Deodorizer catch basin sludges and the metallic soaps found therein

Abstract

SummaryA method of determining and recovering the metallic soaps present in deodorizer catch basin sludges has been described. It is based on the apparent low solubility of calcium and iron soaps in a commercial solvent known as Skellysolve‐F. Using the method evolved, six samples representing material from four refineries were examined. It was found that the metallic soaps varied all the way from 0.51% to 28.02%. The recovered soaps were analyzed for both mineral and fatty acid content. In five of the six soaps examined above 90% of the metal present was found to be calcium, but in one sample about 27% of the metal was iron. In all cases, less than the theoretical amount of fatty acid was obtained from the soaps and the loss was attributed to solubility of some of the acids in water. The fatty acids obtained by hydrolysis of the soaps were all much more saturated than would be predicted from the iodine values of the sludge oils from which they were formed. It is postulated that the free fatty acids found in deodorizer distillates are disproportionally more saturated than are the combined fatty acids. In the course of other work the free fatty acid contents of the various sludges examined were determined. They were found to run usually from 9.5% to 19.9% although one sample ran 53.7%.