Presence Of Precursors Research Articles

The influence of the precursor type in the synthesis of Mg/Al-hydrotalcite through a non-traditional method used for Claisen-Shmidt condensation

Traditionally, the synthesis of MgAl-hydrotalcite is performed in the presence of inorganic alkalis-type precipitating agents using the co-precipitation method. As an viable alternative, the use of organic alkalis and the mechanochemical method can remove some of the issues that the traditional route generates, i.e. the possibility of final solid contamination with alkaline cations; a high energy consumption, relative to the amount of water used but also of electric current; the involvement of a large number of utensils necessary for the synthesis; time allocated to the solid preparation; etc. Changing the regular precursor type (i.e. nitrate) of the target cation with chloride or sulfate leads to obtaining hydrotalcites which have different basicities. The chlorides precursors lead to the synthesis of materials that show a better ability for the reconstruction of the layered structure. Moreover, TMAH acts both as a synthesis agent and as a templating agent. The tight pore distribution is characteristic of all materials obtained from chloride precursors, where the co-precipitation method generates pores of 97Å, while the mechanochemical method generates pores of 140Å. The material with the highest catalytic activity for Claisen-Schmidt condensation, conversion of 92%, is the one obtained by calcination of the hydrotalcite prepared from chloride precursors by the mechanochemical method, while the co-precipitation method leads to conversions of 90%. The novelty of this work is that these type of catalysts obtained from chlorides or sulfate precursors in presence of TMAH have not been used in Claisen-Schmidt condensation until now.

Systematic Literature Review on Ozone Dispersion Correlated with Diurnal Concentration Pattern in Urban and Rural Areas


 
 
 Ground level ozone is known to exhibit a strong daily variation of concentration leading to long-range transport of air pollutants from urban to rural areas. Moreover, the characteristics of O3 relationship between urban, suburban, and rural sites can be explained by O3 photochemical chemistry and meteorological dispersions as indicated by the different result of O3 diurnal pattern. However, little is known about the global phenomenon of diurnal concentration of ozone, meteorological dispersion such as long-range transport, and their correlation with ozone precursors, especially in urban and rural areas. This paper attempt to compare the difference between daily ozone fluctuations in both sites and assess some factors that cause long-range ozone transport from urban and rural areas both in subtropical and tropical areas for global scale. Using systematic literature review analysis with the PRISMA method, it examined 43 peer-reviewed articles published between 2010 and 2022 globally meeting the inclusion criteria. The result showed that the fluctuation patterns of daytime ozone in urban and rural areas are different to those in tropical and subtropical regions, depending on latitude. This was primarily due to the influence of solar radiation and the presence of precursors. Conversely, a slight decrease in ozone rate at night occurs because the precursor was accumulated by the shutdown of photochemical ozone production. Some precursors of ozone from other regions can be transported and accumulated from the long-range transport process in other locations. This paper serves as an initial guideline to analysing the pattern of ozone concentration in urban and rural areas and the factors that influence it.
 
 

Systematic Literature Review on Ozone Dispersion Correlated with Diurnal Concentration Pattern in Urban and Rural Areas


 
 
 Ground level ozone is known to exhibit a strong daily variation of concentration leading to long-range transport of air pollutants from urban to rural areas. Moreover, the characteristics of O3 relationship between urban, suburban, and rural sites can be explained by O3 photochemical chemistry and meteorological dispersions as indicated by the different result of O3 diurnal pattern. However, little is known about the global phenomenon of diurnal concentration of ozone, meteorological dispersion such as long-range transport, and their correlation with ozone precursors, especially in urban and rural areas. This paper attempt to compare the difference between daily ozone fluctuations in both sites and assess some factors that cause long-range ozone transport from urban and rural areas both in subtropical and tropical areas for global scale. Using systematic literature review analysis with the PRISMA method, it examined 43 peer-reviewed articles published between 2010 and 2022 globally meeting the inclusion criteria. The result showed that the fluctuation patterns of daytime ozone in urban and rural areas are different to those in tropical and subtropical regions, depending on latitude. This was primarily due to the influence of solar radiation and the presence of precursors. Conversely, a slight decrease in ozone rate at night occurs because the precursor was accumulated by the shutdown of photochemical ozone production. Some precursors of ozone from other regions can be transported and accumulated from the long-range transport process in other locations. This paper serves as an initial guideline to analysing the pattern of ozone concentration in urban and rural areas and the factors that influence it.
 
 

Occurrence of N-nitrosodimethylamine in roasted Alaska pollock fillets during processing and storage and preliminary cancer risk assessment.

Dried and salt-fermented fish products are important sources of N-nitrosodimethylamine (NDMA) exposure for human. As a potent carcinogen, NDMA was frequently detected in roasted Alaska pollock fillet products (RPFs), which is among the most common fish products in China. Until now, the occurrence and development of NDMA and its precursors (nitrites, nitrates and dimethylamine) in RPFs during processing and storage were not well elucidated, and safety evaluation of this fish product is also urgently needed. The presence of precursors in the raw material was verified and significant increase of nitrates and nitrites during processing was observed. NDMA was found generated during pre-drying (3.7 μg kg-1 dry basis) and roasting (14.6 μg kg-1 dry basis) process. Continuous increase in NDMA content can also be found during storage, especially at higher storage temperature. The 95th percentile of Monte Carlo simulated cancer risk (3.73 × 10-5 ) surpassed the WHO threshold (1.00 × 10-5 ) and sensitivity analysis implies the risk was mainly attributable to NDMA level in RPFs. The occurrence of NDMA in RFPs was mainly a result of endogenous factors originating in Alaska pollock during processing and storage rather than exogenous contamination, and temperature played a pivotal role. The preliminary risk assessment results suggest that long-term consumption of RPFs would impose potential health risks for consumers. © 2023 Society of Chemical Industry.

Enhanced supply of acetyl-CoA by exogenous pantothenate kinase promotes synthesis of poly(3-hydroxybutyrate)

BackgroundCoenzyme A (CoA) is a carrier of acyl groups. This cofactor is synthesized from pantothenic acid in five steps. The phosphorylation of pantothenate is catalyzed by pantothenate kinase (CoaA), which is a key step in the CoA biosynthetic pathway. To determine whether the enhancement of the CoA biosynthetic pathway is effective for producing useful substances, the effect of elevated acetyl-CoA levels resulting from the introduction of the exogenous coaA gene on poly(3-hydroxybutyrate) [P(3HB)] synthesis was determined in Escherichia coli, which express the genes necessary for cyanobacterial polyhydroxyalkanoate synthesis (phaABEC).ResultsE. coli containing the coaA gene in addition to the pha genes accumulated more P(3HB) compared with the transformant containing the pha genes alone. P(3HB) production was enhanced by precursor addition, with P(3HB) content increasing from 18.4% (w/w) to 29.0% in the presence of 0.5 mM pantothenate and 16.3%–28.2% by adding 0.5 mM β-alanine. Strains expressing the exogenous coaA in the presence of precursors contained acetyl-CoA in excess of 1 nmol/mg of dry cell wt, which promoted the reaction toward P(3HB) formation. The amount of acetate exported into the medium was three times lower in the cells carrying exogenous coaA and pha genes than in the cells carrying pha genes alone. This was attributed to significantly enlarging the intracellular pool size of CoA, which is the recipient of acetic acid and is advantageous for microbial production of value-added materials.ConclusionsEnhancing the CoA biosynthetic pathway with exogenous CoaA was effective at increasing P(3HB) production. Supplementing the medium with pantothenate facilitated the accumulation of P(3HB). β-Alanine was able to replace the efficacy of adding pantothenate.

Pyrolysis synthesis of CuWO4@C composite catalysts as Pt-free counter electrode for dye-sensitized solar cells

Transition metal compound catalysts have potential applications in Pt-free counter electrode (CE), which are one of the important strategies for reducing costs and improving power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). Herein, CuWO4@C composite catalysts were synthesized by pyrolyzing Cu-based polyoxotungstate (H3PW12O40) precursor in presence of polyaniline. The effect of pyrolysis temperature (600, 700, 800, 900, 1000 and 1100 ℃) on the compositions, morphologies and structures of CuWO4@C composite was investigated by Thermogravimetry-Derivative thermogravimetry-Differential scanning calorimetry (TG-DTG-DSC) simultaneous, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and N2 adsorption-desorption analysis. The photovoltaic properties of different CuWO4@C composites CEs were determined by photocurrent-photovoltage (J-V) measurement. The results reveal that the pyrolysis at 800 ℃ was optimum to get the best CuWO4@C composite CE, which yielded the highest PCE of 7.11% for the regeneration of I3−/I− couple in the DSSCs. The structure-activity relationship of the CuWO4@C composite catalysts was discussed.

Ligand Decomposition during Nanoparticle Synthesis: Influence of Ligand Structure and Precursor Selection.

Aliphatic amine and carboxylic acid ligands are widely used as organic solvents during the bottom-up synthesis of inorganic nanoparticles (NPs). Although the ligands' ability to alter final NP properties has been widely studied, side reactivity of these ligands is emerging as an important mechanism to consider. In this work, we study the thermal decomposition of common ligands with varying functional groups (amines and carboxylic acids) and bond saturations (from saturated to polyunsaturated). Here, we investigate how these ligand properties influence decomposition in the absence and presence of precursors used in NP synthesis. We show that during the synthesis of inorganic chalcogenide NPs (Cu2ZnSnS4, Cu x S, and SnS x ) with metal acetylacetonate precursors and elemental sulfur, the ligand pyrolyzes, producing alkylated graphitic species. Additionally, there was less to no ligand decomposition observed during the sulfur-free synthesis of ZnO and CuO with metal acetylacetonate precursors. These results will help guide ligand selection for NP syntheses and improve reaction purity, an important factor in many applications.

Metal Oxide Electrospun Nanofibrous Membranes for Effective Dye Degradation and Sustainable Photocatalysis

The fabrication of metal oxide nanofibers using (titanium (IV) isopropoxide) and (tin (IV) tert-butoxide) of weight ratio 1:1 precursor in presence of poly (vinyl pyrrolidone) as a binder using a well-known electrospinning technique is reported. The average diameter of TiO2, SnO2, and composite TiO2-SnO2 nanofibers were found to be in the range 75–110 nm. The nanofibers were characterized using thermogravimetric analysis (TGA) to understand the polymer evaporation temperature and further analyzed using scanning electron microscopy (SEM) to study the morphology of the nanofibers. The oxidation states of titanium (Ti) and tin (Sn) ions were analyzed using X-ray photoelectron spectroscopy (XPS), indicating that the TiO2 undergoes a change even after loading SnO2. The photocatalytic efficiency of the composite TiO2-SnO2 fibers was investigated to study the degradation capabilities under ultraviolet (UV) light towards industrial polluting dyes such as Alcian Blue, Alizarin Red S, Bilirubin, Brilliant Blue, Bromophenol Blue, and Rhodamine B ITC. Rhodamine B showed a significant degradation rate of about 0.0064 min−1 in comparison to the other dyes.

Hydrophilic Core-Sheath fibers of polyvinyl alcohol / polyethylene composites through in situ ethylene polymerization

Core - sheath fibers of polyvinyl alcohol/polyethylene composites are synthesized by ethylene polymerization with titanium tetrachloride incorporated PVA nanofiber (NF) as catalyst precursor in presence of methyl aluminoxane (MAO) as a cocatalyst. The process also involves the initial preparation of PVA nanofiber by electrospinning followed by its reaction with titanium tetrachloride. The obtained titanium incorporated PVA was found to be insoluble in protonic solvent due to the reaction of OH group in PVA with titanium tetrachloride leading to the formation of a cross-linked mat. Thermal analysis of core-sheath fiber composite indicated the presence of polyethylene due to observation of melting peak at 134 °C. PVA-PE fiber composite is characterized by FTIR, SEM, and contact angle data. The results demonstrate that the presented approach is useful for synthesizing incompatible classes of polymer composite fibers such as polyvinyl alcohol/polyethylene with core-sheath morphology.

Social Environment as a Precursor to Coronary Artery Disease in a Small, Resource-Limited Country

Background: Coronary artery disease has been the most prevalent chronic disease over the last two decades. In Trinidad and Tobago—a small, high-income, resource-limited country the median age of presentation of, and premature death from, acute myocardial infarction is more than 12 years earlier to that in high-income, developed countries. This may be attributed to the increased risk of coronary artery disease that stem from the presence of precursors in the social environment. Objective: We aimed to explore the association between “social environment” and coronary artery disease in Trinidad and Tobago. Methods: This is a descriptive ecological study that assessed secondary data. Data were collected from multiple search engines and websites. Data on Trinidad and Tobago’s social environment were also accessed from the World Databank and the Central Intelligence Agency fact book and analyzed. Results: Coronary artery disease was fueled by personal choices that were influenced by the social environment (“fast food” outlets, inadequate sporting facilities, increased use of activity-saving tools [vehicles, phones, and online activities], smoking and alcohol accessibility, and social stressors [murder, family disputes, divorce, child abuse, kidnapping, and rape]). Food imports, as a percentage of merchandise imports, were at 11.42% (2015); the level of physical activity was low (<600 MET-minutes per week; 38 in 2016), and social stressors were high. Conclusion: The social environment has encouraged a “cardiotoxic” or “atherogenic” environment influencing behavior, eventually resulting in a continued high risk of coronary artery disease, presenting at a younger age.

COMPARATIVE ANALYSISOF THE PROPERTIES OF LTA TYPE ZEOLITE DEPENDING ON THE PRODUCTION METHOD: HYDROTHERMAL AND ULTRASONIC

The aim of the work was to establish the main parameters of the study of the use of ultra-sound at the stage of synthesis in search of the physicochemical properties of the LTA type zeolite with the hydrothermal method of production. A maincondition for the synthesis of this zeolite is the presence of precursors, namely aluminates and cubic sodium aluminosilicates. Metakaolin, solid sodium hydroxide and aluminum oxide are used as raw materials for the synthesis of zeolite. Ultrasonic treatment is carried out at a frequency of 22 kHz and a frequency of 8 μm at the end ofthe concentrator for 10 min. The industrial analogue was synthesized according to TU 2163-005-21742510-2004. In this work, ammonia is used as a probe to study the acid–base properties of zeo-lite structures. The choice of ammonia is due to the high degreeof bases, which makes it possible to determine not only strongly acidic centers, but also to combine centers that determine the size of molecules. Dynamic activity in terms of water parameters at breakthrough concentration is ob-served in the flow protocol. The particle size of zeolites is measured by scanning electron micros-copy. It was found that in the sample synthesized using ultrasound, the concentration of exchangeable sodium cations is 2.5 times higher than in the hydrothermal analogue and is 80 and 30 μg-eq/100g, respectively. The strength and number of acid sites of the synthesized zeolites were determined by the method of thermally programmed desorption of ammonia. For the synthesized LTA zeolite, its values are in the range of 0.06 1019 U/m2, for the industrial analogue it is lower by 5-10% and rarely 0.05 1019 U/m2. Using the data on the kinetics of ammonia desorption at various heating rates, the values of activation energy for ammonia desorption were calculated. The results lie in the range from 18.26 to 74.27 kJ/mol. The study of acid-base properties showed a more developed sur-face of the zeolite obtained by the ultrasonic method, which explains the greater acidity and acti-vation energy.

A highly efficient auxin-producing bacterial strain and its effect on plant growth

BackgroundVarious bacteria promote plant root growth in the rhizosphere, as a measure of securing and enlarging their ecological niche. These interactions are mediated by plant growth regulators (PGRs) such as auxin, and indole-3-acetic acid (IAA) is one of the physiologically active auxin. In this study, we isolated an unusual bacterial strain from food process waste with high efficiency and demonstrated its effects on plant rooting and early-stage growth. ResultsThe efficiency of this bacterial strain in producing IAA was 16.6 mg/L/h in Luria-Bertani broth containing 0.05% l-tryptophan (Trp) at room temperature (24 ± 2 °C). Its IAA production was highly dependent on the presence of precursor, Trp. This bacterium was identified as Ignatzschineria sp. by 16S rDNA sequencing. Its bacterial culture supernatant (BCS) enhanced plant root initiation, root growth, and plant growth in the early stages. The root mass formed BCS-treated in apple mint cuttings was twofold of that formed in the control. The root number and length were 46% and 18% higher, respectively, in BCS-treated chrysanthemum cuttings than in the control. ConclusionsThese results show that the BCS of Ignatzschineria sp. CG20001 isolate obtained in this study can be used for agricultural applications. In addition, the novelty of this strain makes it a valuable genetic resource for biotechnological applications.

Determination of the Low Temperature Electrochemical Ammonia Synthesis Using Chromium Nitride

Ammonia is globally produced on an industrial scale, with 142 Mt in 2019 [1]. Most of it is used as nitrogen fertiliser (USA, 88 %, [1]), demonstrating the indispensability for modern agriculture. Ammonia is also considered as a future carbon free, energy dense liquid fuel with high volumetric hydrogen content. Today, the production via the long-established Haber-Bosch process is energy intensive and ill-suited for scaling down, which is important for intermittent, decentralised use. Thus, an electrochemical production of green ammonia directly from water and nitrogen using renewable electricity is of high research interest. Electrochemical ammonia synthesis (EAS) is an emerging technology. It suffers to date from fundamental limitations of known catalyst materials for the nitrogen reduction reaction (NRR). The NRR is assumed to follow an associative Heyrovský mechanism at room temperature. Simulative evaluations of metal catalysts confirmed that weakly nitrogen binding materials adsorb nitrogen insufficiently, while too strong nitrogen binding impedes consecutive reduction of surface bound NHx species, also known as Sabatier principle. As a consequence high overpotentials for an appreciable production rate are required with low reaction selectivity towards ammonia.[2] In conclusion, novel catalyst materials are needed. Theoretical catalyst screening by Abghoui and Skuláson of the NRR via a Mars-van-Krevelen (MvK) mechanism on transition metal nitrides has identified certain ones as potentially active, selective and stable for the EAS. Among these promising candidates are vanadium, niobium, chromium and zirconium.[3] Some of these have been investigated already to some extent, with partially opposing results [4-6]. There is yet no fundamental link between material properties and catalytic activity for the EAS as with established catalyst materials like platinum. Proving the electrochemical activity of catalyst materials requires the quantitative determination of produced ammonia. This can generally prove challenging due to low production rate and several possible sources of advantageous contaminations. [7, 8]In this work chromium and zirconium nitride nanoparticles have been successfully synthesised via a pyrolytic conversion of a suitable metallic precursor in presence of urea as a nitrogen source [9]. Additionally, commercially available chromium and zirconium nitride powders were purchased for comparison. The main focus in this work will be on chromium nitride. These materials were physically characterised in regards to elemental composition, phase composition, physical surface area, thermal decomposition and particle size. Electrochemical characterisation was implemented in a commercial measurement cell for gas diffusion electrodes (GDE). GDEs were spray coated by hand, allowing for fast, flexible processing. Activity and selectivity of the catalyst material for the EAS were determined by quantitative measurement of the electrochemically produced ammonia. Ammonia was collected by acid trap in form of ammonium. Ammonium ion concentration was determined by ion chromatography as a fast, automated, sensitive method. After successful proof of the activity and reproduction thereof, focused parameter variations (e.g. applied potential, temperature, gas flow rate, catalyst loading) are planned to probe possible routes of process intensification in the future. L. E. Apodaca, Nitrogen (fixed) - Ammonia, in, U. S. G. Survey Editor, p. 2, US. Geologica Survey (2021). G. Rostamikia, S. Maheshwari and M. J. Janik, Catalysis Science & Technology, 9, 174 (2019). Y. Abghoui and E. Skúlason, The Journal of Physical Chemistry C, 121, 6141 (2017). X. Yang, J. Nash, J. Anibal, M. Dunwell, S. Kattel, E. Stavitski, K. Attenkofer, J. G. Chen, Y. Yan and B. Xu, Journal of the American Chemical Society, 140, 13387 (2018). J. Nash, X. Yang, J. Anibal, M. Dunwell, S. Yao, K. Attenkofer, J. G. Chen, Y. Yan and B. Xu, The Journal of Physical Chemistry C, 123, 23967 (2019). H.-L. Du, T. R. Gengenbach, R. Hodgetts, D. R. MacFarlane and A. N. Simonov, ACS Sustainable Chemistry & Engineering, 7, 6839 (2019). S. Z. Andersen, V. Colic, S. Yang, J. A. Schwalbe, A. C. Nielander, J. M. McEnaney, K. Enemark-Rasmussen, J. G. Baker, A. R. Singh, B. A. Rohr, M. J. Statt, S. J. Blair, S. Mezzavilla, J. Kibsgaard, P. C. K. Vesborg, M. Cargnello, S. F. Bent, T. F. Jaramillo, I. E. L. Stephens, J. K. Norskov and I. Chorkendorff, Nature, 570, 504 (2019). J. Choi, B. H. R. Suryanto, D. Wang, H. L. Du, R. Y. Hodgetts, F. M. Ferrero Vallana, D. R. MacFarlane and A. N. Simonov, Nature communications, 11, 1 (2020). C. Giordano, C. Erpen, W. Yao, B. Milke and M. Antonietti, Chemistry of Materials, 21, 5136 (2009).

Photocatalytic activity of Sn-doped ZnO synthesized via peroxide route

ZnO*ZnO2 mixture was prepared by thermal hydrolysis of a zinc peroxo-complex precursor in presence of Sn2+ and Sn4+ ions. The effect of different tin valence states on structure and photocatalytic properties of the resulting products was investigated. All samples before annealing contained ZnO2 and except one sample also SnO2. Microstructural analysis showed a difference in morphology between the two sets of samples. A difference was also observed for the specific surface area. The photocatalytic decolorization of Orange II dye was employed to determine the photocatalytic activity of the samples; Sn2+ doped samples were more active than Sn4+ doped ZnO samples. Temperature 600 °C was optimal for annealing - the sample ZnP150Sn2 annealed at 600 °C had the highest rate constant (0.0730 min−1) among the samples. Additional increase of Sn2+ amount led to further increase in rate constant (0.0937 min−1 for the sample ZnP200Sn2) up to a certain point.

Solid-phase synthesis of protonated nitrogen-containing heterocyclic compounds with the boron cluster anions starting from [Eu(H2O)9]2[B10Cl10]3: Synthesis, structure, and thermal properties of (НL)2[B10Cl10] (L = 7-amino-4-methylcoumarin or 1-ethyl-2-(4-methoxyphenyl) azobenzimidazole)

The paper proposes a new method for the synthesis of salts of a perchlorinated derivative of the decahydro-closo-decaborate anion with neutral N-containing organic bases L1 and L2 starting from previously prepared europium precursor [Eu(H2O)9]2[B10Cl10]3. Compound [Eu(H2O)9]2[B10Cl10]3 was first synthesized and characterized by elemental analysis, X-ray powder diffraction, IR spectroscopy and its thermal properties were studied by TGA. The protonation of organic bases L was carried out in the solid phase in the presence of precursor [Eu(H2O)9]2[B10Cl10]3. For comparison, the reaction was carried out in solution: in the CH3CN/CF3COOH system and in an aqueous solution of (H3O)2[B10Cl10] with pronounced acidic properties. The influence of reaction conditions on the composition and structure of the final products was analyzed. Salts of the composition (НL)2[B10Cl10] (L is 1-ethyl-2-(4-methoxyphenyl)azobenzimidazole (L1) and 7-amino-4-methylcoumarin (L2)) and (HL2)(H9O4) [B10Cl10] were synthesized and characterized by X-ray diffraction. The thermal properties of the obtained salts and ligand L1 (C16H16N4O) were studied in air in the temperature range 20–600°С.

Mesoporous amine functionalized SiO2 supported Cu nanocatalyst and a kinetic-mechanistic degradation study of azo dyes

The preparation of stable copper nanoparticles (CuNPs) has remained a challenge for colloid chemists. In this investigation, mesoporous amine functionalized silica (NH2-SiO2) particles have been used as platform to host copper nanoparticles (CuNPs) for preventing their agglomeration. Mesoporous NH2-SiO2 particles are first prepared in one pot by diethyl amine (DEA) catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS) precursor in presence of hexamethylene diamine (HMDA) and cetyltrimethylammonium bromide (CTAB). In the second step, sequential adsorption and chemical reduction of Cu ions are carried out to obtain NH2-SiO2/Cu catalyst nanocomposites. The morphology and structural composition of NH2-SiO2/Cu catalyst nanocomposite particles confirmed the anchoring of evenly distributed ~ 28 nm sized Cu particles. The catalytic activity of nanocomposite particles for reductive degradation of Congo red (CR) and Eriochrome Black-T (EBT) showed maximum degradation at pH values of 7 and 4, respectively. The degradation efficiency increased with the increase in catalyst dose and a maximum degradation of ~ 92% is achieved for CR when 2 mg of catalyst nanocomposite particles is used. Comparatively, the degradation percent for EBT is low (~ 83%). Degradation kinetics of CR preferably followed a pseudo-first-order rate model, but, for EBT degradation hardly any particular kinetic rate model could be preferentially ascertained. The improved stability and increased surface-to-volume ratio of anchored CuNPs enhanced the degradation efficiency of catalyst nanocomposite particles.

Induction of Auxins Synthesis by Rhodococcus erythropolis IMV Ac-5017 with the Addition of Tryptophan to the Cultivation Medium

The ability of surfactant producers to synthesize phytohormones expands the scope of their practical application and provides prospects for the development of microbial preparations with growth-stimulating properties. The possibility to intensify the phytohormone-stimulants synthesis by bacterial strains increases the efficiency of such preparations. Aim. The aim is to research the possibility of extracellular auxin synthesis induction in the presence of tryptophan in the cultivation medium of surfactant producer Rhodococcus erythropolis IMV Ac-5017 and establish the optimal concentration of tryptophan and time of introduction into the medium to ensure maximum synthesis of auxins. Methods. Biochemical, microbiological, biotechnological. Cultivation was performed in the liquid mineral medium using ethanol and waste sunflower oil as substrates. Tryptophan was added to the medium as a 1% solution in an amount of 200 or 300 mg/l at the beginning of the cultivation process or at the end of the exponential growth phase. Phytohormones were isolated by triple extraction with organic solvents from the culture broth supernatant after surfactant extraction. Preliminary purification and concentration of phytohormones was performed by thin layer chromatography. Qualitative and quantitative determination of auxins was performed using high performance liquid chromatography. Results. It was found that regardless of the concentration and time of tryptophan introduction to the culture medium of R. erythropolis IMV Ac-5017 with both substrates, a significant increase (by two to three orders of magnitude) was observed in the amount of synthesized auxins compared to tryptophan-free medium. The highest concentration of auxins (5552–5634 μg/l) was achieved by adding 300 mg/l of tryptophan into the culture medium of R. erythropolis IMV Ac-5017 with ethanol, while without the precursor their amount was only 143 μg/l. In contrast to the cultivation of the strain on culture medium with ethanol, where the synthesis of auxins did not depend on the time of tryptophan introduction, R. erythropolis IMV Ac-5017 formed the maximum amount of auxins when 300 mg/l tryptophan was added to the culture medium with waste oil at the end of the exponential growth phase (2398 μg/l compared to 9.8 μg/l on the medium without tryptophan). As auxin compounds were identified: indole-3-acetic acid, indole-3-carboxylic acid and indole-3-butyric acid. However, the highest amount of indole-3-acetic acid was synthesized, the precursor of which is tryptophan. The synthesis of this auxin (the most common plant auxin) in the presence of 300 mg/l of tryptophan increased more than 40 times on ethanol medium and more than 700 times on medium with waste oil. Induction of auxin synthesis by strain R. erythropolis IMV Ac-5017 correlated with the activity of tryptophan transaminase: when cultured on ethanol without tryptophan, it was 138 nmol·min-1·mg-1 of protein, while cultured in the presence of precursor it was increased by 5.2 times (up to 714 nmol·min-1·mg-1 of protein). The obtained results suggest that indole-3-acetic acid biosynthesis by the strain IMV Ac-5017 occurs due to the formation of indole-3-pyruvate. Conclusions. Thus, it was established the possibility of increasing by two or three orders the amount of synthesized auxins in the case of low concentrations of tryptophan introducing to the culture medium of R. erythropolis IMV Ac-5017 not only with ethanol but also with industrial waste (waste oil). The obtained results can be considered as promising for use of exometabolites of R. erythropolis IMV Ac-5017 with growth-stimulating properties in crop production.

Impact of municipal and industrial waste incinerators on PCBs content in the environment.

Polychlorinated biphenyls (PCBs) have been withdrawn from the market due to their toxicity, bioaccumulation capacity, and persistence. PCBs have been observed to potentially form in combustion processes under appropriate conditions and in the presence of precursors containing chlorine. The study covered a municipal waste incineration plant and an industrial waste incineration plant. The objective of the study was to assess the effect of these objects on PCB accumulation in soil and plants taking into account the distance from the emission object and wind direction. Soil samples were collected from layers: 0-5, 5-10, 10-20, and 20-30 cm. Test plants were collected from the same areas as the soil samples. The highest accumulation of PCBs was found in plants with large leaf area. Around the municipal waste incineration plant, these were Tanacetum vulgare leaves (12.45 ng/g), and around the industrial waste incineration plant–grasses (4.3 ng/g). In the case of soils, the accumulation of PCBs for both kind waste incinerators was similar, reaching approximately 3 ng/g. As the distance from the municipal waste incinerator and industrial waste incinerator increased, the accumulation of PCBs in the soil decreased. For municipal waste incinerator, no effect of wind direction on PCB accumulation in the soil was observed. In the majority of cases, the accumulation of PCBs in soils taken from the leeward side of the industrial waste incinerator was higher than that in soils from the windward side. In soils around the municipal waste incinerator, PCB compounds moved deep into the soil and reached the highest accumulation in the soil layer of 10-20 cm or 20-30 cm. In soils around the industrial waste incinerator, the highest accumulation of PCBs occurred in the soil layer of 0-5 cm.

Transfer of Per- and Polyfluoroalkyl Substances (PFAS) from Feed into the Eggs of Laying Hens. Part 2: Toxicokinetic Results Including the Role of Precursors.

A feeding study was performed to examine the bioaccumulation of per- and polyfluoroalkyl substances (PFAS) in laying hens' tissues and plasma and feed-to-egg transfer rates and half-lives. A 25 day exposure was followed by a 42 day depuration period. A target analysis revealed substantial amounts of the precursors N-methyl and N-ethyl perfluorooctane sulfonamidoacetic acid (Me- and EtFOSAA), perfluorooctane sulfonamidoacetic acid (FOSAA), and perfluorooctane sulfonamide (FOSA). In tissues and eggs, the highest bioaccumulation was found for PFHxS, PFHpS, PFOS, and PFOA. Low levels of PFHxS (all samples), PFOS, and FOSAA (in yolk) were measurable even after the depuration period. The egg elimination half-lives of PFOS and aforementioned precursors were estimated to be 4.3 days, while the transfer rates of PFOS and all precursors taken together were 0.99. The transfer rate of PFOA was around 0.49. PFHxS and PFHpS showed apparent transfer rates of >100%, which is hypothesized to indicate the presence of precursors.

A facile approach towards large-scale synthesis of pristine hematite nanoparticles with enhanced photo/catalytic properties via annealing of iron sulfate precursor in presence of treated egg shell wastes as desulfurizer

This work presents a new green perspective for the synthesis of hematite nanoparticles (HNP) via annealing the plain inorganic ferric sulfate (FS) precursor at (700–900) °C under a caked bed of the treated egg shell wastes as desulfurizer. Morphological and microstructural analyses depict the pristine phase of α-Fe2O3 crystal for the annealed samples along with exhibiting a reduced particles' size of 21 nm for FS annealed at 700 °C compared to the larger sizes of ≈29 and 50 nm for FS annealed at 800 °C and 900 °C, respectively. Moreover, FS annealed at 700 °C exhibited a unique hierarchal structure with various pores system on multi-scales, larger surface area with roughness, lower luminescence, and better uniformity over FS 800 and 900 nanoproducts. FS 700 showed a superior degradation efficiency ≈100% at 10 min with a rate constant of 11.06 × 10−2 min−1 for the pollutant Congo Red dye at room temperature in complete darkness, obeying pseudo-first-order reaction kinetics. Also, FS 700 could catalyze the production rate of biogas yields from the biodegradation of green algae (Enteromorpha) over other products. The photocatalytic study of terephthalic acid hydroxylation revealed that the induced fluorescence intensity is highest for FS 700 and is time dependent, following zero-order reaction kinetics. Accordingly, this contribution can furnish a striking piece of evidence for adopting the present methodology as a novel approach not only for the synthesis of HNP with superior features in good yields for industrial scales but also as a green alternative to the widely-used conventional organic precursors, reducing the greenhouse gases and recycling the environmental egg wastes.