Recovery of Brominated Flame Retardant Plastics from Waste Electrical and Electronic Equipment (WEEE) Mixtures Using the Tribo-electrostatic Separation Process

Waste plastics containing brominated flame retardants (BFRs), classified as persistent organic pollutants (POPs), are a major pollution source. BFRs are a class of man-made chemicals added to plastics to decrease flammability, delay ignition, and slow the spread of fire, which is important in electrical and electronic equipment. Due to their bioaccumulative nature, BFRs are released during use, disposal, and recycling. Acrylonitrile butadiene styrene (ABS), common plastic used in electrical and electronic equipment (EEE) due to its insulating and mechanical properties, often contains high BFR levels, requiring careful management. Tribo-electrostatic separation is a simple, cost-effective and environmentally-friendly method that could be a viable solution for sorting the brominated plastics present in the constantly growing quantities of waste electrical and electronic equipment (WEEE) accumulated worldwide and in need of recycling. This method exploits differences in the triboelectric properties of particles without altering their recyclability, allowing them to be separated according to the Coulomb forces exerted on them in a strong electric field. The aim of the present study was to evaluate the efficiency of a tribo-electrostatic process for sorting a mixture composed of 39% brominated acrylonitrile butadiene styrene (ABS), 25% non-brominated polycarbonate (PC), and 37% non-brominated polypropylene (PP) filled with calcium carbonate (CaCO3). This paper investigated the effect of wall material of fluidized bed tribocharger on electrostatic separation. Tribo-electrostatic separation tests were then conducted on various mixtures. After the first stage of electrostatic separation, 98% of the PP particles were recovered in a 95% pure product. Using a two-stage separation scheme, it was possible to recover 99% of the ABS, with a purity of 96%.