Search results for "SOLVENT"
showing 10 items of 1395 documents
Supramolecular Hydro- and Ionogels: A Study of Their Properties and Antibacterial Activity.
2017
Diimidazolium-based organic salts, bearing peptides or amino acids as anions have been synthesised and tested for their gelling ability in biocompatible solvents. These low molecular weight salts were successfully used as gelators in phosphate buffered saline (PBS) solution and ionic liquids. Then, the properties of the obtained soft materials were analysed in terms of melting temperature and gel strength as accounted for by rheological investigations. The gel-phase formation was studied by using UV/Vis and resonance light scattering measurements, whereas the morphology of the soft materials was analysed by using polarised optical microscopy and scanning electron microscopy. To get informat…
Determination of Glyphosate and AMPA in Food Samples Using Membrane Extraction Technique for Analytes Preconcentration
2021
The method for determining glyphosate (NPG) and its metabolite AMPA (aminomethyl phosphonic acid) in solid food samples using UAE-SLM-HPLC–PDA technique was developed. Firstly, ultrasonic-assisted solvent extraction (UAE) and protein precipitation step were used for the analyte isolation. Then, the supernatant was evaporated to dryness and redissolved in distilled water (100 mL). The obtained solution was alkalized to pH 11 (with 1 M NaOH) and used directly as donor phase in SLM (supported liquid membrane) extraction. The SLM extraction was performed using 2 M NaCl (5 mL) as an acceptor phase. The flow rate of both phases (donor and acceptor) was set at 0.2 mL/min. The membrane extraction t…
Determination of Glyphosate and AMPA in Food Samples Using Membrane Extraction Technique for Analytes Preconcentration
2022
The method for determining glyphosate (NPG) and its metabolite AMPA (aminomethyl phosphonic acid) in solid food samples using UAE-SLM-HPLC–PDA technique was developed. Firstly, ultrasonic-assisted solvent extraction (UAE) and protein precipitation step were used for the analyte isolation. Then, the supernatant was evaporated to dryness and redissolved in distilled water (100 mL). The obtained solution was alkalized to pH 11 (with 1 M NaOH) and used directly as donor phase in SLM (supported liquid membrane) extraction. The SLM extraction was performed using 2 M NaCl (5 mL) as an acceptor phase. The flow rate of both phases (donor and acceptor) was set at 0.2 mL/min. The membrane extraction t…
MICROWAVE-ASSISTED FUNCTIONALIZATION OF HALLOYSITE NANOTUBE SURFACE
2014
Halloysite, Al2Si2O5·2H2O, is a naturally occurring two-layered alluminosilicate, chemically similar to kaolin, which has a predominantly high-aspect-ratio hollow tubular structure in the submicrometer range and an internal diameter in the nanometer range. The size of halloysite nanotubes (HNTs), generally varies from 50 to 70 nm in external diameter, ca. 15 nm diameter lumen, and 0.5 to 1 μm in length. Halloysite tubes have aluminol (Al-OH) groups on the internal surface and siloxan groups (Si-O-Si) on the external surface. The very large diameter of the halloysite lumen makes it potentially suitable for the accommodation of a range of guests. In recent reports, for example, the mesoporous…
The Role Played by Ionic Liquids in Carbohydrates Conversion into 5-Hydroxymethylfurfural: A Recent Overview
2022
Obtaining industrially relevant products from abundant, cheap, renewable, and low-impacting sources such as lignocellulosic biomass, is a key step in reducing consumption of raw fossil materials and, consequently, the environmental footprint of such processes. In this regard, a molecule that is similar to 5-hydroxymethylfurfural (5-HMF) plays a pivotal role, since it can be produced from lignocellulosic biomass and gives synthetic access to a broad range of industrially important products and polymers. Recently, ionic liquids (ILs) have emerged as suitable solvents for the conversion of biomass and carbohydrates into 5-HMF. Herein, we provide a bird’s-eye view on recent achievements about t…
Examples of UV–Vis profiles use as tool for evidence of the metallophthalocyanines transformation
2017
Abstract The UV–Vis spectra for a set of MPcs (Mmetal, Pc = phthalocyanine ligand), i.e.: In(III)PcI (1), Hf(IV)PcI2Pht (Pht = phthalonitrile) (2), Sn(II)Pc (3), Sn(IV)PcI2 (4), and Ge(IV)PcI2 (5) have been examined in two solvents, O-donative acetylacetone, and non-coordinative benzene. The UV–Vis spectra in Hacac solution of 1,2 and 4,5 shows that the axially ligated iodine atoms are replaced by (acac)− anions of the solvent, whereas in 3 the oxygen donors of the solvent causing the auto-oxidation of Sn(II) to Sn(IV) ions and as a result the Sn(II)Pc is transformed into the Sn(IV)Pc(acac)2. The chloride complexes of the 1–5 compounds are formed at Hacac solution after acidification by hyd…
Rapid one-step solvent-free acid-catalyzed mechanical depolymerization of pine sawdust to high-yield water-soluble sugars
2017
Abstract One-step absolute solvent-free acid-catalyzed mechanical depolymerization of pine sawdust (PSD) and commercially available α-cellulose to water-soluble sugars was carried out using ball milling. For comparison purposes, the commonly reported “solvent-free” mechanocatalytic depolymerization of lignocellulose method, which normally involves three steps (acid impregnation in solvent, vacuum drying, and mechanical depolymerization of lignocellulose), was performed. The 3,5-dinitrosalicylic acid (DNS) method was used to measure the total reducing sugar (TRS) of the obtained sugar solution, and major monosaccharides in the solution were analyzed by capillary electrophoresis (CE). More th…
A solvent-free regioselective iodination route of ortho-carboranes.
2006
Tetraiodo-ortho-carborane based X-ray contrast agents can be readily prepared in a high yield, fast, clean, regioselective fashion by a solvent-free reaction of ortho-carboranes with iodine in sealed tubes.
Crystal structure of a CsF-uranyl-salen complex. An unusual cesium-chlorine coordination.
2006
Complexation of CsF with the ditopic uranyl-salen receptor results in a solid-state structure, in which the coordination sphere of cesium is filled by ligation to one of the chlorine atoms of the solvent chloroform. This X-ray structure is the first example of chloroform ligation to an alkali-metal ion.
Barrier properties of chitosan coated polyethylene
2012
The transfer properties of chitosan coated polyethylene (PE) films were studied. The barrier properties of non coated PE were not affected by relative humidity changes. The presence of the hydrophilic chitosan layer acted as a water reservoir on the polyethylene film surface which significantly promoted its sensitivity to the water vapour. The water vapour permeability increased 1.85 times at a higher RH. Coated PE films showed more than two-order decrease in the oxygen permeability (PO2) and three-order-decrease in the carbon dioxide permeability (PCO2). When the chitosan coated PE surface was exposed to the water vapour, the PO2 and the PCO2 were significantly increased. However, the perm…