Investigation of the sorption properties of β-cyclodextrin-based polyurethanes with phenolic dyes and naphthenates

The sorption of p-nitrophenol (PNP), phenolphthalein (phth) and naphthenates (NAs) with β-cyclodextrin (β-CD) based polyurethane sorbents from aqueous solutions are reported. The copolymer sorbents were synthesized at various β-CD/diisocyanate monomer mole ratios (e.g., 1:1, 1:2, and 1:3) with diisocyanates of variable molecular size and hydrogen deficiency. The copolymer sorbents were characterized in the solid state using (13)C CP-MAS NMR spectroscopy, IR spectroscopy and elemental (C,H,N) analysis. The equilibrium sorption properties of the copolymer sorbents in aqueous solution were characterized using isotherm models at pH 4.6 and 9.0 for PNP, pH 9.0 for naphthenates and pH 10.5 for phth. UV-Vis spectroscopy was used to monitor the unbound fraction of the phenolic dyes in the aqueous phase, whereas, electrospray ionization mass spectrometry was used to monitor the unbound fraction of naphthenates. The sorption results of the copolymer sorbents were compared with a commercially available carbonaceous standard; granular activated carbon (GAC). The sorption properties and capacities of the copolymer sorbents (Q(m)) were estimated using the Sips isotherm. The sorption capacity for GAC was 2.15 mmol PNP/g, 0.0698 mmol phth/g, and 142 mg NAs/g, respectively, whereas the polymeric materials ranged from 0.471 to 1.60 mmol/g (PNP), 0.114 to 0.937 mmol/g (phth), and 0 to 75.5 mg/g (naphthenates), respectively, for the experimental conditions investigated. The observed differences in the sorption properties were attributed to the accessible surface areas and pore structure characteristics of the copolymer sorbents. The binding constant, K(eq), for copolymer materials for each sorbate is of similar magnitude to the binding affinity observed for native β-CD. PNP showed significant binding onto the copolymer framework containing diisocyanate domains, whereas, negligible sorption to the sites was observed for phth and naphthenates. The β-CD inclusion sites in the copolymer framework are concluded to be the main sorption site for phth and naphthenates through the formation of well-defined inclusion complexes.     

Thermal properties and combustibility of elastomer–protein composites

This article presents the test results of thermal properties and flammability of crosslinked nitrile rubber in the presence of zinc oxide or nano-zinc oxide containing waste keratin, using the test results obtained by means of a derivatograph, DSC, and oxygen index. The influence of modified montmorillonite (NanoBent) on selected properties of investigated elastomer–protein composites has also been studied. The composites' thermal stability and flammability depend on the method of composite preparation and the quantity of added keratin. The addition of waste keratin reduces the flammability of NBR–keratin composites.     

Thermal properties and combustibility of elastomer–protein composites

The article describes the measurements results of the influence of waste keratin on the properties of cross-linked styrene-butadiene rubber especially taking its thermal properties and flammability into consideration. The biopolymer used was thoroughly examined by means of derivatography, elementary analysis, FTIR spectroscopy, Zetasizer nano S90, and Zetasizer 2000. It has been found that the presence of protein facilitates the cross-linking of the elastomer investigated and the elastomeric-protein materials are characterized by good thermal and mechanical properties as well as a considerably increased resistance to thermooxidative aging. Under the influence of keratin, the flammability of the composites obtained is decreased.     

Ordered nanostructured ceramic–metal composites through multifunctional block copolymer-metal nanoparticle self-assembly

A novel strategy for fabrication of ordered ceramic–metal nanocomposites was demonstrated by multifunctional block copolymer/metal nanoparticle self-assembly. Hybrid organic–inorganic block copolymer poly(3-methacryloxypropyl-T8-heptaisobutyl-polyhedral oligomeric silsesquioxane-block-N,N-dimethylaminoethyl methacrylate) was synthesized and used as a bi-functional structure directing agent for ligand-stabilized platinum nanoparticles to form ordered organic–inorganic nanocomposites with dense loading of inorganic species in both microphase separated domains. Subsequently, thin films of the hybrid material were converted to ordered silica (ceramic)–platinum (metal) nanocomposites via UV-assisted ozonolysis. This is the first time ordered ceramic–metal nanocomposites were achieved through a bottom-up approach, opening up opportunities for the design and synthesis of a broad range of ordered inorganic–inorganic nanocomposites.     

Metal complexes and acid-base properties of Δ1 tetrahydrocannabinol

Despite very extensive efforts employing a wide variety of techniques and procedures, it has not been found possible to isolate solid metal ion complexes of Δ¹-tetrahydrocannabinol. Equilibria of Δ¹-tetrahydrocannabinol with protons and bivalent transition metal ions (Fe²⁺, Co²⁺, Cu²⁺), in t-butanol at 30·0° and ionic strength 0·015 M, have been investigated potentiometrically. The ligand behaves as a monovalent base. With respect to the variation of the metal ion with the same ligand, the stability increases in the order Fe < Co < Cu; this order is in accord with the Irving-Williams series.     

Study of the surface properties and surface concentration of ionic liquid–alcohol mixtures

Surface properties for three binary mixtures containing a 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and a long-chain alcohol (1-butanol, 1-pentanol and 1-hexanol) were determined by surface tension data at the following temperatures: (298.15, 308.15, 318.15, 328.15 and 338.15) K. The surface tension data over the entire mole fraction range are correlated by the Fu et al.(FLW) and Myers-Scott (MS) models. There is good agreement between the experimental data and the results of correlations for 15 binary systems (the three systems at five temperatures) with an average relative error below 1.5%. In addition, the UNIFAC group contribution method is applied for calculation of activity coefficients of components in solution. Moreover, the relative adsorptions of alcohol at the air/liquid interface are determined using Gibbs adsorption isotherm. The obtained results show that the values of adsorption for mixtures of alcohols/[BMIM][SCN] increase with increasing the alkyl chain length of alcohol and decreasing temperature.     

Synthesis and acid-base properties of new β-diaminophosphoryl compounds

Russian Journal of Organic Chemistry -     

Bulk and surface properties of ZnTe–ZnS system semiconductors

Physicochemical studies of a new ZnTe–ZnS semiconductor system are conducted. It is found that at certain ratios of binary components, substitutional solid solutions with a cubic sphalerite structure are formed in this system. Interrelated laws governing changes in the bulk (crystal chemical, structural) and surface (acid–base) properties with varying system composition are identified. It is assumed they can be attributed to the nature of the active (acid–base) sites. The presented data, observed patterns, and an interpretation of them are used not only to confirm earlier proposed mechanisms of atomic–molecular interaction on diamond-like semiconductors, but to search for promising materials for use in highly sensitive selective sensors for environmental and medical purposes as well.     

Thermodynamic and surface properties of Ge–Ga and Ge–Sb liquid alloys

Thermodynamic and surface properties of Ge–Ga and Ge–Sb liquid alloys have been studied using statistical mechanical formulations based on complex formation and that based on the concept of layered structure near the interface. The study showed that low level of complex formation of the form Ge _{2 Sb} exists in Ge–Sb toward the Ge-rich end of the concentration range and the surface properties of Ge–Ga are almost equal to their corresponding bulk equivalent.     

Adsorption and photocatalytic properties of nanodimensional titanium–zinc oxide composites

We have prepared nanodimensional mesoporous titanium–zinc oxide composites consisting of anatase, rutile, and zincite. The pore volume and specific surface of the samples increase with increasing zincite content, while the pore radius decreases. The titanium–zinc oxide nanocomposites display greater photocatalytic activity than ZnO or TiO₂ and the rate constants for the decomposition of substrates increase with their increasing adsorption.     

Catalytic and antimicrobial properties of α-amylase immobilised on the surface of metal oxide nanoparticles

New methods of obtaining products containing enzymes reduce the costs associated with obtaining them, increase the efficiency of processes and stabilize the created biocatalytic systems. In the study a catalytic system containing the enzyme α-amylase immobilized on ZnO nanoparticle and Fe₃O₄ nanoparticles was created. The efficiency of the processes was obtained with variables: concentrations of enzymes, temperatures and times, to define the best conditions for running the process, for which were determined equilibrium and kinetics of adsorption. The most effective parameters of α-amylase immobilization on metal oxides were determined, obtaining 100.8 mg/g sorption capacity for ZnO and 102.9 mg/g for Fe₃O₄ nanoparticles. Base on the best parameters, ZnO-α-amylase was investigated as an antimicrobial agent and Fe₃O₄-α-amylase was tested as a catalyst in the process of starch hydrolysis. As a result of the conducted experiments, it was found that α-amylase immobilized on Fe₃O₄ nanoparticles maintained high catalytic activity (the reaction rate constant K_M?=?0.7799 [g/dm³] and the maximum reaction rate V_max?=?8.660 [g/(dm³min)]).

     

Evaluation of thermal properties of zirconium–PHB composites

Journal of Thermal Analysis and Calorimetry - Most of the synthetic polymers that are used for packaging industry come from fossil fuel; thus, when their life cycle is complete, they normally...     

Structure and surface properties of fluorinated organic–inorganic hybrid films

Fluorinated organic–inorganic hybrid films were prepared by sol–gel process from tridecafluoroctyltriethoxysilane (PFAS), 3-glycidoxypropyltrimethoxysilane, and tetraethoxysilane (TEOS). It has been found that the fluorinated hybrid films possessed fluorinated side chains originating from PFAS as top layer, and silica network as bottom layer, which had very low surface energy and could be used as water repellent functional coatings. The outermost layer of the water-repellent film may be fully covered by the perfluoroalkyl side chains as the molar ratio of PFAS/TEOS increases up to about 0.005:1. The addition of BPA can enhance the cross-link density of fluorinated hybrid films, and make more perfluoroalkyl groups enriching at the coating film-air interface to lower the surface free energy. However, the improvement of the cross-link density of fluorinated hybrid films tends to exhibit brittleness and micro-cracks. Consequently, it can be concluded that a small BPA additive content is preferred for the formation of fluorinated hybrid films with a smooth surface and less detectable cracks.     

Thermal behavior of BST//PVDF ceramic–polymer composites

In this paper, we report the results of a study of microstructure and thermal behavior of ceramic–polymer composites composed of barium strontium titanate Ba_0.6Sr_0.4TiO₃ (BST60/40) and polyvinylidene fluoride (PVDF). The Ba_0.6Sr_0.4TiO₃ ceramic powder was prepared by the sol–gel method. Thermal evolution of the dried gel as well as ceramic powder was studied by simultaneous thermal analysis. The composite BST60/40//PVDF was obtained by hot pressing method for volume fraction of BST60/40 ceramic powder c _v = 50 %. The morphology of BST60/40//PVDF composite powder was observed by transmission electron microscopy and the morphology of BST60/40//PVDF composite sample was observed by scanning electron microscopy. Temperature dependence of dielectric constant and dielectric loss factor of BST60/40//PVDF composites was measured in the frequency range of f = (10 × 10³–1 × 10⁶) Hz. Dynamic mechanical properties of BST60/40//PVDF composites were measured by dynamic mechanical thermal analysis DMTA.     

Surface properties of sol–gel-based fluorine-containing ceramic coatings

In this work, sol–gel-based non-stick ceramic coating formulations were prepared and coated onto aluminum panels in order to investigate their surface properties. The effect of the addition of optimal amount of fluorine-containing silane compound (FAS) on the surface and adhesion properties were also investigated. The morphology, structure, and elemental chemical composition of the coatings were characterized by scanning electron microscopy, atomic force microscopy (AFM), energy dispersion spectrum (SEM/EDAX), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), respectively. Moreover, several properties of the coatings such as cross-cut adhesion, hardness, gloss, and contact angle (CA) were determined. When fluorine was introduced, the pencil hardness was increased to 6H. Fluorinated non-stick ceramic coatings were found to have good adhesion on the aluminum substrates.

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Physicochemical properties and catalytic activity of metal–carbon carrier composite materials

Composite metal–carbon materials are created on the basis of different kinds of carbon (multiwall carbon nanotubes, carbon black, Sibunit carbon–carbon material) and metals (Ag, Ni, Co), and their physicochemical and catalytic properties are investigated. It is shown that interaction between metals and carbon carriers proceeds not only with the functional groups on the surfaces of the carriers, but also through a system of–C–C–conjugated bonds. Silver deposited on the surface of a carbon carrier has a crystalline structure (d _cr = 10–15 nm), while nickel has an amorphous lamellar structure. Based on quantum-chemical calculations using the density functional theory, it is shown that cumene oxidation occurs via a homogeneous–heterogeneous mechanism.     

Effect of structural and thermodynamic factors on the sorption of hydrogen by metal–organic framework compounds

The characteristics of the sorption of hydrogen by metal–organic framework compounds (MOF) were examined, and the structural and thermodynamic factors that favor the sorption of H₂ by such substances were determined. The effect of the structure of the MOF and the size and geometry of the pores on the sorption characteristics was analyzed. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 2, pp. 67-87, March-April, 2009.     

Synthesis and photophysical properties of metal anthraquinone phthalocyanine

A novel anthraquinone phthalocyanine Al(Ⅲ) 4 and Co(Ⅱ) 5 were synthesized and characterized by elemental analysis, IR, UV/ vis, 1H NMR, HPLC and MS. The photophysical properties of the two metal complexes were studied and compared by ?uorescence spectrum method.