Volume 70, Issue 2

A novel structured La 2 O 3 /AAO solid base catalyst was prepared by supporting lanthanum oxide (La 2 O 3 ) on the surface of anodic aluminum oxide (AAO) under hydrothermal conditions. Catalytic activity of the catalyst was tested using self-condensation of acetone to diacetone alcohol as a probe reaction. The conversion of acetone reached 4.14 % with the diacetone alcohol selectivity of 98 % . The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), thermogravimetric analysis (TGA), N 2 adsorption–desorption (BET), and temperature programmed desorption (CO 2 -TPD). XRD patterns and SEM images indicated that La 2 O 3 nanoscale particles with high crystallinity were uniformly distributed over the AAO surface. The results of CO 2 -TPD showed that the calcination temperature led to the formation of medium-strength basic sites, strong basic sites, and to an increase of the basic strength. The strong basic sites and large basic strength are an important factor that influences the catalytic activity in the self-condensation of acetone to diacetone alcohol.

Accurate quantification of ellagic acid and its derivatives, ellagic acid glycosides and ellagitannins, present in plant-based foods is a vital prerequisite for any study of their health-promoting properties. This goal is impeded by the lack of commercially available standards and the fact that these three forms differ widely in solubility. This disparity necessitates careful attention being paid to the choice of extraction solvents to ensure that precise and reproducible content measurements are achieved. This work sought to devise an extraction protocol that is effective for all ellagic acid forms whilst keeping the water-insoluble free ellagic acid solubilised during all analysis stages. To overcome this unavailability of commercial standards, the designated “targeted” ellagic acid derivatives identified in the selected fruit were monitored during the course of extraction that employed a number of commonly used solvents. Large variations in the extraction yield of the solvents tested for the ellagic acid and its derivatives were identified, extending even to the different fruit samples for the same form. It is regarded as unlikely that any selected extraction solvent could be universally employed to effectively extract all the ellagic acid compounds; however, the use of the solvent 50 : 50 vol. methanol–dimethylformamide satisfied most requirements.

This investigation studied the uptake of methylene blue from wastewater by normal and treated bentonites to evaluate the effects of acidification factors on removal efficiency. Hydrochloric, sulphuric and nitric acids were blended in accordance with the response surface methodology to prepare acidic agents. The normal clay was then mixed with the prepared solutions after drying in a laboratory oven. The set-up provided controllable conditions for producing nano-porous powders for which the residence time and temperature were changed. The removal efficiency of the treated powders was assessed by defining an adsorption ratio and determining the optimal composition for acidic agent. Based on the statistical theory and experimental data, nitric acid is a suitable agent for manufacturing porous material to remove methylene blue from wastewater. In addition, the Brunauer–Emmett–Teller method, X-ray diffraction and Fourier transform infrared spectroscopy techniques were applied to identify the structural changes. The experimental data obtained from the batch tests were analysed by a new kinetic model which predicted the data variation with higher regression coefficients and lower relative errors. The proposed procedure can be an important tool in optimising the acidification conditions for manufacturing a nano-porous powder with maximal removal efficiency.

Palladium (Pd) nanoparticles were prepared using the phase transfer method and coated with alkylamines as stabilizing agents stably dispersed in nonpolar solvents. Spherical Pd nanoparticles with an average diameter of 4 nm and a relatively narrow size distribution were obtained using hexylamine or dodecylamine, and they were successfully incorporated in microemulsion-based gelatin organogel (OG); also, an OG network containing Pd nanoparticles was prepared via drying. For the Mizoroki–Heck cross-coupling reaction of iodobenzene with methyl acrylate in supercritical carbon dioxide, the Pd nanoparticles in the OG network exhibited much higher reactivity than those in powder state. Preparation conditions of OG (e.g., gelatin concentration) affected the apparent reactivity of the supported Pd nanoparticles. The Pd nanoparticles in the OG network with high gelatin concentration were recycled with no appreciable change of reactivity. In contrast, the reactivity of the Pd nanoparticles with low gelatin concentration decreased during recycling.

In this study, liquid membranes denoted as polymer inclusion membranes (PIMs) consisting of cellulose triacetate (CTA) as a polymer matrix, o -nitrophenyl octyl ether (NPOE) as a plasticizer and phosphonium ionic liquids, trihexyltetradecylphosphonium chloride (Cyphos ® IL 101) and trihexyltetradecylphosphonium bis (2,4,4-trimethylpentyl)phosphinate (Cyphos ® IL 104), as carriers of metal ions were developed. The transport of Fe(II) and Fe(III) from chloride aqueous solutions across PIMs was investigated. It is shown that these phosphonium ionic liquids are effective carriers of Fe(III) ions through PIMs. While, for Fe(II), the highest value of extraction efficiency and recovery factor after 72 h does not exceed 40 %, by contrast, the values of these parameters for Fe(III) transport ranged from 60 % to almost 100 %. Additionally, the results indicate the transport rate to be strongly influenced by the amount of carrier in the membrane. The highest initial flux of Fe(III) and permeability coefficient are noted for the membrane containing 40 mass % Cyphos ® IL 101. However, it is shown that the transport of Fe(III) increases as the carrier content is increased then decreases at a content of the carrier equal to 40 mass %. It appears that the Fe(III)-carrier complex decomposes with difficulty at the interface of the membrane-receiving phase, hence leading to low values of recovery factor Fe(III).

Coker naphtha was separated into ten distillation fractions equal in volume via Engler distillation. It was found that the mercaptan sulphur compounds were mainly concentrated in the lighter fractions, whereas the basic nitrogen compounds were concentrated in the heavier fractions. The gum content increased gradually with increasing the boiling point of each fraction after storage for 21 days under ambient conditions (25°C, 101 kPa). The active organic acidic compounds in coker naphtha extracted with aqueous solution of 20 mass % NaOH represented 0.26 mass %. The GCMS analysis of the active organic acidic compounds showed the amounts of small molecule thiols, thiophenols (including benzyl mercaptan) and phenolic compounds to be 2.6 %, 4.4 % and 90.0 %, respectively. After removal of the active acidic compounds by caustic scrubbing, the increase in the rate of gum formation was much slower than that of the blank coker naphtha after 27 days of storage under ambient conditions, indicating that the effect of these acidic compounds on the gum formation is more significant than with basic nitrogen compounds. It is demonstrated that the storage stability of coker naphtha was decreased in the presence of large amounts of phenolic compounds, which may accelerate the acid-catalysed polymerisation of olefins.

Biosurfactants have great advantages as an eco-friendly alternative to synthetic surfactants. Surface active properties and antioxidant activity of extracts prepared from Sapindus mukorossi, Verbascum densiflorum, Equisetum arvense, Betula pendula and Bellis perennis have been studied. The extract from Sapindus mukorossi served as a standard because it belongs to the most widely used natural surfactants. The surface active properties of these nonionic surfactants were also compared with the properties of common synthetic surfactants such as sodium lauryl sulfate (SLS) and Tween ® 80. In many cases, the plant-derived surfactants showed better properties than the synthetic ones, e.g. minimum critical micelle concentration values were observed for E. arvense (0.033 g L –1 ), B. perennis (0.076 g L –1 ), or minimum surface tension reached for the extract of B. perennis (36.8 mN m –1 ).

The interactions of selected zirconium alloys used as special construction materials (Zr-pure, Zry-2, E-110) with the molten system of (LiF–NaF–KF) (eut . ) with additions of K 2 ZrF 6 or Na 7 Zr 6 F 31 were studied. Corrosion losses of pure zirconium decrease sharply with 5 mole % addition of K 2 ZrF 6 to (LiF–NaF–KF) (eut). The presence of alloying additives (Sn, Nb) has a positive influence on corrosion resistance in the eutectic mixture – up to 60 % increase in corrosion resistance in comparison with pure zirconium. The mass losses of pure zirconium indicate an increasing corrosion attack with increasing Na 7 Zr 6 F 31 content in (LiF–NaF–KF) (eut . ) mixtures.

Large amounts of hydrocarbons are located in deeper formations where higher temperatures are experienced, hence designing a proper drilling fluid to tolerate such conditions has represented a challenging task for researchers in the field. The current work is focused on evaluating the effectiveness of poly(prop-2-enamide-sodium 2-acrylamido-2-methyl propane sulphonate-ethenyl ethanoate), designated as CP4 and poly(prop-2-enamide-sodium-prop-2-enoate- N,N ′ -dimethylprop-2-enamide- N -vinylpyrrolidone), denoted as CP5 as additives in water-based drilling fluids. The effect of temperature and salt on the copolymer-incorporated mud properties was examined. The reaction conditions were optimised for synthesis of the terpolymer and tetrapolymer. The chemical structures of copolymers were characterised by Fourier transform infrared (FTIR) spectroscopy. The thermal stability of the copolymers was assessed by thermogravimetric analysis (TGA). Both copolymers exhibited effectiveness in mud viscosity enhancement. The presence of the rigid pyrrole ring in CP5 and the bulky sulphonate side-group in CP4 provided thermal resistance and salt tolerance in their respective copolymer structures. CP4 demonstrated greater fluid-loss reduction by providing 7-fold American Petroleum Institute (API) fluid control and 8-fold high temperature high pressure (HTHP) fluid-loss control at 150°C while CP5 achieved 6-fold control in both parameters in comparison with the blank.

A new synthesised triphenylamine-based dye having a branched structure with one OH-ending branch able to interact with the surface hydroxyl moieties of mesoporous TiO 2 is reported. Optical properties of the dye-titania hybrid material are presented and the higher efficiency of the dye on pure anatase TiO 2 compared to the commercial Degussa P25, which contains a rutile phase component, is confirmed. The optical and chemical properties of the dye make it a promising candidate as a metal-free dye for DSSCs or as a host for a variety of transition or main group metal ions for different applications.

In this study, trimetallic catalysts were prepared via the co-precipitation and impregnation methods. In order to investigate the effect of impregnation on the catalytic activity and crystallite size, a trimetallic catalyst, Fe–Ni–Ce, was prepared through the co-precipitation method in one set of experiments, and cerium was impregnated with the Ni–Fe mixture in the final stage of the preparation in another set. Fourier transform infrared spectroscopy was employed to confirm the formation of trimetallic catalysts and the success of the impregnation method. The Brunauer–Emmett–Teller nitrogen adsorption isotherm exhibits a high specific surface area (approximately 39 m 2 g −1 ) for the nanoparticles obtained by the impregnation method. The crystallography and morphology of the trimetallic catalysts thus prepared were characterised by X-ray diffraction and scanning electron microscopy. UV-VIS spectroscopy and methylene blue dye degradation tests were also performed to investigate the catalytic activity of the synthesised catalysts. The crystalline size was found to be smaller for the catalysts prepared by the impregnation method. In addition, the samples synthesised using the cerium impregnation method showed superior activity in the methylene blue dye degradation test. The effect of the catalyst dosage on dye degradation, as well as the effect of the initial dye concentration on the catalyst activity, was also studied for both methods.

The formation and smooth recovery of ibuprofen encapsulated in microcapsules using gelatin and carboxymethyl cellulose (CMC) complex coacervation without glutaraldehyde were the objectives of this investigation. The microcapsules were recovered as ionically cross-linked beads using aqueous ferric chloride in 50 vol. % of 2-propanol. A physical mixture of CMC/gelatin (FP1) and CMC alone (FP2) beads was also prepared for comparison. The drug-entrapment efficiency of complex coacervate beads (FP3–FP5) was dependent on the drug-to-polymer ratio and was in the range of 86–92 mass %. Beads prepared with the highest ratio of the drug (FP5) exhibited the lowest entrapment. FP1 and FP2 beads exhibited an entrapment efficiency of 98.5 mass % and 91.3 mass %, respectively. Infrared spectroscopy (FTIR) revealed different functional groups in complex coacervate, physical mixture and FP2 beads. Optical and scanning electron microscopy revealed the distinct appearance and surface morphology of the various beads. The stable and crystalline nature of ibuprofen in the beads was confirmed by FTIR and differential scanning calorimetry (DSC), respectively. Ibuprofen release from FP1 and FP2 beads was very slow and unsuitable for oral delivery. The bead prepared by complex coacervation (FP5) showed a better release profile over 48 h and could be developed as a sustained drug delivery system.