TW574059B - Method for recovering high purity salt from waste solution of salting-out of dye - Google Patents

Abstract

A method for recovering high purity salt (sodium chloride or potassium chloride crystals) from a waste solution of salting-out of dye without secondary pollution comprises: (1) performing an evaporation concentration treatment in order to crystallize over-saturated inorganic salts, e.g. sodium chloride or potassium chloride etc. contained in a waste solution; (2) adding a salt solution recycled from the subsequent step into the wet crystals obtained by filtration evaporation crystallization to form a suspension, and using an electrolysis oxidation method to oxidize and decompose the dye and intermediates thereof adhered over the surface of the crystals; and (3) filtering and drying crystals and recycling the filtered salt solution.

Description

574059 V. Description of the invention (1) The present invention relates to a method for recovering high-purity salts from a dye salting-out waste liquid, in particular to recovering and obtaining high-purity sodium chloride or chlorination through steps such as evaporation crystallization and electrolytic oxidation. Potassium crystals without secondary pollution. According to the general dye production process, especially reactive dyes and direct dyes, after the synthesis of the reaction, the salting out method must be used to make the dye precipitate or crystallize due to the reduced solubility. In order to improve the dye recovery rate, it is necessary to add A large number of inorganic salts such as sodium chloride or potassium chloride are used for dye salting out. After the dye is obtained as a product by filtration, the waste liquid containing high concentration of inorganic salts must be properly treated. The waste liquid contains 5 ~ 30% sodium chloride or potassium chloride, 0.3 ~ 2.0 w t% dye and its intermediate, ρ Η value is between 1 and 12, and the perspective is extremely low. For the treatment of these waste liquids, the current conventional method is to use a combination of steps such as dilution, chemical coagulation, and biological decomposition, but it has problems such as low biological decomposition efficiency and secondary pollution of organic sludge, and the inorganic salts are not recovered for reuse; There are also those who use liquid direct incineration to treat high-salt waste liquid (dye salting-out waste liquid is a high-salt waste liquid), but sodium chloride and potassium chloride will decompose during the high temperature incineration process to produce sodium oxide and potassium oxide. Highly corrosive substances, such as chlorine and chlorine gas, cause the problem of high equipment maintenance costs, and it is difficult to recycle inorganic salts for reuse. For the high-salt waste liquid produced by epoxy resin plants and polycarbonate plants, rotation is currently used. The kiln method first evaporates and crystallizes the waste liquid. The sodium chloride crystals obtained from the crystallization are oxidized or carbonized on the surface of the crystal β1 body by a rotary kiln at a high temperature of 700 to 100 ° C. Since the melting point of sodium gasified crystals is 80 1 ° C, the temperature of the rotary kiln exceeding 80 1 ° C will melt the sodium gasified crystals.

574059 V. Description of the invention (2) The inclusion of organic matter makes it impossible to completely oxidize or carbonize the organic matter, which results in the purity of the recovered vaporized sodium crystals being the same. It is also disclosed in the Republic of China Patent Publication No. 2 2 3 0 44, entitled "The method of recovering salt from wastewater with high concentration of salt" teaches the use of evaporative crystallization to crystallize sodium chloride or potassium chloride from waste liquid, and then emit it from an infrared generator 6 0 0 ~ 3 0 0 0 The high temperature infrared of ° C will oxidize or carbonize the organic compounds on the surface of the crystal, and then recrystallize to obtain high-purity sodium chloride or potassium chloride crystals. The high temperature infrared of 600 ° C ~ 300 ° C The main disadvantage of this method is that the crystals after infrared treatment must be recrystallized to recover high-purity inorganic salts. In order to improve the shortcomings of the conventional technology, the inventor relied on his many years of experience in related industries, and devoted his mind to the invention. Therefore, the method for recovering high-purity salts from the dye salting-out waste liquid of the present invention does not need to oxidize or carbonize organic substances on the surface of the crystal at high temperature, and does not need to recrystallize. The problem of secondary pollution of sludge. Therefore, an object of the present invention is to provide a method for recovering a high-purity salt from a dye salting-out waste liquid. In order to achieve the above object, the present invention is achieved as follows: A method for recovering high-purity salts from a dye salting-out waste liquid, which comprises (1) evaporating and concentrating the inorganic liquid such as sodium chloride or potassium chloride contained in the waste liquid Salts crystallize due to supersaturation; ® (2) Filter the wet crystals obtained by evaporation and crystallization, add the salt solution recovered in the subsequent steps to form a suspension, and use electrolytic oxidation to attach the dye on the surface of the crystals.

Page 5 574059 V. Description of the invention (3) Organic materials such as materials and intermediates are oxidized and decomposed; (3) Filtering and drying the crystals, filtering salt solution is refluxed and then used. In order for your reviewing committee to understand the purpose, features and effects of the present invention, the following specific examples are given in conjunction with the accompanying drawings to make a detailed description of the present invention, as described below: Example 1 A figure is a processing flow chart of a method for recovering high-purity salts from a dye salting-out waste liquid according to the present invention. As shown in the figure: before the treatment, the pH value of the dye salting-out waste liquid 1 is lower than 4 or high. At 10, the waste liquid must be neutralized 2 and the waste liquid 2 is neutralized with hydrochloric acid solution, sodium hydroxide solution or potassium hydroxide solution to a pH value between 4 and 10. Evaporation and crystallization 4 3 under vacuum or normal pressure, suitable operating conditions are 50 ~ 110 ° C, 30torr ~ latm. During the process of evaporation crystallization 3, as long as the crystal content in the crystallization tank is more than 1 vo 1.%, it is easy. Crystallize sodium chloride or potassium gas into complete crystals, that is, organic impurities are not enclosed in the crystals, but only adhere to the surface of the crystals. In the process of evaporation and crystallization 3, the condensate 4 distilled off can be reused without secondary pollution; the organic substances contained in the waste liquid will also precipitate or crystallize out and float on the liquid surface of the crystallization tank, which forms organics in the upper layer. Suspended matter 5 is removed as secondary dye 6 or incinerated 7. The suspension 8 obtained after evaporating the crystal 3 was filtered 9 and the filtrate 10 was refluxed 11 to the evaporation crystallization tank. Wet crystals 12 were added to fresh salt solution or recovered salt solution 1 3 to form suspension 14 and wet crystals. The volume ratio of 1 2 to the salt solution is preferably between 1. · 0.5 to 2 0, and the suspension 1 1 4 can be moderately agitated as a principle. Put the suspension 14 into the electrolytic cell. The anode plate is preferably made of precious metal, and stainless steel or graphite can also be used. The cathode

574059 V. Description of the invention (4) The material of the plate is preferably the main oxidation phase 15 μ #, using stainless steel or copper, etc .; electrolysis is preferably 40 ~ 95 (Γ〇γ Between room temperature and 100 °, preferably between ^ QC, the potential difference between the cathode and anode is maintained between 14 and 15 ~ 15 ~ 5 V; the suspension must be suspended during electrolytic oxidation 15 4 Stir and stir vigorously. The reaction formula of cathode and anode during electrolysis is as follows: anode (oxidation reaction): 2 C 1 ► C 1 2 ten 2 e-cathode (reduction reaction): 礓 1 2Na ten ten 2H20 ten two e one -> 2 Na OH + H2t or 2K ten ten 2H2 0 ten 2e one to one ► ► 2KOH ten H2t As the suspension 14 is stirred vigorously, the chlorine gas produced by the anode will react with the sodium argon oxide or potassium hydroxide produced by the cathode to form secondary Sodium gas and sodium chlorate · or potassium hypochlorite and potassium chlorate, the reaction formula is as follows:

Page 7 574059 V. Description of the invention (5)

Cl2 ten 2NaOH ten 1/20 2-N a C 1 0 + H2〇

Cl2 ten 2Na〇H ten 5 / 2〇2-►δΝ a C 1 03 + H2〇 or C l2 + 2KOH + l / 2〇2-KC 1 o + h2o C 12 ten 2K〇H + 5 / 2〇2 — —-2KC 1 o3 + h2o Gas produced by electrolysis, sodium hypochlorite and sodium chlorate, or strong oxidants such as potassium hypochlorite and potassium chlorate can effectively oxidize and decompose the organic matter attached to the surface of sodium vapor or potassium chloride crystals. When the solution in the suspension 14 is electrolyzed to become colorless and transparent, 16 suspensions 14 are filtered, and the filtrate 17 (salt solution) can be reused after refluxing 18, and the wet crystals 19 can be dried and dried. High-purity sodium chloride or potassium gas crystals 2 1 were obtained. Example 2 Take 3 0 0 ml of light brown dye salting waste liquid, the pH of the waste liquid is 1. 18, containing 0.62% organic matter such as dyes and intermediates, and 13.97% sodium gasification. 45 ， Neutralize with sodium hydroxide until p Η is 5 · 8, evaporate and crystallize at atmospheric pressure, 103 ~ 107 ° C, and distill off 2 200ml condensate, the condensate pH is 5.45, Contains 4 ppm sodium vaporized sodium, and about 800 m 1 of the suspension containing sodium vaporized crystals remains. Filtered to obtain brown wet sodium chloride crystals on the surface, adding 50 0 in 1 saturated salt

Page 574059 V. Description of the invention (6) Liquid 'electrolytic oxidation under the conditions of 4 5 ~ 5 C_ and the potential difference between cathode and anode is 5 v' 3 After 10 minutes, the Luo liquid became colorless and transparent, and was filtered and dried to obtain 2 3 5 g of white sodium vapor crystals with a purity of 99.57% were higher than A cs reagent grade standard 99.5 ° / 〇. Example 3 3,000 ml of a concentrated violet-blue dye was used to salt out the waste liquid. The pH value of the waste liquid was 8.91, which contained 1.64% dye. Its intermediates and other organic matter and 6．00% sodium chloride. Evaporate and crystallize at 80torr, 60 ~ 65 ° C. 2000ml of condensate is distilled off. The condensate has a pH of 7.85, contains 6.5 ppm sodium chloride, and about 100% remains. 0 m 1 suspension containing vaporized nanocrystals. After filtering, a purple-blue wet emulsified nanobody was added, and a saturated salt solution of 3 〇η 1 was added. The electrolytic oxidation was performed at a temperature of 4 ° to 4 5 ° C and a potential difference between anode and anode of 4 V. After 60 minutes, The solution became colorless and transparent, and was filtered and dried to obtain 220 g of white sodium chloride crystals with a purity of 99.52%. Example 4 2000 ml of concentrated purple dye was used to salt out the waste liquid. The pH value of the waste liquid was 4.78, which contained 1.34% organic matter such as dyes and intermediates, and 14.95% sodium chloride. Evaporate and crystallize at atmospheric pressure at 10 3 ~ 107 ° C, distill off i 3 0 0 0 m 丨 Condensate 'Condensate pH is 3.29, contains 65.5 ppm sodium gasification, and about 7 0 0 m 1 suspension containing vaporized sodium crystals. After filtering to obtain purple wet sodium chloride crystals on the surface, 300 m 1 of saturated saline solution was added, and electrolytic oxidation was performed at a temperature of 4 5 to 50 ° C and a cathode-anode difference of 4V. The solution became transparent, and was filtered and dried to obtain 130 g of a white gaseous color and a body with a purity of 99.43%. 'Nanocrystalline

574059 V. Description of the invention (7) Through the above examples, it is clearly understood that the technology of the present invention can easily recover high-purity sodium chloride or potassium chloride crystals from dye salting-out waste liquid under normal pressure and low temperature conditions. The disadvantages of non-conventional technology are indeed quite advanced, which is conducive to industrial applications. However, the invention patent application is filed in accordance with the law. It is hoped that the examiner would grant the patent earlier. Although the present invention is disclosed as above with a preferred embodiment, it is not intended to limit the scope of implementation of the present invention. Any person skilled in the art can make some changes and decorations without departing from the spirit and scope of the present invention, that is, All equal changes and modifications made in accordance with the present invention shall be covered by the patent scope of the present invention, and the definition shall be based on the scope of the patent application, and shall be declared together.

Page 10 574059 Brief description of the diagram The first diagram is the process flow chart of the present invention. Brief description of the diagram number: 1 · · · · Dye salting out waste liquid 2 3 4 5 6 7 8 9 0

1617 18 19 2 0 2 1 Neutralization evaporation crystallization condensate organic suspension secondary dye incineration suspension filtration filtration, liquid reflux wet crystal fresh salt solution or recovery salt suspension electrolytic oxidation filtration, filtrate reflux wet crystal drying high purity gas Sodium or potassium chloride crystals «

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Claims (1)

574059 -------- 4 、 Scope of patent application j 1 · A method for recovering high-purity salt from waste liquid of salting out of dyes, which can recover and obtain high-purity sodium chloride or potassium chloride crystal, including the following Steps: (1) Evaporate and concentrate to crystallize the inorganic salts such as sodium chloride or potassium gaseous contained in the waste liquid due to supersaturation; (2) Filter the wet crystals obtained by evaporation and add the salt solution recovered in the next step to make A suspension is formed, and organic substances such as dyes and intermediates attached to the surface of the crystal are oxidized and decomposed by electrolytic oxidation method; (3) The crystal is filtered and dried, and the filtered salt solution is refluxed for reuse. 2 · According to the method described in item 1 of the scope of patent application, before evaporating and crystallization, the waste liquid must be neutralized with hydrochloric acid solution, sodium hydroxide solution or bell solution to a pH of 4-10. 3. The method according to item 1 of the scope of the patent application, wherein the operating pressure conditions for the evaporation and crystallization are 30 t 0 r r to 1 a t m. 4 · The method according to item 1 of the scope of patent application, wherein the operating temperature condition of the evaporative crystallization is 50 to 110 ° C. 5. The method according to item 1 of the scope of patent application, wherein the dyes floating on the liquid surface during the evaporation and crystallization process must be taken out. 6 · According to the method described in item 1 of the scope of the patent application, the volume ratio of the wet crystals obtained by filtering and evaporating the crystallization to the salt solution recovered in the subsequent steps added is between 1 ·· (K 5 ~ 2 0. 7 · If applied The method according to item 1 of the patent scope, wherein the electrolytic oxidation step is performed at room temperature to 100 ° C. ≪ 8 · The method according to item 7 of the patent scope, wherein the electrolytic oxidation step is better It is performed between 40 ° C and 50 ° C. Page 12 574059 6. Scope of patent application 9 · The method as described in item 1 of the scope of patent application, wherein the anode and cathode potential difference during the electrolytic oxidation process is 1 to 15 V. 10 · The method as described in item 9 of the scope of patent application, wherein the anode-to-anode potential difference in the electrolytic oxidation process is better between 3 and 5V. 1 1 · The method described in item 1 of the scope of patent application, wherein the suspension must be vigorously stirred during the electrolytic oxidation process. i Page 13