ABSTRACT
The green synthesis of zinc oxide nanoparticles (ZnO NPs) using plant extracts has been receiving tremendous attention as an alternative to conventional physical and chemical methods. The Lamiaceae plant family is one of the largest herbal families in the world and is famous for its aromatic and polyphenolic biomolecules that can be utilised as reducing and stabilising agents during the synthesis of ZnO NPs. This review will go over the synthesis and how synthesis parameters affect the Lamiaceae-derived ZnO NPs. The Lamiaceae-mediated ZnO NPs have been utilised in a variety of applications, including photocatalysis, antimicrobial, anticancer, antioxidant, solar cells, and so on. Owing to their optical properties, ZnO NPs have emerged as potential catalysts for the photodegradation of organic dyes from wastewater. Furthermore, the low toxicity, biocompatibility, and antibacterial activity of ZnO against various bacteria have led to the application of ZnO NPs as antibacterial agents. Thus, this review will focus on the application of Lamiaceae-mediated ZnO NPs for the photodegradation of organic dyes and antibacterial applications.
ABSTRACT
This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite of maghemite nanoparticles coated with silica and carbon doped titanium dioxide. The novel nanocomposite boasts the advantages of efficient photocatalytic degradation of organic pollutants in water and ease of recovery of the fine particles after water treatment. The photocatalytic nanocomposite was successfully synthesized through a stepwise approach via co-precipitation and sol-gel methods. Characterisation by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) substantiated the existence of the intended structure of the nanocomposite and the particles were found to be in the size range of 15-22 nm with a quasi-spherical shape. Brunauer-Emmett-Teller (BET) surface area analysis revealed an average surface area of 55.20 m2/g, which is higher than that of commercial TiO2 (Degussa P25, 50.00 m2/g), and an average pore diameter of 8.36 nm. A 5 ppm methylene blue solution was degraded with an efficiency of 96.8% after 3 h of solar irradiation, which was 19.7% greater than using the same photo-catalyst under strict UV light irradiation. Photo-catalysis using these nanoparticles was observed to be very effective. The prepared novel visible light active nanocomposite has great potential for incorporation into water treatment systems because it exhibits good stability and magnetism, as well as high photocatalytic efficiency.
