Thermal Field-Flow Fractionation and Gas Chromatography-Mass Spectrometry in Determination of Decomposition Products of Expandable Polystyrene after Reactions in Pressurized Hot Water and Supercritica
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- 作者：Juhani Kronholm ; Pertti Vastamä ; ki ; Riikka Rä ; sä ; nen ; Annukka Ahonen ; Kari Hartonen ; and Marja-Liisa Riekkola
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2006
- 出版时间：April 26, 2006
- 年：2006
- 卷：45
- 期：9
- 页码：3029 - 3035
- 全文大小：88K
- 年卷期：v.45,no.9(April 26, 2006)
- ISSN：1520-5045
文摘
Nonbiodegradable polymers are an environmental concern, and various techniques have been developed torecycle and reuse them. Pressurized hot water, or supercritical water, is an interesting alternative as a reactionmedium for depolymerization, since water is a readily available "green" solvent and its physicochemicalproperties can be widely adjusted in the vicinity of the critical point. In the present study, various reactionconditions (reaction time, temperature, and use of additives and catalysts, i.e., H2O2, Pd, NaOH, and HCl)were applied to obtain as high styrene monomer yields as possible in the decomposition of industrial expandablepolystyrene (EPS) in a pressurized, high-temperature aqueous medium. Other main reaction products were ofinterest as well. Reactions were carried out in laboratory-constructed reactors made of Hastelloy. The higheststyrene recoveries, ca. 57 wt % of the initial EPS load as measured by gas chromatography-mass spectrometry(GC-MS), were obtained after NaOH addition in 20 min reaction time at 400 
C. Without additives, thehighest yields were only ca. 13% of the initial load. Other main reaction products were acetophenone,benzaldehyde, benzene, ethylbenzene, phenol, and toluene. Thermal field-flow fractionation (ThFFF) wasused after the degradation of EPS to check for possible high molar mass products. When the temperature wasraised to 400 C and higher, EPS residues were not detected in fractograms. Low molar mass EPS residues(M < 100.000) could not be detected because their signals were overlapped by the enlarged void peak signalsdue to monomer components. As a whole, the analytical techniques (GC-MS and ThFFF) employed in thecharacterization of EPS degradation in a pressurized, high-temperature medium complemented each otherwell and showed good performance.
C. Without additives, thehighest yields were only ca. 13% of the initial load. Other main reaction products were acetophenone,benzaldehyde, benzene, ethylbenzene, phenol, and toluene. Thermal field-flow fractionation (ThFFF) wasused after the degradation of EPS to check for possible high molar mass products. When the temperature wasraised to 400 C and higher, EPS residues were not detected in fractograms. Low molar mass EPS residues(M < 100.000) could not be detected because their signals were overlapped by the enlarged void peak signalsdue to monomer components. As a whole, the analytical techniques (GC-MS and ThFFF) employed in thecharacterization of EPS degradation in a pressurized, high-temperature medium complemented each otherwell and showed good performance.