Influencing Factors in the Synthesis of Photoactive Nanocomposites of ZnO/SiO2-Porous Heterostructures from Montmorillonite and the Study for Methyl Violet Photodegradation

Influence of the Alcohols on the ZnO Synthesis and Its Properties: The Photocatalytic and Antimicrobial Activities

Zinc oxide (ZnO) nanomaterials are used in various health-related applications, from antimicrobial textiles to wound dressing composites and from sunscreens to antimicrobial packaging. Purity, surface defects, size, and morphology of the nanoparticles are the main factors that influence the antimicrobial properties. In this study, we are comparing the properties of the ZnO nanoparticles obtained by solvolysis using a series of alcohols: primary from methanol to 1-hexanol, secondary (2-propanol and 2-butanol), and tertiary (tert-butanol). While the synthesis of ZnO nanoparticles is successfully accomplished in all primary alcohols, the use of secondary or tertiary alcohols does not lead to ZnO as final product, underlining the importance of the used solvent. The shape of the obtained nanoparticles depends on the alcohol used, from quasi-spherical to rods, and consequently, different properties are reported, including photocatalytic and antimicrobial activities. In the photocatalytic study, the ZnO obtained in 1-butanol exhibited the best performance against methylene blue (MB) dye solution, attaining a degradation efficiency of 98.24%. The comparative study among a series of usual model dyes revealed that triarylmethane dyes are less susceptible to photo-degradation. The obtained ZnO nanoparticles present a strong antimicrobial activity on a broad range of microorganisms (bacterial and fungal strains), the size and shape being the important factors. This permits further tailoring for use in medical applications.

Photocatalytic and Electrochemical Activity of Magnesium Oxide Nanoballs Synthesized via a Hydrothermal Route

Currently, there is growing concern about minimizing the environmental impacts caused by the generation of waste on water, soil, air pollution, and contamination of the environment in general. Magnesium oxide (MgO) nanoballs (NBs) were synthesized by the hydrothermal method followed by a calcination process. The average size of particles dispersed in deionized water was 159.2 ± 70 nm. The energy band gap was calculated to be 5.14 eV. The magnetic behavior, cyclic voltammetry, and electrochemical impedance of MgO NBs were studied. Under visible-light irradiation, the photocatalytic activity of MgO nanoballs was investigated by methylene blue (MB) dye. Results showed that photodegradation for MB under visible light irradiation for 120 min and degradation results are fitted well with pseudo-first-order reaction kinetics with a rate constant of 0.00252 min−1 and a correlation coefficient of 0.96.

Clay-Supported Metal Oxide Nanoparticles in Catalytic Advanced Oxidation Processes: A Review

Advanced oxidation processes (AOPs) utilizing heterogeneous catalysts have attracted great attention in the last decade. The use of solid catalysts, including metal and metal oxide nanoparticle support materials, exhibited better performance compared with the use of homogeneous catalysts, which is mainly related to their stability in hostile environments and recyclability and reusability. Various solid supports have been reported to enhance the performance of metal and metal oxide catalysts for AOPs; undoubtedly, the utilization of clay as a support is the priority under consideration and has received intensive interest. This review provides up-to-date progress on the synthesis, features, and future perspectives of clay-supported metal and metal oxide for AOPs. The methods and characteristics of metal and metal oxide incorporated into the clay structure are strongly influenced by various factors in the synthesis, including the kind of clay mineral. In addition, the benefits of nanomaterials from a green chemistry perspective are key aspects for their further considerations in various applications. Special emphasis is given to the basic schemes for clay modifications and role of clay supports for the enhanced mechanism of AOPs. The scaling-up issue is suggested for being studied to further applications at industrial scale.