Mixture Of Nitrate Research Articles

SUBSTITUTED AMINOCHALCONES AS STARTING COMPOUNDS FOR RECEIVING NEW 1,4-BENZODIAZEPINES DERIVATIVES

The aim of this work is the synthesis of a number of substituted E‑1-(2-amino‑5-R1-phenyl)-3-(4-R2-phenyl)prop‑2-en‑1-ones (2-aminochalcones) as precursors for obtaining new derivatives of 7-R1–5-[2-R2-phenylvinyl]-1,4-benzodiazepin‑2-ones. Starting 5-substituted 2-aminoacetophenones with bromo and nitro group were synthesized from 2-aminoacetophenone by bromination of the latter with N‑bromosuccinimide in acetonitrile and nitration of 2-acetaminoacetophenone with a nitrating mixture followed by removal of acetyl protection. 2-Aminochalcones were synthesized according to standard methods during the interaction of a number of 5-substituted 2-aminoacetophenones with para-substituted benzaldehydes under basic catalysis conditions. The target products turned out to be brightly colored compounds with low melting points, their isolation and purification did not cause any difficulties. According to the data of 1H NMR spectroscopy, all synthesized 2-aminochalcones were individual trans isomers, which was also confirmed by X‑ray structural analysis of one of the obtained 2-aminochalcones. A number of new substituted E‑1-(2-amino‑5R1-phenyl)-3-(4-R2-phenylprop‑2-en‑1-ones) were synthesized – compounds with amino and ketofunctions and are precursors for obtaining of a new series of 5-substituted 1,4-benzodiazepines with various arylvinyl groups. 2-aminoacetophenone, 2-amino‑5-bromoacetophenone, and 2-amino‑5-nitroacetophenone were selected as substrates for this series. The methyl groups of these acetophenones were condensed according to Claisen-Schmidt with parasubstituted benzaldehydes. Condensation was carried out under alkaline conditions in an aqueous solution. Yields of aminochalcones reached 60–85%. The methyl group of 2-aminoacetophenones smoothly reacted with aromatic aldehydes to form the corresponding 2-aminophenylchalcones. The structure of the obtained compounds was confirmed by mass spectrometry and 1H NMR spectroscopy. The structure of one of the chalcones was proved by X‑ray structural analysis. The obtained compounds can be used for the synthesis of 1,4-benzodiazepines with 5-arylvinyl substituents.

Эффективность применения азотных удобрений при возделывании озимой пшеницы по предшественнику подсолнечник

Abstract. The current paper has presented the results of applying various terms and types of nitrogen additional fertilizing in the cultivation of winter bread wheat. The purpose of the study was to establish the productivity and grain quality of winter bread wheat sown after sunflower, when using nitrogen additional fertilizing. Ammophos and ammonium sulfate were applied under seedbed cultivation; ammonium nitrate, urea and carbamide-ammonia mixture were used as additional fertilizing at different periods of active winter wheat vegetation. Methods. The research was conducted at the Agricultural Research Center “Donskoy” in 2017–2019. When laying and conducting the experiment, taking into account the yield, generally accepted methods were used; the technology of winter wheat cultivation and the dose of nitrogen fertilizing corresponds to the Zonal farming systems of the Rostov region. Scientific novelty. For the first time there have been determined the best terms, methods and doses of nitrogen additional fertilizing with various types of fertilizers for winter bread wheat in the southern part of the Rostov region. Results. There was established a significant effect of the terms of nitrogen fertilizing on productivity, as well as on winter wheat quality. Portioned application of ammonium nitrate at a dose of N90 contributed to obtaining the maximum productivity of 6.15 t/ha in the trial, and productivity increase in comparison with the control variant was 2.34 t/ha or 61.4%. In other variants of the trial, productivity increase due to the use of nitrogen fertilizers ranged from 0.90 to 2.26 t/ha. Autumn application of ammonium sulfate at a dose of N30 under seedbed cultivation was an effective agricultural method that contributed to an additional productivity improvement on 0.55–0.64 t/ha. The high efficiency of nitrogen additional fertilizing was due to an improvement of the indicators of yield structure elements, namely, ‘kernel weight per head’ and ‘number of productive stems’. Nitrogen additional fertilizing improved qualitative characteristics of the product. There has been found out that under a portioned application of ammonium nitrate at a dose of N90, there were yielded the highest economic indicators, such as 30117 rubles/ha of conditional net income and 112.9 % of production profitability.

Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry

Abstract. Aircraft-borne in situ measurements of the chemical aerosol composition were conducted in the Asian tropopause aerosol layer (ATAL) over the Indian subcontinent in the summer of 2017, covering particle sizes below ∼3 µm. We have implemented a recently developed aerosol mass spectrometer, which adopts the laser desorption technique as well as the thermal desorption method for quantitative bulk information (i.e., a modified Aerodyne AMS), aboard the high-altitude research aircraft M-55 Geophysica. The instrument was deployed in July and August 2017 during the StratoClim EU campaign (Stratospheric and upper tropospheric processes for better Climate predictions) over Nepal, India, Bangladesh, and the Bay of Bengal, covering altitudes up to 20 kma.s.l. For particles with diameters between 10 nm and ∼3 µm, the vertical profiles of aerosol number densities from the eight research flights show significant enhancements in the altitude range of the ATAL. We observed enhancements in the mass concentrations of particulate nitrate, ammonium, and organics in a similar altitude range between approximately 13 and 18 km (corresponding to 360 and 410 K potential temperature). By means of the two aerosol mass spectrometry techniques, we show that the particles in the ATAL mainly consist of ammonium nitrate (AN) and organics. The single-particle analysis from laser desorption and ionization mass spectrometry revealed that a significant particle fraction (up to 70 % of all analyzed particles by number) within the ATAL results from the conversion of inorganic and organic gas-phase precursors, rather than from the uplift of primary particles from below. This can be inferred from the fact that the majority of the particles encountered in the ATAL consisted solely of secondary substances, namely an internal mixture of nitrate, ammonium, sulfate, and organic matter. These particles are externally mixed with particles containing primary components as well. The single-particle analysis suggests that the organic matter within the ATAL and in the lower stratosphere (even above 420 K) can partly be identified as organosulfates (OS), in particular glycolic acid sulfate, which are known as components indicative for secondary organic aerosol (SOA) formation. Additionally, the secondary particles are smaller in size compared to those containing primary components (mainly potassium, metals, and elemental carbon). The analysis of particulate organics with the thermal desorption method shows that the degree of oxidation for particles observed in the ATAL is consistent with expectations about secondary organics that were subject to photochemical processing and aging. We found that organic aerosol was less oxidized in lower regions of the ATAL (<380 K) compared to higher altitudes (here 390–420 K). These results suggest that particles formed in the lower ATAL are uplifted by prevailing diabatic heating processes and thereby subject to extensive oxidative aging. Thus, our observations are consistent with the concept of precursor gases being emitted from regional ground sources, subjected to rapid convective uplift, and followed by secondary particle formation and growth in the upper troposphere within the confinement of the Asian monsoon anticyclone (AMA). As a consequence, the chemical composition of these particles largely differs from the aerosol in the lower stratospheric background and the Junge layer.

Cleaning the Label of Cured Meat; Effect of the Replacement of Nitrates/Nitrites on Nutrients Bioaccessibility, Peptides Formation, and Cellular Toxicity of In Vitro Digested Salami.

Curing salts composed of mixtures of nitrates and nitrites are preservatives widely used in processed meats. Despite many desirable technological effects, their use in meat products has been linked to methemoglobinemia and the formation of nitrosamines. Therefore, an increasing “anti-nitrite feeling” has grown among meat consumers, who search for clean label products. In this view, the use of natural compounds as alternatives represents a challenge for the meat industry. Processing (including formulation and fermentation) induces chemical or physical changes of food matrix that can modify the bioaccessibility of nutrients and the formation of peptides, impacting on the real nutritional value of food. In this study we investigated the effect of nitrate/nitrite replacement with a combination of polyphenols, ascorbate, and nitrate-reducing microbial starter cultures on the bioaccessibility of fatty acids, the hydrolysis of proteins and the release of bioactive peptides after in vitro digestion. Moreover, digested salami formulations were investigated for their impacts on cell proliferation and genotoxicity in the human intestinal cellular model (HT-29 cell line). The results indicated that a replacement of synthetic nitrates/nitrites with natural additives can represent a promising strategy to develop innovative “clean label” salamis without negatively affecting their nutritional value.

Neonicotinoid pesticide and nitrate mixture removal and persistence in floating treatment wetlands.

Mesocosm and microcosm experiments were conducted to explore the applicability of floating treatment wetlands (FTWs), an ecologically based management technology, to remove neonicotinoid insecticides and nitrate from surface water. The mesocosm experiment evaluated three treatments in triplicate over a 21-d period. Floating treatment wetland mesocosms completely removed nitrate-N over the course of the experiment even when neonicotinoid insecticides were present. At the completion of the experiment, 79.6% of imidacloprid and degradation byproducts and 68.3% of thiamethoxam and degradation byproducts were accounted for in the water column. Approximately 3% of imidacloprid and degradation byproducts and 5.0% of thiamethoxam and degradation byproducts were observed in above-surface biomass, while ∼24% of imidacloprid and degradation byproducts, particularly desnitro imidacloprid, and<0.1% of thiamethoxam and degradation byproducts were found in the below surface biomass. Further, 1 yr after the experiments, imidacloprid, thiamethoxam, and degradation byproducts persisted in biomass but at lower concentrations in both the above- and below-surface biomass. Comparing the microbial communities of mature FTWs grown in the presence and absence of neonicotinoids, water column samples had similar low abundances of nitrifying Archaeal and bacterial amoA genes (below detection to 104 ml-1 ) and denitrifying bacterial nirK, nirS, and nosZ genes (below detection to 105 ml-1 ). Follow-up laboratory incubations found the highest denitrification potential activities in FTW plant roots compared with water column samples, and there was no effect of neonicotinoid addition (100 ng L-1 ) on potential denitrification activity. Based on these findings, (a) FTWs remove neonicotinoids from surface water through biomass incorporation, (b) neonicotinoids persist in biomass long-term(>1 yr after exposure), and (c) neonicotinoids do not adversely affect nitrate-N removal via microbial denitrification.

Influence of Nitrate Species A(NO&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; on Physico-Mechanical Properties of the Aluminosilicate Adhesives for Wooden Structure

The article presents the results of studies of the positive effect of compounds of the type A(NO3)2, as modifiers of the aluminosilicate adhesive of the composition Na2O∙Al2O∙6SiO2∙20H2O, on increasing the strength of adhesive joints of wood of various species. The grade strength increases 1.39 times compared to the strength of the adhesive that does not contain these compounds. According to the degree of influence on the shear strength along the fibers, the additives can be ranked in the series Ba (NO3)2 &gt; Ca (NO3)2 &gt; Mg (NO3)2 &gt; 95%Ca (NO3)2+5%NH4NO3. It is noted that for gluing samples from a pine substrate, it is advisable to add magnesium and barium nitrates to the aluminosilicate glue in an amount of 1% (by weight); beech wood - calcium and barium nitrates in the amount of 1 and 0.5% (by weight); oak wood - calcium nitrates in an amount of 1% (by mass), a mixture of nitrates in an amount of 0.5% (by mass) and barium nitrate in an amount of 0.5 and 1.5% (by mass). According to the influence on the strength of adhesive joints, the substrates can be ranked in the order beech &gt; oak &gt; pine. Further studies will present the results of the effect of alkaline earth metal nitrates on the deformation properties of adhesive joints and on rheokinetic and colloid-chemical properties.

Associations of thiocyanate, nitrate, and perchlorate exposure with dyslipidemia: a cross-sectional, population-based analysis.

The aim of this study was to assess the associations of urinary thiocyanate, nitrate, and perchlorate concentrations with dyslipidemia, individually and in combination, which has not previously been studied. Data from the 2001-2002 and 2005-2016 National Health and Nutrition Examination Surveys (NHANES) were analyzed in this cross-sectional study. The dependent variables were continuous serum lipid variables (triglycerides [TG], total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], non-HDL-C, and apolipoprotein B [Apo B]) and binary serum lipid variables, with the latter reflecting dyslipidemia (elevated TG, ≥ 150mg/dL; elevated TC, ≥ 200mg/dL; elevated LDL-C, ≥ 130mg/dL; lowered HDL-C, < 40mg/dL in men and < 50mg/dL in women; elevated non-HDL-C, ≥ 160mg/dL; and elevated Apo B, ≥ 130mg/dL). Multivariate logistic, linear, and weighted quantile sum (WQS) regression analyses were used to explore the associations of thiocyanate, nitrate, and perchlorate with the continuous and binary serum lipid variables. The linearity of the associations with the binary serum lipid variables was assessed using restricted cubic spline (RCS) regression. A total of 15,563 adults were included in the analysis. The multivariate linear and logistic regression analyses showed that thiocyanate was positively associated with multiple continuous (TG, TC, LDL-C, non-HDL-C, and Apo B, but not HDL-C) and binary (elevated TG, TC, LDL-C, and non-HDL-C) serum lipid variables, whereas perchlorate was negatively associated with elevated LDL-C. Multivariate RCS logistic regression revealed a linear dose-response relationship between thiocyanate and elevated TG, TC, LDL-C, non-HDL-C, and Apo B, but a nonlinear relationship with lowered HDL-C (inflection point = 1.622mg/L). WQS regression showed that a mixture of thiocyanate, nitrate, and perchlorate was positively associated with all binary serum lipid variables except for Apo B. Our findings indicate that urinary thiocyanate, nitrate, and perchlorate concentrations, individually and in combination, were associated with dyslipidemia.

A comprehensive study on hygroscopic behaviour and nitrate depletion of NaNO3 and dicarboxylic acid mixtures: implications for nitrate depletion in tropospheric aerosols

Abstract. The nitrate depletion and HNO3 release in internally mixed nitrate and dicarboxylic acid (DCA) particles have been widely detected in field and laboratory studies. Nevertheless, considerable discrepancies are still present among these measurements, and the influencing factors for this acid-displacement reaction have not yet been elucidated. In this work, the hygroscopic growth and chemical composition evolution of mixtures of NaNO3 and DCAs, i.e. oxalic acid (OA), malonic acid (MA), and glutaric acid (GA), were measured using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and vacuum FTIR techniques. The nitrate depletion from NaNO3–OA mixtures was observed in both the measurements, owing to the relatively higher acidity of OA compared to MA and GA. At the same time, the NaNO3 phase state was found to act as a key regulator of nitrate depletion. Amorphous NaNO3 solids at relative humidity (RH) &lt;5 % were inert to liquid OA. With increasing RH, the mixtures experienced three interesting stages of phase changes showing different HNO3 release rates; e.g. at around 15 % RH, the slow HNO3 release was detected by the vacuum IR spectra, potentially indicating the transformation of amorphous solids to semisolid NaNO3. In the second stage (sudden RH increase from ∼15 % to 61 %), the HNO3 release rate was increased by about an order of magnitude. When NaNO3 deliquescence occurred in the third stage, this displacement reaction proceeded due to more available NO3- ion formation. Compared to OA, MA and GA reacted with nitrate only in vacuum FTIR measurement, while in ATR-FTIR measurement, the mixtures tended to be effloresced completely without nitrate depletion. Further, the influences of ambient pressure, chemical composition, and water activity on HNO3 release rates were estimated via Maxwell steady-state diffusive mass transfer equation. The results showed that weaker acidity of MA and GA as well as relatively lower HNO3 diffusion rate in the ambient gas phase mainly contributed to the unobserved nitrate depletion in ATR-FTIR measurement. Our findings reveal that chemical component, phase state, and water activity of particles, as well as HNO3 gas-phase diffusion, play crucial roles in HNO3 release from nitrate and DCA mixtures. This work may provide a new perspective on nitrate depletion in the ageing processes during transport of tropospheric aerosols.

Urea-modified Cu-based materials: Highly efficient and support-free adsorbents for removal of H2S in an anaerobic and dry environment

In this work, we report a novel urea-modified copper-based material (XUrea@Cu) obtained by directly calcinating a mixture of urea and copper nitrate. This material enables the efficient purification of H2S under dry and anaerobic conditions. The performance test results showed that the H2S capacity of the optimal adsorbent (2Urea@Cu) could reach 364.2 mg(H2S)∙gsorbent-1, which is much superior to those of other adsorbents in the literature. Further study demonstrates that the ultra-desulfurization performance of 2Urea@Cu is mainly attributed to the extensive alkaline site, the high concentrations of active oxygen, and the abundance of oxygen vacancy; which are quite effective for capturing H2S (acidic and strong reducibility). Interestingly, the deactivation adsorbent (De-2Urea@Cu) is mainly composed of high-purity CuS, which means that the Urea@Cu adsorbent can simultaneously achieve efficient purification of H2S and recovery of sulfur resources since CuS is a valuable product. In addition, in-situ FT-IR and theoretical calculation results indicate that H2S molecules dissociate on the CuO(111) surface by stepwise dehydrogenation, while S combines with adjacent Cu to form CuS. The consumption of active components (CuO) and the accumulation of reaction products (CuS) are the primary reasons for the deactivation of adsorbents. Considering the simple preparation process, low cost, and excellent H2S adsorption activity, these urea-modified copper-based materials are very promising H2S adsorbents.

Zn(II)-formate Framework of mab topology: Synthesis from tea extract, electronic structure, and DNA-binding

A new synthetic method for developing novel Metal Organic Frameworks(MOFs) of Zn(II) is reported here. Its formation is confirmed by single X-ray crystallography, FT-IR and UV-visible spectroscopy measurement. The polymeric (ZnC2H6O6)n (1) complex was synthesized from a mixture of tea extract, LiCl and zinc nitrate in DMF-Dioxane-H2O solvent. In contrast to the well-known perovskite-type Zn(II)-formate frameworks of pcu topology the resulting compound has topology of different 6-c net mab. Herein we studied the relations between structural characteristics of the less usual mab-type formate and properties. The origin of the formation of formate is not established but may form via the hydrolysis of DMF molecules. The oxidation state of Zn in the complex was +2 and confirmed by BVS calculation. The optical band gap of the polymeric complex was 5.2eV indicates its electronic properties. Density Function Theory (DFT) also justified the structural and electronic parameters of the complex. The bioactivity of the complex 1 has been established by the ability to bind CT-DNA with intercalation mode and the binding constant was Kb =1.74 × 102 M−1.

Influence of Chloride and Nitrate Anions on Copper Electrodeposition onto Au(111) from Deep Eutectic Solvents

AbstractCopper electrodeposition on Au(111) from deep eutectic solvents (DESs) type III was investigated employing cyclic voltammetry as well as chronoamperometry. It was further examined on Au(poly) using the electrochemical quartz crystal microbalance (EQCM). The employed DESs are mixtures of choline chloride (ChCl) or choline nitrate (ChNO3) with ethylene glycol (EG) as hydrogen bond donor (HBD), each in a molar ratio of 1 : 2. CuCl, CuCl2, or Cu(NO3)2 ⋅ 3H2O were added as copper sources. Underpotential deposition (UPD) of Cu precedes bulk deposition in chloride as well as nitrate electrolytes. Cu deposition from Cu+ in chloride media is observed as a one‐electron reaction, whereas deposition from Cu2+ occurs in two steps since Cu+ is strongly stabilized by chloride. Cu+ is less stabilized by nitrate and the beginning of bulk deposition in the nitrate‐containing DES with Cu2+ is shifted by several hundred mV to more positive potentials compared to the chloride DES. A diffusion‐controlled, three‐dimensional nucleation and growth mechanism is found by chronoamperometric measurements and analysis based on the model of Scharifker and Mostany.

Thermal energy storage system with a high-temperature nanoparticle enhanced phase change material: Charging and discharging characteristics upon integration with process preheating

Nanoparticle enhanced Phase Change Materials (NePCMs) are modified forms of phase change materials containing nanoparticles such that the thermophysical properties are improved. Solar salt, a phase change material comprising a eutectic mixture of sodium nitrate and potassium nitrate has a thermal conductivity in the range of 0.5–1 W/m K and the addition of nanoparticles to solar salt (nanoparticle enhanced solar salt) has been demonstrated to improve its thermophysical properties. This work evaluates the charging and discharging characteristics of solar salt and nanoparticle enhanced solar salt, with copper nanoparticles (at 0.5 wt%) and reduced Graphene Oxide nanostructures (at 0.5 wt%) individually as additives. Experiments were performed simulating a thermal energy storage system (TES) for process preheating. Silicone oil and Therminol® 55 were used as heat transfer fluids during charging and discharging cycles respectively. The overall heat transfer coefficients of TES containing copper nanoparticle enhanced solar salt and reduced Graphene Oxide nanostructure enhanced solar salt as an energy storage medium were greater than that containing solar salt during both charging and discharging cycles. The enhancements in overall heat transfer coefficients were due to respective enhancements in PCM side heat transfer coefficients caused by thermal conductivity and specific heat increase brought about by the addition of copper nanoparticles/reduced Graphene Oxide nanostructures to solar salt. Considering >10 % enhancements in overall heat transfer coefficient in both charging and discharging cycles with these two NePCMs, latent heat thermal energy storage systems employing them as phase change material will be suitable for integration with a process preheating application.

Microstructure and improved fracture toughness of borosilicate glass reinforced by 1 vol% Ag nanoparticles

Silver (Ag) nanoparticles (1 vol%) were successfully incorporated into borosilicate glass by spark plasma sintering of powder mixtures of borosilicate glass and silver nitrate. Finer glass powder as the starting material led to the coarsening of Ag nanoparticles in the sintered sample, while starting with coarse glass powder led to a high concentration of Ag nanoparticle precipitates at the original interface. The fracture toughness was enhanced by incorporating Ag nanoparticles. The toughness values of the samples starting from coarse and fine glass powders were 1.76 (1.9-fold increase) and 1.31 MPa m1/2 (1.4-fold increase), respectively. The precipitation of Ag nanoparticles in a large number density in a narrow area of the interface results in significant crack deflection and crack bridging, and thus greater toughness improvement by starting with coarse glass powder.

Innovative Earth-Friendly UV-Spectrophotometric Technique for In Vitro Dissolution Testing of Miconazole Nitrate and Nystatin in Their Vaginal Suppositories: Greenness Assessment.

The combined mixture of miconazole nitrate (MIC) and nystatin (NYS) has proven its efficiency as a prodigious remedy to cure women's frequent infections: vaginal mycosis and vaginal candidiasis. A novel green spectrophotometric technique, namely the Fourier self-deconvolution method (FSD), was employed for the quantitative determination of MIC and NYS in their pure and pharmaceutical forms without prior separation. Moreover, the proposed technique was first employed to study the dissolution profile of the cited drugs in their pharmaceutical formulation according to FDA recommendations without excipient interference. The FSD method is based on a simple mathematical manipulation of zero-order spectra of the cited drugs, which suffered from severe overlapping, so zero-order spectra of the cited drugs were deconvoluted using the Fourier wavelet function in spectrophotometer software. The deconvoluted amplitudes for MIC and NYS were measured at 255 nm and 320 nm, respectively. Linearity ranges were 70-700 µg/mL for MIC and 1-25 µg/mL for NYS. The greenness of the proposed technique was assessed using two assessment tools, namely eco-scale scoring and green analytical procedure index (GAPI), revealing the excellent greenness of this technique. The proposed technique was validated consistent with ICH guidelines and statistically compared to the reported method with no significant differences between them. The proposed technique has advantages of being simple, time-saving, and noting need any modification to be suitable for quantitative analysis of MIC and NYS in both pharmaceutical and laboratory mixtures. An innovative FSD method was developed for quantitative analysis of MIC and NYS in their synthetic and pharmaceutical mixtures and applied for in vitro dissolution testing of their pharmaceutical mixture, producing satisfactory results.

Green Synthesis of Silver Nanoparticles Using Aqueous Citrus limon Zest Extract: Characterization and Evaluation of Their Antioxidant and Antimicrobial Properties.

The current work concentrated on the green synthesis of silver nanoparticles (AgNPs) through the use of aqueous Citrus limon zest extract, optimizing the different experimental factors required for the formation and stability of AgNPs. The preparation of nanoparticles was confirmed by the observation of the color change of the mixture of silver nitrate, after the addition of the plant extract, from yellow to a reddish-brown colloidal suspension and was established by detecting the surface plasmon resonance band at 535.5 nm, utilizing UV-Visible analysis. The optimum conditions were found to be 1 mM of silver nitrate concentration, a 1:9 ratio extract of the mixture, and a 4 h incubation period. Fourier transform infrared spectroscopy spectrum indicated that the phytochemicals compounds present in Citrus limon zest extract had a fundamental effect on the production of AgNPs as a bio-reducing agent. The morphology, size, and elemental composition of AgNPs were investigated by zeta potential (ZP), dynamic light scattering (DLS), SEM, EDX, X-ray diffraction (XRD), and transmission electron microscopy (TEM) analysis, which showed crystalline spherical silver nanoparticles. In addition, the antimicrobial and antioxidant properties of this bioactive silver nanoparticle were also investigated. The AgNPs showed excellent antibacterial activity against one Gram-negative pathogens bacteria, Escherichia coli, and one Gram-positive bacteria, Staphylococcus aureus, as well as antifungal activity against Candida albicans. The obtained results indicate that the antioxidant activity of this nanoparticle is significant. This bioactive silver nanoparticle can be used in biomedical and pharmacological fields.

Removal of Cr(VI) by a simply prepared biochar‐supported nanoscale zero‐valent iron

AbstractBACKGROUNDCr(VI) is highly migratory and toxic, and long‐term exposure to Cr(VI) is likely to cause cancer, teratogenesis and mutagenicity. Therefore, the removal of Cr(VI) in polluted wastewater is the key to ensure the safety of water quality. In this study, a composite material consisting of nanoscale zero‐valent iron (NZVI) particles supported on biochar derived from starch (NZVI/BC) was prepared via carbonizing the mixture of starch and ferric nitrate in inert gas and used for removal of Cr(VI) from solution. The effects of NZVI/BC dosage, initial pH and reaction temperature on the removal efficiency of Cr(VI) were investigated.RESULTSThe results revealed that H2 and CH4 originating from the decomposition of starch acted as reducing agents for in situ generation of NZVI from Fe precursors. The removal efficiency of Cr(VI) was strongly dependent on dosage, pH and reaction temperature. Higher dosage, lower pH value and higher temperature led to an increase in Cr(VI) removal efficiency. Pseudo‐second‐order kinetics was suitable to describe the process of Cr(VI) removal by NZVI/BC.CONCLUSIONSNZVI/BC could be a potential and effective material for removal of Cr(VI) from solution. © 2022 Society of Chemical Industry (SCI).

Facile synthesis of amino acids-derived Fe/N-codoped reduced graphene oxide for enhanced ORR electrocatalyst

A simple and green method for preparing Fe/N-codoped reduced graphene oxide nanosheets with high ORR and Zinc-air battery performance is presented. • 3D porous Fe/N-codoped reduced graphene oxide materials are prepared via a simple thermal drying and pyrolysis process. • Aspartic acid is introduced as an environment-friendly nitrogen and carbon source. • Iron nitrate serves as the pore forming agent and gas producer that prevent the agglomeration of graphene. • The optimized Fe-N-C/NG-3 material exhibits excellent ORR activity and applied to Zn-air battery. Here, a simple and green synthesis process of Fe/N-codoped reduced graphene oxide (Fe-N-C/NG) with high electrocatalytic activity for oxygen reduction reaction (ORR) is reported. The synthesis of 3D porous structure of Fe-N-C/NG composites involves thermal drying the mixture of graphene oxide (GO), iron nitrate and aspartic acid (Asp) directly, follow by pyrolysis the mixture. The Asp is introduced as an environment-friendly nitrogen and carbon source, and the iron nitrate serves as the pore-forming agent and a gas producer that prevents the agglomeration of graphene. The as-prepared Fe-N-C/NG exhibits 3D loose porous structure with larger specific surface area (245 m 2 g - 1 ). The Fe-NC/NG composite exhibits the onset potential of 0.91 V, a half-wave potential (E 1/2 = 0.83 V), low Tafel slope and four-electron selectivity (n = 3.99) in alkaline solution. Furthermore, the stability test manifests the outstanding stability of Fe-NC/NG electrocatalyst and a superior methanol tolerance than Pt/C electrodes. Particularly, when the prepared Fe-NC/NG-3 catalyst is used as an air electrode catalyst in an assembled Zn-air battery, it exhibits a high specific capacity of 848.2 mAh g Zn -1 and displays more stability than Pt/C. This work provides an effective strategy for preparing high ORR and Zn-air battery performance Fe/N-codoped reduced graphene oxide materials.

Photocatalytic properties of Ag-AgBr nanostructures in ion-exchanged layers of bromide sodium-zinc-aluminosilicate glass matrix

The photocatalytic properties of Ag–AgBr nanostructures formed by low-temperature ion exchange method and followed heat-treatment in bromide sodium-zinc-aluminosilicate glass have been investigated. Glasses based on Na2O–ZnO–Al2O3–SiO2 system and doped with Sb2O3, Ce2О3 and Br were synthesized. Layers containing silver ions were formed on the surface of sodium-zinc-aluminosilicate glass by the ion exchange method. The glass samples were immersed in a bath containing a melt of nitrate mixture 5AgNO3/95NaNO3 (mol%) at 320 °C for 2 hours. Subsequent heat treatment at 500 °C resulted in a formation of Ag–AgBr nanostructures in the surface layer. The photocatalytic properties of the Ag–AgBr nanostructures on the glass surface were measured by the decomposition of the methyl orange dye. A comprehensive study of the spectral and photocatalytic properties of Ag–AgBr nanostructures has been carried out. It was shown that, after ion exchange and heat treatment, the AgBr crystal shells with a size of 6 nm were formed around silver nanoparticles. It has been established that the presence of a photocatalyst with Ag–AgBr nanostructures in the surface layer of glass under ultraviolet irradiation leads to degradation of the methyl orange dye by 77 %. Reducing the thickness of the ion-exchange layer to 5 μm by chemical etching decreased the degradation efficiency of the methyl orange dye to 15 %. The results of the work can be applied in devices for the photocatalytic decomposition of water to produce hydrogen.

Cobalt-Containing Nitrogen-Doped Carbon Materials Derived from Saccharides as Efficient Electrocatalysts for Oxygen Reduction Reaction

The development of non-precious metal electrocatalysts towards oxygen reduction reaction (ORR) is crucial for the commercialisation of polymer electrolyte fuel cells. In this work, cobalt-containing nitrogen-doped porous carbon materials were prepared by a pyrolysis of mixtures of saccharides, cobalt nitrate and dicyandiamide, which acts as a precursor for reactive carbon nitride template and a nitrogen source. The rotating disk electrode (RDE) experiments in 0.1 M KOH solution showed that the glucose-derived material with optimised cobalt content had excellent ORR activity, which was comparable to that of 20 wt% Pt/C catalyst. In addition, the catalyst exhibited high tolerance to methanol, good stability in short-time potential cycling test and low peroxide yield. The materials derived from xylan, xylose and cyclodextrin displayed similar activities, indicating that various saccharides can be used as inexpensive and sustainable precursors to synthesise active catalyst materials for anion exchange membrane fuel cells.

Using choline nitrate as solvent and oxidant in direct oxidation of organic halides and alcohols to aldehyde and its derivatives

Choline nitrate is prepared by the anion exchange of choline chloride and sodium nitrate. Also, choline chloride gives a low melting point mixture in the presence of aluminum nitrate. The use of choline nitrate as a safe and environmentally friendly solvent and reactant provides an efficient procedure, simple and mild for oxidizing alcohols and organic halides to aldehydes. Aldehydes using choline nitrate and trimethylsilyl chloride mixture as a selective oxidant and without using catalysts were synthesized from alcohols and the relevant halides. Benzyl chloride in the presence of choline nitrate and trimethylsilyl chloride at 70 °C produced the corresponding aldehyde product with 87% efficiency, while benzyl alcohol at 50 °C with 90% efficiency performed this conversion.The prepared aldehyde is easily separated from the reaction medium by vacuum distillation or extraction by organic solvent without the need for further purification.