Effect of solution temperature, pH and ionic strength on dye adsorption onto Magellanic peat.

The aim of this research was to study the effect of the solution temperature, pH and ionic strength on the adsorption of the Basic Blue 3 (BB3) and Acid Black 1 (AB1) dyes in Magellanic peat. The peat used was physically characterized as fibrous, of low decomposition level, without the presence of crystalline material and with a highly porous morphology. The functional groups with major concentration in the surface adsorbent were the carboxylics and phenolics, with values of 0.91 and 0.47 mmol/g, respectively. The results of the batch assays showed that the adsorption of the AB1 dye was strongly dependent of electrical charge density on the surface, contrary to what occurred to the BB3 dye, because the interactions between the dyes and carboxylic groups of the peat could be either electrostatic or non-electrostatic. The Langmuir, Freundlich and Sips isotherm models were fitted to the experimental data; among them, the Sips model presented the best adjustment quality. The maximum adsorption capacities for BB3 and AB1 dyes were 33.1 and 33.7 mg/g, respectively. The adsorption of BB3 dye onto Magellan peat has an exothermic behaviour, obtaining an adsorption enthalpy of -3.44 kJ/mol. Contrarily the adsorption of AB1 has an adsorption enthalpy of 56.76 kJ/mol.

High-performance liquid chromatographic separation of rolipram, bupivacaine and omeprazole using a tartardiamide-based stationary phase influence of flow rate and temperature on the enantioseparation.

Chromatographic separation of the chiral drugs rolipram, bupivacaine and omeprazole on a tartardiamide-based stationary phase commercially named Kromasil CHI-TBB is shown in this work. The effect of temperature on the chromatographic separation of the chiral drugs using the Kromasil CHI-TBB stationary phase was determined quantitatively so as to contribute toward the design for the racemic mixtures of the named compound by using chiral columns. A decrease in the retention and selectivity factors was observed, when the column temperature increased. Van't Hoff plots provided the thermodynamic data. The variation of the thermodynamic parameters enthalpy and entropy are clearly negative meaning that the separation is enthalpy controlled.

Kinetic modeling of proteins adsorption with a methodology of error analysis.

The estimation of adsorption parameters for chromatographic systems is a very important step for column characterization used in the design of continuous separation equipments. The turbulent hydrodynamics aspect of batch procedures makes the kinetic modeling an interesting tool for the process modeling used for the determination of the main parameters that will be considered in the equipment design. The implemented irreversible kinetic model, which depends on both solute and site concentrations, was found to be very effective in the experimental correlation of two different enzyme adsorption systems: adsorption of Inulinases and beta-Galactosidase using two different adsorbents, the CM-Sepharose CL-6B and Accell plus QMA, respectively. The implementation of an error analysis methodology associated with an inverse problem approach was successful in determining the kinetic parameters with high accuracy. The simulations indicated a decrease in the kinetic constants with an increase in the solute concentration, which can be related to the increase in the competition by sites of adsorption.

Continuous chromatographic separation of a baclofen precursor (N-Boc-4-[p-chloro-phenyl]-2-pyrrolidone) in a simulated moving bed using a polysaccharide carbamate as chiral stationary phase.

Liquid chromatography is known as one of the most flexible, efficient and cost-effective methods to resolve racemic mixture in order to attend the growing demand of the pharmaceutical industry for pure enantiomeric compounds. Cellulose tris(3,5-dimethylphenylcarbamate) is frequently used as a stationary phase for enantiomeric separations because of its attractive properties, including high enantioselectivity, high loading capacity and good mechanical stability. In this study, we investigated the usefulness of cellulose tris(3,5-dimethylphenylcarbamate) as the stationary phase and of ethanol and hexane mixtures as the mobile phases for the chromatographic separation of potential pharmaceutical intermediates. Using adsorption equilibrium data, we determined the optimal operational conditions for the separation of the N-Boc-4-[p-chloro-phenyl]-2-pyrrolidone enantiomers - a baclofen precursor - in a semi-preparative scale simulated moving bed unit. This unit was used to obtain high purity enantiomers on a scale of 1g/day. The outlet streams were analyzed by an on-line system that consisted of a UV-vis spectrophotometric unit, a polarimeter, and HPLC. Enantiomeric purities of up to 97% were obtained for the raffinate stream and up to 90% for the extract stream.