Bi_۲WO_۶-Modified Geopolymer Composite Materials with High Adsorption-Photocatalytic Activity for the Degradation of Toxic Organic Dyes

The fabrication of Bi۲WO۶-modified geopolymer composite materials was achieved through the hydrothermal method and alkaline activation with NaOH as the chemical activator. Various techniques were used to investigate the as-prepared samples, including XRD, BET, SEM-EDS, XPS, FT-IR, UV-Vis-NIR, and PL. The as-prepared samples were investigated for their adsorption-photocatalytic activity by degrading the reactive black ۵ (RB۵) dye under UV light irradiation. Experimental results indicated that Bi۲WO۶-modified geopolymer composite materials exhibited higher adsorption-photocatalytic efficiency than Bi۲WO۶ and geopolymer alone, and the ۵ wt% Bi۲WO۶-modified geopolymer composite material showed the highest efficiency of ۸۲%. Moreover, it was found that the increment of adsorption-photocatalytic activity of Bi۲WO۶-modified geopolymer composite materials was ascribed to the ease of separating electrons and holes and the decrement of recombinating photoinduced charge carriers at the interface between Bi۲WO۶ and geopolymer. Furthermore, the stability and reusability of ۵ wt% Bi۲WO۶-modified geopolymer composite material were investigated by repeating five cycles. The introduction of active scavengers in the photocatalytic process for degrading RB۵ dye under UV light irradiation was measured via trapping experiments. Results showed that superoxide radical () and hydroxyl radical (OHg) were the crucial radical scavengers. A plausible mechanism of composite materials was also proposed.

کلیدواژه ها:

Bi۲WO۶ ، Geopolymer ، Reactive black ۵ dye ، Adsorption-photocatalytic activity