Decolorization of drimarene red dye using palladized bacterial cellulose in a reactor

Palladized bacterial cellulose was used in the present investigations for the reductive decolorization of drimarene red dye in a rotating catalyst contact reactor (RCCR). Approximately 90% of 100 mg/L of dye was decolorized at pH 2 after 25 minutes of reaction in RCCR using hydrogen as the reducing agent. Scanning electron microscopy and energy dispersive X-ray spectroscopic analyses suggested irreversible impregnation of nano-sized zero-valent-form palladium (Pd0) deposits within the bacterial cellulose fibrils. The kinetics of decolorization remained unaffected by varying initial concentrations of dye and rotational speed of discs in the reactor. The rate of decolorization of dye increased with increasing palladium concentration per unit area of bacterial cellulose and decreasing pH of the reaction phase. UV-Visible absorption spectroscopy and liquid chromatography-mass spectroscopy suggested the accumulation of low-molecular-weight products, as a result of the cleavage of azo bonds in the dye molecules. Reusability of immobilized palladium is expected to reduce the treatment cost.