Naresh Hiralal Tarte

In this study, we attempted to synthesize visible light active nano-sized photocatalysts using metal oxides such as zinc oxide, zirconium oxide, tungsten oxide, and strontium titanium oxide with (MoCl₅)₂ as a dopant by the simple ball-milling method. Fourier-transform infrared spectroscopy data confirmed the presence of M-O-Mo linkage (M = Zn, Zr, W, and SrTi) in all the molybdenum-doped metal oxides (MoMOs), but only MoZnO inhibited the growth of the bloom-forming Microcystis aeruginosa under visible light in a concentration-dependent manner up to 10 mg/L. Further, structural characterization of MoZnO using FESEM and XRD exhibited the formation of typical hexagonal wurtzite nanocrystals of approximately 4 nm. Hydroxyl radical (·OH), reactive oxygen species (ROS), and lipid peroxidation assays revealed ·OH generated by MoZnO under the visible light seemed to cause peroxidation of the lipid membrane of M. aeruginosa, which led to an upsurge of intracellular ROS and consequently introduced the agglomeration of cyanobacteria. These results demonstrated that nano-sized MoZnO photocatalyst can be easily synthesized in a cost-effective ball-mill method and utilized for biological applications such as the reduction of harmful algal blooms. Further, our study implies that a simple ball-milling method can provide an easy, green, and scalable route for the synthesis of visible light active doped metal oxides.

In this work, a new metal-to-metal charge transfer (MMCT) heterogeneous catalyst (Nb–O–Mo) was synthesized by a chemical grafting method under an inert atmosphere. The activity of the covalently anchored oxo-bridged Nb–O–Mo catalyst was estimated for decolorization of Rh B, congo red, and crystal violet dyes in an aqueous solution under fluorescent light. The catalyst was characterized via X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectrometer, Fourier-transform infrared, and FT-Raman. The catalytic decolorization was evaluated from the UV spectra of dyes in aqueous solution by changing different factors, including dye concentration, temperature, and catalyst loading. Decolorization percentages were 83%–89%, 86%–95%, 97%–99% for Rh B, Congo Red and Crystal Violet in 1 min at 298 K, showing the best performance among other catalysts. Decolorization efficiency for 50 ppm of Rh B was improved from 92% to 98%, with a temperature increase to 318 K.

In this study, we synthesized the cobalt(II) chelation free complexes ( 1 – 3 ) with the general formula of [CoCl ₂ L ₂ ] containing monodentate ligands (L=2‐methylbenzimidazole ( L1 ), 2‐methylbenzoxazole ( L2 ), and 2‐methylbenzothiazole ( L3 ) and fully characterized by UV‐vis, FT‐IR spectroscopy, and the crystal structures of 1 – 3 were determined by X‐ray crystallography. Complexes 1 – 3 showed substantial antibacterial activity against tested bacteria. Complexes 2 and 3 were more active against S. aureus with the Minimum Inhibitory concentration (MIC) value of 12.5 μg/mL compared to other bacteria. Complexes 1 – 3 exhibited strong synergy with ampicillin (AMP) against Methicillin Resistant S. aureus strains ( MRSA) . Interestingly, complexes 2 and 3 in combination with AMP showed the membrane permeabilization of MRSA . This indicates that complexes 2 and 3 in combination with AMP had bacterial membrane disruption as a possible mechanism of action.

In this study, the synthesis of a novel catalyst WO₃/MoCl₅ was carried out by the thermal method. The method gave an entirely different product compared to previous studies that doped Mo on the surface of semiconductor metal oxides. The degradation reaction of crystal violet (CV) and rhodamine B (RB) dye were done without any energy source. The results showed an incomparably superior result for degradation, with a reaction rate constant of 1.74 s⁻¹ for 30 ppm CV, 1.08 s⁻¹ for 30 ppm RB, and a higher value than 1 s⁻¹ for both cases of 50 ppm dye solution. To the author’s knowledge, this catalyst has the highest reaction rate compared to other studies that targeted CV and RB, with an immense reaction rate increase of more than 100 times. Reusability of the three trials was verified, and the only process required was washing the catalyst after the reaction. One of the drawbacks of the advanced oxidation process (AOP), which has a degradation percent limit, has been solved, since 100% mineralization of the dye was available using this catalyst. FT-IR spectroscopy revealed that W-O-Mo linkage was successfully processed while Mo-Cl linkage has retained. ¹H-NMR spectroscopy results confirmed that the degradation product of the dye treated by simple MoCl₅ and WO₃/MoCl₅ was different. Deep inspection of specific regions of NMR fields gave necessary information about the degradation product using WO₃/MoCl₅.