JP4022267B2 - PCB waste detoxification and product recycling - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for detoxifying PCB waste treated with an aqueous solution of sodium hydroxide and a method for reusing the resulting product. In particular, this method replaces harmful PCB with biphenyl sodium and recycles it as biphenyl by hydrolysis. The present invention relates to a method for treating PCB waste, characterized in that a precipitate containing sodium chloride is solidified with incinerated ash.
[0002]
[Prior art]
PCB is an organochlorine compound and is an abbreviation for poly chlorinated biphenyl. Biphenyl is a combination of two benzene rings bonded to each hydrogen atom of the benzene ring. Biphenyl is a hydrocarbon that does not contain chlorine and can be used as a fuel. By replacing chlorine with hydrogen in this biphenyl, a harmful chlorine compound is produced, and various properties are exhibited depending on the number and position of chlorine.
[0003]
Conventionally, PCBs are managed and stored in the country as hazardous substances prohibited from movement. Recently, a method of oxidative pyrolysis at a high temperature of 1800 ° C has been proposed, but PCB is resistant to heat, and if oxidative pyrolysis is inadvertently performed at low temperature, more toxic dioxins are generated than PCB and the environment is further destroyed. As is known from the above, a complete processing method is not known to date.
[0004]
[Problems to be solved by the invention]
The problem with thermally decomposed PCBs is that chlorine atoms contained in the PCB are decomposed into gases as harmful chlorine compounds by oxidation and are polluted into the air. Thus, discharging a gas containing harmful components into the atmosphere has an adverse effect on the environment. Therefore, harmful chlorine compounds must be made harmless inorganic chlorine compounds, treated after which no harmful substances are eluted, and discarded.
[0005]
The present invention relates to a method for decomposing PCBs into inorganic chlorine compounds and the like , and enables the inorganic chlorine compounds to be solidified with cement together with incinerated ash, and reuse of the solidified product and biphenyl obtained thereby. It is intended.
[0006]
[Means for Solving the Problems]
In the present invention, an organic chlorine compound is stirred with an aqueous ionic solution of anhydrous sodium carbonate, potassium oxide, nitrogen, boron, calcium, etc., and when colloidal, diethyl ether and ethanol are mixed as a solvent and heated at a temperature of 110 ° C. While further stirring, cobalt chloride and pyroligneous acid are added as a catalyst and stirred. Finally, an aqueous sodium hydroxide solution is mixed and stirred to produce an inorganic chlorine compound and biphenyl, thereby stabilizing and solidifying the incinerated ash cement, Biphenyl containing no chlorine is obtained.
[0007]
That is, the PCB stabilizing treatment method of the present invention decomposes a chlorine atom of an organic chlorine compound, which is generated by substitution of a hydrogen atom and a chlorine atom of a benzene ring, into a biphenyl compound and a chlorine compound by substitution of a sodium atom , and further, if necessary, biphenyl. By hydrolyzing sodium, biphenyl and caustic soda are obtained. A part of the reaction for producing biphenyl sodium and biphenyl is simplified and illustrated as follows.
[0008]
[Chemical 1]
[0009]
【Example】
Examples of the present invention will be shown below, but the present invention is not limited to these examples, and it should be understood that these examples are merely to help the understanding of the present invention. Don't be.
[0010]
Example 1
Silicon dioxide SiO ₂ 2.1%, hydrogen fluoride HF 0.3%, calcium oxide CaO 3.2%, anhydrous sodium carbonate Na ₂ CO ₃ 7.3%, aluminum oxide Al ₂ O ₃ 1.7%, anhydrous boric acid _{B 2 O 3 1.3%, 2} O2.1% potassium oxide _K, ammonia NH3 1.0%, 1.0% sodium chloride NaCl, cobalt chloride _{CoCl 2 · 6H 2 O 0.3%} , ferric oxide Fe ₂ O ₃ 0.2%, wood pyroacetate 2%, ethylenediamine NH ₂ CH ₂ CH ₂ NH ₃ 1%, PCB 4000 cc ( trans oil ), ethanol C ₂ H ₅ .OH 40 cc, diethyl ether C ₂ H ₅ − Mix 80 cc of O—C ₂ H ₅ and stir for 30 minutes. The agitated material is heated to 110 ° C., and the agitated main raw material and auxiliary raw material are mixed and stirred for 250 cc.
[0011]
Finally, 50 g of sodium hydroxide is dissolved in 100 cc of water, and mixed and stirred in the PCB mixed solution. After 24 hours, the biphenyl splits into two layers, the upper layer and the lower solvent layer. Biphenyl was extracted by this solvent extraction method. An elution test was conducted on the solidified product obtained by solidifying the sediment precipitated in the lower layer with cement together with incineration ash. The dissolution test was performed only on PCB. The results are shown in Tables 1 and 2. D. mg / l and PCB could not be detected.
[0012]
[Table 1]
[0013]
[Table 2]
[0014]
【The invention's effect】
As can be seen from the results in Tables 1 and 2, PCB could not be detected in the solidified product of incinerated ash treated by the method of the present invention. Moreover, a fuel (biphenyl) can be obtained as a by-product.

Claims (3)

The PCB is decomposed into sodium biphenyl and sodium chloride by treating the PCB with an aqueous solution of sodium hydroxide together with a catalyst and a solvent , wherein the catalyst is cobalt chloride, ferric oxide, ethylenediamine, wood vinegar, A method for treating PCB, wherein the solvent is selected from ethanol and diethyl ether.   2. The process of claim 1 wherein biphenyl sodium is heated to hydrolyze to biphenyl. 2. The method according to claim 1, wherein the treatment with an aqueous solution of sodium hydroxide comprises treatment with an aqueous solution containing a plurality of types of ions such as potassium, calcium, aluminum, fluorine, silicon and boron in addition to sodium.