Design and characterization of a multi-phase annular falling-film reactor for water treatment using advanced oxidation processes

In this work, a laboratory-scale of a 3-phase [(I) immobilized photocatalyst, (II) polluted water and (III) oxygen or ozone] falling-film reactor was designed and developed for heterogenous advanced oxidation processes. Characterization and assessment of the annular falling film reactor for handling different advanced oxidation methods was performed. Degussa P-25 TiO2 particles were immobilized on borosilicate glass (BSG) and polymethylmethacrylate (PMMA) tubes and used as a photocatalyst in this study. The characteristics of the falling film reactor, such as the thickness and distribution of falling films and the level of gas absorption into the liquid falling films, as well as the effect of UVA irradiation on the decomposition of ozone inside the falling film reactor, were studied. The adsorption of a model compound on the surface of the immobilized catalyst was measured and the photoactivity of the immobilized photocatalyst was evaluated for the degradation of the model compound. Oxalic acid was chosen as the model compound in this study.

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► The reactor design is simple, multi-functional with good mass transfer properties.
► The reactor is suitable for handling different advanced oxidation processes.
► The photoactivity of fixed TiO2 on the reactor walls was observed to be remarkable.
► A good distribution of the liquid falling films over the reactor walls was observed.
► An adequate oxalic acid adsorption on TiO2 and gas absorption into water was observed.