Abstract:

Cetyltrimethyl ammonium bromide （CTAB） was selected as the template agent, and thus the CTAB-modified Bi₂WO₆ photocatalyst was prepared by hydrothermal method. Cr（VI） was used as simulated wastewater to verify the photocatalytic performance of CTAB-modified Bi₂WO₆. The photocatalyst was characterized by XRD, SEM, TEM, EDS, XPS, FTIR and PL. The results showed that the CTAB-modified Bi₂WO₆ photocatalyst prepared by hydrothermal method was of tetragonal scheelite type. After adding CTAB, the Bi₂WO₆ nanosheets accumulated to form “flower ball”, and the structure stacking and crystallinity were both improved. The adsorption-desorption isotherm of Bi₂WO₆ photocatalyst modified by CTAB was an Ⅳ-type isotherm with an obvious H3-type hysteresis loop. With the increase of the amount of CTAB, the specific surface area and pore volume of Bi₂WO₆ photocatalyst first increased and then decreased. The specific surface area and pore volume of 1 mmol Bi₂WO₆ added with 2 mmol CTAB reached the maximum values of 39.4 m²/g and 0.117 cm³/g, and the average pore size was 28.1 nm. The fluorescence intensity of 1 mmol Bi₂WO₆ photocatalyst added with 2 mmol CTAB was the lowest, and the photoelectron-hole pair recombination was the lowest. At 240 min, the percentage of degradation for Cr-containing wastewater was 96.48%. Compared with pure Bi₂WO₆, the catalytic efficiency was increased by 194.52%, and the degradation by the photocatalyst on Cr-containing wastewater could be improved under acidic conditions. The degradation by the photocatalyst still exceeded 85% when the catalyst was recycled for 5 times, which showed excellent catalytic degradation and recycling performance.

Key words: surfactant, cetyltrimethyl ammonium bromide （CTAB）, photocatalysis, wastewater, degradation percentage