Lab. de Ing. Química Ambiental, ESIQIE-Instituto Politécnico Nacional, Zacatenco, 07738, México, D.F., México.
Environ Sci Pollut Res Int. 2014 Nov;21(21):12241-8. doi: 10.1007/s11356-014-3176-1. Epub 2014 Jun 21.
Terephthalic acid (TA) is considered as a refractory model compound. For this reason, the TA degradation usually requires a prolonged reaction time to achieve mineralization. In this study, vanadium oxide (VxOy) supported on titanium oxide (TiO2) served as a photocatalyst in the ozonation of the TA with light-emitting diodes (LEDs), having a bandwidth centered at 452 nm. The modified catalyst (VxOy/TiO2) in combination with ozone and LEDs improved the TA degradation and its by-products. The results obtained by this system were compared with photolysis, single ozonation, catalytic ozonation, and photocatalytic ozonation of VxOy/TiO2 with UV lamp. The LED-based photocatalytic ozonation showed almost the same decomposition efficiency of the TA, but it was better in comparison with the use of UV lamp. The oxalic acid accumulation, as the final product of the TA decomposition, was directly influenced by either the presence of VxOy or/and the LED irradiation. Several by-products formed during the TA degradation, such as muconic, fumaric, and oxalic acids, were identified. Besides, two unidentified by-products were completely removed during the observed time (60 min). It was proposed that the TA elimination in the presence of VxOy/TiO2 as catalyst was carried out by the combination of different mechanisms: molecular ozone reaction, indirect mechanism conducted by ·OH, and the surface complex formation.
对苯二甲酸（TA）被认为是一种难降解模型化合物。因此，TA 的降解通常需要较长的反应时间才能实现矿化。在这项研究中，氧化钒（VxOy）负载在二氧化钛（TiO2）上，作为光催化剂，在发光二极管（LEDs）存在下对 TA 进行臭氧化，其带宽中心位于 452nm。改性催化剂（VxOy/TiO2）与臭氧和 LEDs 结合，提高了 TA 的降解及其副产物的去除效率。该系统的结果与光解、单独臭氧化、催化臭氧化和 UV 灯照射下的 VxOy/TiO2 光催化臭氧化进行了比较。基于 LED 的光催化臭氧化显示出与 TA 相同的分解效率，但与使用 UV 灯相比，效果更好。作为 TA 分解的最终产物，草酸的积累直接受到 VxOy 的存在或/和 LED 照射的影响。在 TA 降解过程中形成了几种副产物，如富马酸、马来酸和草酸。此外，在观察到的时间（60 分钟）内，两种未识别的副产物被完全去除。提出在 VxOy/TiO2 作为催化剂的存在下，TA 的消除是通过不同机制的结合来实现的：分子臭氧反应、·OH 介导的间接机制和表面络合形成。
