Bromine recovery

The flowsheet of the air-stripping process for bromine recovery from brines (including seawater brines) is shown in Fig. 5 [60]. The stock brine from a reservoir, mbted with H2SO4 and Clj, is directed to the top of the desorber. The bromine-free brine is collected at the bottom of the desorber, neutralized with thiosulfate and lime milk prior to disposal. Release of the chlorine/bromine air mixture from the top of the desorber is directed to the dechlorinating tower (1) where the mixture is treated with diluted FeBrj solution. The halogen exchange is described by the reaction... 

None of the numerous technological solutions available for bromine recovery from seawater wholly satisfy modem ecological standards. At present, the closest to acceptable methods exclude the use of aggressive... 

A number of ecologically acceptable electrosorption methods have been developed at the Vernadsky Institute of The Russian Academy of Science [74, 75]. It has been demonstrated that these methods can compete successfully with existing techniques of bromine recovery ftom seawater and brines. 

Figure 8 Concentration profiles illustrating the principle of the dual-temperature multistage scheme for bromine recovery from seawater (T2>T ).

Figure 9 Scheme of dual-temperature multistage unit for bromine recovery from seawater. Storage tanks for bromine concentrates (cone. 1-3) are supplied with hicilities for cooling/heating the solution under treatment (T2>Ti). 

Qi Z and Cussler EL, Bromine recovery with hollow fiber gas membrane. Journal of Membrane Science 1985, 24, 43-57. 

Contrary to the proposed WEEE directive many believe that a form of recycling is energy generation from plastic waste with bromine recovery as a form of recycle. 

Recycle should cover mechanical recycle in the originally intended application or in a downgraded application, or feedstock recovery with or without bromine recovery, or energy generation with at least the bromine recovered. 

The BrCl tends to decompose more to the elements as vaporization continues. It is therefore possible to recover elemental bromine. With most salts, the quantity available is too small to be attractive, and any attempt at bromine recovery will also aggravate the problems of the presence of nitrogen trichloride. 

The commercial production of iodine depends on the source of the element. From natural brines, the process is similar to bromine recovery displacement of iodide ion (I ) by chlorine, blowout of the impure iodine, and repurification by sublimation. Other processes employ iodide precipitation by silver nitrate (AgNOs), separation on ion-exchange resins, or oxidation of iodide by sulfuric acid (somewhat similar to the original procedure used by Courtois). 

Pour the resulting dark reddish-brown liquid into 500 ml. of water to which 17 ml. of saturated sodium bisulphite solution has been added (the latter to remove the excess of bromine). Steam distil the resulting mixture (Fig. II, 41,1) , collect the first portion of the distillate, which contains a little unchanged nitrobenzene, separately. Collect about 4 litres of distillate. Filter the yellow crystalline solid at the pump, and press well to remove the adhering liquid. The resulting crude m-bromonitrobenzene, m.p. 51-52°, weighs 110 g. If required pure, distil under reduced pressure (Fig. II, 19, 1) and collect the fraction of b.p. 117-118°/9 mm. it then melts at 56° and the recovery is about 85 per cent. 

Before sample preparation, surrogate compounds must be added to the matrix. These are used to evaluate the efficiency of recovery of sample for any analytical method. Surrogate standards are often brominated, fluorinated, or isotopically labeled compounds that are not expected to be present in environmental media. If the surrogates are detected by GC/MS within the specified range, it is... 

Oil Fields. Oil field waters in the United States containing lithium have been identified in 10 states. The greatest concentrations are in waters from the Smackover formation of southern Arkansas and eastern Texas. Concentrations from this formation have been measured from 300—600 ppm in waters originating at a 2500—3300 m depth. Recovery of lithium from this resource would only be commercially feasible if a selective extraction technique could be developed. Lithium as a by-product of the recovery of petroleum (qv), bromine (qv), or other chemicals remains to be exploited (12). 

Dissolved Minerals. The most significant source of minerals for sustainable recovery may be ocean waters which contain nearly all the known elements in some degree of solution. Production of dissolved minerals from seawater is limited to fresh water, magnesium, magnesium compounds (qv), salt, bromine, and heavy water, ie, deuterium oxide. Considerable development of techniques for recovery of copper, gold, and uranium by solution or bacterial methods has been carried out in several countries for appHcation onshore. These methods are expected to be fully transferable to the marine environment (5). The potential for extraction of dissolved materials from naturally enriched sources, such as hydrothermal vents, may be high. 

Acetaldehyde can be used as an oxidation-promoter in place of bromine. The absence of bromine means that titanium metallurgy is not required. Eastman Chemical Co. has used such a process, with cobalt as the only catalyst metal. In that process, acetaldehyde is converted to acetic acid at the rate of 0.55—1.1 kg/kg of terephthahc acid produced. The acetic acid is recycled as the solvent and can be isolated as a by-product. Reaction temperatures can be low, 120—140°C, and residence times tend to be high, with values of two hours or more (55). Recovery of dry terephthahc acid follows steps similar to those in the Amoco process. Eastman has abandoned this process in favor of a bromine promoter (56). Another oxidation promoter which has been used is paraldehyde (57), employed by Toray Industries. This leads to the coproduction of acetic acid. 2-Butanone has been used by Mobil Chemical Co. (58). 

Eastman Chemical Co. uses only cobalt and bromine, and lower temperature oxidations are held at 175—230°C (83). Solution of 4-formylbenzoic acid is obtained by using hydroclones to replace the mother hquor from the first oxidation with fresh acetic acid. A residence time of up to 2 h is used in order to allow for sufficient digestion to take place and to reduce the 4-formylbenzoic acid content to 40—270 ppm (83). Recovery of dry terephthahc acid is as described above. 

In addition to freshwater, seawater is also a source for sodium, magnesium, chlorides, iodine, bromine, and magnesium metal (see Sodium coLD>ouNDS Magnesium coLD>ouNDS Iodine Bromine Magnesiumand magnesium alloys). Many other elements are certain to be economically obtained from the ocean as technology for the recovery improves. 

Later, recovery of bromine from brine wells in Midland County, Michigan was developed. Brines in Michigan, Ohio, and West Virginia suppHed the principal portion of production in the United States until 1935. Michigan brines are stiU a source of bromine today. A significant source of bromine in 1991 came from wells in southwest Arkansas. Bromine is found in Seades Lake brine and was produced there at one time, but commercial extraction has been discontinued. 

Recovery Process. Commercial processes depend on the oxidation of bromide to bromine. Most of the Hberated bromine remains dissolved in the brine. The brine is then stripped of bromine followed by recovery of bromine from the stripping agent. Subsequent purification by distillation is often a final step. 

Fig. 3. Steaming-out process for recovery of bromine from high bromide brines (22).

Recovery Process. In past years iodine was recovered at Long Beach, California from oil field brine and from natural brines near Shreveport, Louisiana (36,37). The silver process was used. Silver nitrate reacts with sodium iodide to precipitate silver iodide. Added iron forms ferrous iodide and free silver. The ferrous iodide then reacts with chlorine gas to release free iodine. After 1966, the silver process was replaced with the blowing-out process similar to the bromine process. 

Bromine All of the bromine produced in the United States is extracted from naturally occurring brines by steam extraction. The major air pollution concern is H2S from the stripper if H2S is present in the brine. The H2S can either be oxidized to SO2 in a flare or sent to a sulfur recovery plant. 

The commercial recovery of iodine on an industrial scale depends on the particular source of the element.Erom natural brines, such as those at Midland (Michigan) or in Russia or Japan, chlorine oxidation followed by air blowout as for bromine (above) is much used, the final purification being by resublimation. Alternatively the brine, after clarification, can be treated with just sufficient AgNOs to precipitate the Agl which is then treated with clean scrap iron or steel to form metallic Ag and a solution of EeU the Ag is redissolved in HNO3 for recycling and the solution is treated with CI2 to liberate the h ... 

A 100-ml flask is charged with 25 ml of bromine and 10 g of adamantane and heated under reflux for 3 hours. The cooled mixture is dissolved in 100 ml of carbon tetrachloride, and the carbon tetrachloride solution is washed with 100-ml portions of saturated bisulfite solution until the color of bromine is discharged. The solution is then washed twice with water and dried (magnesium sulfate). The solvent is removed (rotary evaporator) and the product is recrystallized from methanol. (For best recovery of the recrystallized material, the methanol solution should be cooled in a Dry Ice cooling bath.) The product has mp 108°. 

Waste HBr is a common byproduct of organic brominations. Frequently, this waste is neutralized with caustic, the resulting sodium bromide salt is discharged, and valuable bromine is lost. The economic advantages of recovery and recycle of this HBr have long been recognized (refs. 1, 3). In practice, recovery typically takes the form of conversion of the HBr to clear drilling fluids or alkylbromides (ref. 4) as shown in equations 1 and 2. 

Chlorine is used to obtain bromine from salt sources in primary production and is an excellent process for such large scale operations. For smaller scale recovery operations it is cheap in reagent terms but requires specialised equipment for handling and use which adversely impact on the process economics. Additionally, large volumes of salt are produced, creating a similar effluent problem to that which it is solving. 

Brominated Compounds Yield of Completely Chlorinated Compound (%) Yield of Mixed Brom./chlor. Compounds (%) Recovery (%)... 

---