Study on deacidification process of waste internal combustion engine oil under the action of ultrasound

Abstract

Internal combustion engine oil must be replaced periodically because it deteriorates during use, owing to the formation of oxidized species, particularly organic acids. The oil can be regenerated by removing the acids through alkali washing and neutralization. However the neutralization forms soaps that can cause significant emulsification that decrease the rate of acid removal. We have found that the washing process can be enhanced by using ultrasound, which produces strong shock waves and cavitation that increase the rates of diffusion and mass transfer, leading to an increased rate of deacidification. Our experiments show that a binary base composed of 58 wt% alum and 1.8 wt% diethylamine works well at a deacidification temperature of 50 °C, ultrasonic power of 800W, deacidification reaction time of 18 min. The extent of deacidification can be as high as 88% at 1.5 h.