Mixed oxides of Zn/Al, Zn/Al-La and Zn-Mg/Al: Preparation, characterization and photocatalytic activity in diclofenac degradation

Layered double hydroxides (hydrotalcites) with Zn/Al, Zn/Al-La and Zn-Mg/Al were synthesized by the coprecipitation method with microwave and ultrasonic hydrotermal aging and nitrate as the interlayer anion; those materials have been used as precursors for the preparation of mixed metal oxides by calcination at 500 °C. The formation of ZnO was detected in the mixed oxides, indicating the destruction of lamellar structure with different degree of crystallinity depending of the hydrotermal method used. All the mixed oxides were tested for the study of degradation of diclofenac (DCF) and TiO2 as reference. The photocatalysis were investigated in term of UV absorbance for a initial DCF concentration (50 mgL-1) in a batch reactor system. All the samples resulted active as heterogenous photocatalysts. These results showed that mixed oxides prepared are promising materials for an effective diclofenac degradation.

Keywords: hydrotalcites Zn/Al-La, photocatalysis, diclofenac, LDH, degradation.