A review of current progress of supercritical fluid technologies for e-waste treatment

Abstract

This paper focuses on current progress of supercritical fluid (SCF) technology for e-waste treatment through reviewing characteristics and challenges of existing technologies. With the high-speed development of science and technology, electronic and electric equipment continually upgrades and updates, which bring a series of problems on dealing with the e-waste. The most serious problem is that the harmless disposal of halogen flame retardants and refractory polymers in e-waste is difficult. In recent years, the recycling technologies for e-waste has entered a new stage through tireless efforts of the researchers. Compared with the common recycling technologies like pyrolysis and acid leaching, SCF technologies have great advantages in the field of environment, without air or water pollution risks. Supercritical fluids such as supercritical water and supercritical carbon dioxide are sustainable green solvents as well as highly promising reaction mediums. The principles, operation procedures and optimized parameters of SCF treatment are discussed and summarized in this paper. Furthermore, SCF technologies applied in the field of e-waste recycling have also achieved satisfactory results. Significant progress has been made in the detoxification of e-waste and removal of refractory polymers by SCF technologies. The dechlorination efficiency and debromination efficiency has been reported to be over 90%. The base metals, the precious metals, and other inorganic materials were all reported to be recovered from e-waste by SCF technologies with a recovery rate of more than 93%. Common challenges in SCF process like corrosion and salt precipitation also came up with some propose solutions. Hence, the application of SCF technology in e-waste treatment demonstrates green reaction and resource recovery with significant economy and environment perspectives.