Biomedical subjects

Alírio E Rodrigues

Publications and source records attributed to Alírio E Rodrigues.

4 recordsLinked to original sources

PubMed2006

Experimental characterization and modelling of analytical monolithic column.

Hydrodynamics, equilibrium and kinetics of adsorption in a silica-based monolithic column Chromolith Performance RP-18e (Merck KgaA, Germany) have been studied. The column permeability was calculated according to the Darcy law for laminar flow. The efficiency of the monolithic column was characterized through the height equivalent to a theoretical plate (HETP) for myoglobin, phenol and progesterone. The 2-D single channel mathematical model has been applied to describe the adsorption dynamics. Parabolic velocity profile, axial and radial diffusion in the monolith channel, linear driving force model for the mass transfer in the monolith channel skeleton wall and linear adsorption equilibrium were assumed. The mathematical model gives good prediction of the experimental elution peaks.

Adsorption↗

PubMed2005

Phenolic wastewaters purification by thermal parametric pumping: modeling and pilot-scale experiments.

Thermal parametric pumping is a cyclic adsorptive process based on periodic changes in the bed temperature simultaneously with flow reversal. This is an innovative technology which may allow removing phenolic compounds from waste solutions to be recovered and recycled. The recovery and/or purification of liquid streams containing phenol and 4-nitrophenol by adsorptive parametric pumping was studied in this work. An automated parametric pumping pilot unit was operated in semi-continuous recuperative mode. The adsorbent used was the polymeric resin Sephabeads SP206 (Mitsubishi Kasei Corporation, Japan) and temperatures of the hot and the cold half-cycles were 333 and 293 K, respectively. Basic data were obtained from batch equilibrium experiments and fixed-bed adsorption. Different experimental conditions were run and two simplified models were used to simulate the results: an equilibrium model and a linear driving force (LDF) model. Experimental and simulated results using the LDF model were in quite good agreement. Purification levels below three orders of magnitude lower than the concentration of the feed solution were obtained for phenol and 4-nitrophenol.

Adsorption↗

PubMed2004

New pi-complexation adsorbents for propane-propylene separation.

New adsorbents were prepared and tested for the separation of propane-propylene mixtures by adsorption. The ordered mesoporous material SBA-15 was used as the starting material for silver-ion deposition for pi-complexation with propylene. Two different loadings of silver were evaluated. Adsorption equilibrium and kinetic measurements of propane and propylene in the matrix (pure SBA-15) and the silver-modified adsorbents were performed at 323, 343, and 373 K. In this temperature range, the selectivity of propylene in one of the materials (Ag/SBA-15 = 0.5) is in the range 13-22 because the amount of propane adsorbed is very small, 0.095 mmol/g of propane versus 1.12 mmol/g of propylene at 100 kPa and 343 K. The diffusivity of both hydrocarbons is not seriously affected by the introduction of silver into the mesoporous structure.

Journal Article↗

PubMed2003

Design of simulated moving bed and Varicol processes for preparative separations with a low number of columns.

Simulated moving bed (SMB) chromatography has received significant attention in the last decade, particularly as regards the production of very valuable products, such as enantiomerically pure pharmaceutical compounds. Recent applications in the pharmaceutical industry use SMB systems containing a low total number chromatographic columns, usually four to eight. This paper deals with the modeling and simulation of SMB systems with only four, five and six columns. In particular, two modeling strategies, the equivalent true moving bed and the real SMB models, are compared for these units in terms of separation regions and system productivity. Also, the recently proposed Varicol process is analyzed and compared with the classical SMB operation, and the advantages of this new operation mode are shown for systems using a low number of columns.

Chromatography↗