Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, SI-1001 Ljubljana, Slovenia; National Institute of Chemistry, Hajdrihova 19, SI-1001, Ljubljana, Slovenia.
Laboratory for Environmental Research, University of Nova Gorica, Vipavska 13, 5000, Nova Gorica, Slovenia.
Environ Res. 2021 Jun;197:110982. doi: 10.1016/j.envres.2021.110982. Epub 2021 Mar 9.
The synergistic effect of the photocatalytic ozonation process (PH-OZ) using the photocatalyst TiO is usually attributed to influences of the physicochemical properties of the catalyst, pollutant type, pH, temperature, O concentration, and other factors. It is also often claimed that good adsorption on the TiO surface is beneficial for the occurrence of synergism. Herein, we tested these assumptions by using five different commercial TiO photocatalysts (P25, PC500, PC100, PC10 and JRC-TiO-6) in three advanced oxidation systems - photocatalysis (O/TiO/UV), catalytic ozonation (O/TiO) and PH-OZ (O/TiO/UV) - for the degradation of two pollutants (dichloroacetic acid - DCAA and thiacloprid) simultaneously present in water. The synergistic effect in PH-OZ was much more pronounced in the case of thiacloprid, a molecule with low adsorption on the surface of the catalyst - in contrast to DCAA with stronger adsorption. The faster kinetics of catalytic ozonation (O/TiO) correlated with the higher exposed surface area of TiO agglomerates, independent of the (lower) BET surfaces of the primary particles. Nevertheless, DCAA mineralization on the TiO surface was much faster than thiacloprid degradation in solution. Therefore, we propose that a high BET surface area of the photocatalyst is crucial for fast surface reactions (DCAA mineralization), while good dispersion - the high exposed surface area of the (small) agglomerates - and charge separation play an important role in photocatalytic degradation or PH-OZ of less adsorbed organic pollutants (thiacloprid).
光催化臭氧氧化工艺（PH-OZ）中使用光催化剂 TiO 的协同效应通常归因于催化剂的物理化学性质、污染物类型、pH 值、温度、O 浓度等因素的影响。也常有人声称，TiO 表面的良好吸附有利于协同作用的发生。在此，我们通过使用五种不同的商业 TiO 光催化剂（P25、PC500、PC100、PC10 和 JRC-TiO-6）在三种高级氧化系统——光催化（O/TiO/UV）、催化臭氧氧化（O/TiO）和 PH-OZ（O/TiO/UV）中，对同时存在于水中的两种污染物（二氯乙酸-DCAA 和噻虫啉）的降解进行了测试，以验证这些假设。在 PH-OZ 中，噻虫啉的协同效应更为显著，这是一种在催化剂表面吸附能力较弱的分子——与吸附能力较强的 DCAA 形成对比。催化臭氧氧化（O/TiO）的更快动力学与 TiO 团聚体的更高暴露表面积相关，而与初级颗粒的（较低）BET 表面积无关。然而，TiO 表面上的 DCAA 矿化速度比溶液中噻虫啉的降解速度快得多。因此，我们提出，光催化剂的高 BET 表面积对于快速表面反应（DCAA 矿化）至关重要，而良好的分散性——（较小）团聚体的高暴露表面积——和电荷分离在光催化降解或吸附性较弱的有机污染物（噻虫啉）的 PH-OZ 中起着重要作用。
