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The petroleum refining industry produces a large amount of spent catalysts which contain sulfur and some valuable metals. During the recovery of these valuable metals, sulfur should be processed and removed from the surface of the spent catalyst. Several chemical reagents including NaOH, Na2CO3, H2O2, CS2, and decanol were employed to investigate the removal of sulfur from the spent catalysts. NaOH and ultrasound-assisted oxidative treatment with H2O2 showed better performance than the other reagents for the removal of sulfur from spent catalyst. Sulfur and valuable metals dissolved together to the solution by using ultrasound-assisted oxidative treatment with H2O2, while the covered sulfur was removed from the spent catalyst without affecting the dissolution of valuable metals. The removal of sulfur as well as the leaching of valuable metals was discussed on the basis of oxidation and reduction reaction. The optimum conditions for sulfur removal were chosen as follows: temperature, 60°C; pulp density, 20 g/dm³; reaction time, 1.5 h; stirring speed, 800 rpm; and NaOH concentration, 0.5 M. The obtained results can be applied to develop an environment-friendly process to treat sulfur from the spent catalysts. [ABSTRACT FROM AUTHOR]

The high content of potassium in molasses limits its usage as a raw material for stock feed. Moreover, its high viscosity makes it difficult to develop an efficient removal process. In this study, ion exchange and solvent extraction experiments have been performed to investigate the removal of potassium from a mixture of molasses with water. Cationic exchange resins (AG50W-X8 and Diphonix) showed a high loading percentage of potassium but the occurrence of breakthrough in few bed volumes was a drawback to the industrial application. Among the cationic extractants (D2EHPA, PC 88A, Cyanex 272) tested in this study, saponified PC 88A was found to be the best extractant for the removal of potassium. Batch simulation studies on a three stage counter current extraction confirmed that 85% of potassium was removed from 50 wt % molasses solution in water by using saponifed PC 88A. [ABSTRACT FROM AUTHOR]

Solvent extraction of Fe(III) from chloride solution by using a mixture of D2EHPA (Di-(2-ethylhexyl)-phosphoric acid) and TBP (Tri-butyl phosphate) and the reductive stripping of Fe(III) from the loaded organic were investigated. Quantitative extraction of Fe(III) from the solution (Fe concentration = 90 g/L) was accomplished in two cross-current extraction stages by using the mixture of D2EHPA and TBP. In order to facilitate the stripping efficiency, a reductive stripping method was employed by using H2SO3 or Na2SO3 as a reducing agent. The addition of H2SO4 into reducing agents led to improvement in the stripping efficiency while high concentration acid would suppress it. Both of the mixtures of H2SO4 + H2SO3 and H2SO4 + Na2SO3 showed good efficiency for the stripping of Fe(III), while the latter was recommended as the stripping solution based on the economics and experimental condition. [ABSTRACT FROM AUTHOR]