Title of Invention

AN IMPROVED PROCESS FOR RECOVERY OF BROMINE

Abstract

An improved process for recovery of bromine by mixing a source of bromide ion with metal complex catalyst Ru-EDTA in a molar ratio of catalyst: bromide ranging from 1:10 to 1:11000 and acidifying the solution by conventional method in the pH range 0.5 to 5, adding oxidant selected from hydrogen peroxide to the above solution followed by continuously passing air at the rate ranging from 20 to 200 ml/min and recovering the bromine vapour by known techniques.

Full Text

The present invention relates to an improved process for the of bromine. More particularly this invention relates to catalytic oxidation of bromide from sea water, bittern and solutions containing bromide ions to produce bromine. Bromine is used in, flame retardants, fire extinguishers, semiconductor devices, pharmaceutical industries, photographic industries, perfumes, disinfectants in swimming pool and photovoltaic batteries etc. Bromine is used in the preparation of other bromo compounds e.g. bromochlorodimethylhydantoin is used in swimming pool and spas. Bromine compounds are intermediates in the production of organic chemicals. In order to extract' bromine from the solution in which it is present as i bromide ion (Br-), it is first necessary to oxidise the bromide and then to recover the free bromine (Br2) remaining dissolved. The oxidation of bromide to bromine can be affected in different ways, e.g. steaming out and air blowing processes, using chlorine as an oxidant and continue to be the commercial processes still in use. Depending upon the concentration of bromine in source either steaming or air-blowing process is used. In both the processes chlorine is used for oxidation of bromide to bromine. In steaming out process, chlorine gas is passed into the brine maintained at pi I between 3 to 4 and a temperature of 100 °C and steam is used to blow out the bromine from the reaction mixture which on cooling forms two separate layers of bromine and water, from which bromine is drawn out. In air blowing process also chlorine is used as an oxidant maintaining the same conditions as in steaming out process. However a stream of air is used to flush the bromine formed. In both the processes air/bromine mixture is then absorbed either in soda ash, caustic soda solutions or moist sulfur dioxide. With the trends towards developing environment friendly, cleaner technologies and minimising the use of hazardous chemicals effort is made to replace chlorine by air/oxygen containing oxidant to catalytically oxidise bromide ion to bromine in homogeneous conditions at ambient temperature and pressure. Reference may be made to K. C. Lesher et. al. in US Patent No. 4,725,425 16 Feb. 1988, which has disclosed a single stage vacuum process for recovering bromine from brine at subatmospheric pressure in presence of chlorine. Vacuum is used in the modified process, which by matching the vapour pressure of the brine eliminate the need for steam to heat the brine. Because of the lower volume of steam used in the vacuum process, the capacity of contact tower is increased and operating temperature of the vacuum process also become lower. At the lower operating temperature of the vacuum process, chlorine under goes fewer side reactions and less hydrolysis so the use of chlorine can be reduced. In further extension of the work K. C. Lesher et. al. in US Patent No. 4,719,096, 12 Jan. | 1988, modified the single stage vacuum process in to double stage vacuum process using chlorine. In the double stage vacuum process the tail brine from the first stripping are stripped again under greater vacuum. Due to greater vacuum, the steam used in double stage vacuum process became much lower. The drawbacks of these processes are use of chlorine, as chlorine is an extremely toxic chemical and extreme care has to be taken while handling chlorine. Also, since chlorine under goes fewer side reactions, hence being an ingredient in the reaction system chorine affects the main reaction of oxidation of bromide to bromine causing less yield of bromine. A. S. Mehta et. al. in their paper on "Bromine manufacture : some modifications in indigenous technology", Chemical Engineering World XIX (10, Oct. 1984, pp 73-77) suggest oxidation of bromide ions in bittern to free bromine, using chlorine as a oxidant. The bittern is acidified up to pH 3 to 4 by conventional method and chlorine is passed to oxidize bromide ion to bromine. The liberated bromine was stripped out by steaming out/air blowing process. Condensation of steam and bromine in case of steaming out process and absorption of bromine in to suitable alkali in case of air blowing process, were done. The feed bittern is pre-heated to a temperature around 90 °C with the help of good heat exchangers using waste heat from debrominated bittern. The double decomposition reaction is better at the boiling point of bittern. Steam fed to the tower is used to pre-heat bittern to it's boiling point and excess steam is used to strip out liberated bromine from tower. For feed bittern with specific gravity around 1.26, the debrominated bittern coming out of the tower is at 110 °C. The steam consumption is reduced by lowering the boiling point of the bittern by operating the tower at lower (0.75 atmosphere) pressure. Less steam consumption also prevented the leakage of bromine from lower. The drawbacks of the process are use of corrosive chlorine and the maintenance of subatmospheric pressure. C. J. Louvar et. al. in US Patent No. 3,346,340, 10 Oct. 1967 reveals a process for the oxidation of hydrogen bromide to bromine in the temperature range 300 - 600 °C, using a heterogeneous catalyst which comprises copper and cerium oxide on alpha- or theta-alumina or zirconium support, having a surface area between 5 and 100 square meters per gram and containing less than about 50 micromoles of hydroxyl per gram. The drawback of the process is that due to heterogeneous catalytic system the reaction takes place at very high temperature. Also the process is for oxidation of hydrogen bromide only, which is feeble source for bromine recover/ unlike sea water and bittern. * R. G. Hay et. al. in US Patent No. 3,437,445, 08 April, 1969, describe a process to catalytically oxidise hydrogen bromide to bromine by using copper bromide catalyst. The reaction is carried out in the temperature range of 175 -700 °C with contact time ranging from 0.1 to 25 seconds. The yield of bromine is only between 28 and 78 molar percentage. It was found that copper bromide during the oxidation process got volatilized to bromine. To overcome this difficulty, copper bromide was replaced by platinum and palladium metals. The drawback of this process is to eliminate the use copper based catalyst in favour of costly metals like platinum and palladium. Reaction temperature is very high and yield of bromine (28 and 78 molar percentage) is also low. Beside this, reaction was carried out at a very high temperature which need additional heating equipment. P. F. Schubert et. al. in US patent No. 9,306,037, 01 April, 1993 describe the use of a cupric bromide catalyst for oxidation of hydrogen bromide to bromine The catalyst comprising of a promoter or stabiliser and a Zirconium-containing support oxidises hydrogen bromide. The hydrogen bromide is vaporized, mixed with an oxygen containing gas and heated to maintain the temperature in the range of 125-475 °C. The heated gas mixture is passed over the catalyst. In further extension of this work, P. F. Schubert et. al. in ACS Symposium Series 1994, 552 (Environmental Catalysis) 405, suggest a catalyst superior to the cupric bromide catalyst as well as resistant to deactivation by propionic acid and hydrochloric acid contaminants. 98% recovery is reported from a waste stream containing 48% hydrogen bromide. Aqueous hydrogen bromide instead of anhydrous hydrogen bromide along with tube and shell reactor was used to control the heat generated as a result of highly exothermic nature of the reaction. At a feed rate of 1.2 kg/h and an inlet temperature maintained at 275 °C the maximum rise noted was 12 °C. The drawback of this process is heating of the mixed gas needs an additional unit operation and heating equipment. Moreover special arrangement is required to maintain the reaction temperature. P. F. Schubert et. al. in US patent No. 9,306,038, 01 April, 1993 describes the use of a catalyst comprising copper bromide and lanthanum bromide supported on zirconium for the recovery of bromine from sea water. In this process sea water is acidified, chlorinated by chlorine and air stripped to remove the bromine. The stripping effluent is reacted with an SO2 stream to convert the bromine to hydrogen bromide and sulphuric acid in the air stream. The process continues by absorbing hydrogen bromide and sulphuric acid from the resulting acidic fog to produce an aqueous sulphuric acid stream containing hydrogen bromide. The hydrogen bromide is stripped and separated from liquid stream and passed to an oxidation reactor where it is catalytically oxidized with an oxygen containing gas to produce a stream of bromine and water. The hot reactor effluent is quenched and product bromine is separated from the water. The drawbacks of this process are use of toxic chemical chlorine, production of corrosive sulphuric acid as by product and separation of hydrogen bromide from the mixture of sulphuric acid and hydrogen bromide. The main object of the present invention is to provide an improved process for preparation of bromine which obviates the drawbacks as detailed above. Another object of the present invention is to catalytically activate non hazardous oxidants for direct conversion of bromide to bromine without forming the intermediate hydrogen bromide. Still another object is the preparation of bromine at ambient/moderate conditions of temperature and pressure. Yet another object is to obtain a high conversion (95%) of bromide to bromine. Still another object of the present invention is to use ethylenediaminetetraacetato ruthenate (Ru-EDTA) catalyst to increase the rate of the reaction. Yet another object of the present invention is to use hydrogen peroxide as oxidant. Accordingly the present invention provides an improved process for recovery of bromine which comprises characterised in that mixing a source of bromide ion as herein described with metal complex catalyst Ru-EDTA in a molar ratio of catalyst: bromide ranging from 1:10 to 1:11000 and acidifying the solution by conventional method in the pH range 0.5 to 5, adding oxidant in the form of hydrogen peroxide to the above solution followed by continuously passing air at the rate of 20 to 200 ml/min and recovering the bromine vapour by known techniques as herein described. In an embodiment of the invention the metal complex catalyst may be ethylenediaminetetraacetato ruthenate (Ru-EDTA). In another embodiment of the invention the metalcomplex catalysst Ru- EDTA may be used in molar ratio of catalyst: bromide is 1:4940.. In yet another embodiment of the invention the oxidant may be hydrogen peroxide (30%) in molar ratio of catalyst : hydrogen peroxide selected from the range of 1:400 to 1: 100000. In yet another embodiment of the invention the oxygen containing gas may be air and was passed in the reaction mixture at the rate selected from the range of 20 to 200 ml/min. In yet another embodiment of the invention hydrochloric acid may be used to maintain the pH of the solution, selected from the range of 0.5 to 5. According to the present invention the bromide ion was oxidised to bromine by using Ru-EDTA catalyst, in which molar ratio of catalyst : bromide was maintained from 1 : 10 to 1 : 11000. In practicing this invention the solution containing catalyst and source of bromide ion, was acidified by hydrochloric acid in the pH range 1 to 4 particularly and in the pH range 0.5 to 5 preferably. Hydrogen peroxide was used as an oxidant in the molar ratio of catalyst : hydrogen peroxide in the range of 1 : 400 to 1 : 100000. An oxygen containing gas, air was continuously passed at the rate of 20 - 200 ml/min in the reaction mixture. Typical catalytic experiments were conducted using solutions containing bromide ions, sea water and bittern as a source of bromide ions. Composition of sea water from the open ocean (brine) and bittern used in present process are given in table 1. Sea water and bittern used were of 3.5 degree baumme (°Be) and 29 °Be, respectively, where °Be is an arbitrary scale originally intended to indicate percent salt in brine and its relation with specific gravity is : °Be = 145 - (1457 specific gravity) TABLE 1 Composition of sea water (brine) and bittern in grams of ions per liter of sea brine as a function of brine density (22.2/15.6) grains per liter of brine at 22.2 °C. (Table Removed) In a typical experiments catalyst, ethylenediaminetetraacetato ruthenate (Ru-EDTA) was dissolved in the solutions containing bromide ions/sea water/bittern in the molar ratio of catalyst : bromide ranging from 1 : 10 to 1 : 11000. After acidifying the solution in the pH range 0.5 to 5, oxidant hydrogen peroxide was added in molar ratio of catalyst: hydrogen peroxide ranging from 1 : 400 to 1 : 100000 and an oxygen containing gas air was blown at a rate ranging from 20 : 200ml/min. The issuing mixture of gas and bromine is absorbed in a suitable alkaline solution. The alkaline solution containing absorbed bromine is acidified and steam distilled. On cooling, bromine forms a separate layer below water and is collected. The amount of the bromine produced in the reaction mixture was estimated by known method, titrimetrically, by using 0,1 N sodium thiosulphate. In 5 ml of reaction mixture containing bromine, 10 ml sulfuric acid (20%) and 10 ml potassium iodate (10%) are added and kept for 5 min. and this solution is titrated with 0.1 N sodium thiosulphate. The conversion were calculated based on the molar concentrations of bromides converted in to bromine and were found to be 90 - 95 % at ambient temperature (30°C) and pressure. The properties of the product bromine are : density, 3.0879 gm/L at 30 °C ; mol. wt., 159.808 ; freezing point, -7.25 °C ; boiling point, 58.8 °C ; vapour density, 7.139 g/L at 0 °C ; viscosity, 0.288 mm2 /s at 30 °C ; surface tension, 40.9 dyn/cm. at 25 °C. In present invention oxidation of bromide has been conducted in homogeneous catalytic conditions at ambient temperature (30 °C) and pressure in which bromine is obtained as oxidation product with high yield (95%). A ruthenium based metal complex (Ru-EDTA) found to be an efficient novel homogeneous catalyst was used to oxidise bromide ion present in sea water, bittern and synthetic solution containing bromide ions. This oxidation process involves some inventive steps viz (i) novelty resides in the catalyst's function for the process of oxidation of bromide to bromine in which catalyst Ru-EDTA effectively catalyses and increases the rate of the oxidation of bromide to bromine, (ii) the process works at ambient temperature (30 °C) and low pressure and obviates the need of high temperature, (iii) the bromide to bromine catalytic oxidation process produces bromine directly without formation of intermediate hydrogen bromide and (iv) the environmentally friendly oxidant hydrogen peroxide and air are used and the process becomes non-hazardous, (v) hydrogen peroxide was used as oxidant instead of corrosive chlorine gas. (vi) cheaper ruthenium based catalyst was used avoiding costlier platinum and palladium based catalyst, (vii) the reaction is conducted at ambient temperature and there is no exothermic heat liberated which needs to be controlled, (viii) there are no hazardous by product(s) formed during oxidation. The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of the present invention. EXAMPLE- 1 A hot solution of Na2(H2edta) (0.5g) in 0.001 M HC1O4 (10 ml) was added to a warm solution of [RuCl5 H2O]K2 (0.5g) in 0.001 M HC1O4 (10 ml) and mixture was refluxed for 30 min. Concentration of the yellow solution on steam bath gave a yellow precipitate which was washed with cold water and ethanol; yield 0.25 g (40 %). The metal complex cthylenediaminetetraacetato ruthenate (Ru-EDTA) was characterised by elemental (CHN) analysis, spectrophotometer and electrochemical methods. The calculated C,H, and N percentage being 24 %, 3.42 % and 5.59 % respectively, was found to be C=23.5 % H=3.27 % and N=5.27 % respectively in the metal complex..-Metal complex catalyst, Ru-EDTA was of characteristic yellow color with 20 % ruthenium by weight. Spectrophotometric analysis showed two characteristic peaks at 280 nanometer (molar extinction coefficient = 2)800) and 350 nanometer (molar extinction coefficient =770) of the metal complex. Electrochemically determination of half wave potential, for Rulll/Ru11 couple of the metal complex against Ag/AgCl electrode, is -0.30 volts. EXAMPLE - 2 To 100 ml of solution, containing sodium bromide and catalyst was dissolved in molar ratio of catalyst: bromide 1 : 4940. Again hydrochloric acid was added to adjust the pH at 3. After addition of hydrogen peroxide with catalyst : hydrogen peroxide molar ratio 1 : 9036, an oxygen containing gas air was continuously passed at the rate of 100 ml/min. till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The yield based on the conversion of bromide ions to bromine was 95 percent. EXAMPLE - 3 To 100 ml of solution, containing sodium bromide and catalyst was dissolved in molar ratio of catalyst : bromide 1 : 4940. Again hydrochloric acid was added to adjust the pH at 2. After addition of hydrogen peroxide with catalyst : hydrogen peroxide molar ratio 1 : 9036, an oxygen containing gas air was continuously passed at the rate of 100 ml/min. till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The yield based on the conversion of bromide ions to bromine was 95 percent. EXAMPLE - 4 To 100 ml of solution, containing sodium bromide and catalyst was dissolved in molar ratio of catalyst: bromide 1 : 4940. Again hydrochloric acid was added to adjust the pH at 4. After addition of hydrogen peroxide with catalyst : hydrogen peroxide molar ratio 1 : 9036, an oxygen containing gas air was continuously passed at the rate of 100 ml/min. till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution ! comprising of 10 % sodium, carbonate solution. The yield based on the conversion of bromide ions to bromine was 93 percent. EXAMPLE - 5 To 100 ml of solution, containing sodium bromide and catalyst was dissolved in molar ratio of catalyst : bromide 1 : 4940. Again hydrochloric acid was added to adjust the pH at 3. After addition of hydrogen peroxide with catalyst : hydrogen peroxide molar ratio 1 : 9036, an oxygen containing gas air was continuously passed at the rate of 50 ml/min. till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The yield based on the conversion of bromide ions to bromine was 91 percent. EXAMPLE - 6 To 100 ml of solution, containing sodium bromide and catalyst was dissolved in molar ratio of catalyst : bromide 1 : 4940. Again hydrochloric acid was added to adjust the pH at 3. After addition of hydrogen peroxide with catalyst.: hydrogen peroxide molar ratio I : 9036, an oxygen containing gas air was continuously passed at the rate of 150 ml/min. till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The yield based on the conversion of bromide ions to bromine was 95 percent. EXAMPLE - 7 To a 100 ml solution of sodium bromide catalyst was dissolved in molar ratio of catalyst : bromide, 1 : 1205 and acidified by hydrochloric acid to maintain the pH at 3. Again hydrogen peroxide was added in molar ratio of catalyst : hydrogen peroxide 1 : 9036 and an oxygen containing gas, air was continuously passed at the rate of 100 ml/min, till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The conversion of oxidation of bromide to bromine obtained was 95 percent. EXAMPLE - 8 To a 100 ml solution of sodium bromide catalyst was dissolved in molar ratio of catalyst : bromide, 1 : 4940 and acidified by hydrochloric acid to maintain the pH at 3. Again hydrogen peroxide was added in molar ratio of catalyst : hydrogen peroxide 1 : 6024 and an oxygen containing gas, air was continuously pass at the rate of 100 ml/min, till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The conversion of oxidation of bromide to bromine obtained was 92 percent. EXAMPLE - 9 To a 100 ml solution of sodium bromide catalyst was dissolved in molar ratio of catalyst : bromide, 1 : 4100 and acidified by hydrochloric acid to maintain the pH at 3. Again hydrogen peroxide was added in molar ratio of catalyst : hydrogen peroxide 1 : 7500 and an oxygen containing gas, air was continuously pass at the rate of 100 ml/min, till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The conversion of oxidation of bromide to bromine obtained was 95 percent. EXAMPLE - 10 To a 100 ml solution of sodium bromide catalvst was dissolved in molar * ratio of catalyst : bromide, 1 : 10250 and acidified by hydrochloric acid to maintain the pH at 3. Again hydrogen peroxide was added in molar ratio of catalyst : hydrogen peroxide 1 : 18750 and an oxygen containing gas, air was continuously pass at the rate of 100 ml/min, till no more bromine was evolved. The issuing bromine vapours were collected in an absorbing solution comprising of 10 % sodium carbonate solution. The conversion of oxidation of bromide to bromine obtained was 93 percent. i EXAMPLE - 11 The catalyst was tested with 100 ml brine solution of 3.5 °Be comprising calcium, magnesium, potassium, sodium, sulphate, chloride, and bromide ions as the major contents. Catalyst was dissolved to 100 ml brine solution of 3.5 °Be (which contains, 8.37 x 10-4 moles/liters of bromide) in molar ratio of catalyst: bromide, 1 : 10, and acidified by hydrochloric acid to adjust the pH at 3. Hydrogen peroxide was added in molar ratio of catalyst : hydrogen peroxide, 1 : 9036 and air was continuously bubbled at the rate of 100 ml/min. The bromine formation started and it's vapours were collected to 10% sodium carbonate solution. The amount of bromine formed calculated from the titration result was found to be 95 percent. The experimental result indicates that the presence of other anions and cations in brine solution does not interfere with the catalytic oxidation of bromide to bromine. EXAMPLE - 12 The catalyst was tested with 100 ml brine solution of 3.5 °Be comprising calcium, magnesium, potassium, sodium, sulphate, chloride, and bromide ions as the major contents. Catalyst was dissolved to 100 ml brine solution of 3.5 °Be in molar ratio of catalyst : bromide, 1 : 100, and acidified by hydrochloric acid to adjust the pH at 3. Hydrogen peroxide was added in molar ratio of catalyst : hydrogen peroxide, 1 : 90360 and air was continuously bubbled at the rate of 100 ml/min. The bromine formation started and it's vapours were collected to 10% sodium carbonate solution. The amount of bromine formed calculated from the titration result was found to be 95 percent. EXAMPLE - 13 The catalyst was tested with 100 ml brine solution of 3.5 °Be comprising calcium, magnesium, potassium, sodium, sulphate, chloride, and bromide ions as the major contents. Catalyst was dissolved to 100 ml brine solution of 3.5 °Be in molar ratio of catalyst : bromide, 1 : 10, and acidified by hydrochloric acid to adjust the pH at 3. Hydrogen peroxide was added in molar ratio of catalyst : hydrogen peroxide, 1 : 480 and air was continuously bubbled at the rate of 100 ml/min. The bromine formation started and it's vapours were collected to 10% sodium carbonate solution. The amount of bromine formed calculated from the titration result was found to be 91 percent. EXAMPLE - 14 The bittern of 29 °Be was used, which comprised calcium, magnesium, potassium, sodium, sulphate, chloride, and bromide ions as the major contents to test the catalytic oxidation of bromide to bromine. The experiment was conducted with catalyst in presence of 100 ml bittern of 29 °Be ( which contains 0.023 moles per liter bromide) with molar ratio of catalyst : bromide, 1 : 277. This solution was acidified by hydrochloric acid to adjust pH at 3. In this reaction mixture hydrogen peroxide with catalyst : hydrogen peroxide molar ratio, 1 : 9036 was added and air was bubbled at the rate of 100 ml/min. The issuing bromine vapours were collected in 10 % sodium carbonate solution. The conversion of bromide to bromine obtained was 95 percent. EXAMPLE- 15 Experiment was conducted with lower concentration of Ru-EDTA catalyst in 100 ml bittern of 29 °Be with catalyst : bromide molar ratio 1 : 2770. The solution was acidified with hydrochloric acid to adjust pH 3. Oxidant hydrogen peroxide with catalyst : hydrogen peroxide molar ratio, 1 : 90360 was added and air was bubbled at 100 ml/min. The bromine formed was collected in 10% sodium carbonate solution and the conversion .obtained was 95 percent. EXAMPLE - 16 A solution containing potassium bromide in 100 ml water, was catalysed by Ru-EDTA with catalyst : bromide molar ratio 1 : 4216 to produce bromine from potassium bromide salt. The solution was acidified by hydrochloric acid to adjust pH at 3. Oxidant hydrogen peroxide with catalyst : hydrogen peroxide molar ratio 1 : 9036, was added and air was bubbled at the rate of 100 ml/min which gave 93% yield of the bromine formed in the reaction mixture. The bromine was collected in 10% sodium carbonate solution. The main advantages of present invention arc : 1. Unlike the catalytic processes described in the literature which either require higher temperatures or conversion of bromide to hydrogen bromide before it can be catalytically oxidised to bromine, present process operates at ambient conditions and does not require prior conversion to hydrogen bromide. 2. The reaction takes place even in presence of other anions without the need to separate bromide ion. 3. Being homogeneous catalytic reaction much less amount of catalyst (ppm level) is required. 4 Unlike,the conventional processes in operation where chlorine is used, the present invention describes the role of oxidants like hydrogen peroxide, oxygen containing gas air, which are non-hazardous. Where other oxidants are used, they are converted to nonhazardous produces). 5. The present process can be easily adopted without major changes in the existing industrial bromine recovery processes. We claim : 1. An improved process for recovery of bromine which comprises characterised in that mixing a source of bromide ion as herein described with metal complex catalyst Ru-EDTA in a molar ratio of catalyst : bromide ranging from 1:10 to 1:11000 and acidifying the solution by conventional method in the pH range 0.5 to 5, adding oxidant in the form of hydrogen peroxide to the above solution followed by continuously passing air at the rate of 20 to 200 ml/min and recovering the bromine vapour by known techniques as herein described . 2. An improved process as claimed in claim 1 wherein the catalyst Ru-EDTA used in molar ratio of catalyst: bromide is 1 : 4940. 3. An improved process as claimed in claims 1 & 2 wherein the flow of air passed in the reaction mixture is preferably in the range of 40 to 150 ml/min. 4. An improved process for recovery of bromine substantially as herein described with reference to the examples accompanying this specification. .

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1201-del-2001-abstract.pdf

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