Application of M 2+ (Magnesium, Zinc)/Alumina-Metal Oxide Composites as Photocatalysts for the Degradation of Cationic Dyes

Abstract

The development of studies on layered double hydroxide (LDH) material as a photocatalyst for the degradation of dye pollutants continues to increase. LDH is an anionic clay, which is a natural or synthetic mixed metal hydroxide. Pristine LDH is written as M2+/M3+ LDH, (M is metal ion). This study prepared pristine Mg/Al LDH and Zn/Al LDH composited with metal oxide TiO2 and ZnO, respectively. Composite is denoted by M2+/M3+-metal oxide. The coprecipitation method used was accompanied by calcination of the composite at a temperature 300 oC that was not high. The prepared composites were morphologically characterized by SEM. The materials that had been used until the fifth cycle of regeneration were characterized by XRD and FTIR which still indicated the presence of LDH-metal oxide composite structure. The materials degraded cationic dyes namely rhodamine-B (RhB) and methylene blue (MB). RhB degraded better than MB by pristine LDH and composites. The percent degradation of RhB for pristine Mg/Al LDH, composites Mg/Al-TiO2 and Mg/Al-ZnO were 53.1%, 59.8%, 62.8%, respectively. The percent RhB degradation for pristine Zn/Al LDH, composites Zn/Al-TiO2 and Zn/Al-ZnO were 51.4%, 58.5%, 58.9%, respectively. The percentage of degradation indicates that the LDH-metal oxide composite has succeeded in increasing the photodegradation catalytic ability and the regeneration ability of LDH pristine.

Keywords

• dyes
• tio 2
• photodegradation
• zno
• layered double hydroxide