Solar/lamp-irradiated tubular photoreactor for air treatment with transparent supported photocatalysts

A novel versatile tubular reactor that may use both types of radiation, solar and/or artificial, and different types of suspended or immobilized photocatalysts is proposed. The photocatalytic reactor was evaluated for air treatment at laboratory scale and semi-pilot-plant scale. UV-A transparent immobilized photocatalysts were employed, which allowed an efficient use of radiation. Two different types of photocatalytic modules were tested: (a) TiO2-coated PET monoliths and (b) TiO2-coated glass slides, arranged in monolith-like units with the help of especially designed star-shaped polygonal structures. Both types of units were easy to handle and assured the adequate distribution of the photocatalyst inside the tubular reactor. The efficiency of the photocatalytic system with both solar and artificial radiation to oxidize the H2S contained in an air stream was demonstrated at the laboratory roof and in the treatment of real air of a wastewater treatment plant located in Madrid (Spain). As a consequence of the chemical nature of the pollutant, the photocatalytic activity decayed over time due to the accumulation of sulfate on the surface, but easy regeneration of the exhausted photocatalyst was achieved by washing with water.

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► Novel versatile annular photoreactor for solar and/or artificial radiation.
► TiO2-coated transparent monoliths – based on PET or glass – as photocatalytic units.
► Efficiency to oxidize H2S in both synthetic air and the real air of a wastewater treatment plant.
► Simultaneous elimination of other volatile organic compounds, such as mercaptanes or aromatic or aliphatic hydrocarbons.
► Adsorption–desorption phenomena are responsible for activity and selectivity hysteresis in daily cycles.