UV/Fe^(0)/H_(2)O_(2)降解乙苯气体的工艺研究

Process study on degradation of gaseous ethylbenzene by UV/Fe^(0)/H_(2)O_(2)

以零价铁(Fe^(0))代替Fe^(2+)作Fenton试剂催化剂,考察H_(2)O_(2)浓度、[H_(2)O_(2)]/[Fe^(0)]摩尔比和pH值对UV/Fe^(0)/H_(2)O_(2)技术降解乙苯气体的影响,分析了反应过程中H_(2)O_(2)和铁物质的浓度变化,通过GC-MS检测不同时间段的液体中间产物。结果表明,以48μm工业级Fe^(0)作催化剂,在H_(2)O_(2)浓度为100 mmol/L、[H_(2)O_(2)]/[Fe^(0)]摩尔比为40和pH值为3的优化条件下,UV 365/Fe^(0)/H_(2)O_(2)体系中乙苯气体降解率在45 min内达到67.5%。检测到不同时间段的液体中间产物,如甲苯、苯乙醇、苯乙酮、苯甲醛、正丙醇和丁烯酮等,没有气体中间产物产生。45 min后,H_(2)O_(2)浓度不足,导致降解率降低,稳定体系内H_(2)O_(2)浓度,能够长期高效地降解乙苯气体,Fe^(0)连续浸出Fe^(2+),确保UV 365/Fe^(0)/H_(2)O_(2)体系良好的铁循环性能。

The zero-valent iron(Fe^(0))as the catalyst of the Fenton reaction instead of Fe^(2+).The catalytic capacity of UV/Fe^(0)/H_(2)O_(2)system was evaluated by the degradation of gaseous ethylbenzene.Considering the complexity of actual reaction,various factors on the degradation efficiency were inquired systematically in this work such as initial H_(2)O_(2)concentration,pH and[H_(2)O_(2)/Fe^(0)]molar ratio.The changes in concentration of H_(2)O_(2)and iron substance were analyzed thoroughly in the degradation process.Simultaneously,the GC-MS was conducted to study the intermediate adducts in the solution at different reaction phases.The result showed that the 48μm industrial grade Fe^(0)was served as the catalyst.The removal efficiency of gaseous ethylbenzene in UV 365/Fe^(0)/H_(2)O_(2)system could reach 67.5%within 45 min when 100 mmol/L H_(2)O_(2)was introduced,and the molar ratio of[H_(2)O_(2)]/[Fe^(0)],initial pH value were adjusted to 40 and 3,respectively.Liquid intermediates were detected in different time periods,such as toluene,phenethyl alcohol,acetophenone,benzaldehyde,1-propanol and methyl vinyl ketone,and no gaseous intermediates were detected.Moreover,the insufficient concentration of H_(2)O_(2)after 45 min reduced the removal efficiency,and the stable concentration of H_(2)O_(2)in the system could degrade ethylbenzene gas efficiently for a long time.Continuous leaching of Fe^(2+)from Fe^(0)could enable excellent iron cycling performance in this reaction system.