Issue Date: February 26, 2007
Cleaner method for recycling 'e-waste'
Growing piles of printed circuit boards and other detritus from outmoded electronic devices have prompted a team of Chinese environmental engineers to devise a new method for recycling the waste (Environ. Sci. Technol., DOI: 10.1021/es0618245). Circuit boards contain about 30% by weight of high-purity metals that are patterned onto a hard substrate made from woven glass fibers infused with epoxy or phenol-formaldehyde resins. Recycling circuit boards to recover the metals is carried out primarily by acid washing or burning the boards in backyards or small workshops in developing countries, the researchers note. In the new method, Zhenming Xu and coworkers of Shanghai Jiao Tong University first pulverize circuit boards and then pass the powdered material through an electric field. Induced static charges in the nonmetallic particles cause them to adhere to a roller as the metal particles fall away. The metals can be segregated, purified, and reused. The polymeric material isn't environmentally suitable for incineration or landfills, but the researchers discovered they can press the powder into molds to make hard tiles that can be used as a building material.
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