André Bernardo

Modification of Cotton Fabrics with Silver Nanoparticles for Use in Conditioner Air to Minimize the Bioaerosol Concentration in Indoor Environments

The pollution of the air and the monitoring of indoor air quality are receiving increasing attention worldwide, and many methodologies are now available to identify sources of pollution. However, there has been less work concerning the development of techniques to mitigate the effects of indoor air pollution. The aim of this study was to modify cotton fabrics with silver nanoparticles in order to use them in air conditioner filters. To achieve this goal, common fabrics purchased from commercial sources were evaluated in terms of their filtration properties (permeability, pressure drop, and collection efficiency) and were subsequently modified by impregnation with nanoparticles. This modification was achieved by immersion of the filters in nanoparticle suspensions. After drying the filter, collection of particulate matter was made in a toilet. The results showed that the filters impregnated with silver nanoparticles were able to significantly reduce the activity of microorganisms present in the airborne particulate matter, resulting in growth inhibition to the microorganisms which were retained (76.70%) and passed through (96.34%) the cotton filters.

Data Reconciliation Applied to Loss Identification in the Sugar Industry

AbstractPursuit of the identification and reduction of losses, and consequently of increased industrial efficiency, is a constant challenge in sugarcane industries. However, little attention is given to the undetermined losses, despite the high impact they can have on industrial efficiency. Therefore, this work aimed to quantify the contribution of the sugar-manufacturing sector to the total undetermined losses of a sugar and ethanol plant, presenting a method that could be applied to any equipment or sector of the industry in order to help identify sugar losses. The method was based on data reconciliation for the process flow rates and concentrations and was applied to the juice concentration sector. A mass balance was then applied to the subsequent sectors (crystallization, centrifugation, and drying) with the purpose of calculating the sugar production and comparing it with the real production. Considering the entire period studied, the calculated sugar production was 1.0% higher than the real production, and 37.3% of undetermined losses were found to occur between juice concentration and sugar bagging.

Ethanol absorption from CO2 using solutions of glycerol and glycols

ABSTRACT CO2 stripping during fermentation is a possible way of increasing the production of ethanol in distilleries. Ethanol, water, and carbon dioxide are the main compounds in the exiting gas mixture. To date, few studies have proposed the use of absorption to recover ethanol from this mixture or have considered different absorbents for this purpose. This work evaluates different absorbent solutions used to recover ethanol vapor from CO2 gas. Glycols and glycerol can provide easier separation of ethanol than water, with lower distillation energy demand. A statistical experimental design was used to compare the mass transfers of ethanol from the gas phase to the liquid phase, using solutions of glycerol, ethylene glycol, and diethylene glycol. High concentrations of these substances did not favor the absorption of ethanol. The best results were achieved with 25% absorbent solutions, which offered better options than water for the recovery of ethanol from CO2 gas in absorption columns and could increase the productivity of first generation bioethanol production.

Synthesis and Characterization of Ag-TiO 2 Nanocomposites for Possible Use as Biocide

Currently nanoparticles are being widely used because they have large surface area and pronounced effect relative to the properties of the material. Silver and Titanium Dioxide nanoparticles, for example, have pronounced biocidal effects, since they can inactivate certain enzymes and alter the DNA synthesis of some microorganisms. It is expected that a composite of the nanoparticles of the two metals can further increase the biocide power. This way, the study of the synthesis and characterization of nanocomposites becomes highly relevant. The aim of this work was to synthesize Ag-TiO2 nanocomposites and to characterize them in order to contribute to the understanding of the preparation of nanocomposite materials. In this study, we used a sol-gel method, which makes use of a reduction reaction using sodium citrate as the reducing agent, and titanium butoxide, acetic acid and silver nitrate as starting material. After being synthesized, the nanocomposite was analyzed with the techniques of Scanning Electron Microscopy coupled to energy dispersive X-ray detector (SEM / EDS) and X-ray Diffraction.

Synthesis and Characterization of Silver Nanoparticles

Nanoparticles have large surface area, which gives them more pronounced effects. Silver nanoparticles, for example, have pronounced biocidal effects, since they can inactivate certain enzymes and alter the DNA synthesis of some microorganisms. In this context, the study of the synthesis and characterization of nanoparticles becomes potentially important. The aim of this work was to synthesize nanoparticles and to characterize them in order to contribute to the development of synthesis and characterization of nanomaterials. Several methods are used for the synthesis of silver nanoparticles; however, in this study we used the Turchevich method which makes use of a reduction reaction using sodium citrate as the reducing agent, and silver nitrate as starting material. After being synthesized, nanoparticles were analyzed with the technique of transmission electron microscopy (TEM). Also, a curve of the size distribution of the particles formed was obtained. This distribution was obtained through a nanoparticle filtration equipment connected to a particle counter-SMPS (Scanning Mobility Particle Sizer).