Rapid identification of polystyrene foam wastes containing hexabromocyclododecane or its alternative polymeric brominated flame retardant by X-ray fluorescence spectroscopy

Abstract

The brominated flame retardant hexabromocyclododecane (HBCDD) was added to Annex A of the list of persistent organic pollutants (POPs) of the Stockholm Convention. Thus, production and use of HBCDD will be banned, and the recycling of HBCDD-containing foam waste will be restricted. In reaction a special polymeric brominated flame retardant (PolyFR) was developed to replace HBCDD in expanded and extruded polystyrene foams for building and construction applications. A decision has to be made at some future time whether expanded and extruded polystyrene foam waste is to be subjected to incineration (with HBCDD) or to recycling (without HBCDD). Therefore, an appropriate and rapid field method is required to distinguish between foams containing HBCDD and foams free from HBCDD. Here we present a screening method for identifying HBCDD containing expanded and extruded polystyrene foams. The test principle is based on the fact that PolyFR (a brominated polymeric macromolecule) is not extractable whereas HBCDD (a low molecular weight substance) is extractable. Following rapid extraction of HBCDD the brominated flame retardant is identified and quantified via bromine analysis using a handheld X-ray fluorescence instrument. The method was applied successfully to 27 expanded and extruded polystyrene foam samples (foams and extruded polystyrene foam raw materials), which were provided without any information about the applied flame retardant. The presence of HBCDD was confirmed for all HBCDD-positive samples in the test. A robustness test revealed a high degree of correctness and a high repeatability for the test system: samples containing HBCDD and HBCDD-free samples were identified correctly with relative standard deviations of quantitative results below 14%. Moreover, X-ray fluorescence spectroscopy test results agree well with HBCDD determinations performed in a laboratory with a gas chromatograph coupled to a flame ionisation detector