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2017-10-03 - Colloque/Présentation - communication orale - Anglais - 20 page(s)

Gervasi Julien , Thomas Diane , Hantson Anne-Lise , "Design of a photocatalytic process for the removal of persistent organic micropollutants for the drinkwater’s production from natural water" in 10th World Congress of Chemical Engineering, Barcelone, Espagne, 2017

  • Codes CREF : Traitement de potabilisation de l'eau (DI3844)
  • Unités de recherche UMONS : Génie des Procédés chimiques et biochimiques (F505)
  • Instituts UMONS : Institut des Sciences et du Management des Risques (Risques)
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Abstract(s) :

(Anglais) Design of a photocatalytic process for the removal of persistent organic micropollutants for the drinkwater’s production from natural water Nowadays, the human activities have an important impact on the water quality, an essential resource. This study aims at the elimination in natural and drinking waters of persistent organic micropollutants (µg.L-1) with an endocrine disruptor effect. Among these, three model pesticides (atrazine (ATZ), bentazone (BTZ) and isoproturon (ISP)) with specific chemical structures and properties, were selected as basic compounds for the design and the scale-up of a supported heterogeneous photocatalytic process. In contact with a sufficiently energetic radiation, a semiconductor, like TiO2, is activated by initiating high-potential oxidation-reduction reactions on its surface [1]. While the suspended TiO2 powder can involve an increased separation cost it is of higher interest to use a supported TiO2 photocatalyst . Studying this interesting technology, the first goal consists in the development of a laboratory scale photobioreactor to characterize degradation properties of the photocatalytic layer. Afterwards, according to the acquired kinetic data, a photocatalytic reactor will be scaled-up for industrial purpose. The UVC irradiation is known as a good photoactivator for TiO2 and under these energy levels, some organic compounds such as pesticides can be eliminated by photolysis. The addition of a photocatalyst in the reactor can enhance the elimination performances of these organic compounds. Experimentations realized on a preliminary apparatus showed an important decrease of the half-life of our targeted pesticides. In order to improve the photocatalysis efficiency for organic traces solutions, activated carbon (AC) can be incorporated in the photocatalytic formulation before spraying the support . AC can increase by adsorption the mass transfer of pesticide from the bulk solution to the photocatalyst active sites. In a first step, adsorption experiments were performed, in order to evaluate and quantify the AC influence. No adsorption was observed on the TiO2 powder. Using the TiO2 and AC, after some days to reach the equilibrium, the pesticides were observed as relatively more significantly adsorbed. Except for ISP which was the most adsorbed compound by the AC globally in our tests, the AC addition in the photocatalytic formulation was not able to improve the photodegradation half-life,. This is explained by the difference in the time scale observed between the adsorption and photocatalysis phenomena (days versus hours In the future, experimental studies will be carried out in an instrumented laboratory photoreactor, in order to determine the kinetic parameters necessary for the design of the final installation, by studying the operating parameters of the system (pH, temperature, dissolved O2 , ...) for its optimization. [1] F. Zaviska, P. Drogui, G. Mercier, and J.-F. Blais, Rev. des Sci. l’eau 22(4), p. 535, 2009.