Subsequently, suspension was illuminated with the power of 60 watt visible irradiation
(Philips, Thailand). An irradiation time intervals of every 30 min, the suspensions were collected
and filtered with 0.45 μm cellulose acetate syringe filter (Filtrex, USA.) to remove BiVO4 powder.
The residual concentration of MB solution was measured by an UV-Vis spectrophotometer (U-
2900, Hitachi, Japan).