Liquid-liquid extraction of naphthalene. Application of a mixture design and optimization

Coke gas treatment process requires fresh fuel oil to remove naphthalene. At the Coke plant of Annaba in Algeria, an amount of about 14.5 tons/day of fuel oil is used as washing oil. At the end of the process, the released fuel is charged at least 7% of naphthalene as impurities. This creates serious problems in the region due to the environmental pollution by this industrial waste. In order to regenerate the fuel, a liquid-liquid extraction of naphthalene by a mixture of solvents was performed. The efficiency of the extraction of naphthalene from an organic phase depends primarily on the choice of the extractant and can also be improved by optimizing the various operating parameters. The aim of this work was to improve the performance of the liquid-liquid extraction of naphthalene from a phase fuel by the research for an optimal composition of a three solvents mixture as the extractant. From preliminary tests, the amount of fuel from the extractant mixture (F/M), stirring speed and the concentration of naphthalene in the fuel oil were fixed. The composition of the extractant mixture was performed by implementing an experimental mixture design where the mixing proportions of the three components dimethylsulfoxide (DMSO), methanol and water, were studied. The response was the effect of the solvent on the extraction yield of naphthalene. This yield was determined by the amount of naphthalene in the fuel oil phase which was followed by refractometry and confirmed by infrared spectroscopy. The use of this design of experiments is very effective to evaluate and to model the effects of these components by developing polynomial regression equations that describe the interdependencies between the input parameters and the yield response. The results treated statistically may be very interesting and can finally determine the optimum conditions for a maximum yield of extraction. (C) 2013 The Authors. Published by Elsevier Ltd. Open access under CC BY-NC-ND license. Selection and/or peer-review under responsibility of the TerraGreen Academy