Methods for purification of acidic tar from acidic components

Abstract The article presents a comparative characteristic of the methods of preparation - purification of acidic tar from free sulfuric acid and organic sulfonic acids. The total content of these components in the composition of acidic tar obtained during the purification of lubricating oils can vary within 15-40 %, which significantly complicates their technological processing. Therefore, the treatment of acidic tar is an urgent task that can be solved by combining known treatment methods (neutralization, washing, drying, etc.) into technological schemes that allow for 92-98 % removal of acidic components from the composition of acidic tar. It has been established that when the acid number of acid tar exceeds 50 mg KOH/g, pH < 1, it is advisable to use schemes that provide for the stage of neutralization of acidic components with a 20 % aqueous NaOH solution in a ratio of 1:1 to the raw material, followed by the separation of neutralization products and washing with distilled water in a ratio of 1:2 to the raw material. If the acid number of acid tar is much lower, it is advisable to use multiple (1:1 to 1:16) washing with hot water.