Recycling of plastic waste: Screening for brominated flame retardants (BFRs)

Abstract

Flame retardants are chemicals vital for reducing risks of fire and preventing human casualties and property losses. Due to the abundance, low cost and high performance of bromine, brominated flame retardants (BFRs) have had a significant share of the market for years. Physical stability on the other hand, has resulted in dispersion and accumulation of selected BFRs in the environment and receiving biota. A wide range of plastic products may contain BFRs. This affects the quality of waste plastics as secondary resource: material recycling may potentially reintroduce the BFRs into new plastic product cycles and lead to increased exposure levels, e.g. through use of plastic packaging materials. To provide quantitative and qualitative data on presence of BFRs in plastics, we analysed bromophenols (tetrabromobisphenol A (TBBPA), dibromophenols (2,4- and 2,6-DBP) and 2,4,6-tribromophenol (2,4,6-TBP)), hexabromocyclododecane stereoisomers (α-, β-, and γ-HBCD), as well as selected polybrominated diphenyl ethers (PBDEs) in samples of household waste plastics, virgin and recycled plastics. A considerable number of samples contained BFRs, with highest concentrations associated with acrylonitrile butadiene styrene (ABS, up to 26,000,000ngTBBPA/g) and polystyrene (PS, up to 330,000ng∑HBCD/g). Abundancy in low concentrations of some BFRs in plastic samples suggested either unintended addition in plastic products or degradation of higher molecular weight BFRs. The presence of currently restricted flame retardants (PBDEs and HBCD) identified in the plastic samples illustrates that circular material flows may be contaminated for extended periods. The screening clearly showed a need for improved documentation and monitoring of the presence of BFRs in plastic waste routed to recycling.

Evaluation of the presence of potential hazardous substances from plastic and textile fibre recycling

“…Finally, the plastic recycling process may also influence the transformation of contaminants contained in the waste material being recycled. As an example, among the three isomers of HBCD measured, α-HBCD was found in relatively higher concentrations compared to β-or γ-HBCD (Pivnenko et al, 2017). This contradicted the common composition of commercial HBCD mixtures, where γ-HBCD is the dominant isomer.…”

Assessment of tetrabromobisphenol-A (TBBPA) content in plastic waste recovered from WEEE

“…Kousaiti, et al Journal of Hazardous Materials xxx (xxxx) xxxx 2.3.2. MAE of TBBPA The MAE procedure followed was in accordance to the one described in (Pivnenko et al, 2017). 1 g of solid sample was directly placed into the microwave designed closed vessels (Multiwave 3000, Anton Paar, Graz, Austria), followed by the addition of 20 mL of extractive solvent, isopropanol/n-hexane (IP/ n-hexane, 1:1, v/v).…”

“…Furthermore, BFRs have been detected in recycled plastic samples indicating that techniques are not properly designed, either for sorting or removing various SoC and additives incorporated in plastic matrices (Hahladakis et al, 2018a, b). Particularly, complete TBBPA removal or degradation may not be achievable during recycling (Pivnenko et al, 2017).…”

“…Among the predominant BFRs, the most commonly used compound is tetrabromobisphenol-A (TBBPA) (Covaci et al, 2007;Tollbäck et al, 2006;Tsydenova and Bengtsson, 2011;Pivnenko et al, 2017;Weber and Kuch, 2003), which is covalently bonded into the polymer matrix as a reactive FR (Tollbäck et al, 2006). The primary application of TBBPA is in the production of brominated epoxy resins and polycarbonate (PC) resins (Tollbäck et al, 2006).…”

“…Based on in vivo experiments, the International Agency for Research on Cancer (IARC) has included TBBPA in group 2A; a carcinogenic potential group (Grosse et al, 2016). TBBPA has been detected in (a) food packaging and household waste plastics (Pivnenko et al, 2017;Driffield et al, 2008), (b) environmental media, such as sludge and sediments (Yu et al, 2017;Brits et al, 2016;de Wit et al, 2010) and (c) biota samples (de Wit et al, 2010;Morris et al, 2004). Thus, further investigation on its presence in waste streams is necessary.…”