Microwave-assisted synthesis of ZnNiAl-layered double hydroxides with calcination treatment for enhanced PNP photo-degradation under visible-light irradiation

In this paper, ZnNiAl-layered double hydroxide (LDH) photocatalysts were successfully prepared using a facile and timesaving microwave-assisted method. ZnNiAl-layered double oxides (LDOs) were then achieved from ZnNiAl-LDHs photocatalyst with calcination treatment. As a control, the corresponding photocatalysts were synthesized using a traditional hydrothermal method. A set of characterization technologies including XRD, SEM, FT-IR, and N-2 adsorption was carried out to investigate the physical and chemical properties of the prepared photocatalysts. The photocatalytic activities were evaluated by the degradation of p-nitrophenol (PNP) under visible-light irradiation. Moreover, the influences of calcination temperature, photocatalyst dosage, and initial PNP concentration were also explored in this system. The results indicated that the sample transformed from LDH to LDO after 700 degrees C calcination treatment and the prepared LDO showed an outstanding photocatalytic activity. When the photocatalyst dosage was 1.0 g.L-1 and initial PNP concentration was 10 mg.L-1, PNP removal efficiency was as high as 93.0% within 180 min under visible-light irradiation. After six cycles, the newly designed photocatalyst showed a good stability and reusability. This study shares a new preparation method for ZnNiAl-LDO as a novel photocatalyst with high efficiency for wastewater treatment. (C) 2018 Elsevier B.V. All rights reserved.