title: Pyrolysis of low density polyethylene waste in subcritical water optimized by response surface methodology.
abstract: Pyrolysis of low density polyethylene (LDPE) waste from local waste separation company in subcritical water was conducted to investigate the effect of reaction time, temperature, as well as the mass ratio of water to polymer on the liquid yield. The data obtained from the study were used to optimize the liquid yield using response surface methodology. The range of reaction temperature used was 162-338°C, while the reaction time ranged from 37 min to 143 min, and the ratio of water to polymer ranged from 1.9 to 7.1. It was found that pyrolysis of LDPE waste in subcritical water produced hydrogen, methane, carbon monoxide and carbon dioxide, while the liquid product contained alkanes and alkenes with 10-50 carbons atoms, as well as heptadecanone, dichloroacetic acid and heptadecyl ester. The optimized conditions were 152.3°C, reaction time of 1.2 min and ratio of water solution to polymer of 32.7, with the optimum liquid yield of 13.6 wt% and gases yield of 2.6 wt%.
authors.affiliation: a Department of Chemical Engineering, Faculty of Chemical Engineering , Universiti Teknologi Malaysia , 81310 Skudai , Johor , Malaysia.
authors.forename: S L
authors.initials: SL
authors.lastname: Wong
authors.affiliation: a Department of Chemical Engineering, Faculty of Chemical Engineering , Universiti Teknologi Malaysia , 81310 Skudai , Johor , Malaysia.
authors.forename: N
authors.initials: N
authors.lastname: Ngadi
authors.affiliation: a Department of Chemical Engineering, Faculty of Chemical Engineering , Universiti Teknologi Malaysia , 81310 Skudai , Johor , Malaysia.
authors.forename: N A S
authors.initials: NA
authors.lastname: Amin
authors.affiliation: b Centre of Hydrogen Energy , Institute of Future Energy, Universiti Teknologi Malaysia , 81310 Skudai , Johor , Malaysia.
authors.forename: T A T
authors.initials: TA
authors.lastname: Abdullah
authors.affiliation: c Department of Polymer Engineering, Faculty of Chemical Engineering , Universiti Teknologi Malaysia , 81310 Skudai , Johor , Malaysia.
authors.forename: I M
authors.initials: IM
authors.lastname: Inuwa
mesh_terms: D004785:Environmental Pollutants / Q000737:chemistry*; D006358:Hot Temperature; D020959:Polyethylene / Q000737:chemistry*; D012037:Refuse Disposal / Q000379:methods*; D014867:Water
chemical_list: D004785:Environmental Pollutants; D014867:Water; D020959:Polyethylene
keywords: optimization; plastics waste; pyrolysis; response surface methodology; subcritical water