Phase tunable nickel doped Mn3O4 nanoparticle synthesis by chemical precipitation: kinetic study on dye degradation.

Nickel (Ni) doped Mn3O4 nanoparticles (NPs) were synthesized by a quick and facile chemical precipitation technique to investigate their performance in the degradation of methylene blue (MB) in the absence of light. XRD, FESEM, TEM, AAS, XPS, and FT-IR were used for the investigation of the structural, surface morphological, and elemental composition of Ni doped Mn3O4 NPs. XRD confirms the formation of a tetragonal phase structure of pure Mn3O4 and 1% and 3% Ni doped Mn3O4 NPs. However, mixed phases were found in the case of 5 to 10% Ni doped Mn3O4 NPs. Well-defined spherical-shaped morphology was presented through FESEM. Particle sizes decreased linearly (58.50 to 23.68 nm) upon increasing the doping concentration from 0% (pure Mn3O4) to 7% respectively, and then increased (48.62 nm) in the case of 10% doping concentration. TEM further confirmed spherical shaped 32 nm nanoparticles for 7% Ni doped Mn3O4. The elemental composition and oxidation state of the prepared NPs were confirmed by using XPS spectra. Mixed valence Mn2+ and Mn4+ states were found in pure Mn3O4 and 1% and 3% Ni doped Mn3O4 NPs in the ratio of 2MnO-MnO2. In addition, three different oxidation states Mn2+, Mn3+, and Mn4+ were found in 5 to 10% Ni doped Mn3O4 NPs. Moreover, as a dopant Ni exists as Ni2+ and Ni3+ states in all Ni doped Mn3O4 NPs. The synthesized NPs were then applied as potent oxidants for the degradation of MB at pH 3. With the increase of doping concentration to 7%, the degree of degradation was increased to 79% in the first 10 min and finally, it became about 98%. The degradation of MB follows the pseudo-first-order linear kinetics with a degradation rate of 0.0342 min-1.

Effect of Reaction Parameters on CO2 Absorption from Biogas Using CaO Sorbent Prepared from Waste Chicken Eggshell.

This study provides an efficient and straightforward approach to eliminate carbon dioxide (CO2) by absorption using a calcium oxide (CaO) sorbent derived from chicken eggshells. The sorbent concentration, stirring speed, and contact time were varied. The optimal condition for CO2 removal was a 10% calcium hydroxide (Ca(OH)2) suspension at 600 rpm with 20 min interaction. This optimum condition conferred the ever-highest absorption (98.71%) of CO2 through Ca(OH)2 suspensions from eggshell-derived CaO. X-ray diffraction was used to identify crystallographic phases and optimum conditions revealed calcium carbonate (CaCO3) formation with the highest intensity, Fourier transform infrared spectroscopy revealed peaks for the carbonate (CO32-) group, field emission scanning electron microscopy was used to investigate the morphological and structural properties of the sorbent before and after CO2 absorption, and thermogravimetric analysis was performed to understand the reaction mechanism. According to the kinetic analysis, the sorbent can be fully decomposed with a minimum activation energy (Ea) of 89.09 kJ/mol.

Influence of Sn doping on the optoelectronic properties of ZnO nanoparticles.

Zinc Oxide (ZnO) nanoparticles (NPs) obtained a lot of attention from researchers and industries because of their superior properties as an optoelectronic material. Doping, especially tin (Sn), can further fine-tune their optoelectronic properties. In this manuscript, we have reported the optoelectronic properties of Sn-doped ZnO NPs, which were synthesized by a simple chemical solution method. A wide range of dopant (Sn) concentrations were used in the ratios of 0, 1, 3, 5, 7, and 10 weight percent. The effects of dopant (Sn) concentration on the structural, morphological, elemental composition, and optical properties of ZnO NPs were investigated by using an X-ray diffractometer (XRD), Field Emission Scanning Electron Microscope (FESEM), X-ray photoelectron spectrometer (XPS) and UV-Vis-NIR respectively. XRD analysis revealed the shifting of diffraction patterns towards a higher angle along with decreasing intensity. The calculated crystallite size using the XRD varied from 40.12 nm to 28.15 nm with an increasing doping percentage. Sn doping notably influences the size of ZnO NPs, along with crystal quality, strain, and dislocation density. The X-ray photoelectron spectroscopy (XPS) study showed the presence of zinc (Zn), oxygen (O), and tin (Sn) with their preferred oxidation states in the synthesized NPs. UV-Visible spectroscopy (UV-Vis) showed that the bandgap changed from 3.55 to 3.85 eV with the increasing concentration of Sn. FE-SEM revealed that the structures and surfaces were irregular and not homogeneous. The above findings for ZnO nanostructures show their potential application in optoelectronic devices.

Numerical Simulation of the Performance of Sb2Se3 Solar Cell via Optimizing the Optoelectronic Properties Based SCAPS-1D.

Antimony trisulfide (Sb2Se3), a non-toxic and accessible substance, has possibilities as a material for use in solar cells. The current study numerically analyses Sb2Se3 solar cells through the program Solar Cell Capacitance Simulator (SCAPS). A detailed simulation and analysis of the influence of the Sb2Se3 layer's thickness, defect density, band gap, energy level, and carrier concentration on the devices' performance are carried out. The results indicate that a good device performance is guaranteed with the following values in the Sb2Se3 layer: an 800 optimal thickness for the Sb2Se3 absorber; less than 1015 cm-3 for the absorber defect density; a 1.2 eV optimum band gap; a 0.1 eV energy level (above the valence band); and a 1014 cm-3 carrier concentration. The highest efficiency of 30% can be attained following optimization of diverse parameters. The simulation outcomes offer beneficial insights and directions for designing and engineering Sb2Se3 solar cells.

Triglyceride Conversion of Waste Frying Oil up to 98.46% Using Low Concentration K+/CaO Catalysts Derived from Eggshells.

In this study, biodiesel, also known as fatty acid methyl ester (FAME), was synthesized from multi-stage frying waste soybean oil using chicken eggshell-derived CaO and potassium-impregnated K+-CaO heterogeneous catalysts. Potassium-impregnated catalysts (1.25% K+-CaO, 2.5% K+-CaO, and 5% K+-CaO) were developed by treating the calcined waste eggshell powder with KOH in different wt % ratios. The catalysts were characterized using FTIR, XRD, FESEM, EDS, BET, and particle size analysis techniques. Box-Behnken design-based optimization was exploited to optimize the reaction parameters. A maximum yield of 98.46%, calculated via 1H NMR, was achieved following a 5% K+ doping, 12:1 methanol to oil molar ratio, 3% catalyst amount, 180 min reaction time, and 65 °C reaction temperature. The catalyst (5% K+-CaO) responsible for maximum biodiesel production was found to be highly reusable, with a 30.42% conversion decrease in activity after eight cycles of reuse. Gas chromatography was used to determine the composition of FAME produced from different cycles of waste soybean oil. Physicochemical parameters of the synthesized biodiesel were found to be compatible with EN and ASTM standards. This study has shown that the waste eggshell-derived heterogeneous catalysts have significant catalytic activity at relatively low K+ doping and catalyst loading leading to high biodiesel conversion.