Cesar Costapinto Santana

Brazilian Bioethanol Program

Brazil is the largest producer of bioethanol, and sugarcane is the main raw material. Bioethanol, is produced by both batch and continuous processes, and in some cases, flocculating yeast is use. This article analyzes the Bracilian Ethanol Program. for the 1996–1997 havest, Brazil produced 14.16 billion L of ethanol and 13.8 million metrict of sugar, from 286 million metrict of sugarcane. These products were produced by 328 industries inactivity, with 101 autonomousethanol plants producing only ethanol, and 227 sugar mills producing sugar and ethanol. The sugar-ethanol market reaches about 7.5 billion US

Simulated moving-bed adsorption for separation of racemic mixtures

/yr, accounting for direct and indirect revenues.

Influence of Calcification Solution on in vitro Chitosan Mineralization

The two enantiomers that constitute a racemate have different activities when employed as pharmaceuticals. Due to this fact, fully recognized today, the pharmaceutical industry has been forced to market pure enantiomers instead of the racemic mixture whenever a chiral compound is involved. The simulated moving bed (SMB) is a chromatographic process that, unlike traditional HPLC systems, operates continuously without losing the enantiomeric purity of the outlet streams. The present work describes the enantioseparation of the anesthetic ketamine in a semipreparative-scale SMB unit. The chiral stationary phase employed was the microcrystalline cellulose triacetate. The outlet streams were analyzed by an on-line system, composed by an UV/VIS meter and a polarimeter, and also by HPLC. The analysis indicated purity values up to 100% for the stream of interest and up to 97.7% for the other stream.

Albendazole sulfoxide enantiomers: Preparative chiral separation and absolute stereochemistry

The influence of the calcification solution on the mineralization of chitosan membranes was analysed. Two factors were studied: pH and chemical composition (excess of calcium or phosphate ions) of solutions. Substrates (membranes) of chitosan underwent mineralization by soaking in calcification solutions for 7 days at 36.5 °C. As expected, SEM-EDS analyses demonstrated that higher pH and concentration of ions increases deposition, however, the morphology and composition of these deposits varies depending on which ion (phosphate or calcium) is in excess. Larger spherical deposits are observed when a calcium-rich solution is used instead of a phosphate-rich one. In the latter, the interconnectivity of the inorganic and organic (matrix) phases is very different, suggesting a different mechanism of deposition for each situation.

HPLC Determination of Pesticides in Soybeans using Matrix Solid Phase Dispersion

The enantiomeric separation of albendazole sulfoxide was carried out by simulated moving bed chromatography with variable zones (VARICOL). An overall recovery of 97% was achieved and enantiomeric ratios of 99.5% for raffinate and 99.0% for extract were attained. A total of 880 mg of (+)-albendazol sulfoxide and 930 mg of its antipode were collected after 55 cycles or 11 h of process, resulting in a mass rate of 2 g/day. Furthermore the absolute configuration of the enantiopure compounds was determined for the first time by vibrational circular dichroism (VCD) with the aid of theoretical calculations as (-)-(S) and (+)-(R)-albendazole sulfoxide.

Concentration of alpha-lactalbumin from cow milk whey through expanded bed adsorption using a hydrophobic resin

Abstract A method to determine six pesticides applied in soy cultivation (imazethapyr, imazaquin, metsulfuron‐methyl, carboxin, chlorimuron‐ethyl, and tebuconazole) using matrix solid phase dispersion (MSPD) as the extraction technique followed by a clean‐up step, using a C8 co‐column, and subsequent chromatographic analysis by high performance liquid chromatography diode array detection (HPLC‐DAD) was developed. The validated method showed good recuperation for all pesticides (60–120%), except for metsulfuron‐methyl and tebuconazole at their lowest concentration levels, and the quantification limits of the method (0.04–0.08 µg g−1) were below the maximum residue limits imposed by the principal regulatory agencies. This article not subject to U.S. copyright law.

A hybrid approach with artificial neural networks, Levenberg–Marquardt and simulated annealing methods for the solution of gas–liquid adsorption inverse problems

The design of novel applications for the use of new high-density adsorbents in the direct recovery of proteins requires analysis of the fluid dynamics and mass transfer characteristics of the column used with the solid-liquid system. In this article we describe the operating parameters related to the use of a high-density, hydrophobic resin (Streamline® Phenyl) for the recovery of a-lactalbumin from cow milk whey in an expanded-bed adsorption mode of operation. The adsorption isotherm, kinetic curves and chromatographic curves for adsorption and elution were determined for a-lactalbumin recovered from whole whey. The experiments were used to confirm the theoretical model that involves the combination of resistance to the mass transfer in the liquid phase and diffusivity in the adsorbent resin pores. The model solution was obtained through the orthogonal collocation method. A nonlinear multivariable optimization method was used to fit the model to experimental results. A purity of 79% was obtained with the adsorption/elution protocol prior to any polishing procedure.

Produção e caracterização de microesferas de quitosana modificadas quimicamente

In the present work the inverse problem of gas–liquid interface adsorption isotherm identification is investigated using a combination of an artificial neural network (ANN), and the Levenberg–Marquardt (LM) and the simulated annealing (SA) methods.

Characterization of chemically modified chitosan microspheres as adsorbents using standard Proteins (bovine serum albumin and lysozyme)

Chitosan microspheres can be used as biomaterial, in biotechnology processes and as adsorbents. This work is concerned with the production of chitosan microspheres using spraying and coagulation processes, which allows us to control the operating parameters and to produce chitosan microspheres of several ranges and sizes. The microspheres were modified chemically in order to study their thermal, mechanical and chemical resistance. The methods used were: 1) crosslinking with glutaraldehyde; 2) crosslinking with epichlorohydrin; 3) acetylation. The microspheres obtained presented mean particle size of 140 µm and standard deviation of 11.9 µm. The modified microspheres showed thermal degradation around 300 °C, an increase of chemical stability using HCl solution and a decrease of mechanical resistance.

Síntese e caracterização de estruturas densas e porosas de quitosana

Chitosan microspheres with a mean size of 140 ± 119 µm were produced by the spray and coagulation methods. The microspheres were chemically modified using the following routes: a) crosslinking with glutaraldehyde b) crosslinking with epychlorohydrin and c) acetylation. For investigation of their ability as adsorbents, the following standard proteins were chosen as adsorbates: bovine serum albumin - BSA (pI = 4.8 and MW = 66 kDa) and lysozyme (pI = 11 and MW = 14 kDa). The adsorption experiments were performed using a static method. The adsorption media and equilibrium concentration of adsorbates were varied in the ranges of pH 4-11 and 0.07-0.70 mg.ml-1, respectively. The maximum adsorption capacities (qm) and the constant of the Langmuir model (Ks) were shown to be dependent on charge interactions and on the kind of treatment performed on chitosan microspheres. The satisfactory fit of a kinetic model to the experimental data shows that the step that controls the adsorption kinetics is probably the initial adsorbate transport.