In the present study the supercritical water (SCW) degradation of polyethylene (PE) plastics (virgin LDPE, PE waste) has been investigated in a batch reactor at 380–450 °C and reaction time of 15–240 min. The experiments (virgin LDPE) were also performed with the addition of acetic acid. During the SCW decomposition of PE plastics oil or wax, aqueous, gas and solid (only in PE waste) phases were formed. The obtained oil phase was composed of alkanes, alkenes, cycloalkanes, aromatics, and alcohols, while the gas phase manly contained light hydrocarbons (C₁–C₆). By performing reaction at high temperatures (425–450 °C) and reaction times from 30 to 240 min the concentrations of long-chain hydrocarbons (>C₂₀) and C₉–C₂₀ (diesel) fraction in oil phase decreased, while concentration of C₆–C₈ hydrocarbons (gasoline fraction) increased. Finally, the influence of acetic acid on the PE degradation has been discussed and the potential degradation mechanism of PE waste in SCW is proposed.

在本研究中，已经在间歇式反应器中于380–450°C，反应时间为15–240分钟的条件下研究了聚乙烯（PE）塑料（原始LDPE，PE废料）的超临界水（SCW）降解。还通过添加乙酸来进行实验（纯LDPE）。在PEW塑料或蜡的SCW分解过程中，形成了水，气和固相（仅在PE废料中）。所获得的油相由烷烃，烯烃，环烷烃，芳烃和醇组成，而气相中仅含有轻烃（C ₁ -C ₆）。通过在高温（425–450°C）和30至240分钟的反应时间下进行反应，长链碳氢化合物（> C ₂₀）和C ₉ –C ₂₀的浓度油相中的（柴油）馏分减少，而C ₆ –C ₈碳氢化合物（汽油馏分）的浓度增加。最后，讨论了乙酸对PE降解的影响，并提出了SCW中PE废料的潜在降解机理。