TiO2光催化联合技术降解苯酚机制及动力学

主要研究了TiO2光催化体系结合H2O2或外加电催化(EC)体系对苯酚催化降解效率的影响,评价比较TiO2/UV、H2O2/UV、TiO2/UV/H2O2、TiO2/UV/EC体系下苯酚降解机制及动力学.结果表明,TiO2/UV/H2O2和TiO2/UV/EC体系下苯酚降解效率明显高于TiO2/UV体系,当苯酚溶液pH值为6,TiO2质量浓度0.2 g·L-1,紫外光照2 h,光催化降解效果达到86%,当电流密度为12 mA·cm-2,则苯酚可达到100%去除.比较了不同催化体系下的能量利用率,苯酚降解15 min,TiO2/UV/EC体系能量利用率最大为0.030 6 g·(kW·h)-1,其能量消耗为0.0640 kW·h-1,说明采用TiO2/UV/EC体系能更多地利用能量降解苯酚.通过不同催化体系下中间产物分析,建立苯酚及其中间产物对苯二酚、邻苯二酚和苯醌的拟一级降解动力学模型,通过模型验证各催化体系下苯酚的降解历程,同时也说明了TiO2/UV/EC体系有利于苯酚及其中间产物的降解.

Mechanism and Kinetics of Phenol Degradation by TiO2 Photocatalytic Combined Technologies

The combination H₂O₂ or electrical catalytic (EC) system with TiO₂ photocatalytic system for phenol degradation was investigated. The catalytic systems of TiO₂/UV, H₂O₂/UV, TiO₂/UV/H₂O₂ and TiO₂/UV/EC were compared to investigate the phenol degradation mechanism and kinetic model. The degradation of phenol in TiO₂/UV/H₂O₂ and TiO₂/UV/EC system is more effective than that in TiO₂/UV system. With the solution pH of 6, TiO₂ concentration of 0.2 g·L^-1, UV illumination of 2 h, the photocatalysis removal efficiency of phenol reaches to 86%, if the current density of 12 mA·cm^-2 is added, the removal efficiency of phenol could reach to 100%. The energy utilization in different catalytic systems was also compared. When phenol is degraded in 15 min, in TiO₂/UV/EC system the energy utilization is the highest of 0.0306 g·(kW·h)^-1 with the energy consumption of 0.0640 kW·h^-1. It indicates that much more energy is used in TiO₂/UV/EC system for phenol degradation. During the analysis of intermediate products in different catalysis systems, the first-order kinetic model of phenol degradation and intermediate products such as hydroquinone, catechol and benzoquinone formation were established. The kinetic model is validated the phenol degradation pathway in different catalysis systems, and also indicates the TiO₂/UV/EC system could enhance phenol and intermediate products degradation.