Presence Of Atmospheric Oxygen Research Articles

Characterization of atmospheric pressure plasma deposited (APPD) coatings to improve the friction behavior of thermoplastic surfaces

Achieving a significant friction reduction is crucial for using thermoplastic materials as substrates in tribological applications and presents an eligible alternative to the use of light metals. In this study, previously developed MoS2/graphite/zinc composite coatings, applied by an atmospheric pressure plasma deposition (APPD) process, were investigated to extend the understanding of their characteristics and the influence of the process and environmental parameters on friction behavior. Tribological tests were conducted in ambient conditions and at elevated temperatures (110 °C) to study the friction behavior under application-oriented conditions. The presence of atmospheric oxygen during the deposition process was shown to influence the durability of the coatings, which motivated the application of an inert gas atmosphere for the coating deposition. A novel shrouding plasma nozzle was introduced, which further lowered the friction coefficients. The oxidizing effect of the plasma spray deposition was studied with X-ray photoelectron spectroscopy to investigate the strong impact of the deposition current on the friction behavior and durability of the deposited coatings. Coating composition, morphology, and the effects of the tribological testing were evaluated using optical microscopy, 3D surface measurements, scanning electron microscopy, X-ray diffraction, and nanoindentation. The fabricated coatings with thicknesses in the 10 μm range and good adhesion on the polyamide substrate were stable under extended testing durations and at elevated temperatures and accomplished a significant friction reduction compared to the uncoated polyamide. Thus, APPD-fabricated MoS2/graphite/zinc coatings represent an excellent candidate for low-friction applications of thermoplastic substrates.

Corrosion behavior of high- and low-chromium steel grinding balls in chloride solution

The corrosion behaviour of three types of alloys (two low-alloy carbon steel and one stainless iron with ~15 wt.% Cr), in a solution which simulates seawater (3% NaCl solution, pH 8.1) was tested. Tested samples are used to make steel (iron) balls applied in mils for grinding copper and other ore. The corrosion tests were performed using three electrochemical methods, at room temperature in the presence of atmospheric oxygen. The linear polarization resistance (LPR) method, electrochemical impedance spectroscopy (EIS) method, and linear sweep voltammetry (LSV) method were applied. Based on measurements by LPR and EIS methods (as non-destructive methods), the value of polarization resistance (Rp) was determined and the general corrosion rate (vcorr) of the examined samples was calculated. The obtained values of the general corrosion rate can be used to calculate the service life of steel (iron) balls under exploitation conditions (seawater). The appearance of the surface after linear sweep voltammetry (LSV) measurement showed the presence of localized corrosion (pits were formed) of the tested samples, especially stainless iron, and the LSV method is not suitable for the determination of the general corrosion rate of tested samples in seawater. This form of corrosion occurs at high anodic polarizations, during performing LSV measurements.

New Biodegradable Copolymers Based on Betulin and Hydroxycarboxylic Acid Derivatives.

In this study, we propose an approach to the synthesis of new biodegradable polymer materials based on renewable raw feedstock (betulin) and derivatives of hydroxycarboxylic acids using a catalyst/catalytic system (γ-Al2O3, γ-Al2O3/TBHP) that is safe for health and the environment. The resulting polymers are linear thermoplastic polymers that undergo collapse upon melting in the presence of atmospheric oxygen. Moreover, these polymers demonstrate non-toxicity towards a range of Gram-positive and Gram-negative bacteria. The polycondensation of betulin with butyl lactate is particularly noteworthy.

Effect of Silica Nanofiller on Thermal-Oxidative Degradation of Epoxy Composites Synthesized by the Sol-Gel Method

Using the sol-gel method, amine-curing polymer silica composites based on cycloaliphatic epoxy resin were obtained. The content of SiO2 filler in the composites was 0.5–10 wt %. The formed mass fractal of silica nanoparticles during the synthesis of composites has a reinforcing effect on the epoxy polymer matrix. The patterns of non-isothermal destruction of polymers and composites in the presence of atmospheric oxygen have been established. At 5 wt % SiO2, the effective activation energy of the main stage of destruction of composites increases from 165 to 254 kJ mol–1. As a result, the rate of weight loss of the samples decreases (the temperature corresponding to 50% weight loss shifts towards higher values by 30°C). The mechanism of high-temperature oxidation of pure polymer and composite with oxygen has been studied. It has been established that the introduction of SiO2 into the composition of composites increases the activation energy of isothermal oxidation of the substrate.

Probiotics and Prebiotics as Nutraceuticals

Its miles predicted that 500–1,000 species of micro organism live in the human body [Sears 2005]{1} Bacterial cells are a whole lot smaller than human cells and there are at least 10 instances as many microorganisms as human cells within the frame (about 1014 versus 1013[1013 = 1 trillion]) [Savage 1977; Berg 1996]even though everyday plant life is found on all surfaces uncovered to the environment (on the pores and skin and eyes, in the mouth, nostril, small intestine, and colon), the large majority of microorganisms stay inside the big intestine. The phrases intestinal “Microflora” or “microbiota” discuss the microbial surroundings colonizing the GI tract. 90-nine percent of the bacteria isolated from human fecal specimens will no longer develop in the presence of atmospheric oxygen [Savage 1977). Bacteria make up most of the flowers in the colon [University of Glasgow, 2005]4 and 60% of the dry mass of feces [Guarner and Malagelada 2003]. This makes feces an ideal source for testing intestinal plant life

Cross-Coupling of Amines via Photocatalytic Denitrogenation of In Situ Generated Diazenes.

A method for C(sp3)-C(sp3) cross-coupling of amines is described. Primary amines are converted to 1,2-dialkyldiazenes by treatment with O-nosylhydroxylamines in the presence of atmospheric oxygen. Denitrogenation of the diazenes with an iridium photocatalyst then forges the C-C bond. The substrate scope accommodates a broad latitude of functionality, including heteroaromatics and unprotected alcohols and acids.

One-Pot Synthesis of Pentasubstituted Pyridines following the Gold(I)-Catalyzed Aza–Enyne Metathesis/6π-Electrocyclization–Aromatization Sequence

The one-pot de novo synthesis of pentasubstituted pyridines was realized following the process of Au(I)-autotandem catalysis and subsequent aromatization. The process involves aza-enyne metathesis with aryl propiolates to yield 1-azabutadienes and their addition/6π-electrocyclization sequence with the other propiolate units. The resultant 1,4-dihydropyridines were aromatized to furnish the pyridines in the presence of atmospheric oxygen. The aryl propiolates were regioselectively incorporated into the ring system to afford 2-arylpyridines as the sole product.

Solar Photocatalysis of A Pesticide in A Tubular Reactor on Titaniferous Sand as A New Semi-Conductor

This present study comes in addition to overcome the problems of separation of fine particles of TiO2 in heterogeneous photocatalysis after treatment. It aims to show the potential for using titaniferous sand as a new semiconductor under solar irradiation. The photocatalytic efficiency of this titaniferous sand was tested on a pesticide (Azadirachtin). A tubular photocatalytic reactor with recirculation of the polluting solution was designed for the elimination of the pesticide in an aqueous solution. Before its use as a photocatalyst, the titaniferous sand has undergone a specific treatment that consists of calcination at 600℃ followed by extraction of the calcined natural organic materials, which can interfere with the measurement of analytical parameters such as COD. The titaniferous sand was also characterized by X-ray fluorescence spectroscopy (XRF). XRF analyses have shown that TiO2 is predominant in the titaniferous sand with a percentage that has been estimated at 46.34%. The influence of various experimental parameters such as the flow rate of the polluting solution, the concentration of titaniferous sand, the presence of oxygen and the intensity of the overall rate of sunshine, was studied to optimize the photocatalytic degradation of the pesticide. The results showed that the highest removal rate (70%) was observed under the following conditions: a pH of 6, a titaniferous sand concentration of 150 g/L, a flow rate of 0.3 mL/min, and a sunshine rate of 354 W/m2 and in the presence of atmospheric oxygen. Under these experimental conditions, the rate of photodegradation of the pesticide follows the pseudo first order kinetic model of Langmuir Hinshelwood with a coefficient of determination R2 of 0.9869 and an apparent rate constant of 0.0029 min-1. The results clearly demonstrated the potential of titaniferous sand as a photocatalyst sensitive to sunlight for the effective removal of pesticides in the aquatic environment.

Determination of optimal conditions and kinetic laws of hydrogen chloride separation reaction from simm-dichloroethane (1,2-dichloroethane)

In the work, a catalytic optimal system was selected for the hydrochlorination of important components of chlorinated organic waste in the production of vinyl chloride. Information on the active and selective effect of various substances increasing the speed of the reaction in the hydrogen chloride release reaction was given. Operating modes of the reactor selected for oxidative chlorination of ethylene with hydrogen chloride in the presence of oxygen, designed for oxidative chlorination of ethylene with hydrogen chloride in the presence of atmospheric oxygen, were calculated. Also, the operating modes of the reactor were calculated, the kinetic equations of the rate of formation were constructed, and the equations of the relationship between the reactants and the reaction products were studied. As a result of the experiments, important kinetic parameters of simm-dichloroethane were determined to create a model of the simm-dichloroethane (1,2-dichloroethane) synthesis process. Kinetic studies were carried out in a temperature range of 300-350 ℃ in an ideal displacement flow reactor. In it, the reaction proceeded with no more than 70% conversion of sym-dichloroethane (1,2-dichloroethane). In addition, the material and heat balance of the reactor designed for oxidative chlorination of ethylene with hydrogen chloride in the presence of air oxygen was calculated. The purpose of the work is to study the optimal conditions and kinetic laws of hydrogen chloride separation reaction from simm-dichloroethane (1,2-dichloroethane).

Quantum-chemical modeling of reactions initiating sulfuric vulcanization of isoprene rubber

The quantum-chemical method of the density functional DFT B3LYP / 6-311G ** have been used for calculation of thermodynamic functions and changes in the total electronic energy during the initiation of sulfur vulcanization of isoprene rubber using the N - cyclohexyl - 2 benzthiazolyl sulfenamide accelerator in the presence of atmospheric oxygen. Since sulfur, in the process of vulcanization of rubber compounds, is in a larger amount in a dissolved state, unlike oxygen, it is concluded that in the presence of sulfur, the formation of a valid vulcanization agent (DAV) will occur, and oxidation will occur to a lesser extent. When comparing the values of the reaction energy with the addition of the S8 molecule, it was found that sulfur in the accelerator radical acceptance reactions is a more active acceptor than oxygen in similar reactions. The effect of the number of sulfur atoms on the activity of the radicals of the sulfidating complex arising upon the acceptance of sulfur by the radicals formed during the decay of the accelerator is analyzed. It was found that the cyclohexyl radicals of the accelerator are the most active, however, in subsequent reactions of DAV with rubber, the radicals of DAV obtained with the participation of benzthiazolyl fragments are more active. The study of the effect of the number of atoms on the energies of the reactions of the formation of persulfhydryl suspensions shows that the primary suspensions are most likely to contain 8 sulfur atoms formed in reactions involving biradicals formed during the decay of the eight-membered ring of a sulfur molecule

Fermentation of soymilk by Lactobacillus acidipiscis isolated from Chinese stinky tofu capable of efficiently biotransforming isoflavone glucosides to dihydrodaidzein and dihydrogenistein.

The soy isoflavone microbial metabolites dihydrodaidzein (DHD), dihydrogenistein (DHG), equol and 5-hydroxy-equol are generally more biologically active than their precursors daidzein and genistein. Bacteria responsible for isoflavone metabolism have been isolated and identified. Fermented soymilk is a potential functional food; however, there are few lactic acid bacteria capable of metabolizing soy isoflavones. A newly isolated Gram-positive facultative anaerobic bacterium, which was named Lactobacillus acidipiscis HAU-FR7, was isolated from the traditional Chinese fermented soy product 'stinky tofu'. Bacterium strain HAU-FR7 can grow under aerobic conditions and can also convert most of the daidzin and genistin in soymilk into DHD and DHG, respectively. The concentrations of DHD and DHG produced were 183 and 134 μmol L-1 , respectively, after fermentation for 24 h. Strain HAU-FR7 does not produce the biogenic amines cadaverine, putrescine, histamine or tyramine, and an antibiotic susceptibility test showed that HAU-FR7 is sensitive to nine of the ten tested antibiotics, except for vancomycin. Moreover, the 1,1-diphenyl-2- picrylhydrazyl free radical scavenging capacity of soymilk fermented with HAU-FR7 was significantly higher than that of unfermented soymilk. A facultative anaerobic lactic acid bacterium, designated Lactobacillus acidipiscis HAU-FR7, is capable of reducing the soy isoflavone glucosides daidzin and genistin in soymilk to DHD and DHG efficiently, even in the presence of atmospheric oxygen. The biotransformation activity of HAU-FR7 grown in soymilk is higher than that in de Man-Rogosa-Sharpe liquid culture medium. © 2022 Society of Chemical Industry.

Two out of Three Musketeers Fight against Cancer: Synthesis, Physicochemical, and Biological Properties of Phosphino CuI, RuII, IrIII Complexes.

Two novel phosphine ligands, Ph2PCH2N(CH2CH3)3 (1) and Ph2PCH2N(CH2CH2CH2CH3)2 (2), and six new metal (Cu(I), Ir(III) and Ru(II)) complexes with those ligands: iridium(III) complexes: Ir(η5-Cp*)Cl2(1) (1a), Ir(η5-Cp*)Cl2(2) (2a) (Cp*: Pentamethylcyclopentadienyl); ruthenium(II) complexes: Ru(η6-p-cymene)Cl2(1) (1b), Ru(η6-p-cymene)Cl2(2) (2b) and copper(I) complexes: [Cu(CH3CN)2(1)BF4] (1c), [Cu(CH3CN)2(2)BF4] (2c) were synthesized and characterized using elemental analysis, NMR spectroscopy, and ESI-MS spectrometry. Copper(I) complexes turned out to be highly unstable in the presence of atmospheric oxygen in contrast to ruthenium(II) and iridium(III) complexes. The studied Ru(II) and Ir(III) complexes exhibited promising cytotoxicity towards cancer cells in vitro with IC50 values significantly lower than that of the reference drug—cisplatin. Confocal microscopy analysis showed that Ru(II) and Ir(III) complexes effectively accumulate inside A549 cells with localization in cytoplasm and nuclei. A precise cytometric analysis provided clear evidence for the predominance of apoptosis in induced cell death. Furthermore, the complexes presumably induce the changes in the cell cycle leading to G2/M phase arrest in a dose-dependent manner. Gel electrophoresis experiments revealed that Ru(II) and Ir(III) inorganic compounds showed their unusual low genotoxicity towards plasmid DNA. Additionally, metal complexes were able to generate reactive oxygen species as a result of redox processes, proved by gel electrophoresis and cyclic voltamperometry. In vitro cytotoxicity assays were also carried out within multicellular tumor spheroids and efficient anticancer action on these 3D assemblies was demonstrated. It was proven that the hydrocarbon chain elongation of the phosphine ligand coordinated to the metal ions does not influence the cytotoxic effect of resulting complexes in contrast to metal ions type.

Structure – Functionality of lentil protein-polyphenol conjugates

Lentil protein isolate (LPI) was conjugated with plant polyphenols (quercetin, rutin, ellagic acid), and the structural and functional characteristics of the conjugates were determined in comparison with the proteins and pure polyphenols. The interaction between polyphenols and protein was achieved by a grafting method at pH 9.0 in the presence of atmospheric oxygen. Surface plasmon resonance measurements showed polyphenols’ direct interaction with LPI, with the order of binding strength quercetin > ellagic acid > rutin. The degree of conjugation also followed the same order. Structural analysis of the conjugates was performed using FTIR, intrinsic fluorescence, and surface hydrophobicity. A significant improvement in DPPḢ radical scavenging and ferric reducing antioxidant power of the conjugates was observed compared to the polyphenols. However, there was a decrease in the surface activity of the conjugates compared to LPI. Such conjugation provides a novel way to combine the advantages of using plant protein and polyphenols in developing a novel food ingredient.

Influence of Chemically Modified Ultra-High Molecular Weight Polyethylene on the Properties of Butadiene Nitrile Rubber

For the manufacture of frost-resistant oil and petrol-resistant rubber products, one of the most widely used rubbers is nitrile-butadiene rubber (NBR) with a low acrylonitrile content of 17–20 %. However, the technical properties of its vulcanizates do not always meet all high performance requirements. Therefore, the study of the possibility of improving the technical characteristics of vulcanizates based on frost-resistant NBR is an urgent task. This paper presents the results of studying nitrile-butadiene rubber BNKS‑18AMN filled with ultra-high molecular weight polyethylene (UHMWPE). A feature of this work is the study of the possibility of increasing the technical properties of the obtained elastomeric composites by increasing the interaction between chemically inert UHMWPE and BNKS‑18AMN using the chemical modification of UHMWPE. The modification of UHMWPE was carried out by chemical etching in a solution of chromic acid for 3 and 20 hours. A complex of laboratory studies of the obtained samples was carried out. The influence of the duration of chemical etching of UHMWPE on the rheological and vulcanization properties has been studied on the analyzer of the processing of rubber. It is shown that the filling of UHMWPE into BNKS‑18AMN, in general, leads to an increase in the viscosity of the rubber compound. Chemical etching of UHMWPE leads to a decrease in the rate of vulcanization and the density of the three-dimensional spatial structure of the vulcanizate. The study of the physical and mechanical properties in tension, wear resistance during abrasion and swelling in standard hydrocarbon liquid for testing rubbers SZR‑3 showed that chemical etching of UHMWPE leads to a decrease in strength characteristics, but at the same time leads to an increase in resistance to abrasion and has no significant effect on swelling. The study of changes in the properties of samples after heat exposure showed that chemical etching of UHMWPE significantly reduces the resistance to thermal oxidative destruction in the presence of atmospheric oxygen, but does not affect the resistance to thermal aging in the SZR‑3 hydrocarbon environment

Analysis of the blast waves from the explosions of stoichiometric, rich, and lean propane/oxygen mixtures

The blast waves from a series of explosions of stoichiometric, rich, and lean propane/oxygen mixtures have been analysed. The explosive mixtures were contained in hemispherical soap bubbles, 0.05 m in radius, with total masses in the order of 1 g. The blast waves were measured with a series of piezoelectric transducers, flush mounted in the horizontal surface supporting the charges, at various distances from the centres of the explosions. The measured time history of hydrostatic overpressure from each transducer was least-squares-fitted to the modified Friedlander equation to provide the best estimates of the peak hydrostatic overpressure immediately behind the primary shock and the positive phase duration. The times-of-arrival (TOA) of the primary shocks at each gauge location were used to determine the shock Mach numbers as functions of distance, and these values were used in a Rankine–Hugoniot relationship to calculate the peak hydrostatic overpressures, also as functions of distance. For all explosive mixtures, there was excellent agreement between the direct gauge measurements and the values from the TOA analyses. In order to compare the relative strengths of the blast waves from the three mixtures, the measured results were scaled to those for a 1-kg charge using the masses of propane and applying Hopkinson’s cube root scaling. This analysis showed that the blast wave from the lean mixture, for which there was an excess of oxygen, was stronger than that from a stoichiometric mixture, indicating a more efficient detonation. The blast wave from the rich mixture, for which there was a deficiency of oxygen, was weaker than that from the stoichiometric mixture, but gradually strengthened relatively, probably due to the afterburning of the undetonated propane in the presence of atmospheric oxygen. The peak overpressures as functions of distance and the overpressure time histories from the three types of explosive were compared with predictions by a Propane Blast interface and in all cases showed excellent agreement. The interface predictions were based on measurements from a nominal 20-ton propane/oxygen explosion, and the agreement with results from charges with masses of less than 1 g indicates the validity of Hopkinson’s cube root scaling applied to propane/oxygen explosions over a range of charge masses in excess of six orders of magnitude.

Surface photovoltage response of zinc oxide microrods on prismatic planes: effect of UV, temperature and oxygen ambience

In this study, we report the time evaluation of work function measurements on ZnO microrods in Kelvin probe method under photoexcitation, called Surface Photovoltage (SPV). The SPV measurements are one of the most important techniques for characterizing both surface and bulk of the semiconductors. The ZnO microrods synthesized by hydrothermal method are highly crystalline with typical length of 50–100 µm and hexagonal cross section of about 2 µm. Upon drop-casting, most of the rods lie flat on the surface making the basal (002) plane vertical and the prismatic (101) and (100) plane on top. Thus, the SPV measurements are performed on these prismatic planes which are non-polar in nature. The SPV response of microrods has been studied for UV laser of photon energy 3.45 eV which is higher than that of the observed bandgap of 3.3 eV of ZnO microrods. The response is studied in varying oxygen ambience and temperatures. The average work function of the material at room temperature (25 °C) and ambient atmosphere is found to be 4.52 ± 0.3 eV. The work function was found to decrease with increasing temperature and upon photoexcitation. The photovoltage recovery time depicts that the presence of oxygen in atmosphere greatly accelerates the photocurrent recovery through trapping of photo-generated charge carriers by the surface states. The minority carrier diffusion length thus estimated from variable energy photoexcitation is found to be 160 nm.

Acid mine drainage and heavy metals contamination of abandoned and active mine site at Old Repas Dam in Bentong, Pahang, Malaysia

Acid Mine Drainage (AMD) occurs as a result of mining activities during mineral exploration. Interaction of the minerals in the presence of atmospheric oxygen and water produces AMD as an end product. AMD can also be produced by weathering of sulphide minerals through series of process, which includes oxidation and hydrolysis. The main aim of the study is to determine the presence of Acid Mine Drainage (AMD) and contamination of the active and abandoned mining sites with heavy metals in Bentong Pahang. This study deals with the identification of heavy metal toxins traces in water bodies that result in discoloration of the water catchment, downstream of the Old Repas dam. Any discoloration of the water present proves the occurrence of AMD. In order to have better comprehension of the scenario, site reconnaissance and survey is carried. This is to examine the areas affected and thus recognising two different sampling points that have traces of AMD contamination. Water sampling and testing are carried out in the chosen sampling point using four in-situ parameters and five selected heavy metals. The chosen parameters are water pH, dissolved oxygen content, total dissolved solids and ammoniacal nitrogen. The selected heavy metals are Zinc, Lead, Tin, Mercury and Arsenic. Four samples were collected each from two sampling point on two different sampling days. In addition to that, the surface water with sediments was also collected and analysed for the presence of heavy metals. From the results, it was found that the pH of the sampling point was ranging from 5 to 7 indicating the presence of AMD, which is the major finding in this study. Based on the heavy metal analysis, it was found that the concentration of Pb, Sn, Hg, As & Zn was present in greater than the allowable standard limits for treated water by the Malaysian Ministry of Health. This concludes an urgent intervention required to treat the site to prevent any further environmental deterioration.

Interaction and thermal stability of carboxymethyl cellulose on α-Fe2O3(001) surface: ReaxFF molecular dynamics simulations study

Reactive (ReaxFF) molecular dynamic simulations were performed to elucidate the nature of interaction between hematite and carboxymethyl cellulose (CMC) considering effect of moisture and temperature. Simulations showed that the presence of moisture prohibited CMC to interact directly with hematite surface. However, the moisture helps to disperse CMC along the hematite surface thus maximizing the interaction. In dry condition, it was found that the negatively charged oxygen present in the functional groups and in CMC backbone (–CH2OCH2–) take part to form chemical bond with the positively charged surface Fe. The bonding interaction with polymer back bone is a new finding from this simulation. The binding energy estimated as −56.2 kcal/mol clearly indicates chemisorption with bond length ∼2.00 Å. Upon heating up the complex in presence of atmospheric oxygen it was observed that CMC decomposed at high temperature rather than desorbed from the surface. This study clearly shows that CMC is a suitable binder for iron ore pelletization and will pave the way for more rationale design of organic binders.

Novel ZnSQDs-SnO2/g-C3N4 nanocomposite with enhanced photocatalytic performance for the degradation of different organic pollutants in aqueous suspension under visible light

We report the synthesis of ZnS quantum dots (ZnSQDs)–SnO2/graphitic C3N4 (g-C3N4) ternary nanocomposites with different mass ratios via solid-state calcination of a mixture of 10 wt% ZnSQDs–SnO2 and g-C3N4. The proposed solid-state procedure does not require any solvent and offers a general route to synthesize composite materials on a large scale. The synthesized products were carefully characterized by traditional analytical techniques such as Fourier transform IR spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the nanocomposites was assessed by our studying the degradation of two different chromophoric dyes (rhodamine B and methylene blue) and a colorless pollutant (paracetamol) in aqueous suspension under visible light in the presence of atmospheric oxygen. Among the series of synthesized samples, 7 wt% ZnSQDs–SnO2/g-C3N4 showed significantly improved photocatalytic performance in comparison with the other photocatalysts. In addition, adsorption of dyes onto the surface of the synthesized nanocomposite was studied with different catalyst amounts and time intervals. Moreover, the synthesized material also mineralizes paracetamol, which was measured in terms of depletion of total organic carbon content as a function of time. The remarkable increased photocatalytic efficiency of the synthesized materials could be related to the synergistic interaction between ZnSQDs, SnO2, and g-C3N4 leading to photoseparated electron and hole pairs. The main reactive species involved in the degradation process were determined by our performing quenching experiments with electron donors and acceptors, and a possible mechanistic pathway for the degradation process is proposed.

Development of homogeneous polyamine organocatalyst for the synthesis of 2‐aryl‐substituted benzimidazole and benzoxazole derivatives

AbstractA new polyamine was prepared by the ring opening polymerization of epichlorohydrin and properly characterized. The catalytic property of the prepared polymer was assessed by synthesizing 2‐aryl‐substituted benzimidazole and benzoxazole derivatives by the conjugation of o‐phenylenediamine/o‐aminophenol with various aromatic aldehydes in the presence of atmospheric oxygen. Significant attributes of the present synthesis include short reaction time, good to excellent yield, high purity, easy reusability, and room temperature reaction. The reaction was carried out in the absence of any metal catalyst and other cooxidants.