SU941311A1 - Process for purifying effluents from hexacyanoferrates - Google Patents

Description

(54) METHOD FOR CLEANING WASTE WATER FROM HEXACYANEFERRATES

1 The invention relates to wastewater treatment.

waters of enterprises of electrolack production, film industry and similar productions containing hexacides.

A known method of purification of wastewater from hexacyanoferrates (P), including the treatment of calcium chloride in the amount of 2-2.5 parts by weight. on 1 weight. gaxacyanoferrates (P) in an acidic medium (pH 2-2.1) for 20-25 minutes at boiling: t, t.

The shortcomings of the method are the formation of large gelatinous, difficult to filter precipitates, the high cost of the process due to its multi-stage character, and the possibility of using it for dilute solutions.

The closest to the proposed technical essence and the achieved result is a method of wastewater purification from hexacyanoferrates, including oxidation of them with sodium hydrochloride when heated in the presence of a catalyst.

In this method, the wastewater is first passed through a weakly basic selective ion exchange resin to recover from

they are ferro- and ferricyanides, then the resin is regenerated with 1N alkali solution, and the eluate (concentrate) containing ferro- and ferricyanides is treated with sodium hypochlorite at 85-95 ° C in the presence of potassium bromide catalyst and caustic alkali (pH-12) (2).

The disadvantages of this method are its complexity, due to the use of ion exchange resins, the long duration of the process (about 6 hours) and the high cost

10 through the addition of reagents and the use of an expensive and less affordable catalyst.

The purpose of the invention is to simplify the process, shorten its duration and reduce

15 process.

This goal is achieved by the fact that according to the method of wastewater purification from hexacyanoferrates, including oxidation with sodium hypochlorite when heated in the presence of a catalyst, in which salt of divalent manganese is used as a catalyst, preferably in an amount of 50100 mg / l, and psoochlorite is introduced predominantly 394 but in 1 , 3-2.0 times the amount of stochiometric amount. The method is carried out in the following way. Highly concentrated wastewater containing up to 45 g / l hexacyanoferrates and up to 120 g / l caustic soda is mixed to reduce the alkaline GC content with wash water containing up to 10 g / n hexacyanoferrate and alkali - 1.6 g / l, treated with a dose of hypochlorite ng. sodium, amounting to 1.3-2.0 times the excess of the stoichiometry 1chest amount in the presence of a catalyst salt of divalent manganese b amount of 5G -100 mg / l when heated. Groness of oxidation of hexacyanoferrates proceeds according to the following reaction equation: Fe (CFsJ) + 90Н + 50СГ Fe (ОН) З1 + + ЗМл-Н 15СГ t- ЗНоО + СО; Purified stop water, content of up to 3 g / l of active chlorine together with precipitate of gvd rooxi jelly: 5a is reused after treatment with water containing wastewater from the electroplating plant. Stage 1. High-concentration 200-liter stoves with a volume of 200 liters, containing up to 45 g / l of hexacyanoferrates, are mixed to reduce the alkalinity of water to 30 g / l with industrial waters containing up to 10 g / l of hedgehooferrates and caustic soda to 1 , 6 g / l, are treated with 1.3 times as much sodium hapochlorite in the presence of a manganese sulphate catalyst MnS04, in an amount of 50 mg / l, heated for 3 hours at 90 ° C. Purified wastewater with a volume of 200 l, containing up to 3 g / l of active chlorine, mixed with cyan-containing stochpysh waters of an electroplating shop with a volume of 500,600 l for reuse. The degree of purification of clear water from hexacyanoferrates is 96.5%. P R I M e r 2. Highly concentrated sewage with a volume of 200 p containing up to 45 g / p of hexacyanoferrates, similarly as in process 1, is treated with 1.7 quantities of sodium psochlorite in the presence of a catalyst of manganese chloride in an amount of 80 mg / l, heated for 3 hours at and further / proceed as in Example 1. The degree of wastewater treatment from hexacyanoferrates is 97.5%. EXAMPLE 3: Highly concentrated 200 liter wastewater containing up to 45 g / l of hexacyanoferrates as in Example 1 is treated with a 2.0 fold excess of sodium hypochlorite in the presence of a manganese sulfate catalyst in an amount of 100 mg / l and heated for 3 h at 87 ° C. The treated wastewater is reused as in Example 1. The degree of wastewater treatment from hexacyanoferrates is 96%. The results of wastewater treatment of hexacyanoferrates are given in Table. 1. Comparative data on the consumption of reagents for the known and proposed methods are presented in Table. 2. The proposed method, in comparison with the known method, ensures the cleansing of the purification process by eliminating the purification stage on ion-exchange resins and their regeneration, which is due to this shortening of the process, as well as reducing the purification process, eliminating the additional introduction of reagents and using bivalent salt as catalyst manganese, as a more dengovogo and dostagshogo reagent and 10 times less. In addition, the reuse of treated wastewater. Table 1

4970

30 30

4970

50 80

99

97

97

Claims (3)

99 Claims 1. A method for purifying waste water from hexacyanoferrates, including oxidation with sodium hypochlorite when heated in the presence of a catalyst, characterized in that, in order to simplify the process of reducing its duration and reduce the price, divalent manganese salt is used as a catalyst. 2. A method according to claim 1, characterized in that the catalyst is introduced in amounts of 50-100 mg / l. 3-5 1000 3. The method according to claim 1, tl. 4 ayo w and with the fact that pshohlorit iatr enter 8 13 2,0 times the amount from the stowometric. Sources of information taken into account prn examination 1.Avtorskoe certificate of the USSR N 420573. cl. C 02 C 5/02, 1977. 2. Dwano N., Shimanura 3. and Abe A. Feriency Fern and Ferrocyanide from Photographic Processing Wastes byipA Exchange Resin. Mratographic Scienceftldr Engineering 1975, V 19, p. 219-223.