Characteristic and mechanism of pollution by laser cleaning high-value vehicle parts with a complex structure in remanufacturing industry

Remanufacturing high-value vehicle parts is of substantial significance for the circular economy because it provides a second service life and reduces solid waste generation. Laser cleaning is a promising method in the remanufacturing industry owing to its high energy, precision, and efficiency. However, the pollution caused by laser cleaning remains unknown and has rarely been reported, limiting the application of this method. In this study, pollution removal and conversion using a high-energy laser were explored, and environmental life cycle and health risk assessments were conducted. The results showed that high-energy lasers might induce new organic pollutants, such as olefins, alkynes, and aldehydes. During laser cleaning, thermal elastic expansion and shock wave generation were the main mechanisms of rust removal, and evaporation and small-scope boiling were used for waste oil removal. The mean concentration of PM10 was above 7000 μg/m3 in laser rust removal, and the total concentration of volatile organic compounds (VOCs) was the highest in laser oil removal (∼2568 μg/m3). Particulate matter contained high amounts of Fe, Al, and Mn. An environmental life cycle assessment indicated that laser cleaning for stain removal significantly reduced the total environmental impact compared with that of traditional solvent-ultrasonic cleaning (∼40.0%) and sandblasting (∼83.3%). This study provides an environmental protection basis for increasing the use of laser cleaning in the remanufacturing industry.