Enhanced photocatalytic degradation of textile dyeing wastewater under UV and visible light using ZnO/MgO nanocomposites as a novel photocatalyst

Abstract

Textile industries utilize various toxic azo dyes that cause a hitch to all living organisms. To overcome such problem, the semiconductor photocatalysts are very much helpful. Zinc oxide (ZnO) nanoparticles (NPs), Magnesium oxide (MgO) NPs and Zinc oxide/Magnesium oxide nanocomposites (ZnO/MgO NCs) namely 0.9 M ZnO:0.1 M MgO, 0.7 M ZnO:0.3M MgO, and 0.5 M ZnO:0.5 M MgO NCs were synthesized by simple wet chemical method and used as an effective photocatalyst for the degradation of toxic and harmful organic dye present in textile dyeing wastewater. The average crystallite sizes for the ZnO/MgO NCs were 31 nm, 30 nm, and 29 nm. The energy band gap (E_g) for the NCs was estimated as 3.7eV, 4 eV, and 4.4eV using Tauc’s plot. Uniform, flaky and porous morphology of the ZnO/MgO NCs were observed in the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The 0.5 M ZnO:0.5 M MgO NCs with textile dyeing wastewater under UV light of 254 nm and visible light irradiation showed superior photocatalytic degradation with the rate constant of 0.005/min and 0.0008/min respectively. Furthermore, they showed good antibacterial activity against Staphylococcus aureus and Escherichia coli with 7 mm and 6 mm of inhibition zone. This study suggests that ZnO/MgO NCs can serve as an ideal commercial pollutant degradation method.

Keywords:

• ZnO/MgO nanocomposites
• x-ray diffraction
• textile dyeing wastewater
• photocatalytic degradation
• antibacterial activity

Acknowledgment

The authors are thankful to UGC - University Grants Commission - Rajiv Gandhi National Fellowship [F1-17.1/2016-17/RGNF-2015-17-SC-TAM-23657/(SA-III/Website)], New Delhi, India for financial assistance.

Disclosure statement

The authors declare that they have no conflict of interest.