Vol 89, No 12 (2016)

Possibility of forming the solid phase of copper(I) and (II) sulfides in ammonia and acetate solutions at pH values exceeding 10 was demonstrated by calculation with the use of thiocarbamide. Mirror-like nanocrystalline layers of exclusively monovalent copper sulfide Cu₂S of stoichiometric composition with thicknesses of up to 110 ± 10 nm were formed on glass-ceramic substrates at 298–343 K via chemical deposition from solutions of both kinds due to the reducing properties of thiocarbamide. The films produced from the acetate system are more uniform and are constituted by globules (~10 nm) forming agglomerates up to 80–150 nm in diameter. According to X-ray diffraction data, they are crystallized in the chalcocite structure (space group P21/c) with crystal lattice constants a = 1.5307(5) Å, b = 1.1908(5) Å, c = 1.3485(6) Å, and β = 116.60(1)°.

Sodium-carboxymethylcellulose inhibits the crystallization of calcium carbonate and sulfate on the surface of stainless steel in a supersaturated aqueous solution at 80°C. An increase in the size of calcium carbonate crystals and a change of their structure is observed in the presence of sodium-carboxymethylcellulose. The data obtained indicate that development of new “green” reagents for oil and gas extraction, scale inhibitors, on the basis of sodium-carboxymethylcellulose is promising.

Effect of the catalyst composition on the structure of nanotubes layers obtained on the surface of carbon nanofibers was studied. We found the preliminary functionalization of the surface of carbon fibers to affect the coating uniformity and the thickness of synthesized nanotube layer. We determined the optimal surface concentration of the catalyst (Fe–Co) which provides uniform layer of nanotubes on the surface of carbon fibers. The effect of modification of the surface of carbon fibers with multi-walled carbon nanotubes on the mechanical properties of carbon fiber–epoxy resin composites was examined. The modification of the carbon fibers with multi-walled carbon nanotubes were shown to increase the flexural modulus and the flexural strength.

In this project, microwave (MW) irradiation, photolysis, and photo catalyst were used for degradation of 4-chloro-2-nitro phenol (4-C2NP) in aqueous environment. The influence of main operating parameters such as initial pH, initial concentration of 4C2NP, power dissipation and the dosage of TiO2 on the degradation efficiency has been investigated. The optimum conditions was obtained such as initial concentration of 4C2NP at 30 mg L⁻¹, initial pH at 6, power dissipation at 16 W for UV irradiation, and the amount of TiO₂ at 0.2 g L⁻¹. The removal of 4C2NP and chemical oxygen demand (COD) after 100 min of reaction in the combined method (MW/UV/TiO₂) was obtained as 80.5% and 47.3%, respectively. Almost all processes are followed from the pseudo first order kinetics and the degradation rate of 4C2NP obeyed the following order: UV/TiO₂/MW > UV/TiO₂ > MW/UV > UV>MW.

N,N′-dipyridoxyl(1, 4-butanediamine) (PYBA) (2 wt % ), nitrobenzene (66 wt %), sodium tetra phenyl borate (2 wt ), and poly vinyl chloride (30 wt %) were applied to create a PVC membrane in Ho³⁺ selective electrode (Ho-SE). Over the concentration range of 1.0 × 10^‒5 to 1.0 × 10^‒2 M in holmium(III) solution a linear response with lower detection of limit equal 4.0 × 10^‒6 M was exhibited by new holmium(III) sensor. Ho-SE possessed a Nernstian slope of 20.1 ± 0.8 mV decade^‒1 in very short time spans (~9 s). The potential response of electrode remains without any changes over a pH range of 2.77–8.71. The selectivity coefficient data which was considered by matched potential method for variety of common cations indicated no significant interference. An acceptable recovery for Ho³⁺ in the blend of several cations has been achieved. The utility of Ho-SE in potentiometric titration as an end point indicator electrode gave successfully results.

The viscoelastic surfactant (VES) fracturing fluid is new fracturing system, which is primarily made up of viscoelastic surfactant and some other auxiliaries. The traditional VES fracturing fluid has the obvious advantages in gel breaking, flowing back, carrying sands, etc. However, they are centered largely in the aspects of medium and low temperature system. In this paper, the work is focus on the need for the VES fracturing fluid with high temperature resistance. In the experiment, four kinds of viscoelastic surfactants with hydroxyl were firstly synthesized, which were named C₁₄-1, C₁₆-1, C₁₄-2 and C₁₆-2 respectively. Then the formulation of VES fracturing fluid was determined in accordance with the apparent viscosity of solution, and the formulation was that concentration of C₁₆-2 and NaSal were 2.5% and 1% respectively. It was found that the VES fracturing fluid has excellent effectiveness via testing properties of temperature resistance, shear stability, sand-carrying and gel breaking. When the temperature of system was 144°C, the apparent viscosity of the VES fracturing fluid was 25 mPa s, which could demand the requirements of carrying sands as well as support agents, and it could resist high temperature well. It is also observed that the VES fracturing fluid is the pseudoplastic fluid, which contributes to getting the cracks with excellent negotiability.

Some inorganic-organic hybrid pigments were fabricated by depositing pigment yellow 12(P.Y.12) on the surface of three inorganic cores with different particle size (white carbon black,microsilica,palygorskite). Effect of inorganic cores on the morphology and structure of the hybrid pigments were systematically investigated by nanoparticle analyzer, Fourier transforms infrared spectroscopy, and X-ray diffraction. Results showed that all three inorganic cores were encapsulated by the organic pigment. The particle size of hybrid pigments was all smaller and had narrower diameter scatter than the original pigment. The water dispersion and flow ability of these fabricated pigments were slightly improved. Thermal and UV-Vis analyses showed that the hybrid pigments had better thermo- and photo-stabilities. Additionally, the properties of the hybrid pigments including color strength, lightness, and yellow hue index were also improved and the modified pigment with white carbon black had the best coloring performance and better heat resistance than original P.Y.12.

Nanostructures TiO₂–SiO₂ photocatalysts were successfully synthesized using the sol-gel method, hydro-calcination, co-precipitation and room-temperature solid-phase synthesis technology. X-ray powder diffraction pattern (XRD), Fourier transform infrared spectrum (FTIR), photoluminescence (PL) spectra, thermal analyses (TG–DTA), scanning electron micrographs (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) were used to characterize the as-synthesized catalysts. Photocatalytic performances of the catalysts were evaluated by the degradation of methyl orange (MO) under s imulated natural light and the degradation rate of MO is 97.2%. The composites showed a good stability: after five recycling runs there are no significant decreases in the photocatalytic activity. The photodegradation of methylene blue, rhodamine B, methyl violet, naphthol green B, basic fuchsin, malachite green, and methyl red were also tested, and the degradation rate of dyes could reach over 94.2 %. A possible mechanism for the photocatalysis with the TiO₂–SiO₂ was proposed.

Biodiesel containing almost no glycerol has been produced by coupling reaction carried out over K₂CO₃ supported by calcium oxide as solid base catalysts. The solid base catalysts synthesized by wet impregnation exhibit an exceedingly high activity in biodiesel production. It was found that the reaction time required for the highest yield of biodiesel, 99.2%, can be shortened to 30 min over K₂CO₃/Al₂O₃ under the optimum reaction conditions: 8: 1: 1 molar ratio of methanol/DMC/oil, 30 wt % K₂CO₃/Al₂O₃ catalyst, and 65°C reaction temperature. Solid basic catalysts examined in the study were characterized by BET surface area, XRD, CO₂-TPD, and SEM techniques. The strong interaction between K₂CO₃ and the support yields a new basic active site, which can be probably responsible for the high activity of K₂CO₃/Al₂O₃.

The photocatalytic oxidative desulfurization is one of the promising processes to realize the deep desulfurization of the fuel. A series of TiO₂ nanoparticles (TiO₂ NPs) were prepared to investigate the effect of annealing temperatures on its physical properties and the photocatalytic oxidative desulfurization performance. Their physicochemical properties were investigated by X–ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermal gravimetric and differential thermal analysis (TG–DTA), scanning electron microscopy (SEM), and X–ray energy dispersive spectrometer (EDS). The results show that, the crystallite structure of TiO₂ NPs annealed at 250–450°C was mainly composed of anatase phase. The rutile phase appeared when the anneal temperature increased to 550°C and all of the anatase converted into rutile phase when annealed at 750°C. The effect of crystallite structure of TiO₂ on its photocatalytic oxidative desulfurization performance was investigated using benzothiophene (BT) as the model sulfur compound. The anatase phase was preferable for the photocatalytic oxidation of BT. Phase transfer catalyst plays an important role for improving the photocatalytic desulfurization rate. The photocatalytic oxidative reaction mechanism was also proposed in the presence of TiO₂ as catalyst, H₂O₂ as oxidant, and the DMDAAC as phase transfer catalyst. In the heterogeneous catalytic system, the entire reaction rate is mainly determined by the oxidation reaction and the extraction process, in which the oxidation process could be the rate determining step.

With thermal chemical reaction, the chemically bonded ceramic coatings are prepared on A3 steel. Influence of zinc oxide on corrosion resistance of the coating is investigated by corrosion polarization analysis. It is found that the chemically bonded ceramic coatings show the outstanding corrosion resistance. In addition, the coating with zinc oxide possesses a smaller reaction rate and corrosion current density than the coating without zinc oxide. Scanning electron microscope (SEM) analysis and X-ray diffraction (XRD) analysis are conducted to find the reason. Without adding zinc oxide, AlPO₄ is the main binding phase connecting with the particles in the coating, and the micro structure of the particles can be seen clearly. However, with adding zinc oxide, a new binding phase Zn3(PO₄)₂ is found in the coating. Besides, the particles in the coating are fully covered with Zn₃(PO₄)₂ and AlPO₄, and the micro structure of the particles cannot be clearly seen. The particles have a better cover with the binding phase compared with the particles without zinc oxide. Therefore, adding zinc oxide makes the coating more compact that hinders access of H₂O, O₂, and Cl^– to the substrate with the compact coatings, which improves the corrosion resistance of the chemically bonded ceramic coatings.

Specific features of synthesis of network polymers based on tetrazolylethyl cellulose ethers by alkylation of tetrazole rings in the structure of the cellulose derivative with di- and polyfunctional oligomeric and polymeric oxiranecontaining compounds were studied. The influence exerted by the structure of the cross-linking agents on the time parameters of the network structure formation, degree of the polymer cross-linking, ability of the network polymers obtained to absorb various liquids, and pH and temperature sensitivity of the hydrogels based on cross-linked tetrazolylated cellulose was considered.