Valorization of wipe wastes for the synthesis of microporous carbons and their application in CO2 capture, gas separation and H2-storage.

Wipe wastes have been used as a cellulosic source to synthesize biochars. Prior to the synthesis of the adsorbents by the pyrolysis of wipes wastes, this waste was treated to remove the pathogenic agents. Then, the wipe wastes were pyrolyzed between 500 and 900 °C to obtain biochars, whose microporosity increased proportionally to the pyrolysis temperature, achieving a maximum CO2-adsorption uptake of 2.53 mmol/g at a pressure of 760 mm of Hg and 25 °C for the biochar pyrolized at 900 °C. The synthesized biochars are also highly selective towards CO2-adsorption in CO2/N2 or CO2/H2 mixtures. Hence, these adsorbents have shown a great potential to be used in flue gas treatment and H2-purification processes. Biochar treatment with KOH further improves microporosity due to chemical activation although the addition of a large amount of KOH leads to excessive microporosity causing a collapse in the pore structure and decreasing CO2-adsorption capacity.

Experimental designs for optimizing the purification of immunoglobulin G by mixed-mode chromatography.

The main aim of this study was to define the optimal adsorption and elution conditions for the purification of human immunoglobulin G (IgG) by mixed-mode chromatography using the multimodal resin Capto MMC. To this end, Central Composite Experimental Design (ED) was performed for both the adsorption and desorption stages. In the first case, the conditions were systematically studied in batch mode while in the latter case, these were performed in column. For both studies, the experimental design was conducted using high-purity human IgG samples. Buffer pH and concentration as well as the salt concentration were the parameters under study in the ED. Adsorption kinetics and equilibrium experiments were performed under the best conditions defined in the ED (phosphate buffer 60 mmol/L, pH 6.75, no salt). The equilibrium experimental data were fit to the Langmuir equation, with maximum uptake qmax equal to 549.2 mg/g. The qmax value found for IgG in Capto MMC was quite high as compared to other chromatographic techniques that employ single modes of interaction. Regarding elution, the best conditions were obtained with acetate buffer (56.40 mmol/L), pH 5.2 and 0.2 mol/L NaCl. An ultimate recovery of 46.96% for high-purity IgG was achieved. Thus, the effectiveness of Capto MMC for IgG adsorption and recovery could be confirmed. Moreover, electrophoretic runs in the human serum indicated that although co-elution of HSA and IgG proteins occurs, substantial HSA removal and a high IgG recovery were achieved in the elution step.

Metal-impregnated carbon applied as adsorbent for removal of sulphur compounds using fixed-bed column technology.

Metal-impregnated carbons (Cu--AC; Ag--AC and Pd--AC) were studied as adsorbents for the desulphurization of liquid fuels. A real gasoline was examined for sulphur compounds. Textural characteristics of adsorbents were determined by nitrogen adsorption/desorption isotherms at 77 K. The adsorption isotherms were obtained by frontal analysis in a single fixed bed at 30 degrees C and 45 degrees C. Breakthrough curves were simulated according to a mathematical model that assumed axially dispersed flow and mass transfer described by a linear driving force approximation and nonlinear adsorption equilibrium reached instantaneously on the external surface of the adsorbents particles. The model was solved numerically by orthogonal collocation in finite elements, using the commercial solver gPROMS. The proposed model matched experimental data reasonably well. Resistance to mass transfer was significant and thought to be due to intraparticle diffusion kinetics. The results confirmed the efficiency of the use of activated carbon (AC) in the adsorption of sulphur compounds, especially when its surface is modified with metals. Comparing adsorption capacities of sulphur compounds from real gasoline, AC-Pd material appeared more selective than other materials, even presenting a behaviour of rapid saturation explained by the presence of other components competing for adsorption sites, reducing their effectiveness in removing sulphur compounds. Both pristine AC and Pd--AC showed good regenerability. The regenerated Pd--AC sorbent can recover about 85% of the desulphurization capacity.

Adsorptive separation of fructose and glucose from an agroindustrial waste of cashew industry.

Nearly all agroindustrial wastes have appreciable sugar content including cashew apples (Anacardium occidentale, L.), which are an important sub-utilized biomass source in Northeastern Brazil. Adsorption in fixed bed, both in batch and continuous modes, is a low-cost separation technique, which has been widely used in the concentration, separation and purification of bioproducts, such as sugars. The present work is an experimental study aimed at measuring responses in fixed bed, needed for design purposes. Two commercial ion-exchange resins were studied: DOWEX Monosphere 99/Ca and DIAION UBK555. The adsorbents showed linear isotherms for both sugars with marked selectivity for fructose (2.2 for DOWEX and 1.5 for DIAION). A mathematical model was used to estimate kinetic parameters and predict breakthrough behaviour of binary solutions and complex feeds. The kinetics of mass transfer was well described by a linear driving force approximation (LDF) and estimated kinetic constants were around 1 min(-1). The results indicate that the use of independent experiments with synthetic monocomponent solutions leads to reliable parameters, and the model is capable to foresee reasonably well the breakthrough curve of the sugars present in the juice, under different purification conditions. The use of complex feeds led to overshoot behaviour, possibly due to the irreversible adsorption of oligosaccharides.

Enantiomers separation by simulated moving bed chromatography. Non-instantaneous equilibrium at the solid-fluid interface.

The simulated moving bed (SMB) technology, first conceived for large bulk-scale separations in the petrochemical industry, has found increasingly new applications in the pharmaceutical industry. Among these, the separation of fine chemicals has been the subject of considerable study and research. This work presents the modeling, simulation and design of the operation of a SMB plant in order to separate a binary chiral mixture. The usual assumption of instantaneous equilibrium at the solid-fluid interface is questioned and a first-order kinetics of adsorption is taken into account. The cases of linear, Langmuir and modified Langmuir equilibria are studied. The equivalent true moving bed (TMB) model was used assuming axial dispersion for the fluid flow and plug flow for the solid-phase flow. Intraparticle diffusion was described by a linear driving force (LDF) approximation. Simulation results indicate that, under certain conditions, equilibrium is not actually reached at the adsorbent surface. This leads to different unit performances, in terms of product purities and recoveries, as compared to those predicted assuming instantaneous equilibrium. Moreover, SMB units may be improperly designed by the usual methods (flow-rate ratio separation regions) if non-equilibrium effects are overlooked.

Doenca de Peyronie - tratamento cirurgico. / Peyronie's disease - surgical treatment

Os autores relatam dois casos de doenca de Peyronie, onde foram usadas duas tecnicas cirurgicas diferentes de tratamento. Descrevem a tecnica utilizada em cada caso e fazem referencias aos resultados obtidos por outros autores no tratamento cirurgico desta patologia

Cistite enfisematosa. / Emphysematous cystitis

Dois casos de cistite enfisematosa sao relatados desta rara entidade patologica.Sao feitas consideracoes sobre aspectos clinicos, radiologicos, patologicos e terapeuticos. Atencao especial e dada as duas formas com que esta patologia se apresent