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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, CeαMn1-αO2 catalysts supported over g-Al2O3 prepared by modified redox-coprecipitation methods for n-hexane combustion(Sociedade Brasileira de Quimicaquimicanova@sbq.org.br, 2020-04-01)A series of Ce Mn 1- O 2 catalysts supported on g-alumina with various molar concentrations of Ce (, from 0 to 0.90) was synthesized by coprecipitation, applying two different precipitating agents, namely, sodium hydroxide (method 1) and sodium carbonate (method 2), with the use of sodium permanganate as a redox agent for precipitation. XRD profiles of the supported samples revealed the predominant abundance of a typical fluorite crystalline structure. TPR thermograms of supported samples were displaced towards lower temperatures with increasing Mn concentration, in contrast with the bulk samples. The supported Ce-Mn samples exhibited a greater performance in n-hexane elimination than did the corresponding simple oxides. The sample Ce 0.33 Mn 0.67 O 2 obtained by method 2 presented the best activity, probably due to the enrichment of Ce 4+ , Mn 3+ and Mn 4+ surface species, an excess of superficial oxygen species and an easy reducibility as well as the lowest apparent activation energy. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Comparative study of anion removal using adsorbents prepared from a homoionic clay(Elsevier, 2021-05-01)The adsorption capacity of adsorbent materials (organophilic clays) prepared from a homoionic clay was compared for the removal of nitrates and nitrites present in aqueous solution in batch systems at room temperature.The organophilic clays were obtained by replacing the exchange cations present in the precursor clays with quaternary ammonium cations. For this purpose, two precursor clays were used, a natural clay (FS) and the same clay exchanged with sodium (CP) and two ammonium cations with different structure: hexadecyltrimethylammonium (HDTMA) and benzyltriethylammonium (BTEA) with amounts equivalent to 1.5, 2.5 and 4.0 cation exchange capacity (C.E.C.). Ion exchange is important to obtain a good affinity between organoclay and anionic contaminants. The clays were characterized by XRD, FTIR and SEM-EDX. The maximum adsorption capacities of the CP-HDTMA-4.0 clay for nitrate and nitrite ion were 7.23 and 0.65 mg g−1, respectively, indicating that the organophilic clay obtained from the homoionic clay with 4 C.E.C. ion exchange and the surfactant HDTMA had significant effects on the adsorption of nitrate and nitrite ions. Finally, the possible mechanisms and implications of the results for the use of these organophilic clays as adsorbent materials for the removal of the ions under study are discussed. - 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, Use of multivariate analysis for determining the most influential physicochemical properties of activated carbon in cadmium removal(Emerald Group Holdings Ltd., 2022-04-19)The goal of this paper is to model the activated carbon adsorption capacity of cadmium using a polynomial regression model. The properties that influence the removal of heavy metals by activated carbon must be taken into consideration in order to synthesize materials specific to the characteristics of the pollutant. Design/methodology/approach: Multivariable analysis applications allow a comprehensive description of the relationship between activated carbon surface properties and heavy metal adsorption. Findings: The authors use a second-grade polynomial regression model to determine the influence of porosity and surface acidity in cadmium adsorption by activated carbon. Originality/value: The authors propose a statistic analysis to correlate the carbon properties with its cadmium adsorption capacity. Model coefficient analysis will give a better comprehension of the influence of activated carbon porosity and surface acidity of cadmium removal. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, SnO2-TiO2 and SnO2-MoO3 based composite gas sensors to develop an e-nose for Peruvian Pisco varieties differentiation(IOP Publishing Ltd, 2022-01-01)There is great interest in the development of a simple system that could identify adulteration or counterfeiting of Peruvian Pisco (a grape-based alcoholic drink). In this study, sensors based on SnO2-TiO2 and SnO2-MoO3 composites with different weight composition ratios were synthesized and characterized. These sensors were tested with aqueous solutions of EtOH/MeOH and Pisco samples of Italia and Quebranta varieties in order to explore their capacity to identify variations in these beverages. The response profile of the most sensitive sensors showed an enhanced response to alcoholic samples with greater content of ethanol up to a concentration of 45%v/v, while the increased content of methanol in the range of 0.1 to 0.3% v/v diminished the intensity of the sensor response. Differences in the composition of methanol and ethanol in the Pisco varieties studied (Italia and Quebranta) were correlated to the capacity of the composite-based sensors to differentiate them with greater performance. Sensors based on SnO2-TiO2-1/2 composites showed greater reproducibility in their response profile over time in comparison to SnO2-TiO2-1/1 and SnO2-MoO3 composites. The PCA showed that composite sensors were able to differentiate Pisco samples according to the varieties, Italia and Quebranta. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Application of Machine Learning Algorithms to Classify Peruvian Pisco Varieties Using an Electronic Nose(Multidisciplinary Digital Publishing Institute (MDPI), 2023-07-01)Pisco is an alcoholic beverage obtained from grape juice distillation. Considered the flagship drink of Peru, it is produced following strict and specific quality standards. In this work, sensing results for volatile compounds in pisco, obtained with an electronic nose, were analyzed through the application of machine learning algorithms for the differentiation of pisco varieties. This differentiation aids in verifying beverage quality, considering the parameters established in its Designation of Origin”. For signal processing, neural networks, multiclass support vector machines and random forest machine learning algorithms were implemented in MATLAB. In addition, data augmentation was performed using a proposed procedure based on interpolation–extrapolation. All algorithms trained with augmented data showed an increase in performance and more reliable predictions compared to those trained with raw data. From the comparison of these results, it was found that the best performance was achieved with neural networks. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Adsorption of Congo red on montmorillonite modified with titanium and aluminum pillars(Springer Science+Business Media, 2025-01-01)The present work aimed to synthesize pillared clays with titanium (Ti-PILC) and aluminum (Al-PILC) from montmorillonite (LG-PILC) and to verify their efficiency in removing the anionic diazo dye Congo red via adsorption. The clays were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, zeta potential, Brunauer–Emmett–Teller (BET) surface area, and energy-dispersive X-ray spectroscopy (EDS). In the adsorption tests, the kinetics of equilibrium, adsorption dosage, and adsorption isotherms were studied, as well as the recovery and reutilization of the adsorbents. The results of the adsorption tests indicated that the process reached equilibrium after 90 min; the amount of dye removed per gram of adsorbent (qe, mg.g−1) was 23.01, 34.92, and 25.45 for the clays LG-PILC, Ti-PILC, and Al-PILC, respectively. In the kinetic studies of adsorption, all samples followed the pseudo-second-order model. The optimal adsorbent dosage for removing Congo red across all samples was 0.5 g.L−1. Among the adsorption isotherm models tested, the isotherms found in LG-PILC and Al-PILC samples were closest to the Henry isotherm (R2 = 0.94 and 0.84 for LG-PILC and Al-PILC, respectively). In contrast, the isotherm found in Ti-PILC clay was closest to the Langmuir model in linear form (R2 = 0.98). XRD results showed that the clay composition is mainly montmorillonite, and all other characterization results indicated that the pillars formed within the clay. In the recovery and reuse of clays (with post-treatment), it was observed that the clays maintained the ability to remove Congo red at each reuse stage. Still, they decrease after each cycle (reaching stability as the cycles go by). The clays studied in this research demonstrated high potential for removing Congo red, with the most promising being titanium pillared clay (Ti-PILC). The Ti-PILC clay showed superior adsorption properties to other adsorbents reported in the current literature.2