High-performance photocatalytic degradation and antifungal activity of chromium-doped nickel oxide nanoparticles.

The elimination of pollutants such as dyes and fungi has become a tedious process hence there is a need for multifunctional materials that can be used for the removal or degradation of various pollutants from wastewater. Here, a nickel oxide nanoparticle (NiONPs) was synthesized by the co-precipitation method. In the current study, a composite of nickel oxide nanoparticles (NiONPs) was synthesized using nitrogen and chromium as dopants to create (N/NiONPs) and (Cr/N/NiONPs), respectively and used for the removal of dyes and fungi. The synthesized nanocomposites were characterized using zeta potential (ZP), scanning electron microscopy (SEM), X-rays diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The NiONPs, N/NiONPs and Cr/N/NiONPs were tested for the degradation of two dye pollutants, Reactive blue 13 (RB13) and eosin dye. The obtained results showed that Cr/N/NiONPs were more efficient than NiONPs and N/NiONPs for dye degradation by applying the same irradiation conditions. The Cr/N/NiONPs nanocomposites showed very good degradation efficiency of dye up to 94.2% for the RB13 and 90.8% for the eosin. We also examined the antifungal action of the NiONPs, N/NiONPs and Cr/N/NiONPs against Trichoderma fungus. The results showed that the Cr/N/NiONPs have an extremely strong antifungal impact on Trichoderma. This could be explained by the strong adhesion of Cr/N/NiONPs to the Trichoderma surface due to electrostatic attraction. This work has demonstrated that it is possible to create environmentally safe materials that can be used for the degradation of different dyes and the improvement of more effective antifungal treatments with lower active agent doses for fungus control with potential big economic benefits.

Escherichia coli inactivation using a hybrid ultrasonic-electrocoagulation reactor.

In the current study, a new hybrid ultrasonic-electrocoagulation reactor (U-E reactor) has been used to inactivate Escherichia coli in water. The new hybrid reactor consists of an ultrasonic bath fitted with four perforated aluminium electrodes. These perforated electrodes are designed to act as baffle-plates to enhance the water-mixing process. The electrodes eliminate the need for external mixing devices, which in turn, enhances the cost-effectiveness of the unit. Initially, the ability of the electrocoagulation to inactivate E. coli was optimised for different operating parameters such as electrolysing time (Te), electrodes spacing (ES) and current density (CD). The ultrasonic field was then applied over different time periods (Tu), during the course of the electrolysing process. Statistical analyses have been conducted to assess the relative effect of each operating parameter on the inactivation of E. coli. An economic study has also been conducted to assess the operating costs of the U-E reactor. The results revealed that the new U-E reactor inactivated 100% of the E. coli within 11 min of electrolysis at ES of 5 mm, CD of 1.5 mA/cm2, and an operation cost of 0.212 US $/m3. It was been established that the relative effect of operating parameters on E.coli inactivation followed the order: Te>Tu>CD>ES.