Estolide production with modified clay catalysts and process conditions

The 20% yields of estolides prepared from oleic acid and meadowfoam oil fatty acids are improved when the montmorillonite clay catalysts are modified to increase their activity. Changes we explored included acidifying the clay, treating to increase the surface area of clay to introduce new active sites, and decreasing the ionic character of the clay surface to enhance adsorption of the fatty acids. We also evaluated the use of higher levels of clay in the reactions. Clays treated with Fe³⁺ salts increase the estolide yield from 21 to 27%, a 28% increase. Clay catalysts were also treated with surface-active reagents. The most active were cationic surfactants, and montmorillonite clays treated with cetyltrimethylammonium chloride increased the estolide yield to 30%. Estolide yields could not be improved beyond 30% by increasing the amount of clay. However, nitrogen sparging increases the efficiency of stirring and increased the estolide yield to 35% estolide.     

Equal Random Crystal Field of Mixed Spin-1 and Spin-3/2 System

The mixed spin-1 and spin-3/2 Ising system is investigated on the Bethe lattice at random distribution of crystal field which are taken equal at both spin sites. The investigations of thermal variations of the sublattice, net and average magnetizations have revealed that the system gives three compensation temperatures in contrary to the literature where only two of them are mentioned so far. The phase diagrams of the random crystal field case with probability p are also calculated at the range of 0 ≤ p < 1.0. It is found that in this range for equal crystal field case, the tricritical points disappear and only the second-order phase transitions are exhibited which is opposite to the case p = 1.0. In addition, we have also classified the thermal variations of average magnetizations according to the Néel nomenclature.     

Effect of Soil and Substructure Properties on Live-Load Distribution in Integral Abutment Bridges

This study is aimed at investigating the effect of soil–structure interaction and substructure properties at the abutments on the distribution of live-load effects in integral abutment bridge (IAB) components. For this purpose, numerous 3D and corresponding 2D structural models of typical IABs are built and analyzed under AASHTO live-load. In the analyses, the effect of various geotechnical and substructure properties such as foundation soil stiffness, considering and neglecting the effect of backfill, backfill compaction level, considering and neglecting the effect of wingwalls, abutment height and thickness, as well as number, size, and orientation of the piles are considered. The results from the 2D and 3D analyses are then used to calculate the live-load distribution factors (LLDFs) for the components of IABs as a function of the above-mentioned properties. The analyses results revealed that soil–structure interaction has a significant effect on the LLDFs for the abutment, but negligible effects on those for the girders and piles. Furthermore, the abutment height is observed to have a considerable effect on the LLDFs calculated for the abutment and pile moments. Moreover, the wingwalls are observed to have only a negligible effect on the LLDFs for all the IAB components.     

Metal chelating properties of Cibacron Blue F3GA‐derived poly(EGDMA‐HEMA) microbeads

Metal chelating properties of Cibacron Blue F3GA‐derived poly(EGDMA‐HEMA) microbeads have been studied. Poly(EGDMA‐HEMA) microbeads were prepared by suspension copolymerization of ethylene glycol dimethacrylate (EGDMA) and hydroxy‐ethyl methacrylate (HEMA) by using poly(vinyl alcohol), benzoyl peroxide, and toluene as the stabilizer, the initiator, and the pore‐former, respectively. Cibacron Blue F3GA was covalently attached to the microbeads via the nucleophilic substitution reaction between the chloride of its triazine ring and the hydroxyl groups of the HEMA, under alkaline conditions. Microbeads (150–200 μm in diameter) with a swelling ratio of 55%, and carrying 16.5 μmol Cibacron Blue F3GA/g polymer were used in the adsorption/desorption studies. Adsorption capacity of the microbeads for the selected metal ions, i.e., Cu(II), Zn(II), Cd(II), Fe(III), and Pb(II) were investigated in aqueous media containing different amounts of these ions (5–200 ppm) and at different pH values (2.0–7.0). The maximum adsorptions of metal ions onto the Cibacron Blue F3GA‐derived microbeads were 0.19 mmol/g for Cu(II), 0.34 mmol/g for Zn(II), 0.40 mmol/g for Cd(II), 0.91 mmol/g for Fe(III), and 1.05 mmol/g for Pb(II). Desorption of metal ions were studied by using 0.1 M HNO₃. High desorption ratios (up to 97%) were observed in all cases. Repeated adsorption/desorption operations showed the feasibility of repeated use of this novel sorbent system. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1397–1403, 1999     

An efficient synergistic Co@CQDs catalyst for hydrogen production from the hydrolysis of NH3BH3

Journal of Materials Science: Materials in Electronics - We report the synthesis of carbon quantum dots supported-Co (Co@CQDs) catalyst and its catalytic activity. The synthesized Co@CQDs catalyst...     

An environmentally friendly process; adsorption of radionuclide Tl-201 on fibrous waste tea

This work presents an investigation of the adsorption of the radionuclide of Tl-201 from waste water on the fibrous tea factory waste. The experimental parameters were chosen as temperature, pH, stirring speed, adsorbent dose and nominal particle size in the ranges of 10.0-40.0 degrees C, 2.0-10.0, 300-720 rpm, 1.0-15.0 g/L and 0.15-0.71 mm, respectively. The most effective parameter on the adsorption yield was found to be pH of the solution. Fourier transforms infrared and electron paramagnetic resonance spectroscopy studies were performed for the characterisation of the adsorption on tea waste. The experimental data were found to be in good agreement with the isotherm models of Freundlich, Halsey, Handerson and Dubinin-Radushkevich. Thermodynamic analysis showed that the values of Delta G and Delta H are negative. It was obtained that the adsorption rate can be represented very well by second-order pseudo homogeneous kinetic model. All the results proved that fibrous tea plant waste makes an excellent adsorbent for Tl-201 radionuclide.     

Modification of epoxidized soybean oil for lubricant formulations with improved oxidative stability and low pour point

To produce soybean oil-based lubricants with good oxidative stability and low pour point, epoxidized soybean oil (SBO) was chemically modified. Epoxidized SBO was reacted with various alcohols in the presence of sulfuric acid as a catalyst to give a ring-opened intermediate product. In this step, the epoxy group was transformed to the functional group of-CH(OR¹)CH(OH)-(where the R¹=methyl, 1-butyl, 2-butyl, 1-hexyl, cyclohexyl, 2,2-dimethyl-1-propyl, or 1-decyl). The ¹H nuclear magnetic resonance spectra of the products indicated that transesterification was accompanied by the ringopening reaction except when the bulky 2,2-dimethyl-1-propanol was used. Acid anhydride was used to esterify the hydroxy groups in the ring-opened product. This resulted in a fluid that is a lubricant candidate with the functional group of −CH(OR¹)CH(OCOR²)−. Pour point studies of the resulting products showed that the pour points varied with the substituents, R¹ and R². Products with R¹=CH₃(CH₂)₅₋ and R²=CH₃(CH₂)₂₋, (CH₃)₂CH−, or CH₃(CH₂)₄-showed the lowest pour points (−39, −39, and −45°C, respectively) when 1% of pour point depressant was added. For the oxidative stability test, two products, in which R¹, R²=CH₃(CH₂)₅₋, (CH₃)₂CH− and R¹, R²=CH₃(CH₂)₅₋, CH₃(CH₂)₄₋, were chosen for a modified Penn State micro-oxidation test. In the oxidative stability test, the products gave 69–71% of oxidative evaporation and 10–17% of tetrahydrofuran-insoluble deposits in 3 h at 175°C. The amounts of deposits were much lower than those of soybean oil (96%) and epoxidized SBO (83%) and even less than those of most petroleum-based lubricant basestocks (3–93%).     

Specific sorbents for bilirubin removal from human plasma: Congo red-modified poly(EGDMA/HEMA) microbeads

Congo Red-modified poly(EGDMA–HEMA) microbeads were investigated as a specific sorbent for bilirubin removal from human plasma. Poly(EGDMA–HEMA) microbeads were prepared by a modified suspension copolymerization technique. Congo Red was covalently incorporated into the poly(EGDMA–HEMA) microbeads via condensation reactions between the aromatic amine groups of the dyes and the hydroxyl groups of the HEMA, under alkaline conditions. Bilirubin adsorption was investigated from hyperbilirubinemic human plasma on the poly(EGDMA–HEMA) microbeads containing different amounts of attached Congo Red (between 2.5 and 14.6 μmol/g). The nonspecific bilirubin adsorption on the unmodified poly(EGDMA–HEMA) microbeads were 0.32 mg/g from human plasma. High adsorption rates were observed at the beginning, and the adsorption equilibrium was then gradually achieved in about 30–60 min. Much higher bilirubin adsorption values, up to 11.7 mg/g, were obtained with the Congo Red-modified microbeads especially at 37°C. The numbers (as μmol) of bilirubin molecules to albumin molecules adsorbed on the sorbent microbeads were in the range of 15–20, which showed that bilirubin molecules were preferentially adsorbed to the Congo Red-modified microbeads. Bilirubin adsorption increased with increasing temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:373–380, 1998     

Comparison of metal chelate affinity sorption of BSA onto Dye/Zn (II)-derived poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) microbeads

Poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) [poly-(EGDMA-HEMA)]microbeads in the size range of 150–200 μm were produced by a modified suspension copolymerization of EGDMA and HEMA. The dyes (Congo red, Cibacron blue F3GA, and alkali blue 6B) were covalently immobilized; then, Zn(II) ions were incorporated within the microbeads by chelation with the dye molecules. The maximum amounts of dye loadings were 14.5 μmol/g, 16.5 μmol/g, and 23.7 μmol/g for Congo red, Cibacron blue F3GA, and alkali blue 6B, respectively. Different amounts of Zn(II) ions(2.9–53.8 mg/g polymer) were incorporated on the microbeads by changing the initial concentration of Zn(II) ions and the pH of the medium. Bovine serum albumin (BSA) adsorption onto dye/Zn(II)-derived microbeads containing Congo red, Cibacron blue F3GA, and alkali blue 6B was investigated. The maximum BSA adsorptions onto the dye/Zn(II)-derived microbeads from aqueous solutions containing different amounts of BSA were 159 mg/g, 122 mg/g, and 93 mg/g for the Congo red, Cibacron blue F3GA, and alkali blue 6B dyes, respectively. The maximum BSA adsorptions were observed at pH 6.0 in all cases. Desorption of BSA molecules was achieved by using 0.025M EDTA (pH 4.9). High desorption ratios (more than 93% of the adsorbed BSA) were observed in all cases. It was possible to reuse these novel metal chelate sorbents without significant losses in their adsorption capacities. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2085–2093, 1997     

Dithiocarbamate-incorporated monodisperse polystyrene microspheres as specific sorbents: Adsorption of cadmium ions

In this study, adsorption of cadmium ions from aqueous solutions by using dithiocarbamate-incorporated monodisperse crosslinked polystyrene (PS)-based sorbents was investigated. Monodisperse PS microspheres with a diameter of 2 μm were produced by dispersion polymerization of styrene in isopropyl alcohol/water by using polyvinylpyrrolidone and azobisisobutyronitrile as stabilizer and initiator, respectively. These microspheres were then crosslinked by using divinylbenzene. In order to incorporate dithiocarbamate functional groups on the PS microsphere, first benzylamine was physically absorbed, then the amine groups were transformed into dithiocarbamate groups by interacting these microspheres with carbon disulphide. These PS-based sorbents carrying physically entrapped benzyl dithiocarbamate were characterized by scanning electron microscopy, optical microscopy, FTIR, and elemental analysis. Adsorption of cadmium ions on the PS-based sorbents were investigated in the batch equilibrium experiments by using atomic absorption spectrophotometer. Adsorption rates were very fast. Adsorption equilibria were achieved within 5-60 min. The highest adsorption capacity achieved was 154.1 mg cadmium/g sorbent. The most suitable pH was 6.0. © 1996 John Wiley & Sons, Inc.