducing agent was
This method was mainly carried out by removing metal ions, such as nickel ions and phosphite ions, but this method does not easily remove hypophosphate ions from the waste solution, and therefore the phosphorus content and COD in the processing solution are reduced. It was becoming a problem. In this case, it is possible to reduce COO by subjecting the treated liquid to appropriate treatments such as electrolytic oxidation treatment and activated sludge treatment after metal ion removal; however, in reality, the COD concentration in the treated liquid is Since it is very expensive, it takes a considerable amount of time to perform electrolytic oxidation treatment, etc., which is not practical. Therefore,
Therefore, a method for efficiently treating waste liquid containing hypophosphite ions has been desired. As a result of various studies in order to meet the above-mentioned needs, the inventors of the present invention have discovered that hypophosphite ions can be efficiently oxidized by treating waste liquid containing hypophosphite ions with a divalent steel salt such as sulfuric acid steel under acidic conditions. In particular, even when hypophosphate ions and head phosphate ions coexist, oxidation of hypophosphite ions occurs preferentially, thus ensuring that hypophosphite ions are oxidized. Therefore, it was found that it is extremely effective in treating electroless plating solution waste liquid using hypophosphite ion and hypophosphite ion as a reducing agent, in which phosphite ion coexists. Furthermore, by treating the treated solution treated with copper salts with a calcium compound, the sedimentation separation property is very good compared to the case where the treated solution treated with other oxidizing agents is subjected to precipitation treatment, and the filtration property is also extremely high. When treating the waste liquid of non-electro-competitive liquid that produces excellent precipitates and uses hypophosphite ions as a reducing agent, rusting agents are contained in the furnace liquid from which the precipitates are removed. It can be treated by electrolytic oxidation in a very short time, and therefore, by roughly combining treatment with copper salts and treatment with calcium compounds, waste liquid containing hypophosphite ions can be treated efficiently and economically. This discovery led to the present invention. That is, the present invention involves adding a divalent copper salt to a waste solution containing hypophosphite ions and reacting it under acidic conditions, then adding a calcium compound to form a precipitate, and then removing this precipitate. The present invention provides a method for treating waste liquid containing characteristic hypophosphite ions.

The present invention will be explained in detail below.

The waste liquid treatment method according to the present invention is applied to waste liquid containing hypophosphite ions, and is particularly applicable to electroless scale nickel plating solutions using hypophosphite ions such as sodium hypophosphite as a reducing agent. Suitable for waste treatment of electroless plating solutions such as electroless cobalt plating solutions.

In the method of the present invention, divalent steel salt is first added to the waste liquid to be treated and reacted with it, thereby oxidizing hypophosphite ions in the waste liquid, and in particular hypophosphite ions. Even when coexisting with phosphite ions, hypophosphite ions are preferentially oxidized.

On the other hand, even when other treatment agents, such as hydrogen peroxide, chlorate, and ferric chloride, which are known as oxidizing agents, are added, hypophosphite ions are not produced, as shown in the experimental examples described later. It is not effectively oxidized and the purpose of the present invention is not achieved. In addition, hypophosphite ions are preferentially oxidized when hypophosphite ions coexist with phosphite ions. It is not preferable to treat electroless plating waste liquid using hypophosphite ions, which coexist and also contain phosphite ions at a high concentration, as a reducing agent. In the present invention, divalent steel salts such as copper sulfate and steel chloride are preferably used as the steel salt.

Note that the steel salt may be an inorganic steel salt or an organic steel salt. Further, the amount of copper salt added is preferably 0.5 mol or more, more preferably 2/3 mol or more, particularly 0.8 mol or more per 1 mol of hypophosphite ion in the waste liquid. . Hypophosphite ions can be reliably oxidized by adding a copper salt of 0.5 mole or more, more preferably -2/3 mole or more, particularly 0.8 mole or more, based on the hypophosphite ion. can. When a copper salt is added to the waste liquid and reacted, the pH of the waste liquid is acidic, and it is effective to treat the waste liquid preferably at a pH of 3 or lower, particularly at a pH of 2 or lower. Further, since the reaction proceeds relatively quickly even at room temperature, heating the waste liquid is not essential, but by heating the waste liquid, the reaction is completed in a very short time. In this case, the heating temperature is preferably 40°C or higher. Furthermore, copper salts are added to the waste liquid,
During the reaction, it is preferable to drain the waste liquid. In the present invention, after performing the oxidation treatment using the copper salt described above, a calcium compound is added to perform a precipitation treatment to generate a soluble salt of calcium.

In this case, the calcium compound may be any compound as long as it reacts with the phosphorus compound to produce scale-soluble salts, but especially calcium hydroxide, calcium chloride,
It is preferable to use other calcium salts such as calcium sulfate in combination, and by adding a calcium compound, especially a combination of calcium hydroxide and other calcium salts, to a product that has been oxidized with a copper salt.
Sedimentation occurs with a small sedimentation volume and excellent filtration properties. On the other hand, even if magnesium compounds, barium compounds, aluminum compounds, iron compounds, etc. are used, they do not precipitate, or even if they do precipitate, they only produce colloidal substances with poor sedimentation properties and oxidation properties, which defeats the purpose of the present invention. It cannot be achieved. The pH of the precipitation treatment is not necessarily limited, but may be pH 4.
Phosphate ions to be removed precipitate well at pH 5 or higher, especially at pH 5 or higher.

In addition, the more preferable pH range of precipitation treatment is 6 or more, especially 7-12.5. Further, pH adjustment can be carried out using sodium hydroxide or the like, but it is preferable to use calcium hydroxide to adjust the pH. The amount of the calcium compound added is preferably 1 mol or more, more preferably 1.2 mol or more, per 1 mol of the total phosphorus in the waste liquid, so that phosphorus can be satisfactorily precipitated and removed. can.

In this case, in the present invention, as described above, it is preferable to use a mixture of calcium hydroxide and other calcium salts as the calcium compound. When a mixture of calcium hydroxide and other calcium salts is used, the ratio is The amount of calcium hydroxide is the amount used for pH adjustment,
Preferably, the remaining amount is calcium salt. The conditions for the precipitation treatment are not particularly limited, but preferably 60 to 8
It is preferable to perform takahai for 30 to 60 minutes at 0°C.

In the above-mentioned precipitation treatment, the phosphorus content in the waste liquid reacts with calcium and becomes a crystalline precipitate that is easy to settle and has excellent filtration properties. However, if the waste liquid contains metal ions, for example, If the waste liquid is an electroless scaler, metals will also precipitate as hydroxides.

After the precipitation treatment, the precipitate is removed by an appropriate separation method such as solid-liquid separation by sedimentation or treatment using a filter press. In the present invention, since the precipitate has good filtration properties, the separation operation is simple.

Note that if the waste liquid contains rusting agents, such as electroless plating waste liquid, the complexing agent etc. will not be oxidized by the oxidation treatment and precipitation treatment described above, and the furnace liquid after the precipitation treatment will not be oxidized. The COD value inside may not decrease sufficiently (below a certain value).

In this way, if the COD value based on the remaining keying agent in the furnace liquid after the precipitation separation is high, electrolytic oxidation treatment, activated sludge treatment, etc. should be performed after the precipitation is formed or after the generated precipitate is removed. It is preferable to perform treatment. In this case, since the phosphorus content in the waste liquid, especially hypophosphite ions, is removed by treatment with copper salts and precipitation treatment, electrolytic oxidation treatment, activated sludge treatment, etc. can be completed in a relatively short time. for example,
In the case of electrolytic oxidation treatment, the current is 1 to 1/d per so.
It is sufficient to electrolyze for about 0 to 5 q hours. In addition, depending on the case, it is also possible to treat the reactor liquid after Sakai-an separation by mixing it with other wastewater.

As explained above, in the present invention, when treating waste liquid containing hypophosphite ions, hypophosphite ions are given particular priority by first treating it with a divalent copper salt under acidic conditions. By using a calcium compound to precipitate the oxidized and treated steel salts, a precipitate that is very easy to precipitate and has good separability is generated. It is possible to treat waste liquids containing waste extremely efficiently and economically.

Furthermore, when electrolytic oxidation treatment or the like is performed after precipitation separation, it can be easily carried out, and there is no need for long-term electrolysis. Next, an experimental example will be shown.

[Experimental Example 1] 0.5 molar sodium hypophosphite aqueous solution 20 m
Add sulfuric acid to make the pH below 2, and add 0.5 mol/
Add the sulfuric acid water-saving solution to 1 mole of subbox sodium phosphate at a molar ratio of 0.5 to 1.2, and
After heating for 0 minutes, it was filtered in a furnace, and then water was added to the furnace solution to make it 50°C.

Next, the furnace solution was adjusted to pH 9 with sodium hydroxide to precipitate the copper content, and after the furnace was separated, hypophosphite ions (
P02) and phosphite ion (P03) were determined by the iodine method. For comparison, 1 mol/the ferric chloride aqueous solution was added to 20' of the 0.5 mol/the sodium hypophosphite aqueous solution at a molar ratio of 1.0 to 1.5, and the pH was adjusted to 2 with hydrochloric acid. 8000 after adjustment.

The mixture was heated for 30 minutes, and then water was added to bring the temperature to 50°C.

Next, the pH was raised with sodium hydroxide, excess iron was precipitated, and after the furnace solution was regulated, subhead phosphate ions and phosphite ions in the furnace solution were determined by the iodine method. Similarly,
, hydrogen peroxide, and potassium chlorate were also tested.

The results are shown in Table 1.

Table 1 [Experiment Example 2] 0.5 mol/sodium hypophosphite aqueous solution was adjusted to pH 2 or less with sulfuric acid, and 0.5 mol/sodium sulfuric acid steel aqueous solution was added to the sodium hypophosphite aqueous solution in mol ratio of 0.5 mol/sodium hypophosphite aqueous solution to sodium hypophosphite. Add so that the ratio is 0.7 or 0.8, and at 40-80℃, IQ min ~ 6
I worshiped the time heating lamp.

The following operations were carried out in the same manner as in Experimental Example 1, and the results shown in Table 2 were obtained. Table 2 [Experiment Example 3] Sample aqueous solution containing 0.20 mol of sodium hypophosphite/1.0 mol of sodium phosphite and electroless nickel solution using sodium hypophosphite as a reducing agent. Use the waste liquid of the soaking liquid, add sulfuric acid to it to make the ratio less than 2, and then make the molar ratio of 0.5 mol/sulfuric acid steel aqueous solution to sodium phosphate 0.7 or 0.8. In addition,
The mixture was heated at 80°C for 30 minutes.

Thereafter, the same operations as in Experimental Example 1 were carried out, and the results shown in Table 3 were obtained. Table 3 Also for comparison, sodium hypophosphite 0.25 mol/
Sublight sodium chlorate (available chlorine 1306%) was added to a sample aqueous solution containing 1.0 mol of sodium phosphate/sodium phosphate, and after reacting at 80°C for 30 minutes, the solution of sodium phosphate in the Atsushina aqueous solution was added. Acid ion, hypophosphite ion, and phosphate ion concentrations were investigated.

The results are shown in Table 4. Table 4 From the results shown in Tables 1 to 4, it was confirmed that hypohyperphosphate ions could be reliably oxidized to phosphite ions by using steel salt.

On the other hand, even when ferric chloride, hydrogen peroxide, and potassium chlorate are used, hypophosphite ions are not effectively oxidized, and when Jito chlorate is used, hypophosphite ions are not effectively oxidized. It has been found that the coexistence of ion and phosphite ion is undesirable because oxidation of phosphoric acid ion takes precedence. [Experimental Example 2] Various oxidizing agents were added to a sample aqueous solution in which sodium hypophosphite or sodium hypophosphite and sodium phosphite were dissolved, and the reaction was performed under specified conditions. Meat was subjected to broiling to produce a precipitate, and the state of the precipitate, sedimentation volume, and oxidation properties were investigated.

In addition, the toplight solution was collected, and hypophosphite ion, phosphite ion, and phosphate ion were quantified in the same manner as in Experimental Example 1. The results are shown in Table 5. The test methods and evaluation criteria for sedimentation volume and filtration properties are as follows.

A sample was placed in a settling volume measuring cylinder, and the volume of precipitate that settled over a certain period of time was compared.

◎ Very little ○ Little △ Relatively little × Many Furnace turbulence Using a top charge leaf tester, a relative comparison was made based on the amount of furnace liquid at a given time.

◎ Very good ○ Good △ Relatively good It was found that a good precipitate was formed.

In addition, when forming a precipitate with a calcium compound, the pH
It has been confirmed that precipitation can be performed satisfactorily at a ratio of 4.5 or higher, especially 5 or higher.

Examples will be shown below, but the present invention is not limited to the following examples.

〔Example〕

A non-densified Fuji nickel liquid waste liquid having the following composition was treated.

Nickel ion 0.1 mol/Hypophosphite ion 0.535〃Phosphite ion 1.379〃Phosphate ion 0.057〃C〇〇
51900 Misaki no So PH
5. First, sulfuric acid was added to the waste liquid to make the pH below 2, and then 0.8 mol of sulfuric acid steel was added to 1 mol of sodium hypophosphite, and the mixture was reacted for 9 minutes at 60°C. Next, add 1.2 calcium hydroxide to 1 mole of total phosphorus in the waste liquid.
mol, 0.12 mol of calcium chloride added, pH 12
．． 5 After praying for 6G at 8 p.m., it calmed down and was separated from the furnace. The results of analyzing the furnace liquid are as follows.

Nickel ion 0 mol/sequence Phosphate ion 0.001〃Phosphite ion 0.029〃Phosphate ion
0.0003〃COD
After electrolytically oxidizing the above furnace solution under the following conditions, the treated solution was analyzed. The following results were obtained. Fin decomposition oxidation condition sample 500 Z current IA magnetic pole lead peroxide (0. phantom) e platinum wire time 2 anchor time treatment liquid analysis results

Claims (1)

[Claims] 1. Adding a divalent copper salt to a waste solution containing hypophosphite ions and reacting under acidic conditions, adding a calcium compound to form a precipitate, and then removing this precipitate. A method for treating waste liquid containing hypophosphite ions, characterized by: 2 The amount of copper salt added is 0 per mole of hypophosphite ion.
．． The method according to claim 1, wherein the amount is 5 moles or more. 3 The amount of copper salt added is 2 per mole of hypophosphite ion.
3 mol or more.
4. The method according to any one of claims 1 to 3, wherein the copper salt is added at a pH of 2 or less. 5 pH4.5
The method according to any one of claims 1 to 4, wherein a precipitate is produced in the above. 6. The method according to any one of claims 1 to 5, wherein the amount of the calcium compound added is at least an equivalent mole per mole of total phosphorus in the waste liquid. 7. The method according to any one of claims 1 to 6, wherein the calcium compound is a mixture of calcium hydroxide and other calcium salts. 8. The method according to claim 7, wherein the amount of calcium hydroxide used is sufficient to adjust the pH at the time of precipitation formation. 9. The method according to claim 7 or 8, wherein the calcium salt is calcium chloride or calcium sulfate or a mixture thereof. 10. The method according to any one of claims 1 to 9, wherein the waste liquid containing hypophosphite ions is a waste liquid of an electroless plating solution using hypophosphite ions as a reducing agent.