Theoretical and Experimental Chemistry最新文献

A novel magnetic composite material, which is prospective for adsorption removal of phosphate ions from aqueous solution, was prepared by immobilization of CuFe₂O₄ on graphene-like carbon nitride nanosheets. The obtained material is shown to ensure the removal more 97% phosphate ions within the 2-6 pH range at 15 mg/mL phosphate concentration (100 mg of the sorbent for 30 mL of a solution). The isotherm of phosphate sorption is described with Langmuir model. The nanocomposite maintains the efficiency (>94 %) at least during 5 cycles when reused.

As a result of mechanochemical processing of graphite (Gr), sulfur, and MoSe₂ mixtures, nanocomposites nsGr/S, gMoSe₂-nsGr and gMoSe₂-nsGr/S have been prepared. Their structure and electrochemical performance in lithium-sulfur cells are investigated. It has been demonstrated that the nsGr/S forms a conductive porous matrix, but shows poor cycling stability due to the polysulfide shuttle effect. Coating the separator with a gMoSe₂-nsGr layer leads to an initial specific capacity increasing up to ~400 mA·h/g and its maintaining up to ~50 % after 50 charge–discharge cycles. The best performance is observed when gMoSe₂-nsGr is used both in the cathode and as a separator coating (~620 mA·h/g and ~80 % capacity retention after 50 cycles)

Micellization in a solution of sodium dodecyl sulfate (SDS) containing the antibiotic ofloxacin (OFX) in the presence of glucose or urea in the temperature range of 293-323 K has been studied by conductometry. It is shown that the critical micelle concentration (CMC) of SDS increases in the presence of OFX. The addition of urea increases the CMC in the SDS-OFX mixture, while in the presence of glucose the CMC decreases. The thermodynamic parameters of micellization, ∆({G}_{text{m}}^{0}), ∆({H}_{text{m}}^{0}), and ∆({S}_{text{m}}^{0}), have been determined and it is proved that the SDS-OFX mixture undergoes spontaneous micellization both in pure water and in an aqueous solution of glucose or urea.

X-ray amorphous zirconium dioxide samples have been obtained by calcination of a mixture of zirconium oxychloride with sodium bicarbonate, sodium carbonate, or potassium oxalate. It is established that the efficiency of phosphate anion removal from Ringer’s solution by zirconium dioxide synthesized using sodium carbonate is higher (91.2%) than that achieved when sodium bicarbonate is used (85.7%). It is shown that zirconium dioxide obtained by solid-state synthesis may be considered as a promising oxide material for hemodialysis systems aimed at blood purification in patients with chronic renal failure.

A novel non-conjugated aromatic polymer that contains azo-linked moieties of diphenylmethane and 2,5-bis-4-(hydroxyphenyl)-1,4-dimethoxybenzene ((MeO)₂AzoPhO) has been obtained. The structure of the polymer is corroborated using IR spectroscopy, 1H, 13C NMR, and CP-MAS NMR spectroscopy. With the use of thermogravimetry, it is shown that the compound is thermally stable up to 150°C. Based on the analysis of the electron spectra, it is established that the band gap width (E_g) of (MeO)₂AzoPhO equals 3.0-3.4 eV. This value is higher than E_g for the polymeric analogue with a conjugated linker (≈2.9 eV) and consistent with the size of the electron density delocalization regions.

A stable colloid of Zn- and Ag-doped CuO nanoparticles has been synthesized using a co-precipitation method in the presence of sodium dodecyl sulfate. The synthesis parameters that significantly affect the stability of the final product have been optimized. The nanoparticles in the stable suspension exhibit a rod-like morphology with an average size of 40-60 nm. It is shown that the obtained colloidal system has higher antimicrobial activity of against M. fortuitum, M. bovis, and M. avium in comparison with undoped analogues.

A new multifunctional magneto-responsive composite polymer material with an increased content of β-cyclodextrin was synthesized using nanoscale magnetite and a copolymerization reaction between β-cyclodextrin and hexamethylene diisocyanate. The structure and physicochemical properties of the surface functional groups of the resulting nanocomposite were characterized by IR spectroscopy, thermogravimetry, low-temperature nitrogen adsorption–desorption, X-ray phase analysis, chemical analysis, and scanning electron microscopy. The composite demonstrated a pronounced ability for the selective extraction of strontium(II) ions from a mildly acidic aqueous medium.

It has been shown that in the presence of Ag(I) ions, the rate of the oxidation reaction of isoleucine (ILe) by potassium permanganate in an acidic aqueous medium increases by 5.4 times, and in the presence of sodium lauryl sulfate (SLS) micelles does by 4.2 times. The combined action of Ag(I) and SLS micelles leads to a 9.6-fold acceleration of the reaction, which is a manifestation of the cooperative effect. The oxidation process is accelerated due to the electrostatic interaction between permanganate and the negatively charged micelle.

The possibility of obtaining Fe-N-C and Fe,Co-N-C electrocatalysts for the oxygen reduction reaction (ORR) by pyrolysis of Vulcan XC72R carbon black suspension in deep eutectic solvents (DESs) based on 1-butyl-3-methylimidazolium chloride and iron(III) chloride, or a mixture of iron(III), cobalt(II), and zinc(II) chlorides, has been demonstrated. The influence of the DES type on the composition, structure, morphology, and electrocatalytic properties of the obtained materials has been found. It is established that the Fe-N-C catalyst obtained without the involvement of Co- or Zn-containing DES is the most effective in ORR and is characterized in an alkaline electrolyte by E_onset (964 mV vs. RHE) and E_1/2 (891 mV vs. RHE) potentials, which exceed those of most analogues obtained using ionic liquids, ensures the ORR proceeds mainly by a 4-electron mechanism, and also does not require additional heat treatment to achieve high ORR characteristics.

It has been shown that the thermal decomposition of Co(II) oxalate in a hydrogen atmosphere leads to a mixture of cobalt nanoparticles of hexagonal and cubic modification. The decomposition of heterometallic oxalates obtained as a result of partial substitution of Co(II) by Mg(II) or Mn(II) causes a significant decrease in the average size of the formed Co nanoparticles and an increase in the content of its cubic modification. In the hydrogenation of quinoline on Co and Co-Mg catalysts, a higher yield of 1,2,3,4-tetrahydroquinoline is achieved with an increase of the hexagonal cobalt modification content. In the case of Co-Mn systems, a high yield of 1,2,3,4-tetrahydroquinoline is observed when the content of cubic Co modification is prevailing, which is explained by the promoting effect of Mn.