JPS6023874B2 - 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 sub-phosphoric acid ions, for example, a waste liquid of an electroless nickel plating solution using sub-sodium phosphate as a reducing agent.

Conventionally, waste liquid (aging waste liquid, washing waste liquid, etc.) of finless scale nickel plating liquid using subbox sodium phosphate as a reducing agent was
This method was mainly carried out by removing metal ions, such as nickel ions and hypophosphite ions, but this method does not easily remove hypophosphite ions from the waste liquid, and therefore the phosphorus content and COD in the treated liquid are difficult to remove. was becoming a problem.
In this case, after removing metal ions, the treatment solution is subjected to electroless oxidation treatment.
COD can be reduced by applying appropriate treatment such as activated sludge treatment.
Although it is possible to reduce the COD concentration in the treatment liquid, in reality, the COD concentration in the treatment liquid is very high, so it would take a considerable amount of time to perform an electrolytic oxidation treatment or the like, which is not practical. Therefore, there has been a desire for a method for efficiently treating waste liquids containing hypo-lotus phosphate ions. The present invention was developed as a result of various studies in order to meet the above-mentioned needs.When waste liquid containing hypophosphite ions is treated with a persulfate such as ammonium persulfate,
Hypophosphite ions can be oxidized efficiently, and even when hypophosphite ions and phosphite ions coexist, the oxidation of hypophosphite ions has priority over the oxidation of phosphite ions. Therefore, it is possible to reliably oxidize hypophosphite ions, and for this reason, electroless treatment using hypophosphite ions as a reducing agent, where hypophosphite ions and phosphite ions coexist. It was found that this method is extremely effective in treating plating solution waste.

Furthermore, by treating the treatment solution treated with persulfate with a calcium compound, a precipitate with very good precipitate separation properties and good furnace permeability is generated, and hypophosphite ions are used as a reducing agent. When disposing of waste electroless plating solution,
Although the furnace liquid from which the above precipitate has been removed contains a curing agent,
This can be treated by electrolytic oxidation in a very short time, and therefore, by roughly combining the treatment with persulfate and the treatment with calcium compounds, waste liquid containing hypophosphate ions can be treated efficiently and economically. The present inventors have discovered that it is possible to do so, and have come up with the present invention. That is, the present invention provides hypophosphite ions, which is characterized in that after adding persulfate to a waste solution containing hypophosphite ions and causing a reaction, a calcium compound is added to form a precipitate, and then this precipitate is removed. The present invention provides a method for treating waste liquid containing phosphate 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. It is suitable for waste liquid treatment of electroless plating solutions such as electroless shark cobalt plating solutions.

In the method of the present invention, persulfate is first added to the waste liquid to be treated and allowed to react.This oxidizes the hypophosphite ions in the waste liquid. Even when coexisting with head phosphate ions, hypophosphite ions are preferentially oxidized.

On the other hand, even if an oxidizing agent other than persulfate, such as hydrogen peroxide, chlorate, or ferric chloride, is added, hypophosphite ions are not effectively oxidized, as shown in the experimental examples described later. figure,
The purpose of the invention is not achieved. In addition, hypochlorite is
When hypophosphite ion coexists with IJ phosphate ion, phosphite ion is preferentially oxidized, so especially when hypophosphite ion coexists with IJ phosphate ion, and It is not preferable to treat electroless plating solutions that use hypophosphite ions as a reducing agent, which contain a high concentration of phosphorous acid ions. In the present invention, ammonium persulfate, sodium persulfate, and the like are preferably used as the persulfate.

Further, the amount of persulfate added is preferably 1 mol or more, more preferably 2 mol or more, particularly 2.5 mol or more per 1 mol of hypophosphite ion in the waste liquid. By adding persulfate to 1 mole of hypophosphite ion at least 1 mole, more preferably at least 2 mole, particularly at least 2.5 mole, hypophosphite ion can be reliably oxidized. . When a persulfate is added to the waste liquid and reacted, the bait for the waste liquid is not particularly limited.

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, when adding persulfate to the waste liquid and causing the reaction, it is preferable to drain the waste liquid. In the present invention, after performing the above-mentioned oxidation treatment using a persulfate, a calcium compound is added to perform a precipitation treatment to generate an elutritable salt of calcium.

In this case, the calcium compound may be any compound that reacts with the phosphorus compound to produce a soluble salt, but especially calcium hydroxide and other calcium salts such as calcium chloride and calcium sulfate are used in combination. It is preferable to add a calcium compound, especially a combination of calcium hydroxide and other calcium salts, to a product that has been oxidized with a persulfate. Excellent precipitation occurs. On the other hand, even when 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 precipitates with poor settling properties and poor oxidation properties. cannot achieve the purpose. Although the precipitation treatment is not necessarily limited, it is preferably carried out at a pH of 4.5 or above, particularly at a pH of 5 or above. Phosphate ions and the like to be removed are precipitated well at a pH of 4.5 or above, particularly at a pH of 5 or above.

In addition, the more preferable bait range for sedimentation treatment is 6 or more, especially 6
~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, but if a mixture of calcium hydroxide and other calcium salts is used, the ratio It is preferable that the amount of calcium hydroxide is the amount used for pH adjustment, and the remaining amount is the calcium salt. In addition,
There are no particular restrictions on the conditions for precipitation, but room temperature to
It is preferable to perform Toazusa for 0 minutes to 2 hours.

In the above-mentioned precipitation treatment, the phosphorus content in the waste liquid reacts with calcium and precipitates easily, resulting in a precipitate with excellent furnace permeability. However, if the waste liquid contains metal ions, for example, if the waste liquid is In the case of plating solution waste, metals 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.

In addition, if the waste liquid contains a locking agent, etc., such as electroless plating waste liquid, the locking agent etc. will not be oxidized by the above-mentioned oxidation treatment and precipitation treatment, and the furnace liquid after the above-mentioned 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 residual pyridizing agent in the furnace liquid after precipitation separation is high, electrolytic oxidation treatment, activated sludge treatment, etc. should be performed after precipitation or after removing the generated precipitate. It is preferable to perform treatment. In this case, the phosphorus content in the waste liquid, especially hypophosphite ions, is removed by oxidation treatment with persulfate and precipitation treatment with calcium compounds, so electrolytic oxidation treatment, activated sludge treatment, etc. can be completed in a relatively short time. For example, in the case of electrolytic oxidation treatment, it is sufficient to electrolyze for about 10 to 50 hours at a current of 1 to ship/d per night. Further, depending on the case, it is also possible to treat the furnace liquid after the Yo-Sakai 8 separation by mixing it with other wastewater.

As explained above, in the present invention, when treating waste liquid containing hypophosphite ions, by first treating it with persulfate, hypophosphite ions are sometimes preferentially oxidized and By using a calcium compound to precipitate the material treated with sulfate, a precipitate that is very easy to precipitate and has good separability is generated, and therefore waste liquid containing hypophosphite ions can be treated. It can be processed 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.

[Experiment Example 1] Various oxidizing agents are added to a sample aqueous solution in which sodium hypophosphite or sodium hypophosphite and sodium phosphite are dissolved, and the hypophosphite in the sample is reacted under predetermined conditions. Acid ion (Ni2PQ-) and phosphate ion (POAshi-)
was determined by absorbance method, and head phosphate ion (HPO
) was quantified by the iodine method (in this case, hypophosphite ions were also quantified by the iodine method).

The results are shown in Table 1. Table 1 Note 1: (NH4) in parentheses
2S208 (ammonium persulfate) addition amount is HPO≧-
It is a molar ratio to 1 mole.

Note 2: Day 202 (hydrogen peroxide) is day 20230.
% hydrogen peroxide solution was used.

Note 3: As NaC and 0 (sodium hypochlorite), one with an effective chlorine content of 13.06 was used. As is clear from the results in Table 1, hypophosphite ions can be reliably oxidized by using ammonium persulfate, especially when hypophosphite ions coexist with phosphite ions. It was found that oxidation of phosphate ions progresses preferentially. On the other hand, it was found that hydrogen peroxide and potassium chlorate did not effectively oxidize hypophosphite ions.

Further, no good results were obtained using ferric chloride or nitric acid. Furthermore, when hypochlorite is used, good oxidation occurs in a system containing only hypophosphite ions, but in a system in which hypophosphite ions and phosphite ions coexist, phosphite ions It was observed that the oxidation of hypophosphite ions progressed preferentially, while the oxidation of hypophosphite ions hardly progressed.Therefore, it was found that persulfates have a remarkable effect as a treatment agent for hypophosphite ions. Ta. [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 mixture was reacted under specified conditions. Sedimentation was caused by rope scouring at a designated fence, and the state of the sedimentation, 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 2. The test methods and evaluation criteria for sedimentation volume and filtration properties are as follows.

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

○ Less △ Relatively less × Many Using a tidal top charge reef tester, a relative comparison was made based on the amount of furnace fluid at a given time.

○ Good △ Relatively good It was found that a precipitate with a small sedimentation volume and good filtration properties was produced.

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〕

Electroless scale nickel plating solution waste having the following composition was treated.

Nickel ion 0.12 mol/Hypophosphite ion 0.535 Phosphite ion 1.379 Phosphate ion
0.057 〃COD
52,000 secrets/sopH
5 First, 2.5 mol of ammonium persulfate per 1 mol of sodium hypophosphite was added to the above waste liquid, and the mixture was reacted for 30 minutes at 40:00.

Next, 1.2 mol of calcium hydroxide and 0.15 mol of calcium chloride were added to 1 mol of total phosphorus in the waste liquid, and after three minutes of sea breaming at fences 12 and 8, the furnace was separated. did. The results of analyzing the furnace fluid are as follows. Nickel ion 0 mol/Hypophorite ion 0.003 Phosphite ion
0.052 Phosphate ion
0 〃COD 14000
9/Next, the above furnace solution was subjected to electrolytic oxidation under the following conditions, and then the treated solution was analyzed.

The following results were obtained. Electrolytic oxidation condition sample 500' fly flow IA electrode lead peroxide (0.0%) e platinum wire time 4 hours treatment solution fractionation nickel ion 0 mol/dos hypophosphite ion 0

Claims (1)

[Claims] 1. Hypophosphite, which is characterized in that a persulfate is added to a waste solution containing hypophosphite ions to cause a reaction, a calcium compound is added to cause precipitation, and then this precipitation is removed. A method for treating waste liquid containing acid ions. 2. The method according to claim 1, wherein the amount of persulfate added is 1 mol or more per 1 mol of hypophosphite ion. 3. The method according to claim 2, wherein the amount of persulfate added is 2 mol or more per 1 mol of hypophosphite ion.
4. The method according to any one of claims 1 to 3, wherein the amount of the calcium compound added is 1 mol or more per 1 mol of total phosphorus in the waste liquid. 5. The method according to any one of claims 1 to 4, wherein the calcium compound is a mixture of calcium hydroxide and other calcium salts. 6. The method according to claim 5, wherein the amount of calcium hydroxide used is sufficient to adjust the pH at the time of precipitate formation. 7. The method according to claim 5 or 6, wherein the calcium salt is calcium chloride, calcium sulfate, or a mixture thereof. 8. The method according to any one of claims 1 to 7, wherein the waste liquid containing hypophosphite ions is a waste liquid of an electroless plating solution using hypophosphite ions as a reducing agent.