Synthesis and Characterization of Novel Surfactants: Combination Products of Fatty Acids,Hydroxycarboxylic Acids and Alcohols

The reaction of hydroxycarboxylic acids, such as citric, malic and tartaric species with an excess of fatty acid chlorides produces the corresponding O-acylated hydroxycarboxylic anhydrides in one step and in a near quantitative yield. These molecules are excellent electrophiles which react readily with a variety of nucleophiles including alcohols, diols and polyols. Their reaction with triethylene glycol and triethylene glycol monomethyl ether leads to two series of novel anionic surfactants, which are unsymmetrical gemini surfactants. The determination of their properties (CMC, foaming, HLB) revealed that these molecules are—depending on the chain length of the fatty acid—excellent emulsifiers, and that they also display interesting antimicrobial activity. These novel functional surfactants are of interest for applications in food and personal care products and for the formulation of pharmaceuticals.     

Cross‐metathesis of methyl 10‐undecenoate with diethyl maleate: Formation of an α,ω‐diester via a metathesis reaction network

The cross‐metathesis of methyl 10‐undecenoate 1 derived from castor oil as a renewable raw material with diethyl maleate 2 was investigated. These reactions were carried out with several phosphine and N‐heterocyclic carbene ruthenium catalysts. The reaction conditions were optimised for high conversions in combination with high cross‐metathesis selectivity. This single‐step and atom‐economic synthetic method illustrates an efficient and selective preparation procedure of linear α,ω‐dicarboxylic acid esters starting from renewable resources and comparatively inexpensive base chemicals. Further by‐products are hardly obtained due to their consumption in secondary metathesis reactions. Hence, a sustainable alternative for polyamide and polyester monomers is presented.     

Recycling and Oligomerization Activity of Ni/Al Catalyst in a Biphasic System with Ionic Liquids

The catalyst decomposition in homogeneously catalyzed reactions is a very important factor that has been studied for the oligomerization of n‐butenes in a system of two liquid phases. A highly active catalyst [NiCl₂(PMe₃)₂] was investigated with an emphasis on the long‐term catalyst activity using N‐methylpyrrole as a buffer. The recycling experiments indicated that this catalyst is viable for five runs. Furthermore, introducing aluminum chloride or an ionic liquid in small concentrations led to increased stability, though fine adjustments were necessary to arrive at optimal results.     

Solid‐phase extraction of lead and copper on a polyhydroxybutyrate‐b‐polydimethyl siloxane (PHB‐b‐PDMS) block copolymer disc and flame atomic absorption spectrometric determination of them in water and food samples

A separation and preconcentration procedure based on solid‐phase extraction of Cu(II) and Pb(II) as their Sudan III chelates on polyhydroxybutyrate‐b‐polydimethyl siloxane (PHB‐b‐PDMS) block copolymer disc has been established. Various analytical parameters including pH, amount of Sudan III, eluent type and volume, sample volume, flow rates were optimised. The effects of concomitant ions on the retentions of the analyte ions on PHB‐b‐PDMS disc were also examined. The detection limits for Cu(II) and Pb(II) were found to be 2.3 and 4.9 μgL^?1, respectively. Preconcentration factor was found to be sixty. Relative standard deviation was found to be 5%. The accuracy of the method was confirmed by analysing certified reference materials (TMDA 54.4 fortified lake water and NIST 1515 Apple leaves). Optimised method was applied to determine the analyte ions in various water and food samples from Turkey.     

Silver/selenium/chitosan co-substituted bioceramic coatings of Ni–Ti alloy: Antibacterial efficiency and cell viability

The effects of silver (Ag), selenium (Se), and chitosan (Cht) additives on the antibacterial activity and cell viability of NiTi were investigated. Three different hydroxyapatite (HA)-based bioceramic coatings to improve the antibacterial activity and cell viability of NiTi; HA, HA/Ag, and HA/Se–Cht were applied to NiTi substrates by a sol–gel method. The coated samples were characterized by scanning electron microscopy–electron-dispersive spectroscopy and X-ray diffraction and surface hardnesses were measured. The antimicrobial efficiency of the coatings and uncoated surfaces were tested against Escherichia coli-JM 103 and Staphylococcus aureus-ATCC29293. In vitro cell–material interactions using Saos-2 osteoblast cells were characterized by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (mitochondrial activity test) assay for cell viability. A homogeneous, crack-free, and porous surface morphology is achieved in coatings. It has been shown that the Se–Cht additives did not have a significant effect on the surface hardness of the HA coating, but the Ag additive increased the hardness. Through in vitro antibacterial activity and cell viability tests, it was shown that Ag additive to bioceramic coatings significantly increased (p < .05) antibacterial properties but caused a decrease in cell viability. However, although Se–Cht additives did not have a significant effect on antibacterial properties (p < .05), it was observed that they increased cell viability.     

Antioxidant activity and phenolic content of wine vinegars produced by two different techniques

BACKGROUND: The presence of phenolics in fruit, red wine and vinegar has positive health effects due to their significant antioxidant activity. The aim of the study was to determine the effects of two different vinegar production methods on antioxidant activity and phenolic level of vinegars derived from Ulugbey Karasi grapes. Traditional surface and industrial submerge methods were used to make vinegar. Samples were taken from fresh red grape juice, maceration, wine, traditional vinegar and industrial vinegar. RESULTS: Total phenolic content of traditional and industrial vinegar samples were 2690 mg L^?1 and 2461 mg L^?1 GAE, respectively. ORAC values of traditional and industrial vinegar samples were 10.50 µmol mL^?1and 8.84 µmol mL^?1 TE, respectively. Antioxidant activity values of traditional and industrial vinegars were 13.50 mmol L^?1 and 10.37 mmol L^?1 TEAC, respectively. Gallic acid, catechin, epicatechin, chlorogenic acid, caffeic acid, syringic acid, p‐coumaric acid and ferulic acid were detected in grape juice, wine and vinegar samples. The content of catechin in industrial vinegar (27.50 mg L^?1) was significantly higher than that of in traditional vinegar (13.76 mg L^?1) (P < 0.05). Traditional vinegar had higher amounts of chlorogenic and syringic acids than the industrial vinegar (P > 0.05). CONCLUSION: Results of this study showed that different production methods affected the functional constituents of wine vinegars. Copyright © 2010 Society of Chemical Industry     

Monodisperse Pd nanoparticles assembled on reduced graphene oxide-Fe3O4 nanocomposites as electrocatalysts for borohydride fuel cells

5 nm palladium nanoparticles (Pd NPs) are synthesized and assembled on reduced graphene oxide-iron oxide nanocomposite (rGO-Fe₃O₄) to be used in oxygen reduction reaction (ORR) and borohydride oxidation reaction (BOR) studies in alkaline media. The structure and morphology of the resulting Pd/rGO-Fe₃O₄ hybrid material are evaluated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS) analyses. The electrochemical behavior of Pd/rGO-Fe₃O₄ hybrid material for the ORR and BOR is investigated by voltammetry with rotating disk and rotating ring disk electrode and electrochemical impedance spectroscopy, enabling evaluation of the number of exchanged electrons, Tafel slope, exchange current density and activation energy. The results reveal that ORR at Pd/rGO-Fe₃O₄ proceeds as a 2-electron process with Tafel slope of 0.133 V dec^?1, while BOR proceeds as a 5.6-electron process with Tafel slope of 0.350 V dec^?1 and exchange current density of 1.38 mA cm^?2. The BOR activation energy was found to be 12.4 kJ mol^?1. Overall, this study demonstrates the good efficiency of Pd/rGO-Fe₃O₄ hybrid material for BOR.     

The effects of heat treatment temperatures on photocatalytic activity of cobalt ferrite nanoparticles synthesised by microwave-assisted combustion method

In this study, the effects on the photocatalytic activities of particles after heat treatment has been applied to cobalt ferrite nanoparticles produced by microwave-assisted combustion method were observed. The heat treatment applied to the samples was produced with only the microwave effect, at temperatures ranging from 300 to 1000°C. Thermogravimetric analysis was performed on the precursor sample in air atmosphere. During this analysis, the gases released up to 1200°C were identified with a Fourier-transform infrared (FTIR) spectrometer integrated into a thermogravimetric analysis system. Then, the cobalt ferrite nanoparticles produced with heat treatments applied at various temperatures were used as a photocatalyst to remove the dyestuff content in synthetic wastewaters prepared by using Astrazon Red GTL textile dye by photocatalytic oxidation, and their photocatalytic activities were compared. In these experiments, the operational parameters for photocatalysis processes were applied as 400 rpm for stirring speed, 50 mg/L for initial contaminant concentration, 0.5 g/L for catalyst dosage, 25°C for temperature, and 4400 μW/cm² for light intensity. As a result of the experiments, it was observed that the crystal structure of the cobalt ferrite nanoparticles produced with the increase of the applied heat treatment temperature improved significantly. The obtained data show a strong relationship between the structural properties of materials and their photocatalytic activities. In addition, it was determined that the dyestuff in the solution was completely degraded in the experiments, and it was determined that all processes were compatible with the pseudo-first-order kinetic model.