Quality Improvement of Spent Lubricating Oil

Abstract

The acidity of spent lubricant was treated using sodium hydroxide solution. The effect of three variables on the treatment have been studied . These are mixing time rangingfrom 5-35 minutes, NaOH to lubricant weight ratio ranging from  0.25-1.25 and weight percentage  of NaOH ranging from  2-6 % .

The experimental design of Box-Wilson method is adopted to find a useful relationship between the three controllable variables and the lowering in the acidity of the spent lubricant. Then the effective variables and interactions are identified using the statistical analysis(F-test) of  three variable fractional design. The mathematical model is well represented  by a second order polynomial.

By the analysis of the experimental results, the best treatment conditions which achieved an acceptable acidity of the spent lubricant are 20 minutes mixing time ,  1 weight ratio of NaOH  to spent lubricant and 4.5 weight percentage  of N aOH. At these condition the acidity of the lubricant decreases from  0.62 to 0.0602 mg KOH/g oil.