Ultraviolet-visible Spectroscopy Research Articles

Aloebarbadensis - Assisted MgBiO/MgCuBiO/MgBaBiO nanocomposites as effective gamma shielding novel materials

For the first of its kind, MgO/Bi2O3 (1:1) (MBO), MgO/CuO/Bi2O3 (1:1:1) (MCBO) and MgO/BaO/Bi2O3 (1:1:1) (MBBO) binary/ternary nanocomposites (NCs) were synthesized by Aloe barbadensis (Aloe vera) mediated solution combustion method. The as-formed NCs are subjected to calcination for 3 h at 600oC.The Mg-based NCs acquired are subjected to various analytical characterization methodologies, including PXRD (Powder X-ray Diffraction), SEM (Scanning Electron Microscopy), EDS (Energy Dispersive X-ray Spectroscopy), FTIR (Fourier Transform Infrared Spectroscopy), and Ultraviolet–Visible Spectroscopy (UV–Vis). The Bragg reflections confirm the formation of monoclinic phase BaO, Bi2O3, cubic MgO and tetragonal CuO nanoparticles. The surface morphology of MBO, MCBO and MBBO NCs consists of irregular sized, leafy and burrow like structured agglomerated NPs with hollows and voids/pores. The Eg (direct energy band gap) determined from W-H (Wood and Tauc's) plot was found to be 3.09, 3.19 and 3.12 eV for MBO, MCBO and MBBO NCs respectively. The evaluation of gamma radiation shielding properties was conducted using a NaI (Tl) detector connected to a multi-channel analyzer. Shielding parameters of MBO, MCBO and MBBO, such as μ/ρ (mass attenuation coefficient), λ (mean free path), HVL (half-value layer), TVL (tenth-value layer) are measured. Among the as-synthesized Mg-based NCs, MBO exhibits better shielding properties compared to MCBO and MBBO. Thus, the procured Mg-based NCs are suitable for applications where weight reduction is critical, such as aerospace or portable radiation shielding systems.

Visible Light-Triggered Catalytic Performance of Reduced Graphene Oxide Decorated With Copper Oxide Nanocomposite for Degradation of Rhodamine B Dye and Kinetics Studies.

Herein, novel nanocomposites based on reduced graphene oxide decorated copper oxide nanoparticles (rGO/CuO) were prepared by the in situ co-precipitation method. The structural, morphological, and optical characterization of as-prepared nanocomposites was performed by powdered x-ray diffraction (p-XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR), Raman, and ultraviolet-visible (UV-Vis) spectroscopy, respectively. The as-prepared nanocomposites exhibited better photocatalytic activity of rhodamine B dye with maximum ~94% degradation in 120 min with a rate constant of 0.2353 min-1 under optimized conditions. Furthermore, the effects of solution pH and catalyst loading are studied on the degradation process. Therefore, this state-of-the-art strategy for the decoration of CuO nanoparticles onto the surface of rGO nanosheets could be an ideal platform for fabricating highly efficient photocatalysts.

Synthesis and Characterization of Nanostructured Cerium-Doped Zinc Oxide Thin Films for Selective Nitrogen Dioxide Gas Sensing Applications

Zinc oxide thin films doped with cerium were synthesized through facile spray pyrolysis technique and subsequently characterized via an array of analytical methods, including X-ray diffraction, ultraviolet-visible diffused reflectance absorption spectroscopy, photoluminescence, scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques. The operative mechanism of the semiconductor metal oxide gas sensors is predicated on the modulation of electrical conductivity in response to varying gaseous atmospheres, under the influence of disparate thermal conditions. The nitrogen dioxide gas-sensing performance of the films demonstrated a noteworthy gas response of 18% at an elevated temperature of 400°C for a concentration of 100 ppm, accompanied by rapid response and recovery times of 23 and 60 s, respectively.

Biogenic synthesis and characterization of antimicrobial, antioxidant, and antihemolytic zinc oxide nanoparticles from Desertifilum sp. TN-15 cell extract

Cyanobacteria, being a prominent category of phototrophic organism, exhibit substantial potential as a valuable source of bioactive compounds and phytonutrients, including liposomes, amino derivatives, proteins, and carotenoids. In this investigation, a polyphasic approach was employed to isolate and characterize a newly discovered cyanobacterial strain from a rice field in the Garh Moor district of Jhang. Desertifilum sp. TN-15, a unique and less explored cyanobacterial strain, holds significant promise as a novel candidate for the synthesis of nanoparticles. This noticeable research gap underscores the novelty and untapped potential of Desertifilum sp. TN-15 in the field of nanomedicine. The characterization of the biogenically synthesized ZnO–NPs involved the application of diverse analytical techniques. Ultraviolet–visible spectroscopy revealed a surface plasmon resonance peak at 298 nm. Fourier transform infrared spectral analysis was utilized to confirm the involvement of biomolecules in the biogenic synthesis and stability. Scanning electron microscopy was employed to probe the surface morphology of the biogenic ZnO–NPs unveiling their size of 94.80 nm and star-shaped. Furthermore, X-ray diffraction analysis substantiated the crystalline nature of ZnO–NPs, with a crystalline size measuring 46 nm. To assess the physical stability of ZnO–NPs, zeta potential and dynamic light scattering measurements were conducted, yielding values of + 31.6 mV, and 94.80 nm, respectively, indicative of favorable stability. The antibacterial capabilities of Desertifilum sp. TN-15 are attributed to its abundance of bioactive components, including proteins, liposomes, amino derivatives, and carotenoids. Through the synthesis of zinc oxide nanoparticles (ZnO–NPs) with this strain, we have effectively used these chemicals to generate nanoparticles that exhibit noteworthy antibacterial activity against Staphylococcus aureus (MIC: 30.05 ± 0.003 µg/ml). Additionally, the ZnO–NPs displayed potent antifungal activity and antioxidant properties, as well as significant antihemolytic effects on red blood cells (IC50: 4.8 µg/ml). Cytotoxicity assessment using brine shrimps revealed an IC50 value of 3.1 µg/ml. The multifaceted actions of the biogenically synthesized ZnO–NPs underscore their potential applications in pharmacological and therapeutic fields. This study proposes a novel method for ZnO–NPs production utilizing the recently identified cyanobacterial strain Desertifilum sp. TN-15, highlighting the growing significance of biological systems in the environmentally friendly fabrication of metallic oxide nanomaterials.

Facile fabrication of Cu/kaolin nanocomposite as highly efficient heterogeneous catalyst for 4-nitrophenol reduction in aqueous solution

Hazardous organic pollutants in industrial wastewaters are becoming a major global challenge that threatens life on earth and particularly poses a serious health risk to human beings. 4-Nitrophenol (4-NP) is a highly hazardous organic contaminant that has been extensively utilized across multiple industries, and their wastewater disposal into water streams leads to a higher accumulation of 4-NP. It is therefore important for both academia and industry to make catalysts that are cheap, very effective, good for the environment, easy to recover, and can be used more than once for reducing 4-NP in normal conditions. This paper reports the synthesis, characterization, and application of Cu/kaolin nanocomposite as an efficient heterogeneous catalyst for decomposing 4-NP, a model organic molecule. The catalyst was synthesized by incorporating a copper precursor into layered kaolin clay and directly reducing the metal precursor using sodium borohydride (NaBH4). The morphology, structure, surface property, and interaction of the resulting Cu/kaolin nanocomposite (NC) were characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron spectroscopy/energy-dispersive X-ray spectroscopy, selected area electron diffraction, X-ray diffraction, and N2 adsorption/desorption, and the results clearly demonstrated the growth of copper nanoparticles on the kaolin surface. It was discovered that the Cu nanoparticles (NPs) on the kaolin surface had a crystallite size of about 23.6 nm. The significance of Cu NPs and the high catalytic activity of the synthesized Cu/kaolin NC toward 4-NP reduction by NaBH4 were evaluated by the catalytic reduction experiments. Among the different nanocomposites synthesized, 30-Cu/kaolin showed the highest catalytic activity for 4-NP reduction, with a reduction efficiency of over 99 % within 4 min with a pseudo-first-order rate constant, kapp, of 1.23 min−1. Furthermore, the reusability test indicated that Cu/kaolin NC can be reused for up to six runs efficiently without significant decrease in its catalytic performance, indicating the nanocomposite has excellent stability and great potential applications in industrial and agricultural wastewater treatment.

Marine-Derived Magnetic Nanocatalyst in Sustainable Ultrasound-Assisted Synthesis of 2,3-Diphenyl-2,3-Dihydroquinazolin-4(1H)-One Derivatives

This research presents a sustainable approach to fabricate iron oxide nanoparticles by employing phytochemicals derived from marine grass extract as both reducing and stabilizing agents. Formation of magnetic nanoparticles (MNPs) initially confirmed by ultraviolet-visible spectroscopy (UV-vis) showing absorption peak at 370 nm. X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques unveiled magnetic iron oxide NPs with a rod shape, an average size of 21 nm, and an inverse spinel crystal structure. The participation of organic compounds in the production and stabilization of MNPs was evidenced through Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). A vibrating sample magnetometer (VSM) demonstrated the magnetic properties of iron oxide NPs showing a saturation magnetization value of 21.46 emu/g. The catalytic efficiency of these marine-assisted MNPs was evaluated in a one-pot three-component reaction involving isatoic anhydride, aromatic aldehydes, and amines under ultrasonic conditions. Under optimal conditions, a low dose of 1.5 mg of biobased magnetite nanoparticles yielded dihydroquinazolin-4(1H)-One products with up to 95% efficiency in a brief duration of 15 min at an ultrasonic power intensity of 130 W. Different directing groups were investigated, and control experiments were carried out to enhance the understanding of the reaction mechanism. The obtained results highlight the synergistic effect of marine grass-mediated magnetic nanocatalysts combined with ultrasonic-assisted synthesis in developing sustainable green methodologies in organic synthesis.

4-Diphenylaminobenzaldehyde-formulated isonicotinohydrazide for the rapid recognition of Cu2+ ions; Application of RGB tool, pharmaceutical samples, and DFT studies

High copper concentrations have been linked to several harmful illnesses in humans and negatively affect the kidneys and liver. The design and synthesis of simple and effective chemosensors for recognizing copper (Cu2+) ions are extremely significant. However, most of the colorimetric chemosensors have been developed using an intramolecular charge transfer binding mechanism based on donor-acceptor conjugation systems. This study aimed to fabricate a novel Schiff base colorimetric chemosensor, N'-(4-(diphenylamine) benzylidene) isonicotinohydrazide (DPBA-INH), with high sensitivity and selectivity towards copper ions in the semi-aqueous medium (DMSO: H2O, 7:3, v/v). The synthesized receptor DPBA-INH was distinguished using various spectroscopic methods, including NMR analysis, Fourier transform infrared spectroscopy, HRMS, and ultraviolet-visible (UV-vis) spectroscopy. When exposed to sunlight, the receptor DPBA-INH with Cu2+ ion complexation exhibited a color change from orange to pale yellow. A Job's plot and electrospray ionization mass spectra confirmed the presence of complexation at a stoichiometric binding proportion of the receptor to Cu2+ ions of 1:1. The receptor DPBA-INH interacts with Cu2+ ions in a 1:1 stoichiometric manner with a detection limit of 1.40 × 10−7 M. The experimental results were supported by a theoretical DFT study. Moreover, the receptor effectively measured Cu2+ ions in pharmaceutical samples and test strip analyses. Furthermore, the rapid colorimetric recognition of Cu2+ ions in a semi-aqueous medium was achieved using DPBA-INH, which was demonstrated to be an excellent receptor. Notably, DPBA-INH was employed to detect copper ions in real water samples.

Antifungal films for strawberry packaging using carbon quantum dots derived from lemon and onion juice via green hydrothermal method

Fungi are the prime concern since they cause post-harvest decay in fruits such as strawberries; the fungi motivate the need for new antifungal agents. Among all these nanoparticles, the carbon quantum dots (CQDs) show the most promising results for their use in food packaging applications. Lemon carbon quantum dots (LCQD), which is derived from lemon juice, and onion carbon quantum dots (OCQD), which is derived from onion juice, were synthesized using the one-step hydrothermal method. The synthesized materials were then characterized using a transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and ultraviolet-visible (UV-Vis) spectroscopy. LCQD and OCQD solutions were applied to fresh strawberries for the purpose of conducting studies on weight loss, decay, and shelf-life extension. The antifungal activity of both CQDs was assessed against Rhizopus sp., Penicillium sp., Candida albicans, Aspergillus sp., and Botrytis cinerea using the agar-well diffusion technique. The obtained average size was 4.33±1.67 nm for LCQDs and 3.34±1.72 nm for OCQDs. Strawberries packaged with OCQDs and LCQDs showed weight loss of 5.21%±1.03% and 8.14%±1.09% on the fourth day of observation, respectively, against 18.71%±2.2% by control. On the same day, the decay rate for OCQDs was 11%, 40% for LCQDs, and 96.65% for control. Both exhibited antifungal activity, with inhibition zones ranging from 12.6-44.5 mm for various fungi. OCQD exhibits higher activity packaging compared to LCQD due to their smaller size and superior antifungal activity against a variety of fungi.

Experimental comparison of the effects of the two designed probes for exfoliation of graphene by sonication.

In the present research, comparative simulation and experimental investigation were carried out for two different probes to improve the efficiency and quality of few-layer graphene utilizing liquid-phase exfoliation. Two differently designed shaped probes are fabricated for this study, i.e., a simple probe and a stepped probe. The acoustic pressure distribution in the vessel is simulated for both probes at different output powers. In the experiment, both probes exfoliate graphite powder in a mixture of deionized water and ethanol. Different sonication times and output power were studied for different pulse modes. The graphene layers were characterized using Ultraviolet-visible spectroscopy (UV‒Vis), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Raman Microscope. The simulation shows that the total displacement on the tip of the stepped probe is 5.7% greater than that of the simple probe. Also, the pressure difference produced by the stepped probe is 9.15 × 106 pa compared to the pressure difference of the simple probe which is 8.23 × 106 pa. Consequently, the stepped probe was more effective in exfoliating graphene. The experimental results show that the absorbance peak in the stepped probe is approximately 32% greater than the absorbance peak in the simple probe with the same output power. Also, the graphene with better quality is produced with the stepped probe compared to the simple probe, which verifies the simulation findings. Additionally, the optimum output power, pulse duration, and sonication time to produce graphene with less time and energy consumption are obtained. The best graphene flakes were obtained via sonication with a pulse duration of 0.7 s, an output power of 282 W, and a sonication time of 45 min using a stepped probe. UV-Vis., SEM and TEM analysis show increases in quantity and quality of the exfoliated flakes. These results are approved by the peak ratio of I2D/IG around 1 in Raman spectra revealed the production of the few-layer graphene by the simple probe and the bilayer graphene by the stepped probe. So, this method is suitable for the production of graphene flakes from graphite in suitable quantity and quality.

Fabrication of Chitosan-Cu2O Nanocomposite through Ethanol Assisted Reduction

The semiconducting characteristics of copper oxides have intrigued researchers like photocatalysis and sensors. Coating these nanoparticles with biocompatible polymers like chitosan enhances their properties, such as biocompatibility and non-toxicity, while reducing production costs. This work details the successful in situ production of a biocompatibile nanocomposite, with Cu2O nanoparticles dispersed in a chitosan matrix using ethanol as a reducing agent. Advanced techniques including ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging combined with selected area electron diffraction (SAED) analysis, have been employed to characterize the nanocomposite material with additional relevant properties analyzed.

Catechol/m-Phenylenediamine Modified Sol–Gel Coating with Enhanced Long-Lasting Anticorrosion Performance on 3003 Al Alloy

Aluminum alloys, characterized by their low density and high mechanical strength, are widely applied in the manufacturing sector. However, the application of aluminum alloys in extreme environments presents severe corrosion challenges. Sol–gel organic coating techniques have garnered significant attention due to their excellent stability, barrier properties, and cost-effectiveness, as well as their simpler processing. Nevertheless, conventional sol–gel coatings are unable to withstand the corrosive effects of high-chloride and high-halide ion environments such as marine conditions, owing to their inherent structural defects. Therefore, this study proposes the utilization of a simple method to synthesize catechol (CA) and meta-phenylenediamine (MPD)-derived catecholamine compounds to modify sol–gel coatings. Surface characteristics of the modified coatings were analyzed using Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The thickness of the modified coating was approximately 6.8 μm. The CA/MPD-modified substance effectively densifies the sol–gel coating, enhancing its corrosion protection performance. A 3.5 wt% NaCl solution was used to simulate a marine environment, and electrochemical impedance spectroscopy (EIS) was conducted using an electrochemical workstation to evaluate the coating’s protective properties over a long-term period. The results indicate that the modified coating provides protection for 3003 aluminum alloy for a minimum of 30 days under corrosive conditions, outperforming unmodified sol–gel coatings in terms of corrosion resistance.

Antimicrobial studies of visible light-responsive nanoflower spheres Bi2WO6/ZnO

The contamination of water resources in recent years has resulted in the dissemination of harmful bacteria via water sources, posing a significant threat to the safety and well-being of humans, animals, and plants. Consequently, there is a growing concern over the health and sanitation of water resources. Photocatalysis, a novel and very effective antibacterial method, has gained significant attention in the area of antibacterial research. Bismuth nitrate pentahydrate and sodium tungstate dihydrate were used in a straightforward hydrothermal process to create nanoflower spheres Bi2WO6/ZnO photocatalytic composites in molar ratios of 1:1, 1:2, 1:3, and 1:4. The first-ever demonstration of the photocatalytic broad-spectrum antibacterial activity of porous nanoflower spheres Bi2WO6/ZnO composites was shown. The samples were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet–visible spectroscopy (UV–vis). The antibacterial activity was evaluated using the dilution coated plate technique, with LED light irradiation. The findings indicate that the Bi2WO6/ZnO composite has a much superior antibacterial activity against both bacteria and fungus compared to individual Bi2WO6 and ZnO. When exposed to LED lighting with an intensity of 35 W, the Bi2WO6/ZnO nanoparticles in a 1:2 ratio at a concentration of 1000 mg/L demonstrated complete antibacterial effectiveness against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis within 30 min. Similarly, the nanoparticles achieved 100 % antibacterial efficiency against Candida albicans within 90 min. The antibacterial efficacy of 1000 mg/L 1:2 Bi2WO6/ZnO nanoparticles against Escherichia coli and Staphylococcus aureus was found to be 100 % within 5 min under natural lighting conditions. The findings indicate that Bi2WO6/ZnO nanoparticles have excellent photocatalytic broad-spectrum antibacterial efficacy.

Enhanced charge separation at the interface of Cu2O/CuSCN composite thin films synthesized by electrodeposition technique

This study focuses on the synthesis and characterization of hole transport layers (HTLs) for solar cells, par- ticularly copper(I) thiocyanate (CuSCN) and cuprous oxide (Cu2O), synthesized via electrodeposition tech- niques. CuSCN and Cu2O offer promising properties for efficient charge transport in photovoltaic devices. The synthesis processes involve precise control of deposition parameters to achieve desired film morpholo- gies and properties. Characterization techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), and ultraviolet-visible (UV-Vis) spectroscopy provide insights into film morphology and optical properties. Optimization of synthesis parameters for Cu2O films is explored to enhance their electrical properties. Photoelectric response measurements indicate improved charge separation at the interface of Cu2O/CuSCN composite films. These findings can contribute to the advancement of solar cell technology. Furthermore, the study extends its exploration to the fabrication of Cu2O by electrodeposition at different pH levels. SEM and X-ray diffraction (XRD) analyses reveal the impact of deposition parameters on film mor- phology and crystal structure, providing valuable insights for tailored synthesis approaches. Overall, this comprehensive study not only advances the understanding of HTL materials synthesis and optimization but also provides valuable guidance for the development of high-efficiency and stable solar cell devices.

Diatomite with gold nanoparticles for atrazine adsorption

Atrazine is a commonly used herbicide worldwide, and it has significant environmental concerns due to its toxic ecological effects. This work uses diatomite decorated with gold nanoparticles to evaluate its capacity for atrazine adsorption. The structural characterization was studied by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive spectroscopy (EDX), Fluorescence microscopy and X-ray photoelectron spectroscopy (XPS). Our findings reveal that diatomite decorated with gold nanoparticles with an average particle size of 10 nm enhances the Raman signal and fluorescence intensity for atrazine detection. Experimental conditions, such as atrazine concentration, pH, contact time, and diatomite mass, have been optimized to quantify the maximum removal conditions using ultraviolet–visible spectroscopy, reaching a maximum adsorption of 2.5 mg/g in 4 h. FTIR and XPS evidence the interaction of the amine groups of the atrazine with the diatomite-decorated surface. The impact of this work relies on environmental remediation using naturally available diatomite decorated with gold nanoparticles and understanding the binding interactions for the removal of atrazine.

PH-sensitive and redox-responsive poly(tetraethylene glycol) nanoparticle-based platform for cancer treatment

Effective drug delivery with precise tumour targeting is crucial for cancer treatment. To address the challenges posed by the specificity and complexity of the tumour microenvironment, we developed a poly(tetraethylene glycol)-based disulfide nanoparticle (NP) platform and explored its potential in cancer treatment, focusing on drug loading and controlled release performance. Poly(tetraethylene glycol) NPs were characterised using nuclear magnetic resonance spectroscopy, mass spectrometry, and ultraviolet-visible spectroscopy. Additionally, we evaluated physicochemical properties, including dynamic light scattering, zeta potential analysis, drug loading capacity (DLC), and drug loading efficiency (DLE). The impact of NPs on the mouse colorectal cancer cell line (CT26) and NIH3T3 cells was assessed using a cytotoxicity assay, live/dead staining assay, flow cytometry, and confocal fluorescence microscopy. The experimental results align with the expected chemical structure and physicochemical properties of poly(tetraethylene glycol) NPs. These NPs exhibit high DLE (78.7%) and DLC (12%), with minimal changes in particle size over time in different media.In vitroexperiments revealed that the NPs can induce significant cytotoxicity and apoptosis in CT26 cells. Cellular uptake notably increases with increasing concentration and exposure time. The confocal microscopic analysis confirmed the effective distribution and accumulation of NPs within cells. In conclusion, poly(tetraethylene glycol) NPs hold promise for improving drug-delivery efficiency, offering potential advancements in cancer treatment.

Spontaneous formation of reactive redox radical species at the interface of gas diffusion electrode

The aqueous interface-rich system has been proposed to act as a trigger and a reservoir for reactive radicals, playing a crucial role in chemical reactions. Although much is known about the redox reactivity of water microdroplets at “droplets-in-gas” interfaces, it remains poorly understood for “bubbles-in-water” interfaces that are created by feeding gas through the porous membrane of the gas diffusion electrode. Here we reveal the spontaneous generation of highly reactive redox radical species detected by using electron paramagnetic resonance under such conditions without applying any bias and loading any catalysts. In combination with ultraviolet-visible spectroscopy, the redox feature has been further verified through several probe molecules. Unexpectedly, introducing crown ether allows to isolate and stabilize both water radical cations and hydrated electrons thus substantially increasing redox reactivity. Our finding suggests a reactive microenvironment at the interface of the gas diffusion electrode owing to the coexistence of oxidative and reductive species.

Determination of morphine sulfate anti-pain drug solubility in supercritical CO2 with machine learning method

Accurate solute solubility measuring and modeling in supercritical carbon dioxide (ScCO2) would address the best working conditions and thermodynamic boundaries for material processing with this type of fluid. Theory- and data-driven methods are two general modeling approaches. Using theory-driven methods, the solubility is estimated based on the principles of thermodynamics, while data-driven methods are developed by training the algorithms. Despite acceptance of each of these methods, more experimental solubility data are still needed to promote modeling performances. In this study, for the first time, solubility of morphine sulfate is determined and modeled by a set of 13 semi-empirical (theory-driven) and random forest (data-driven) models. Using a laboratory system with an ultraviolet-visible (UV-Vis) spectroscopy, the experimental solubilities including 48 data points were obtained at different temperatures (308–338 K) and pressures (12–27 MPa). The minimum (0.806 × 10−5) and maximum (5.902 × 10−5) equilibrium mole fractions were observed at working pressures of 12 and 27 MPa, respectively, both at the same temperature of 338 K. It was indicated that random forest model (with AARD% of 1.29%) had an excellent predictive performance against semi-empirical models (with AARD% from 9.33 to 19.76%). The results showed that solute molecular weight had the highest effect on random forest modeling. Using modeling results from Chrastil and Bartle models, total and vaporization enthalpies of dissolution of morphine sulfate in ScCO2 were found to be 35.12 and 59.04 kJ/mole, respectively.

Rapid fabrication of polyoxometalate-enhanced photo responsive films from ethyl cellulose (EC) and polyvinylpyrrolidone (PVP)

Ethyl cellulose (EC), polyvinylpyrrolidone (PVP), and phosphomolybdic acid (PMoA) were the components of a new photochromic hybrid film composed of heteropoly acids (abbreviated EC-PVP/PMoA), created by solvent evaporation. The EC-PVP/PMoA mechanism, visible light photochromic behaviors, and microstructure were closely studied by transmission electron microscopy (TEM), atomic force microscopy (AFM), ultraviolet-visible (UV–visible) spectroscopy, X-ray photo electronics (XPS), and Fourier transmission infrared spectroscopy (FTIR). FTIR spectra show that neither the core structures of EC, PVP, nor the Keggin structure of PMoA in the EC-PVP/PMoA composite hybrid film were damaged during fabrication. In the presence of oxygen, the yellowish transparent hybrid film exhibited reversible photochromism and significant photochromic reactivity, becoming blue in the presence of visible light. Upon heating the film at 90 °C for 1 h its photoresponsive properties were enhanced, making the blue color more vibrant and stable due to polyethylene glycol (PEG). The XPS spectra demonstrated a proton transfer procedure during the photochromic process, and the presence of Mo+5 species indicated a photoreduction interaction between the PMoA particles and the EC-PVP matrix. To the best of our knowledge, this is the first EC-PVP combined hybrid film with POMs with promising prospects for solar UV detection and smart glass windows applications.

Elusive supported surface M2Ox dimer active site (M = Re, W, Mo, Cr, V, Nb, and Ta)

Supported transition metal oxide catalysts are extensively used as heterogeneous catalysts for various energy, chemical, and environmental applications. The molecular structures of dehydrated surface metal oxide phases are crucial for understanding structure-activity/selectivity relationships that guide the design of enhanced catalysts. Some early studies suggested that dimeric (aka binuclear) surface metal oxide sites were more active/selective than monomeric (aka mononuclear) sites, prompting interest in synthesizing catalysts with supported dimeric metal oxide structures. This review examines the literature on dehydrated silica-based supported group 7-5 MOx catalysts (ReOx, WOx, MoOx, CrOx, VOx, NbOx, and TaOx on SiO2, MCM-41, AlOx/SiO2, and H-ZSM-5) for their surface metal oxide structures. In situ Raman, extended x-ray absorption fine structure, and ultraviolet-visible spectroscopy indicate that monomeric surface MOx structures predominate in all such catalysts. Therefore, the cursory use of dimeric surface M2Ox sites in catalytic mechanisms and reaction models in heterogeneous catalysis by supported metal oxides is questionable, and moving forward, the invoking of supporting dimeric surface M2Ox sites should be critically examined and backed up with direct spectroscopic methods.

An investigation on pyrite floatability using stable micro-nanobubble-assisted flotation

This study critically examines the impact of micro-nanobubble (MNB)-assisted flotation on pyrite recovery in bulk ore, and clarifies the intricate relationship between pyrite and its associated ore. The physicochemical properties of MNBs and the interaction mechanisms between xanthate collector and pure pyrite mineral were evaluated using advanced analytical techniques, including Dynamic Light Scattering (DLS), Field-Emission Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (FESEM-EDX), and Ultraviolet-Visible Spectroscopy (UV-Vis), in the absence and the presence of MNBs. MNBs were created through hydrodynamic cavitation, and their characteristics revealed a size increase from 600 nm to 3 µm over 25 days. Notably, the zeta potential measurements indicated an increase from -2.5 to 0 mV at a constant pH of 8, correlating with the geometric mean size of MNBs coarsening from 600 nm to 2-3 µm. The FESEM and EDS analyses disclosed that ultrasonic treatment effectively dispersed ultrafine surface coatings on pyrite particles, increasing iron and sulfur purity by 8% and 6%, respectively, and significantly reducing surface oxygen by 53%. Micro-flotation and batch rougher kinetic flotation experiments were conducted with and without MNBs, leading to a 7% and 8% improvement in recovery for pyrite mono-minerals (-105+53 µm) and its ore (d<sub>80</sub>=150 µm), respectively. The sorption behavior of sodium isopropyl xanthate (SIPX) collector on the particle surface was also investigated at various concentrations (ca. 10-160 µM) in the presence and absence of stable MNBs and demonstrated that the presence of MNBs resulted in a 1.6-fold increase in collector absorption on the pyrite surface, confirming the findings obtained from micro-flotation. Moreover, adsorption behavior is up to 1.3 times compared to the scenario without MNBs. The adsorption process was controlled by a pseudo-second-order model, indicating a chemical sorption mechanism.