Alkaline reforming of brominated fire-retardant plastics: fate of bromine and antimony.
High-impact polystyrene (HIPS) flame retarded with decabromodiphenyl ether (DDE), has been reacted in supercritical water from 380 to 450 degrees C and 21.5 to 31.0 MPa pressure in a batch reactor. Different concentrations of sodium hydroxide additive were used in situ to neutralize the corrosive inorganic bromine species released during the reactions. It appeared that supercritical water conditions lowered the decomposition temperature of both the fire-retardant DDE and HIPS. The reaction products included oils (up to 76 wt%), char (up to 18 wt%) and gas (up to 2.4 wt%) which was mainly methane. The presence of the alkaline water led to up to 97 wt% debromination of the product oil, producing virtually bromine-free oil feedstock. The removal of antimony from the oil product during processing was of the order of 98 wt%. The oil consisted of many single- and multiple-ringed aromatic compounds, many of which had alkyl substituents and/or aliphatic C(n)-bridges (n=1-4). The major single-ringed compounds included toluene, xylenes, ethylbenzene, propylbenzene and alpha-methylstyrene. Bibenzyl (diphenylethane), stilbene, diphenylmethane, diphenylpropane, diphenylcyclopropane, diphenylpropene, diphenylbutane, diphenylbutene and diphenylbuta-1,3-diene were the major C(n)-bridged compounds. Diphenyl ether and acetophenone were the major oxygenated compounds found. The process thus has the potential to produce bromine-free and antimony-free oils from fire-retardant plastics.
Onwudili
Jude A
JA
Energy and Resources Research Institute, The University of Leeds, Leeds LS2 9JT, UK.
Williams
Paul T
PT
D000965:Antimony / Q000737:chemistry*; D001966:Bromine / Q000737:chemistry*; D005411:Flame Retardants; D010969:Plastics / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry
D005411:Flame Retardants; D010969:Plastics; D011137:Polystyrenes; D012972:Sodium Hydroxide; D000965:Antimony; D001966:Bromine