PL151268B2 - Method of neutralizing rhodanates containing liquid wastes - Google Patents

Description

RZECZPOSPOLITA PATENT ^DESCRIPTION 151 268

POLAND OF THE PROVISIONAL PATENT

OFFICE

PATENT

RP

Provisional patent additional to the patent No. - Filed: 88 04 11 (P. 271774)

Priority - Application announced: 89 01 23

Patent description published: 1990 12 31

Int. Cl. ⁵ CO2F 1/42

Creators of the invention: Romuald Bogoczek, Elżbieta Kociołek-Balawejder, Janusz Krawczyk Andrzej Kędzierski, Leon Sobota

Authorized by a temporary patent: Akademia Ekonomiczna im. Oskar Lange, Wroclaw (Poland)

Way of rhodium wastewater neutralization

The subject of the invention is a method of neutralizing rhodanic sewage, especially diluted sewage, such as sewage from the production of synthetic polyacrylonitrile fibers and from chemical synthesis, as well as from coke chemical plants.

There are known methods of neutralizing rhodium wastewater based on the action of chlorine gas or hypochlorites, oxidation by electrolytic or biological methods.

The disadvantage of chemical methods using chlorine or its soluble compounds is the possibility of the formation of cyanides and chlorocyanates, i.e. components even more harmful than the rhodium, and the need to add excess chlorinating agents. This may cause the utilized sewage to become no less harmful. These difficulties increase as the waste water to be disposed of is more diluted, as this requires the use of an excess of homogeneous reactants, their reaction rate is very slow, and the reaction equilibrium is unfavorable. The permissible concentration of rhodanides in surface waters of the 1st purity class is 0.02 mg · dm ^-3 . At this concentration, the water-soluble reagents hardly react with the rhodiides unless a large excess of these reagents is used.

The method according to the invention consists in that the rhodium wastewater with a content of preferably less than 1 g · dm ^{-3 is made} alkaline in order to obtain a molar ratio of hydroxide to rhodate ions not lower than 6, and then it is contacted in the temperature range of 2 + 60 ° C with the copolymeric water-insoluble but swellable in water N-halogeno-sulfonamides, using at least 4 moles of halogen per 1 mole of neutralized rhodanic ion until the disappearance of rhodanic ions and their harmful derivatives in the solution is noticed. Deactivated copolymeric sulfonamides are regenerated in a known manner.

It is particularly advantageous if the contacting of the rhodate wastewater takes place in a layer, i.e. a bed of copolymeric N-halogensulfonamides, when the wastewater flows through this bed more slowly than is indicated by the rate of chemical decomposition of rhodate ions into harmless reaction products. as long as the effluent shows incomplete rhodate decomposition products, and the bed is shaken periodically, preferably by means of ultrasound. Deactivated polymeric N-halogen sulfonamides are regenerated in a known manner.

151 268

The copolymeric N-halogen-sulfonamides used in the process according to the invention are known from PRL patents Nos. 138 767, 138768, 138970, 138988, 138989 and 138990.

The chemical reaction of rhodium ions with copolymeric N-halogensulfonamides, as a result of which the rhodium waste water is rendered harmless, has not been known to date. The final products of this reaction are sulfate, carbonate and ammonium ions, and partly nitrogen. Cyanides may be incomplete decomposition products. They can appear in a leak after the active bed is depleted. It is therefore necessary to provide a certain excess of active bed, as indicated in the process according to the invention.

The rate of rhodate decomposition is greatest when the copolymeric N-halosulfonamides are in powdered form; it is smaller in the case of fibrous products and even smaller in the case of granulated products, depending on the diameter of the granules. This speed increases with increasing temperature and with the concentration of rhodium effluent, and also depends on the type of halogen. This speed can be easily determined experimentally for specific apparatus conditions. This reaction takes place much faster than the chemical reaction which rhodides undergo in known methods of utilization of dilute wastewater. Therefore, the method according to the invention, in contrast to the homogeneous methods known to date for the treatment of dilute rhodium waste water, is particularly well suited for the treatment of very diluted waste water. This is due to the fact that rhodium ions get into the swollen solid reactants, where there is a high concentration of active functional groups that determine the high speed of the decomposition of these ions. Due to the destruction of rhodium ions, copolymeric N-halogen-sulfonamides do not send any harmful substances to the solution. Only the active halogens (X ⁺¹ ) contained in the copolymer change into halides (X ^-1 ) which go into solution.

Example I. 0.8 dm ^{3 of} rhodanic wastewater with a concentration of 0.75 g'dm ^{-3 was} placed in a glass vessel, to which 2.1 g of NaOH was added, and then 15 g of copolymeric N-halosulfonamide obtained according to the patent description of the Polish People's Republic No. 138 767 and powdered . This copolymer contained 37.5 moles of active halogen (X ⁺¹ ). The suspension was stirred with a magnetic stirrer for several hours, and a decrease in the content of rhodate ions in the solution was observed. As soon as this concentration dropped to 0.02 mg · dm ^-3, the rhodium wastewater treatment process was considered completed.

Example II. In a glass column with dimensions: diameter 15 mm, height 120 cm equipped with a heating mantle by means of which the temperature of 45 ° C was maintained in it, 175 cm ^{3 of the} swollen copolymer, obtained according to the patent description of the Polish People's Republic No. 138 768, in the form of granules with a diameter of 0.8 + 1.3 mm. The copolymer contained 527 moles of active halogen (X ⁺¹ ). Rhodium effluent with a concentration of 0.52 g · dm ^-3 NaSCN and 1.65 g · dm ^-3 NaOH was passed through this column. The flow volume velocity was 10 cm ³ · min ^-1 . At 7-hour intervals, the column was subjected to ultrasonic shocks for 5 minutes. The column leak was free of rhodate ion until 29 hours of operation, when a breakdown occurred and incomplete rhodate destruction products appeared in the leak. After another five hours, rhodides appeared in the effluent, and after another six hours, the concentration of rhodate in the column effluent reached the value of 0.52 g · dm " ^J NaSCN, which indicated complete deactivation of the column bed. The deposit was thus reactivated in a known manner.

Claims (2)

Patent claims A method of neutralizing rhodium wastewater, characterized in that rhodium wastewater with the content of SCN "ions, preferably lower than 1 g · dm ^-3 , is made alkaline in order to obtain a molar ratio of hydroxide ions to rhodate ions not lower than 6, after which they are contacted in the temperature range of 2 + 60 ° C with copolymeric, insoluble, but water-swellable N-halogeno-sulfonamides, using at least 4 moles of halogen per 1 mole of neutralized rhodanic ion until the disappearance of rhodate ions, as well as their harmful derivatives. 151 268 2. The method according to p. The process according to claim 1, characterized in that contacting the rhodate wastewater takes place in the flow through the layer of copolymeric N-halogeno-sulfonamides at a speed lower than the speed of the decomposition of rhodate ions, the process being carried out until products of incomplete decomposition of radicals appear in the leak, and the bed the copolymer is shaken periodically, preferably by ultrasound.