PBDE (PBDE)

Polybrominated Diphenyl Ether (PBDE) is a family of organobromine flame retardants — diphenyl ether molecules with one to ten bromine substituents on the two aromatic rings, giving 209 possible congeners. Commercial PBDE products were marketed as three formulations: penta-BDE (used in polyurethane foam for furniture and auto interiors), octa-BDE (used in ABS plastic housings for consumer electronics), and deca-BDE (used in PCB substrates, TV housings and textile back-coatings). PBDEs were the dominant brominated flame retardant class globally from 1980 through the 2000s.

The hazard profile is well-characterised. PBDEs are persistent (half-life in soil 7-10 years), bioaccumulative (log Kow 6-10) and toxic — particularly to thyroid function and neurodevelopment, with the lower-brominated congeners (tetra- to hexa-BDE) showing stronger endocrine disruption. Penta-BDE and octa-BDE were listed under the Stockholm Convention's Annex A (elimination) in 2009; deca-BDE was added in 2017. Under India's E-Waste (Management) Rules 2022 in conjunction with the Plastic Waste Rules, PBDEs above 0.1% in homogeneous material in new EEE placed on market are restricted — the same 1,000 ppm threshold as RoHS in the EU.

For e-waste recyclers, PBDE contamination is the principal reason recovered ABS, HIPS and polycarbonate from old TVs, monitors and printers cannot enter food-contact or toy applications. Detection follows the same workflow as PBB: handheld XRF flags total bromine above 1,000-2,000 ppm; GC-MS or LC-MS/MS confirmation distinguishes the congener mix. Density-based separation in float-sink tanks (PBDE-loaded plastics sink in 1.0-1.05 g/cc media due to bromine mass) is a viable bulk separation method — 70-90% of brominated plastics report to the sink stream. Optical NIR sorters cannot detect bromine directly but can identify PBDE-loaded ABS by its characteristic spectrum.

The trade-off is economic. ABS-PBDE represents 15-25% of the plastics fraction in a typical Indian e-waste mix; sending it all to hazardous-waste incineration costs Rs 12-25 per kg, eating any margin on the recovered metal fraction. Bromine-recovery technologies — pyrolysis at controlled temperatures recovering HBr scrubbed as ammonium bromide for fertiliser-grade reuse — exist commercially in Japan and Germany but are not yet operational in India. For now, Indian recyclers either sub-segregate by age of equipment (post-2008 ABS assumed RoHS-compliant) or accept the bromine penalty as a fixed disposal cost.