Browsing Articles publicats (Química) by Issue Date
Now showing items 41-60 of 294
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Conditional equilibrium constants in multicomponent heterogeneous adsorption: The conditional affinity spectrum
(American Institute of Physics, 2006)The concept of conditional stability constant is extended to the competitive binding of small molecules to heterogeneous surfaces or macromolecules via the introduction of the conditional affinity spectrum (CAS). The CAS ... -
Transient biouptake flux and accumulation by microorganisms: the case of two types of sites with Langmuir adsorption
(Elsevier, 2006)The uptake of a chemical species by an aquatic microorganism is modelled considering two kinds of sites where Langmuirian adsorption is followed by first order internalisation kinetics. Simpler models, such as only one ... -
Procedimiento biotecnológico para la recuperación de Cr(III) de los efluentes de curtición
(Asociación Química Española de la Industria del Cuero, 2006)Hoy por hoy las aguas residuales de los procesos de curtición, donde el cromo se encuentra presente en cantidades significativas, pueden tratarse por métodos fisico-químicos y la eliminación de este metal es considerable. ... -
Transport Properties of the Ionic Liquid 1-Ethyl-3-Methylimidazolium Chloride from Equilibrium Molecular Dynamics Simulation. The Effect of Temperature
(American Chemical Society, 2006)We present here equilibrium molecular dynamics simulation results for self-diffusion coefficients, shear viscosity, and electrical conductivity in a model ionic liquid (1-ethyl-3-methylimidazolium chloride) at ... -
Interactions of Cadmium(II) and protons with dead biomass of marine algae Fucus sp.
(Elsevier, 2006)Samples of dead biomass from the marine brown algae Fucus ceranoides, F. vesiculosus and F.serratus were studied for their ability to remove cadmium from aqueous solutions. The metal sorption process is rapid, with 90% ... -
Computing steady-state metal flux at microorganism and bioanalogical sensor interfaces in multiligand systems. A reaction layer approximation and its comparison with the rigorous solution
(The Royal Society of Chemistry, 2007)In complicated environmental or biological systems, the fluxes of chemical species at a consuming interface, like an organism or an analytical sensor, involve many coupled chemical and diffusion processes. Computation of ... -
Full-wave analysis of stripping chronopotentiograms at scanned deposition potential (SSCP) as a tool for heavy metal speciation: Theoretical development and application to Cd(II)-phthalate and Cd(II)-iodide systems
(Elsevier, 2007)A new mathematical treatment has been developed and implemented in an EXCEL spreadsheet in order to determine average equilibrium functions from the full set of data measured by scanning stripping chronopotentiometry (SSCP) ... -
The use of microelectrodes with AGNES
(Elsevier, 2007)Absence of gradients and nernstian equilibrium stripping (AGNES) is a new electroanalytical technique designed to determine free heavy metal ion concentrations in solutions. AGNES had been applied, up to date, with ... -
A comparison between the determination of free Pb(II) by two techniques: Absence of gradients and Nernstian equilibrium stripping and resin titration
(Elsevier, 2007)Absence of gradients and Nernstian equilibrium stripping (AGNES) is an emerging electroanalytical technique designed to measure free metal ion concentration. The practical implementation of AGNES requires a critical selection ... -
AGNES: a technique for determining the concentration of free metal ions. The case of Zn(II) in coastal Mediterranean seawater
(Elsevier, 2007)Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) is a recently suggested electroanalytical technique designed for the determination of the free concentration of heavy metals (such as Zn, Cd or Pb) which is ... -
Electrostatic and specific binding to macromolecular ligands: a general analytical expression for the Donnan volume
(Elsevier, 2007)The dependence of the apparent acid dissociation constant of charged polyacids on the ionic strength and on the degree of dissociation is analysed in terms of the Donnan model. We introduce a new approximate analytical ... -
Electrostatic Effects in Biosorption. The Role of the Electrochemistry
(Sociedade Portuguesa de Electroquímica, 2007)Biosorption is the passive sequestration of pollutants by non-metabolizing non-living biomass. The technique emerged in 1980's as a possible alternative method for wastewater treatments in an environmentally friendly manner. ... -
Glycerol as a starting material to prepare palmitate derivatives
(Asociación de Químicos e Ingenieros del Instituto Químico de Sarriá, 2007)Glycidyl palmitate, used to obtain high purity monoglycerides and epoxy resins, can be obtained from glycerol using a two-step process. The first step of this new approach consists in a reaction of esterification-chlorination ... -
Volatile emission after controlled atmosphere storage of Mondial Gala apples (Malus domestica): relationship to some involved enzyme activities
(American Chemical Society, 2007)Mondial Gala apples were harvested at commercial maturity and stored at 1 °C under either air or controlled atmosphere (CA) conditions (2 kPa O2/2 kPa CO2 and 1 kPa O2/1 kPa CO2), where they remained for 3 or 6 months. ... -
Combining regio- and enantioselectivity of lipases for the preparation of (R)-4-chloro-2-butanol
(Wiley, 2007)Preparation of 98% ee (R)-4-chloro-2-butanol was carried out by the enzymatic hydrolysis of chlorohydrin esters, using fungal resting cells and commercial enzymes. Hydrolyzes were carried out using lipases from Candida ... -
Interpreting ion fluxes to channel arrays in monolayers
(American Chemical Society, 2007)The exponentially decaying permeability model interprets the chronoamperometric currents arising from Tl+ reduction at a Hg electrode covered with a phospholipid monolayer (DOPC) containing gramicidin monomer by combining ... -
Effect of the flexibility and the anion in the structural and transport properties of ethyl-methyl-imidazolium ionic liquids
(Elsevier, 2007)This work summarizes some results obtained through equilibrium molecular dynamic simulations regarding the structure and transport properties of several ionic liquids (ILs). The Green–Kubo relationships were employed to ... -
Competitive Ion Complexation to Polyelectrolytes: Determination of the Stepwise Stability Constants. The Ca2+/H+/Polyacrylate System
(American Chemical Society, 2007)This work presents a new methodology aimed at obtaining the stepwise stability constants corresponding to the binding of ions (or other small molecules) to macromolecular ligands having a large number of sites. For complexing ... -
Optimization and validation of PEF processing conditions to inactivate oxidative enzymes of grape juice
(Elsevier, 2007-12)White grape juice was processed using high intensity pulsed electric fields (PEF). The effect of this preservative technology on polyphenoloxidase (PPO) and peroxidase (POD) as well as on refractometric index, sugar content, ... -
[BMIM][PF6] Promotes the synthesis of halohydrin esters from diols using potassium halides
(Japan Society for Analytical Chemistry, 2008)Haloesterification of diverse diols with various carboxylic acids was achieved using potassium halides (KX) as the only halide source in ionic liquids. The best yield was obtained in [BMIM][PF6] when 1,2-octanediol, palmitic ...