WEEE recycling: Pyrolysis of fire retardant model polymers M.P. Luda * , N. Euringer, U. Moratti, M. Zanetti Dipartimento di Chimica, IFM dellÕUniversita ` Via P. Giuria 7, 10125 Torino, Italy Accepted 17 December 2004 Abstract Pyrolysis treatments of model polymers were made with the aim of studying the recycling of wastes from electronic, electric equipment containing brominated flame retardants. Pyrolysis of flame retarded high impact polystyrene and epoxy resins were made both in flow and closed systems. Products of pyrolysis were analysed with FT–IR spectroscopy and GC–MS and the evolution of bromine was followed with a bromine ion specific electrode. The effect of alkali on pyrolysis was also studied demonstrating, as far epoxy resin is concerned, to be effective on decreasing bromine content in oil and volatile products leading to the recovery of bromine from the residue by washing. The alkali treatment was shown to be less effective in styrenic polymers containing brominated flame retardants. Ó 2005 Elsevier Ltd. All rights reserved. 1. Introduction Polymer wastes from electronic, electric equipment (WEEE) include mainly epoxy resins and styrene poly- mers. They often contain brominated aromatics; in the early 1980s indeed halogenated fire retardants were lar- gely applied to decrease the flammability of polymeric materials. Reactive fire retardants (FRs) such as diglyci- dylether of (3,3 0 ,5,5 0 -tetrabromobisphenol) A (DGEBT- BA) is often used as comonomer with diglycilylether of bisphenol A (DGEBA) to obtain FR epoxy resins; addi- tive FRs such as polybromo diphenyl oxides are used for styrene polymers instead. Thermal treatment of WEEE is one of the most attractive approaches to recycling which enables the recovery of bromine, monomers and other chemicals and of precious metals which account for the economic convenience of the whole recycling process. However, one of the most relevant drawbacks in dealing with ther- mal treatment of WEEE is the likely production of super-toxic halogenated dibenzodioxins and dibenzofu- rans from the bromine containing structures. Environ- mentally friendly fire retardant systems currently developed to substitute halogen based systems will de- crease the content of halogen in forthcoming WEEE, however actual WEEE and those collected in the near future still contain relatively large amounts of bromi- nated FR (Buekens, 1991; Buser, 1986). In effect, amongst the various technologies of poly- mer recycling, WEEE are not suitable for foundry operation in the blast furnace due to the amount of halogens, metals and inert materials. On the contrary, WEEE can be thermally treated in the cement indus- tries as a substitute for conventional fuel. Here, be- cause of the alkaline conditions in the cement making process, the exhaust gases will contain only a minimum of pollutants. It has been recently shown that CaCO 3 has a suppressive effect in the dioxins emission from PVC incineration (Sun et al., 2003). In this context pre- liminary experimental results show that electronic scrap can be processed into halogens containing fractions fuels with an amount of about 500 ppm halogens and residues with or nearly without halogens, depending 0956-053X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.wasman.2004.12.010 * Corresponding author. E-mail address: mariapaola.luda@unito.it (M.P. Luda). www.elsevier.com/locate/wasman Waste Management 25 (2005) 203–208