Biomedical subjects

M C Rollemberg

Publications and source records attributed to M C Rollemberg.

5 recordsLinked to original sources

PubMed2006

Preparation and characterization of activated carbon from rice bran.

A study on the preparation of rice bran-based activated carbon was conducted, with and without an acid treatment step prior the activation process. The influence of the activation time on the structure of the activated carbons was evaluated. The acid treatment had a significant positive influence on sorption properties. The rice bran-activated carbon presented a BET surface area of 652m(2)g(-1) and a pore volume of 0.137cm(3)g(-1), with mesopores predominance (ca. 55%). These experimental results indicated the potential use of rice bran as a precursor in the activated carbon preparation process, thus representing an economically promising material.

Adsorption↗

PubMed2005

Removal of metal ions from aqueous solutions by sorption onto rice bran.

A new sorbent (raw rice bran) was investigated for heavy metal ions removal from aqueous solutions. Rice bran characterisation was carried out in order to identify the functional groups possibly involved in the metal binding. The binding process was studied in terms of binding capacity and metal affinity. The adsorption equilibrium was well described by the Freundlich isotherm model. The negative Gibbs free energy values obtained in this study with rice bran confirm the feasibility of the process and the spontaneous nature of sorption.

Ions↗

PubMed2001

On-line preconcentration with different solid adsorbents for lead determination.

An on-line column preconcentration method based on the combined use of ammonium O,O-diethyldithiophosphate and activated carbon or polyurethane foam as adsorbents has been developed for the determination of Pb in water samples. The complexed Pb was eluted with ethanol and determined by flame atomic absorption spectrometry. The optimum preconcentration conditions are given for each adsorbent. The enrichment factors were 63 and 294, and the detection limits (3sigma) 3 microg L(-1) and 0.8 microg L(-1), respectively, for the carbon and foam systems. When the optimized procedures were applied to the determination of Pb in water samples the recovery efficiency was > 96%.

Adsorption↗

PubMed2000

Kinetics of uptake of cadmium by Chlorella marina in different media.

The kinetics of cadmium binding to living Chlorella marina cells during a short time (a few minutes) has been studied in seawater conditions, being also considered separately the influence of calcium and chloride. Cadmium complexes with surface groups of C. marina cells are labile in terms of differential pulse anodic stripping voltammetry in media (0.01-0.7) M NaNO3 since the complexation reaction is kinetically fast. However, in media 0.7 M NaCl, 0.7 M NaCl + 10(-2) M Ca2- and in synthetic seawater diluted 1:4 or not, the complexes are inert, since kinetics is determined by the rate of exchange with alkaline-earth metals and/or the chloride anion.

Cadmium↗

PubMed1999

Thermodynamics of uptake of cadmium by Chlorella marina.

From voltammetric titration curves of living Chlorella marina cells with cadmium ion, at constant pH, the surface binding capacity of the alga was determined and interpreted in terms of average conditional equilibrium constants and of differential equilibrium function. Since the alga can live in estuaries, the influence of ionic strength and competition of alkaline and alkaline earth cations has been considered. Cadmium complexation with dead algae killed by heat or using formaldehyde has also been studied for comparison.

Algorithms↗