Waste Not
Researchers Discover Process to Absorb Toxic Metals from Water, Using E-Waste

A team of Hong Kong researchers has found a way to use ground-up circuit boards from discarded cell phones, computers and other gadgets to absorb toxic heavy metals found in water, according to Chemical & Engineering News

Each year, around 20 to 50 million tons of electronic waste is produced worldwide, most of which is incinerated or dumped into landfills. Burning the plastic/metal combo in printed circuit boards releases toxic compounds such as dioxins and furans. In landfills, the metals on the circuit boards can contaminate groundwater.

According to C&E News, a major problem lies in the expensive process required to recycle circuit boards. As only the metal parts of the boards have reuse value, the nonmetallic parts must be separated out from the e-waste, which is a costly process.

In hopes of making e-waste recycling more economically viable, Gordon McKay and his team at the Hong Kong University of Science & Technology began looking for alternative uses for this nonmetallic portion that is made of plastic and aluminosilicates.

Previously, the research team had developed adsorbent materials to remove toxic heavy metals from wastewater effluents produced in the microelectronics industry. It was believed that the aluminosilicate material in the circuit boards would make an effective adsorbent, much like zeolite materials currently used for this purpose.

To test this theory, C&E News says McKay and his colleagues worked with a powder made by grinding up the nonmetallic fraction of circuit board, heating it and treating it with potassium hydroxide, a common technique used to increase porosity in carbon-based adsorbents. The researchers then added the powder to solutions of copper, lead and zinc.

The team learned that the metals adsorbed to the treated powder more efficiently than three commonly used industrial adsorbents. The powder soaked up about 25 percent more copper than the same amount of a common ion-exchange resin did. C&E News reports that the ground-up circuit boards also had a higher adsorption capacity for these metals than several low-cost adsorbents, including soybean hulls and blast furnace slag.

The researchers are now conducting a pilot study to make a 10-kg batch of the adsorbent, and are discussing developing the project on an industrial scale with an e-waste recycling company in Hong Kong, C&E News says. The new adsorbent could be used to treat wastewater effluent from electronics production.

Dell has had an ongoing program, in partnership with Goodwill, called Dell Reconnect, which takes used computer equipment of any brand, working or not, and puts it back to good use or recycles it responsibly for free.

Last year, the U.S. Environmental Protection Agency launched an e-waste initiative with the support of several global brands that agreed to increase collection rates of used electronics and send 100 percent of the devices to third-party certified refurbishers and recyclers. Best Buy, LG Electronics, Panasonic, Samsung, Sharp, Sprint and Staples were among the companies joining the Sustainable Materials Management (SMM) Electronics Challenge, which aims to provide a transparent and measurable way for electronics companies to commit to environmentally protective practices for the refurbishment and recycling of used electronics, and publicly show progress toward recycling goals.

Last month, the Electronics TakeBack Coalition released a scorecard that showed over half of the top 16 consumer electronics retailers in the U.S. have sub-par recycling programs; Staples, Best Buy and Office Depot earned the highest marks.


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