Disposal of used oils as a prospective method of production of biodiesel

The article is devoted to the improvement of the production technology of diesel biofuel from waste oils, which are a significant source of environmental pollution. Environmental pollution is one of the biggest environmental problems of our time. Used oils that are not properly disposed of cause serious environmental problems, including water and soil pollution. The use of waste oils for the production of biofuel is a promising technology that allows reducing the amount of pollution and reducing dependence on fossil fuels. Biodiesel from waste oils has significant environmental, economic and sustainable advantages. The main goal of the article is a detailed analysis of modern technologies for the production of diesel biofuel from waste oils and an assessment of their improvements and impact on ecology, economy and society. The article discusses innovative approaches to the processing of used oils, their purification and preparation for further use. An analysis of the main methods of transesterification, hydrogenation, esterification and enzyme catalysis, as well as the latest technologies, such as ultrasonic and microwave intensification of biofuel production, was carried out. New technological solutions for the preliminary preparation of used oils with a high content of free fatty acids using a combination of acid catalysts are proposed, and a technological scheme of the full production cycle is developed. The rational parameters of the equipment for the preliminary preparation of used oils with a high content of free fatty acids have been determined. Recommended conditions include hydrogenation temperature not higher than 80°С, duration of the process not less than 40 minutes; separation of the water-protein part by centrifugation at a rotation frequency of the centrifuge rotor of 3000 rpm for 20 minutes; the esterification reaction temperature is no more than 60°C; molar ratio of alcohol to oil 9:1; acid catalyst concentration within 1-15%; the intensity of mixing in the reactor is 31.42 s-1; the duration of the process is not less than 120 minutes. It was established that it is advisable to use potassium hydroxide for the transesterification reaction. The use of potassium hydroxide is beneficial because the potassium salts formed during the technological process of diesel biofuel production can be used as mineral fertilizers. According to the results of the research, the optimal parameters for the transesterification reaction were chosen: the amount of methanol - 20% by mass. from the weight of the oil, the KOH 1 catalyst is 1.5%, the temperature of the process is 60°C and the duration is 60-70 minutes. Examples of successful implementation of these technologies in various countries of the world, in particular in Europe, the USA and Asia, are presented. Additionally, recommendations are provided for further research and technology development, including the need to improve waste oil purification methods, optimize transesterification processes, and integrate renewable energy sources. The prospects and challenges of the industry of biofuel production from waste oils are considered, in particular the issues of regulatory support, financial incentives and investment attraction.