Departamento de Ingeniería Química y Química Física, Instituto Universitario de Investigación del Agua, Cambio Climático y Sostenibilidad (IACYS), Universidad de Extremadura, Avda. Elvas S/N 06006, Badajoz, Spain.
Departamento de Ingeniería Química y Química Física, Instituto Universitario de Investigación del Agua, Cambio Climático y Sostenibilidad (IACYS), Universidad de Extremadura, Avda. Elvas S/N 06006, Badajoz, Spain.
Water Res. 2021 Nov 1;206:117727. doi: 10.1016/j.watres.2021.117727. Epub 2021 Sep 30.
Numerous studies report on the synergy between ozonation and photocatalytic oxidation (TiO/UVA), which could open the way to the application of photocatalytic ozonation (PCOz) in water treatment. With the aim of establishing the existence of this synergy and its origin, in this work, using TiO P25, 365 nm UVA LEDs and ozone transferred doses up to 5 mg (mg DOC) (DOC 7 - 10 mg L), a systematic study has been carried out featuring the effect of pH, alkalinity and water matrix in each of the systems involved in PCOz, with special attention to the role of organics adsorption onto TiO. In ultrapure water, an increase in pH and carbonates content exerted a slight negative effect on the photocatalytic degradation of primidone (low adsorption onto TiO and mainly abated by free HO), this effect being higher on its mineralization. The negative effect of pH and alkalinity was much stronger for oxalic acid (high tendency to adsorb and mainly oxidized by positive holes). Accordingly, the results obtained at pH < pH (point of zero charge of the catalyst) in ultrapure water cannot at all be extrapolated to secondary effluents, since their composition negatively affects the photocatalytic performance. At the experimental conditions applied, only for the secondary effluent a synergy between O/UVA and TiO/UVA systems was observed. This synergy would be related, on the one hand, to the generation, from the matrix itself, of reactive entities or intermediates that promote the decomposition of ozone into HO; and, on the other hand, to an increase in catalyst activity as the matrix UVA absorption decreases, rather than from direct interactions between both systems. Despite de above, ozone requirement to achieve a significant reduction of DOC is high and would only be an interesting strategy for the elimination of ozone-refractory micropollutants.
大量研究报告了臭氧氧化和光催化氧化（TiO/UVA）之间的协同作用，这为光催化臭氧氧化（PCOz）在水处理中的应用开辟了道路。本工作旨在确定这种协同作用的存在及其起源，使用 TiO P25、365nm UVA LED 和臭氧转移剂量高达 5mg（mg DOC）（DOC 7-10mg/L），在 PCOz 所涉及的每个系统中进行了系统的研究，重点关注有机物在 TiO 上的吸附作用对系统的影响。在超纯水中，pH 值和碳酸盐含量的增加对扑米酮的光催化降解产生了轻微的负面影响（对 TiO 的吸附作用较低，主要由游离 HO 消除），这种影响在其矿化过程中更为明显。pH 值和碱度的负面影响对于草酸（高吸附倾向，主要由空穴氧化）要强得多。因此，在超纯水中 pH<pH（催化剂的零电荷点）条件下获得的结果根本不能外推到二级出水，因为其组成会对光催化性能产生负面影响。在应用的实验条件下，仅在二级出水中观察到 O/UVA 和 TiO/UVA 系统之间的协同作用。这种协同作用一方面与从基质本身产生的反应性实体或中间物有关，这些物质促进臭氧分解为 HO；另一方面与催化剂活性的增加有关，因为基质 UVA 吸收减少，而不是两个系统之间的直接相互作用。尽管如此，臭氧去除DOC 的需求量很高，这仅对消除臭氧难降解的微量污染物是一种有趣的策略。
