158 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 19 3 4 



SELECTION OF PROCESS AND PLANT SITE 



Considerable other research work was done before the final process 

 was selected. Other natural waters, as well as sea water, were inves- 

 tigated as sources of bromine, and improved methods were devised 

 for their use. More economical methods in conjunction with the 

 liberation of bromine were studied, including the use of lime or 

 metallic iron to remove bicarbonates from solution and thus to save 

 acid. Many different processes for removing bromine from very 

 dilute solutions were tried extensively in the laboratory, some on 

 semiplant scale. These included precipitation (1), extraction, and 

 vaporization of the bromine as well as its absorption and adsorption 

 in various agents, particularly in charcoal {£) . "While some showed 

 fair success, the technic of blowing the bromine from solutions as 

 dilute as the tailings from previous practice was improved and devel- 

 oped to a sound process as already described. Various methods were 

 devised for recovering the bromine from the blowing-out air by both 

 physical and chemical means, including immediate reaction of the 

 bromine with ethylene. It is possible that some such improvements 

 may be employed in the next few years. Finally, the commercial 

 phases of correlating this industry with others were given careful 

 study, and publication of the more interesting and important possi- 

 bilities may be expected. 



A comparison of the two general methods of obtaining bromine 

 from sea water indicated that the direct extraction process possessed 

 several economic advantages over the tribromoaniline method : 



1. The direct process requires theoretically only 1 mole of chlorine for each 

 mole of bromine which is liberated, whereas the other scheme requires 2 moles 

 of chlorine per mole of bromine. 



2. Smaller quantities of sulphuric acid are required by the direct process 

 than by the other method. 



3. Aniline is a relatively expensive raw material and is at a further economic 

 disadvantage as a carrier of bromine for gasoline treatment when it is con- 

 sidered that tribromoaniline contains only 73 percent bromine, whereas ethylene 

 dibromide is 85 percent bromine. 



At this point in the history of the development it was decided to 

 build and operate a pilot plant for extracting bromine from sea 

 water by the Dow Chemical Company's process. The site for this 

 unit was selected after considerable careful investigation, as it was 

 proposed to build a commercial plant in the same location if the 

 results of this venture were satisfactory. The chief requisites for 

 such a site were : 



1. The sea water at the point selected should not be diluted by fresh-water 

 streams. 



