At present, there are many domestic methods for determining the acid value of oil products, which are mainly divided into indicator method and potentiometric titration method. The indicator method is represented by GB / T264, but the accuracy is often affected, which is not suitable for dark oil products and Determination of viscous oil products; Potentiometric titration method is represented by GB / T7304. The adaptability of oil products is wide. The judgment of the endpoint is more objective, which represents the future development direction of oil acid value determination. However, this method has the defects that a large amount of toluene solvent is used, the potential jump of some oil products is small, and the toxicity needs to be used. The preparation of cumbersome m-nitrophenol assists in the determination of the end point. This paper proposes an improved method for determining the acid value of oil products by the GB / T7304 method. In this method, the KOH solution of the titrant is changed to the organic alkali titrant tetramethylammonium hydroxide, and the toxic reagent toluene in the titration solvent is changed to a non-toxic petroleum ether combined with a small amount of alcohol amine alkaline reagent. Leap, eliminating the preparation of m-nitrophenol non-aqueous solution used to assist in indicating the end point, further improving the accuracy of the method, the oil acid value above 0.005mg (KOH) / g can be measured, and the relative standard deviation of the results is not More than 3.0%, less than 6.0% of the standard method. The method has been applied in daily work and the results are satisfactory.
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