Ambient pressure and temperature advanced oxidation processes (AOP) are the unique technologies able to destroy refractory pollutants in water (priority or emergent) that remain unaltered when subjected to conventional operations in wastewater treatment. Among these operations both biological and chemical oxidation are included, the latter involving the possible use of ozone. Main problem of AOP is the high reactivity and low selectivity of hydroxyl radicals, so that high concentrations are needed which make the search of new processes necessary. Another important question is to reduce reaction times and improve environmental sustainability. Therefore, there is a continuous search for alternative AOPs.

 

In this Project, it is proposed the study of the removal of refractory contaminants, in model and real wastewater from urban sewage and chemical sectors, using two AOPs of recent interest: photocatalytic ozonation and the catalytic oxidation by in situ generation of hydrogen peroxide. In both cases, it is proposed to prepare new catalysts that can activate both AOPs under sustainable environmental conditions allowing, in such a way, a synergistic combination between the different oxidizing agents and radiation (in some case) be developed to improve the removal rate of contaminants or wastewater depuration. Thus, for the case of photocatalytic ozonation, the main objective is to prepare catalysts that must be active with UVA-visible and, especially, solar radiation sources and, consequently, in combination with ozone, the efficiency in pollutant removal be significantly improved. In the second AOP, the main objective is to obtain new multifunctional catalytic materials, more active, stable, and with a lower cost, that allow the synergistic combination of the in situ generation of hydrogen peroxide and its activation by catalysis and photocatalysis for the removal of highly refractory organic contaminants.

 

Thus, the main objectives to be reached in this Project are:

1. Establish appropriate methodologies for the synthesis of new catalysts to achieve the aforementioned objectives: stable and active catalysts (without leaching of the active phase) and, if possible, appropriate for both types of AOPs.

2. Investigate the addition of magnetic iron oxide nanoparticles in the structure of the catalyst in order to facilitate the catalyst separation from treated water.

3. Analyze the influence of variables and establish kinetic models to predict the level of depuration to be reached in order to optimize the process.

4. Compare the results obtained in this project with other more traditional processes such as Fenton, Photo-Fenton, catalytic ozonation, ozone combined with hydrogen peroxide that use radiation, ozone, catalysts and/or hydrogen peroxide.

5. Study, with the best catalysts obtained in this project with model organic compounds, its application to real wastewater of different industrial sectors containing refractory pollutants, with the aim of achieving conditions of reuse (according to RD 1620/2007).

 

In both AOPs to study, refractory compounds will be those that do not or hardly react with ozone (such as some pesticides: t-butylazine, 2-4-D, etc, pharmaceuticals compounds or used in medicine such us: ibuprofen, iopromida, etc, aromatic hydrocarbons: nitrobenzenes, fluorene, phthalates, etc) or real urban and industrial wastewater that cannot be mineralized (to reach TOC reductions higher than 40%) with the direct action of ozone, catalytic or photocatalytic oxidation.