Russian Journal of Applied Chemistry最新文献

Following the development demand for photocatalytic materials that are available, economical, and active in mild conditions, this work presents an investigation on the way to enhance the photocatalytic activity of TiO₂ towards formaldehyde degradation (HCHO) using carbon aerogel (CA) as a support material. Hereby, composites nTiO₂/(1−n)CA-t_c, where n – the mass ratio of TiO₂ precursor and CA (n = 0.5, 0.7, 0.8, and 0.9); t_c – the experimental calcination temperature (t_c = 400, 500, 600, and 700°C), were synthesised by the solvothermal method. As a relevant result, the CA component was found to be in its amorphous form, while TiO₂ existed in both anatase and rutile phases, which were finely dispersed on the composite surface. The unit cell volume (V_c) of the anatase structure and its average crystallite size (D) varied depending on t_c and n, and so did the corresponding samples’ photocatalytic performance. It was discovered that the sample 0.5TiO₂/0.5CA-400 showed the highest HCHO conversion (x_HCHO) compared to the other synthesised ones, with x_HCHO ≈97% after a conversion time of 75 min. The enhanced activity of 0.5TiO₂/0.5CA-400 was due to its higher V_c (~137.2520 nm³) and lower D (~6.7 nm), which was predicted to have a higher specific surface area. Thus, this study has confirmed the effectiveness of developing TiO₂ photocatalysts based on the CA substrate for HCHO oxidation and exhibited the potential to extend the application to other volatile organic compounds (VOCs).

Ionic liquids, as catalysts for carbonate derivatives, have high conversion rates and strong selectivity, and are environment-friendly. In this study, [HO–(CH₂)₂–mim]5[Ti(H₂O)FeMo₁₁O₃₉] (IL-Fe) was prepared using sodium molybdate, TiCl₄, and 1-hydroxypropyl-3-methylimidazolium bromide salt ([HO–(CH₂)₂–mim]Br). The products were characterised by IR, XRD, TGA, and UV spectroscopy, which showed that the structures were correct and that the catalysts were thermally stable. The synthesis of BISBC by IL-Fe-catalysed ISB was carried out and the structural characterisation and synthetic conditions of BISBC were optimised by orthogonal tests. The experimental results showed that four factors, i.e. feeding ratio, catalyst dosage, reaction temperature, and reaction time, affected the yield of the BISBC prepolymer in descending order. The optimum process conditions for the BISBC yield were defined: feeding ratio n(DMC) : n(ISB) = 5; catalyst dosage = 1.0 wt %; reaction temperature = 80°C; reaction time = 5 h. Under these reaction conditions, one-way experiments were again carried out for validation, and the BISBC yield was as high as 75.32%.

The present communication reflects different approaches for the synthesis of tetrazole biomimetic replacement of carboxylic acid. Tetrazole is one among the many isosteres that represent the true replacement to carboxylic acid. Tetrazole tethered molecules exhibit many biological activities and catalytic activities in organic transformations. Synthetic methodologies for the construction of free tetrazole, substituted tetrazole, fused tetrazoles, etc., were substantiated that would offer a platform to encompass the researcher to avail complete information on the tetrazoles.

The study of the influence the type of plasticizing organic/inorganic agents on structural-mechanical properties (plastic strength, molding pressure, limit shear stress, greatest plastic viscosity, plasticity and etc.) of the pseudoboehmite pastes is presented. Samples of the pastes were prepared using plasticizing agents of organic nature (acetic, malic, tartaric, oxalic and citric acids and diethyelen glycol) and inorganic nature such as nitric and phosphoric acids, aqueous ammonia solution and ammonium hydrocarbonate. Our results suggest the pastes plasticized with nitric/phosphoric acids or with diethylene glycol demonstrate the highest plastic strength in the set. Plastic strength values were found to correlate well with the molding pressure necessary for the paste shaping through a piston extruder. The structural-mechanical type of paste was determined using a modulus of elasticity, viscosity and limit shear stress. All pastes were found to be suitable for extrusion molding and did not belong to SMT types 0 and III. The plasticizing agent was found to affect SMT type of paste. Paste types I, II, IV, and V were obtained by changing the plasticizing agent. Alumina granules without visible defects and with sufficient crush strength value were prepared using the investigated pastes. This allows them to be used as supports/adsorbents/catalysts for industrial processes.

A novel calix[4]arene-bonded nano silica gel (C4A–SiO₂) is prepared by covalent attachment of a calix[4]arene derivative to nano silica gel. The structure and properties of C4A–SiO₂ were studied by Fourier Transform Infra-Red (FTIR), thermogravimetric (TG), elemental analysis (CHN), scanning electron microscopy (SEM), and surface area analysis (BET). In addition, the organocatalytic activity of C4A–SiO₂ for synthesis of some biologically active cores xanthenes was investigated by comparison of the yields and reaction times. The results prove that utilization of catalyst causes the reaction time reduction and yield expansion. Xanthene structures have been proved by FT-IR, ¹H NMR, ¹³C NMR and comparison of melting points. Easy work-up, acceptable reaction times, eco-friendly solvent, recyclable of catalyst and high yields are remarkable advantages of these processes. The catalyst C4A–SiO₂ is recyclable for at least five cycles without substantial loss of activity. Thus, C4A–SiO₂ can be introduced as an efficient organocatalyst in synthesis of xanthenes.

Protonated diallylammonium polymers attract attention due to a number of properties, in particular high antimicrobial activity, including activity against the mycobacterium M. tuberculosis. To reduce the cytotoxic effect of polymers in the case of practical use, samples with a low MW are required. The work investigated the free radical polymerization of protonated diallylammonium monomers, diallylammonium trifluoroacetates, in excess of the initiator ammonium persulfate (10^–1 M) and at average polymerization temperatures (40 and 50°C) to obtain polymers with a low degree of polymerization. It has been shown that under such conditions it is possible to obtain polymers with values suitable within the aim: 16000 < MW < 28000 g/mol. Using NMR and IR spectroscopy, it was shown that with an increase in the concentration of the initiator and, accordingly, a decrease in the molecular mass of polymers, the relative number of characteristic terminal vinyl groups decreases, and the terminal groups formed by the interaction of macroradicals with primary radicals of the initiator become predominant, in this case, sulphate groups of ammonium persulfate. The data obtained indicate that at high concentrations of the initiator, the characteristic reactions of chain transfer to the monomer are largely kinetically suppressed by the interactions of macroradicals with the primary radicals of the initiator. The approach used, which makes it possible to synthesize polymers with a low MW and terminal groups of the initiator, can be applicable in the future to vary the properties of antimicrobial activity and toxicity of polymers.

A new method for producing glassy carbon microspheres in solutions containing furfuryl alcohol, ethylene glycol, isooctylphenol decaglycol ether (OP-10), and sulfuric acid was developed. The morphology of the microspheres was examined. Their electrochemical tests in a solution containing 0.1 M KCl, 0.005 M K₃[Fe(CN)₆], and 0.005 M K₄[Fe(CN)₆] were performed. The relationship between the solution temperature during the synthesis (the heat released in the polycondensation reaction) and the volume of the acid added was established using a noncontact thermometer. The polymer microspheres obtained in the solution were washed, dried, and calcined at 900°C. The materials obtained were examined by scanning electron microscopy and X-ray fluorescence elemental analysis. The elemental analysis showed that the materials contained about 98% carbon and less than 2% potassium, copper, oxygen, sulfur, and iron. Scanning electron microscopy revealed that the microspheres had a regular spherical shape, a developed surface, and the diameter ranging from 0.5 to 10 μm. The characteristic microsphere size was determined by dynamic light scattering, and the dependences of the size on the reactant ratio during the synthesis were constructed. A paste with the microsphere to vacuum oil weight ratio of 80 : 10 was prepared for the electrode fabrication. This mixture was stirred to obtain a homogeneous paste and stuffed into a tubular electrode 3 mm in diameter. The peak current and peak potential values determined using cyclic voltammetry for the electrodes with pure microspheres and, for the best sample, with the addition of barium hexaferrite as an electrochemical catalyst. Among the nineteen solutions studied, the solution containing 100 mL of ethylene glycol, 5 mL of furfuryl alcohol, 5 mL of OP-10, and 50 mL of sulfuric acid is the most promising.

In the present study we have synthesized interpenetrating polymer network (IPN) of fullerene (C₆₀) and N-vinyl carbazole (NVC). The IPNFC was characterized using infrared (IR) spectroscopy, scanning electron microscope (SEM) and conductivity techniques which reveals desirable and interesting results. IR spectroscopy reveals presence of fullerene at 527 and 1600 cm^–1 and poly (N-vinyl carbazole) at 1101 cm^–1. A thin polymeric interconnected film is seen via SEM technique, revealing transparent and dual phase morphology. IPN is also analyzed for permeability and permittivity, which reveals maximum value of ε_r', ε_r'' and tan δ_ε at 2.77, 0.48, and 0.11, respectively, and maximum values of μ'_r of μ''_r, and tan μ _r ranging from 0.99 to 1.50, 0.01–0.103, and 0.01–0.08, respectively. Moderate values of permeability and permittivity reveals electromagnetic property of the IPN. Conductivity IPN was calculated and found to be 4.98 S/m, which describes the semiconducting nature of the polymeric network.