3. Producción
Browse
4 results
Search Results
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, The interaction of metallic ions onto activated carbon surface using computational chemistry software(SAGE Publishing, 2020-07-01)Activated carbon was prepared from the seeds of aguaje palm ( Mauritia flexuosa L.f.) by a chemical activation with phosphoric acid. This activated carbon was used for adsorbing metal ions: Pb(II), Cd(II), and Cr(III). To understand the mechanism of adsorption of these heavy metals (Cr, Cd, and Pb), the activated carbon surface was oxidized with nitric acid (1 M) increasing the oxygenated surface groups showing an increasing in their adsorption capacities of these metals. The oxidized activated carbon slightly increased the maximum adsorption capacity to 5–7%. The order of adsorption for unoxidized and oxidized activated carbons was Pb> Cd> Cr. This experimental information was corroborated by molecular modeling program Hyperchem 8 based adsorption mainly on two factors: the electron density and orbitals—highest occupied molecular orbital and lowest unoccupied molecular orbital.Activated carbons were characterized by adsorption/desorption of N 2 , obtaining an increase of microporous surface area for oxidized activated carbon. An increase of surface acidity and a reduction of isoelectric points were observed in oxidized activated carbon. According to these results, the adsorption of metal ions is favored in contact with an oxidized activated carbon, which has more amount of phenolic and carboxylic functional groups. Similarly, decreasing the isoelectric point indicates that the surface has a higher negative charge. The surface information was corroborated by Hyperchem, which indicates that the surface of the oxidized activated carbon has a higher electron density, indicating a larger amount of electrons on its surface, which means the surface of oxidized activated carbon charges negatively and thereby attracts metal ions. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Determination of the working temperature of the MOS sensors for detection of ethanol and methanol(Atena Editora, 2022-09-05)In this work, some peruvian red wines were analyzed using gas chromatography coupled to mass spectrometry (GC-MS) and it was determined that ethanol was the major volatile component present in the aroma (12 % in volume). followed by methanol (2-3 % in volume). Some MOS sensors based on SnO 2 doped with Pd and Pt were prepared by wet impregnation with metallic charges from 0.1 to 0.5% and were tested with the same Peruvian wines. The stability and reproducibility of the sensing signal was analyzed at different working temperatures (200, 220, 240, 260 and 280 C). The best working temperature at which the highest intensity of the response signal of the sensors was obtained at 260 C. In most of the cases studied, the sensing signal of the sensors was in general repetitive and stable, maintaining its amplitude and shape during long periods of the analysis. However, at the temperature of 280 C the signal loses intensity and in contact with methanol the signal is distorted. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Application of multivariate methods to the differentiation of Peruvian wines(2022-01-14)This work presents the results of the sensing analysis of Peruvian wines of known (Commercial wines) and handmade brands, using electronic noses (E-noses) which consist of an array of sensors based on tin oxide doped with Pd or Pt, and some with zeolite coating. The combinations of the sensors were performed seeking to obtain the best discrimination of the wines with the multivariate methods, with a high level of confidence and a good distribution of the results. The Principal Component Analysis (PCA), cluster and factorial results showed that the electronic noses allowed to efficiently identify wines of known brand from those of handmade brand, revealing the way in which the wines have been produced. On the other hand, the multivariate methods applied to the electronic noses made up of SnO2 sensors doped with palladium showed a clear differentiation of Borgoña-type wines from wines of handmade brand and evidenced the formation of agglomerations between red and Rosé wines. The application of PCA, cluster and factorial obtained in this study allowed to obtain good results in the differentiation of wines, even with electronic noses formed with a low number of sensors. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Study of the Methanol Concentration in Commercial Wines and Its Influence on the Detection of Quality and Possible Adulteration of Wines(2023-04-06)In the present study, the variation of the sensitivity of the sensors prepared from SnO 2 doped with Pt, in contact with different concentrations of methanol present in Peruvian wines using an array of sensors (electronic noses), in order to find which sensors were the most appropriate to differentiate commercial wines from adulterated ones, it was found that methanol It is found in a higher percentage in adulterated wines than in commercial ones.sensors Pt-SnO 2 coated with zeolite Y were the ones that presented a higher detection of this alcohol.Zeolite can act as a selective element, especially in platinum-doped sensors.In the principal component analysis (PCA) obtained, a good total variance was observed (the value is missing) in the results for both Nose 1 and Nose 2 (greater than 70%) with correlations close to zero, which indicates the independence of the observations.With Nose 1, built by sensors based on Pt-SnO2, a good differentiation of Peruvian wines of known brands was achieved with respect to those of unknown brands (possible adulterated wines) when applying the PCA method.Through the cluster analysis and the Factorial Analysis, the results obtained from the PCA were corroborated.Additionally, with the Factorial Analysis a high value was obtained in the variance (99.26%) of the two factors.