An advanced oxidation process by photoexcited heterogeneous sodium decatungstate for the degradation of drugs present in aqueous environment

[Display omitted] •A heterogeneous photocatalytic system for water remediation is proposed.•Photoexcited sodium decatungstate oxidizes water producing OH radicals which oxidize drugs.•The drug degradation ability of decantungstate strongly depends on the catalyst support.•Proper characteristics of the support can be successfully combined with decatunstate photoactivity. The ability of decatungstate anion (W10O324−) to photoproduce OH radicals from water is retained when the polyoxoanion is immobilized on solid supports and can be exploited as a heterogeneous photocatalytic process aimed to water remediation. However, we show that interaction between OH radicals and drug molecules depends on the physical chemical properties of the chosen support. In fact, we demonstrate that silica particles covered by decatungstate anions are not efficient in the degradation of carbamazepine and sulfamethoxazole (ubiquitary contaminants of natural waters) that are respectively neutral and negatively charged at operating pH of 6. On the contrary, entrapment of W10O324− inside a mesoporous organosilica matrix leads to a heterogeneous photocatalytic system with proper characteristic of hydrophobicity. Organic molecules enter mesopores and easily leave the aqueous environment. Inside pores, the reaction between photoproduced OH radicals is favored. Mono- and di-hydroxylated products precede fragmentation and degradation of the investigated drug.