Synthesis and Properties of the Copper Composite Membranes

Composite catalysts based on track-etched membranes (TeMs) and metal nanoparticles (NPs) or nanotubes (NTs) deposited by different approaches have drawn a special attention because of attractive catalytic properties coupled with large catalytically active surface, high mechanical strength and efficient flexibility, which allows them to be successfully used for several reaction cycles without additional manipulation of purification and activation

Impact of Testing Temperature on the Structure and Catalytic Properties of Au Nanotubes Composites

In the paper, the catalytic activity of composites based on gold nanotubes and ion track membranes was studied using bench reaction of the p-nitrophenol (4-NP) reduction in the temperature range of 25-40 °C. The efficiency of the prepared catalysts was estimated on the rate constant of the reaction and by conversion degree of 4-NP to p-aminophenol (4-AP). The comprehensive evaluation of the structure was performed by X-ray diffraction and scanning electron microscopy. A decreasing of the composites activity was observed when the reaction were carried out at the temperature over 35 °C, due to an increased average crystallite size from 7.31±1.07 to 10.35±3.7 nm (after 1st run). In temperature range of 25-35 °C the efficiency of the composite catalyst was unchanged in 3 runs and decreases by 24-32 % after the 5th run. At the high temperature of 40 °C after the 5th run the composite become completely  catalytically inert. Copyright © 2018 BCREC Group. All rights reserved Received: 23rd January 2018; Revised: 19th March 2018; Accepted: 19th March 2018 How to Cite: Mashentseva, A.A., Zdorovets, M.V., Borgekov, D.B. (2018). Impact of Testing Temperature on the Structure and Catalytic Properties of Au Nanotubes Composites. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (3): 405-411 (doi:10.9767/bcrec.13.3.2127.405-411) Permalink/DOI: https://doi.org/10.9767/bcrec.13.3.2127.405-41

Allobetulin and Its Derivatives: Synthesis and Biological Activity

This review covers the chemistry of allobetulin analogs, including their formation by rearrangement from betulin derivatives, their further derivatisation, their fusion with heterocyclic rings, and any further rearrangements of allobetulin compounds including ring opening, ring contraction and ring expansion reactions. In the last part, the most important biological activities of allobetulin derivatives are listed. One hundred and fifteen references are cited and the relevant literature is covered, starting in 1922 up to the end of 2010

The Study of the Structure-Activity Relationship For a Cinnamic Acid Derivatives

Для изучения взаимосвязи «структура-активность» исследован ряд производных коричной кислоты. С использованием современных методов проведен скрининг антирадикальной активности, для всех соединений рассчитаны эффективные коэффициенты ингибирования. Показано, что введение гидроксильного заместителя в молекулу коричной кислоты значительно повышает восстановительные свойства последней. Наличие заместителя в м-положении несколько снижает значение эффективного коэффициента ингибирования IC50. Наиболее эффективными антиоксидантами являются орто-дигидроксизамещенная кофейная и феруловая кислоты; так, по способности ингибировать DPPH-радикал кофейная кислота превосходит коричную в 3,2 раза, бутилированный гидроксианизол (BHA) - в 1,6 раза. Методами квантовой химии произведен расчет некоторых физико-химических параметров, определяющих восстановительные свойства молекул - потенциал ионизации (IP), энергию сродства к электрону и энтальпию диссоциации ОН-связи. Коричная кислота, не имеющая в структуре молекулы гидроксильных групп, имеет самый высокий IP, м-положение ОН- группы в гидроксикоричной кислоте, немного понижает восстановительную способность по сравнению с о-замещением. Минимальное значение IP хлорогеновой и аскорбиновой кислот подтверждает их высокий антиоксидантный статус. Проведен корреляционный анализ экспериментальных и теоретических данных (коэффициентом достоверности R2=0,5265).The structure-radical scavenging activity relationship for some cinnamic acid derivatives was investigated. The radical scavenging activity (RSA) using modern assays were studied and the effective coefficients for all compounds were calculated. It was founded that hydroxyl group presence is increasing the reduction properties of the cinnamic acid, and the m- substitute presence is decreasing the IC50 value. The most effective antioxidants are o-dihydroxy substituted caffeic and ferulic acids; it could exceed the DPPH RSA of the cinnamic acid in 3.2times, BHA - in 1.6 times. Using quantum-chemistry program some physic-chemical properties like as ionization potential (IP), electron affinity energy and O-H bond dissociation enthalpy, which can be used as an antioxidant activity descriptors were calculated. The not having any O-H group in structure cinnamic acid has the highest value of IP, m-substitution of O-H group in hydroxyl cinnamic acid is decreasing the reduction ability as compared to o-substitution. The highest antioxidant potential of the chlorogenic and ascorbic acids is confirmed by the least IP values. The correlation analysis foe the experimental and theoretical data was searched with the confidence factor value R2=0.526

Synthesis and Properties of the Copper Composite Membranes

Composite catalysts based on track-etched membranes (TeMs) and metal nanoparticles (NPs) or nanotubes (NTs) deposited by different approaches have drawn a special attention because of attractive catalytic properties coupled with large catalytically active surface, high mechanical strength and efficient flexibility, which allows them to be successfully used for several reaction cycles without additional manipulation of purification and activation

The Study of the Structure-Activity Relationship For a Cinnamic Acid Derivatives

Для изучения взаимосвязи «структура-активность» исследован ряд производных коричной кислоты. С использованием современных методов проведен скрининг антирадикальной активности, для всех соединений рассчитаны эффективные коэффициенты ингибирования. Показано, что введение гидроксильного заместителя в молекулу коричной кислоты значительно повышает восстановительные свойства последней. Наличие заместителя в м-положении несколько снижает значение эффективного коэффициента ингибирования IC50. Наиболее эффективными антиоксидантами являются орто-дигидроксизамещенная кофейная и феруловая кислоты; так, по способности ингибировать DPPH-радикал кофейная кислота превосходит коричную в 3,2 раза, бутилированный гидроксианизол (BHA) - в 1,6 раза. Методами квантовой химии произведен расчет некоторых физико-химических параметров, определяющих восстановительные свойства молекул - потенциал ионизации (IP), энергию сродства к электрону и энтальпию диссоциации ОН-связи. Коричная кислота, не имеющая в структуре молекулы гидроксильных групп, имеет самый высокий IP, м-положение ОН- группы в гидроксикоричной кислоте, немного понижает восстановительную способность по сравнению с о-замещением. Минимальное значение IP хлорогеновой и аскорбиновой кислот подтверждает их высокий антиоксидантный статус. Проведен корреляционный анализ экспериментальных и теоретических данных (коэффициентом достоверности R2=0,5265).The structure-radical scavenging activity relationship for some cinnamic acid derivatives was investigated. The radical scavenging activity (RSA) using modern assays were studied and the effective coefficients for all compounds were calculated. It was founded that hydroxyl group presence is increasing the reduction properties of the cinnamic acid, and the m- substitute presence is decreasing the IC50 value. The most effective antioxidants are o-dihydroxy substituted caffeic and ferulic acids; it could exceed the DPPH RSA of the cinnamic acid in 3.2times, BHA - in 1.6 times. Using quantum-chemistry program some physic-chemical properties like as ionization potential (IP), electron affinity energy and O-H bond dissociation enthalpy, which can be used as an antioxidant activity descriptors were calculated. The not having any O-H group in structure cinnamic acid has the highest value of IP, m-substitution of O-H group in hydroxyl cinnamic acid is decreasing the reduction ability as compared to o-substitution. The highest antioxidant potential of the chlorogenic and ascorbic acids is confirmed by the least IP values. The correlation analysis foe the experimental and theoretical data was searched with the confidence factor value R2=0.526

Serratula coronata L. Mediated Synthesis of ZnO Nanoparticles and Their Application for the Removal of Alizarin Yellow R by Photocatalytic Degradation and Adsorption

In this study, the potential of biogenic zinc oxide nanoparticles (ZnO NPs) in the removal of alizarin yellow R (AY) from aqueous solutions by photocatalytic degradation, as well as adsorption, was investigated. The synthesized ZnO NPs were prepared by the simple wet-combustion method using the plant extract of Serratula coronata L. as a reducing and stabilizing agent and characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy. Photocatalytic degradation of AY was monitored by UV–visible spectroscopy and the effects of parameters, such as light source type (UV-, visible- and sunlight), incubation time, pH, catalyst dosage and temperature on degradation were investigated. It was demonstrated that the source of light plays an important role in the efficiency of the reaction and the UV-assisted degradation of AY was the most effective, compared to the others. The degradation reaction of AY was found to follow the Langmuir-Hinshelwood mechanism and a pseudo-first-order kinetic model. The degradation kinetics of AY accelerated with increasing temperature, and the lowest activation energy (Ea) was calculated as 3.4 kJ/mol for the UV-light irradiation system, while the Ea values were 4.18 and 7.37 kJ/mol for visible light and sunlight, respectively. The dye removal by the adsorption process was also affected by several parameters, such as pH, sorbent amount and contact time. The data obtained in the kinetics study fit the pseudo-second-order equation best model and the rate constant was calculated as 0.001 g/mg·min. The isotherm analysis indicated that the equilibrium data fit well with the Freundlich isotherm model. The maximum adsorption capacity of AY on biogenic ZnO NPs was 5.34 mg/g

Kinetic and Isotherm Study of As(III) Removal from Aqueous Solution by PET Track-Etched Membranes Loaded with Copper Microtubes

This paper reports on the synthesis and structure elucidation of track-etched membranes (TeMs) with electrolessly deposited copper microtubes (prepared in etched-only and oxidized polyethylene terephthalate (PET) TeMs), as well as on the comparative testing of arsenic (III) ion removal capacities through bath adsorption experiments. The structure and composition of composites were investigated by X-ray diffraction technique and scanning electron and atomic force microscopies. It was determined that adsorption followed pseudo-second-order kinetics, and the adsorption rate constants were calculated. A comparative study of the applicability of the adsorption models of Langmuir, Freundlich, and Dubinin–Radushkevich was carried out in order to describe the experimental isotherms of the prepared composite TeMs. The constants and parameters of all of the above equations were determined. By comparing the regression coefficients R2, it was shown that the Freundlich model describes the experimental data on the adsorption of arsenic through the studied samples better than others. Free energy of As(III) adsorption on the samples was determined using the Dubinin–Radushkevich isotherm model and was found to be 17.2 and 31.6 kJ/mol for Cu/PET and Cu/Ox_PET samples, respectively. The high EDr value observed for the Cu/Ox_PET composite indicates that the interaction between the adsorbate and the composite is based on chemisorption

Kinetic and Isotherm Study of As(III) Removal from Aqueous Solution by PET Track-Etched Membranes Loaded with Copper Microtubes

This paper reports on the synthesis and structure elucidation of track-etched membranes (TeMs) with electrolessly deposited copper microtubes (prepared in etched-only and oxidized polyethylene terephthalate (PET) TeMs), as well as on the comparative testing of arsenic (III) ion removal capacities through bath adsorption experiments. The structure and composition of composites were investigated by X-ray diffraction technique and scanning electron and atomic force microscopies. It was determined that adsorption followed pseudo-second-order kinetics, and the adsorption rate constants were calculated. A comparative study of the applicability of the adsorption models of Langmuir, Freundlich, and Dubinin–Radushkevich was carried out in order to describe the experimental isotherms of the prepared composite TeMs. The constants and parameters of all of the above equations were determined. By comparing the regression coefficients R2, it was shown that the Freundlich model describes the experimental data on the adsorption of arsenic through the studied samples better than others. Free energy of As(III) adsorption on the samples was determined using the Dubinin–Radushkevich isotherm model and was found to be 17.2 and 31.6 kJ/mol for Cu/PET and Cu/Ox_PET samples, respectively. The high EDr value observed for the Cu/Ox_PET composite indicates that the interaction between the adsorbate and the composite is based on chemisorption