HydrophobicW10O324−/silica photocatalyst for toluene oxidation in water system

• A new hydrophobic silica containing Na4W10O32 is prepared via sol–gel method.
• Due to its high hydrophicity the material scavenges all the toluene present in water.
• W10O324− photoassisted formation of OH radicals is responsible of the oxidizing ability.
• More than 90% of the adsorbed toluene is converted to CO2.
• The heterogeneous photocatalyst is recyclable without any loss of activity.

A new photocatalyst (Na4W10O32/SiO2/BTESE) has been prepared by simultaneous hydrolysis of tetraethyl orthosilicate (TEOS) and 1,2-bis(triethoxysilyl)ethane (BTESE) in the presence of Na4W10O32. This material is able to scavenge and accumulate significant amounts of toluene from water solutions saturated with the hydrocarbon. This is due to its large specific surface area, micro and mesoporosity, and, above all, to the high hydrophobicity of its surface. Moreover, photoexcited Na4W10O32/SiO2/BTESE show savery strong oxidizing ability, allowing an almost complete mineralization of toluene to CO2 through the formation and reactivity of OH radicals. Considering both the sorption capability and the photocatalytic activity, the efficiency of Na4W10O32/SiO2/BTESE is significantly higher than those of Na4W10O32/SiO2 and Na4W10O32dissolved in homogeneous solution. At the end of a cycle of reaction, Na4W10O32/SiO2/BTESE is reusable without any loss of activity opening to the development of new efficient and stable photocatalytic systems addressed to clean wastewater containing aromatic hydrocarbons.

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