Deep purification of pesticide waste salt containing high-concentration organic pollutants by ethanol solvents washing and heating treatment

Abstract

The increasing production of industrial waste salt has become a growing concern. These waste salts are usually filled or deposited without treatment, causing serious environmental pollution and a waste of salt resources. The ideal solution to this problem is to recycle the waste salts after the removal of organic pollutants. In this study, organic solvent washing and heating are chosen to deeply remove the organic pollutants from actual pesticide waste salts. The experimental results showed that the optimum removal efficiency of organic pollutants in waste salts achieves as high as 99.82% under the conditions of 3:5 mass-to-volume ratio of waste salts-to-ethanol (EA), heating temperature of 400 °C (60 min). In addition, the removal mechanism and migration pathways of organic pollutants in the washing and heating were proposed. Salts washing with EA could remove most of the organic pollutants and subsequent heating treatment could completely purify the waste salts without the emission of the harmful gaseous compounds. As the best eluent, EA can not only effectively remove organic pollutants, but also be readily recycled. At the same time, the EA washing and heating process could avoid the pollution of organic waste liquid and noxious tail gas. Therefore, the EA washing process has the advantages of green, high efficiency, safety and energy saving. The EA washing and heating effectively avoids the problem of environmental pollution caused by harmful gases generated by heating and promotes the purification process and reuse of industrial waste salts.