No abstract

La semilla de aguaje (fruto típico de la selva amazónica) fue empleada como un material precursor para la preparación de carbón activado usando ácido fosfórico como agente activante en dos concentraciones diferentes: 0,75 y 1,0 g /g . Las propiedades H3PO4 Precursor fisicoquímicas se estudiaron mediante mediciones de adsorción de nitrógeno, titulación Boehm, microscopía electrónica de barrido y espectroscopía de rayos X por energía dispersiva. Los carbones activados se utilizaron en la adsorción de tres metales pesados: plomo, cadmio y cromo. La máxima capacidad de adsorción se logró utilizando el carbón activado AG0,75_600 con soluciones con un pH mayor a 4; los valores obtenidos estaban en el -1 -1 -1 siguiente orden: plomo (74,8 mg g ) , cadmio (26,5 mg g ), cromo (18,8 mg g ). Los factores más importantes que influyen en el proceso de adsorción fueron el pH de la solución, la estructura porosa y la acidez superficial del carbón activado.

Activated carbons (ACs) prepared from chestnut shell were used as adsorbents for the removal of benzoic acid, salicylic acid and phenol from aqueous solutions. Adsorption studies were carried out by modifying activation temperature, concentration of activating acid and pH. The samples presented a microporous texture with acidic groups on the surface. It was found that the adsorption process not only depended on the porosity and the functional groups present in the AC, but was also affected by the solubility, the number and type of substituent groups, the superficial acidity in the adsorbate and the adsorbate-adsorbent interactions. The order of removal capacity was determined as follows: salicylic acid > benzoic acid > phenol. The differences in energy between the orbital frontier of the electronic densities of the adsorbent and the adsorbates, predicted by the HyperChem program, explained the experimental data pretty well.

The present work develops a MOS-based e-nose with sensors modified with zeolite Y. For this purpose, the following SnO2 doped with Pd and/or Pt have been prepared: M1 ((0.25 Pd/0.75 Pt)/SnO2), M2 ((0.50 Pd/0.50 Pt)/SnO2), M3 ((0.75 Pd/0.25 Pt)/SnO2), Pd/SnO2, and Pt/SnO2, at the total concentrations of the noble metals of 0.1% and 0.2% for use in gas sensors and be part of the electronic nose. Then, the sensors were assembled with the oxides using the screen printing method. Different electronic noses of four sensors were prepared by combining tin oxides doped with palladium and/or platinum and zeolite Y. The physicochemical characterization of oxides using FRX, FTIR, sorption of N2, and RAMAN has been performed. Measurements for the detection of wine volatile compounds such as ethanol, methanol, 1-phenyl ethanol, propionic acid, and acetic acid were carried out with these sensors located in a gas chamber and using a program that includes the Labview software, which serves to automate the sensing process. It was found that the sensors modified with zeolite were the ones that in general had higher detections of volatile compounds and PCAs showed positive correlations only for ethanol and the mixture of ethanol at 12% and methanol at 3%. This is related to better detection of these sensors.

No abstract