Green synthesis of Zinc sulphide (ZnS) nanostructures using S. frutescences plant extract for photocatalytic degradation of dyes and antibiotics

Pollutants such as dyes and pharmaceuticals have become a problem in the environment, thus there is a need to find multifunctional materials that are safe and can be used for the removal of various pollutants. In this study, we report on the synthesis of Zinc sulphide (ZnS) nanostructures and their use as photocatalysts for the degradation of dyes and various antibiotics. Fourier transform infrared spectroscopy(FTIR) confirmed the functional groups found in plants and these were linked to the biomolecules identified through Liquid chromatography-mass spectrometry (LCMS). Ultraviolet-visible spectroscopy (UV-vis) and X-ray diffraction (XRD) confirmed the formation of the ZnS nanostructures. Thermal Gravimetric Analysis (TGA) and Brunner Emmet Teller (BET) confirmed the material was thermally stable up until 480oC and mesoporous in nature, respectively. Scanning electron microscope (SEM) and transmission electron microscope (TEM) showed that the material is spherical in shape and energy dispersive spectroscopy (EDS) further corroborated their formation. From the degradation analysis, 90% of the malachite green (MG) dye could be degraded in 60 min at optimum conditions (pH 6, 25 mg and 10 mg/L) and the holes were responsible for the degradation. Lastly, when tested against antibiotics, the ZnS material managed to degrade both the sulfisoxazole (SSX) and sulfamethoxazole (SMX). These results showed that the ZnS nanoparticles could be used as a multifunctional material for the degradation of various pollutants.

Aptamer Conjugated Indium Phosphide Quantum Dots with a Zinc Sulphide Shell as Photoluminescent Labels for Acinetobacter baumannii

Acinetobacter baumannii is a remarkable microorganism known for its diversity of habitat and its multi-drug resistance, resulting in hard-to-treat infections. Thus, a sensitive method for the identification and detection of Acinetobacter baumannii is vital. However, current methods used for the detection of pathogens have not improved in the past decades and suffer from long process times and low detection limits. A cheap, quick, and easy detection mechanism is needed. In this work, we successfully prepared indium phosphide quantum dots with a zinc sulphide shell, conjugated to a targeting aptamer ligand, to specifically label Acinetobacter baumannii. The system retained both the photophysical properties of the quantum dots and the folded structure and molecular recognition function of the aptamer, therefore successfully targeting Acinetobacter baumannii. Confocal microscopy and transmission electron microscopy showed the fluorescent quantum dots surrounding the Acinetobacter baumannii cells confirming the specificity of the aptamer conjugated to indium phosphide quantum dots with a zinc sulphide shell. Controls were undertaken with a different bacteria species, showing no binding of the aptamer conjugated quantum dots. Our strategy offers a novel method to detect bacteria and engineer a scalable platform for fluorescence detection, therefore improving current methods and allowing for better treatment.

Effect of absorber layer bandgap of CIGS-based solar cell with (CdS/ZnS) buffer layer

This article uses computational models to evaluate the potential of copper-indium-gallium-diselenide (CIGS) thin film solar cells. The use of cadmium sulphide (CdS) renders the solar cell environmentally hazardous. A zinc sulphide (ZnS) that is non-toxic and has a large bandgap is studied as a potential replacement for cadmium sulphide in CIGS-based solar cells. The present research focuses on the impact of the CIGS-based solar cell bandgap absorber layer by increasing the absorber layer thickness (0.1-2 μm) using the solar cell simulator simulation tool SCAPS. The basic simulation produces 18.2 % efficiency with a CdS buffer layer, which is 9.95% better than the previously published work. The Simulated efficiency is 22.16% for the CIGS solar cell using ZnS. The simulation of solar cell characteristics of how the thickness of the absorber layer, the gallium grading (efficiency ranges up to 22.25 %) is demonstrated, showing the effect of buffer layer (ZnS) on the current of short-circuit density (JSC), open-circuit voltage (Voc), fill factor (FF), and efficiency (η) of the solar cell.

Properties of poly (vinyl chloride) membranes containing cadmium pigments, irradiated with UV radiation

The cadmium pigments were yellow, orange and red pigments. They consisted of cadmium sulphide and cadmium sulphide with zinc sulphide as well as cadmium sulphide with cadmium selenide. Their quantitative composition and specific surface area were examined. The pigments were used to color the poly (vinyl chloride) plastisol films, which were then exposed to UV radiation. The surfaces of the coloured membranes were examined by infrared spectroscopy before and after irradiation with UV. The changes occurred in the PVC membrane were investigated by thermogravimetric analysis. The degree of crystallinity of the pigments and the membrane was determined by X-ray diffraction. The color change of the membranes was determined from the spectra obtained by reflection spectroscopy, and the components of colour L*, a* and b* were calculated. Base of them, the tolerance of colour deviations (ΔE*) was determined. The calculations allowed for the determination of the effect of UV irradiation on the change of the colour of the membranes and confirmation of the degradation of the pigments and polymer membrane.

Synthesis and Electron-Beam Modification of Zinc-Sulphide Phosphors for Solid-State Radioluminescent Light Sources (SRLS)

Radioluminescence technologies are at the front line of the optic and electronic studies. Effective, self-contained and safe radioluminescent light sources can find their application in space industry, in medicine and in military technologies. The question of the performance improvement of the solid-state radioluminescent light sources (SRLS) without raising the included activity of working radionuclide can be solved by upgrading the phosphor crystalline structure. The electron-beam treatment for zinc-sulphide phosphors initial batch has been studied in a wide range of concentrations of the activating agent (Cu) for improving the radioluminescent performances of the phosphors, for creating the structural defects that form centers of luminescence. The changes of the phase composition were investigated under different synthesis conditions. It is revealed that electron-beam treatment of the initial batch leads to the growth of the wurtzite phase content in zinc-sulphide phosphors synthesized below the phase transition temperature. The changes of the phase content promote the spectral redistribution under the tritium beta-excitation. It is obviously the reflection of the fact of «green» luminescence centers rearrangement between the volume of the crystal and its surface. The correlations between structural configuration and performances of ionizing luminescence were found. Electron beam treatment gave the 20% increase of brightness of the radioluminescence. The achieved enhancement of luminescence performances allows the development of advanced tight-packed SRLS with minimal radioactivity and high energy-light conversion.