Renato Cataluña Veses

Applications of Brazilian pine-fruit shell in natural and carbonized forms as adsorbents to removal of methylene blue from aqueous solutions-Kinetic and equilibrium study

The Brazilian pine-fruit shell (Araucaria angustifolia) is a food residue, which was used in natural and carbonized forms, as low-cost adsorbents for the removal of methylene blue (MB) from aqueous solutions. Chemical treatment of Brazilian pine-fruit shell (PW), with sulfuric acid produced a non-activated carbonaceous material (C-PW). Both PW and C-PW were tested as low-cost adsorbents for the removal of MB from aqueous effluents. It was observed that C-PW leaded to a remarkable increase in the specific surface area, average porous volume, and average porous diameter of the adsorbent when compared to PW. The effects of shaking time, adsorbent dosage and pH on adsorption capacity were studied. In basic pH region (pH 8.5) the adsorption of MB was favorable. The contact time required to obtain the equilibrium was 6 and 4h at 25 degrees C, using PW and C-PW as adsorbents, respectively. Based on error function values (F(error)) the kinetic data were better fitted to fractionary-order kinetic model when compared to pseudo-first order, pseudo-second order, and chemisorption kinetic models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. For MB dye the equilibrium data were better fitted to the Sips isotherm model using PW and C-PW as adsorbents.

Preliminary characterization of anhydrous ethanol used in Brazil as automotive fuel

This work reports preliminary studies on the characterisation of anhydrous ethanol (AEA) used as an automotive fuel mixed with gasoline in Porto Alegre (South Brazil). Pre-concentration of the impurities contained in 1000 ml of AEA was carried on through solid-phase extraction using XAD4 resin. The main compounds in the extract were identified by means of spectral data from the library of the equipment. The concentrate was then fractionated using a preparative liquid chromatographic column filled with activated silica gel and the elution procedure was carried out with, n-hexane, n-hexane-benzene (1:1, v/v) and dichloromethane. Prior to analysis by GC-MS, each fraction was reduced to 1 ml with a gentle stream of nitrogen. Saturated linear hydrocarbons and aromatic hydrocarbons eluted in the first fraction and oxygenated compounds such as aldehydes. ketones and alcohols, eluted in the second one. were the main compounds detected in the sample.

Solar-driven photodegradation of 17-β-estradiol and ciprofloxacin from waste water and CO2 conversion using sustainable coal-char/polymeric-g-C3N4/RGO metal-free nano-hybrids

Herein, we report the synthesis of a metal-free coal-char supported polymeric g-C3N4/RGO (RPC) nano-photocatalyst for the efficient solar powered degradation of the noxious emerging pollutants ciprofloxacin (CIF) & β-estradiol (ESD) and conversion of CO2 into CH4, CO & O2. RPC shows good photocatalytic and adsorption activity owing to its high surface area and reduced charge recombination rate. The photodegradation results of the treated water sample were investigated in terms of reaction kinetics, active species trapping experiments, high resolution mass spectrometry (HR-MS) and Chemical Oxygen Demand (COD) analysis. The higher solar photoactivity is attributed to the higher surface area, higher visible absorption, charge transfer, and reduced recombination. The superoxide radical anions were found to be the major active species in photodegradation, which is also supported by the band structure analysis. The catalytic activity is highly enhanced by the addition of H2O2, O2 and O3 as they facilitate the formation of radicals. The possible degradation pathways for the degradation of CIF and ESD have been proposed. This work shows promising solar-active metal-free photocatalysts for efficient environmental remediation and CO2 conversion to fuels.

DECOMPOSIÇÃO CATALÍTICA DE ÓXIDOS DE NITROGÊNIO

Contaminant gases in the atmosphere constitute an important problem to be solved in the world. The NOx gases produced as a consequence of engine high temperatures are deleterious to environment and human health, as they promote acid rain and can act in the same way as freons in the destruction of the ozone layer in the stratosphere. In this review, three way and selective reduction catalysts for decomposition of these contaminant gases are described. Details about conditions and problems, such as catalyst poisoning, and the search for new catalysts are shown.

Selective reduction of NOx by propylene over silver catalyst under oxidative conditions

Neste trabalho foram estudados catalisadores Ag/Al2O3 e Ag/Al2O3/Corderita, preparados por um metodo de impregnacao convencional, na reacao de reducao de NO utilizando propeno como agente redutor. Os catalisadores foram caracterizados por reducao a temperatura programada (RTP), quimissorcao de oxigenio e area superficial, pelo metodo BET. A atividade catalitica foi determinada utilizando uma mistura reacional contendo 100 ppm de NO, 250 ppm de C3H6 e 2% de oxigenio e uma velocidade espacial de 100000 h-1. Os produtos da reacao foram estudados por FTIR. Os resultados dos testes cataliticos mostraram 56% de conversao de NO para o catalisador 2,22%Ag/Al2O3 a 723 K. Os catalisadores de cordierita apresentaram um comportamento semelhante, mas a temperatura de maxima conversao de NO deslocou-se para temperaturas menores.

Using GC-MS to Analyze Bio-Oil Produced from Pyrolysis of AgriculturalWastes - Discarded Soybean Frying Oil, Coffee and Eucalyptus Sawdust in thePresence of 5% Hydrogen and Argon

Pyrolysis is a thermal process for converting various biomasses, wastes and residues to produce high-energydensity fuels (bio-oil). In this paper, we have done some important analysis of bio-oil which is obtained from the pyrolysis of agricultural wastes - discarded soybean frying oil, coffee and eucalyptus sawdust in the presence of 5% Hydrogen and Argon. The bio oil was obtained in one step pyrolysis in which temperature of the system kept 15°C and then increased up to 800°C but in two step condensation processes. 1st condensation step is done on temperature 100°C and 2nd is done on 5°C. So we got two types of fractions, HTPO (Oil condensed at high temperature 100°C after pyrolysis) and LTPO (Oil condensed at low temperature 5°C after pyrolysis). After pyrolysis the thermal cracking is done for both types of oil on the same two temperatures, then we again got two type of fractions HTCO (high temperature 100°C condensed oil after cracking) and LTCO (Low temperature 5°C condensed oil after cracking), these fractions are distillated and analyzed in GC-MS. The resulted compounds are given in the paper and are explained with the help of graphs and tables. The ultimate aim of hydrogenation and Argon is to improve stability and fuel quality by decreasing the contents of organic acids and aldehydes as well as other reactive compounds, as oxygenated and nitrogenated species because they not only lead to high corrosiveness and acidity, but also set up many obstacles to applications.

Bio-Oil Production by Thermal Cracking in the Presence of Hydrogen

This paper describes the bio-oil production process of a mixture of agricultural wastes: discarded soybean frying oil, coffee and sawdust, by pyrolysis and thermal cracking in the presence of hydrogen. The fractions obtained in the pyrolysis and/or cracking processes were divided into a light fraction and a heavy one. All the fractions were analyzed by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detection (GC×GC/ TOFMS). The characteristics of the fractions obtained in resulting from the cracking process in the presence of hydrogen were have characteristics similar to those of petroleum-based naphtha, while the fractions obtained by from the pyrolysis contained process produced significant quantities of compounds such as furanmethanol, hexanol, and benzofuran, whose commercial value is high.

Photocatalytic Studies of Tio2/Sio2 Nanocomposite Xerogels

The use of titania-silica materials in photocatalytic processes has been proposed as an alternative to the conventional TiO2 catalysts, in order to facilitate the separation of products after the reaction. However, despite the large number of research in this field, the mechanism governing the photocatalytic activity of the mixed TiO2/SiO2 oxides is not clear. Titania-Silica nanocomposite xerogels were prepared by sol-gel method. This work has been used to describe the synthesis and the photocatalytic properties of TiO2-SiO2 nanocomposite xerogel. The nanocomposite xerogels were prepared by keeping the molar ratio of TEOS:TTIP:MtOH:DIW at 1: 1:6:14 respectively and the catalysts used were HCl and NH4OH. After the preparation xerogels were characterized by FTIR, XRD, UV and LLS. All these techniques show the amorphous nature of Titania-silica xerogel.

A Comparative Study and Analysis of Two Types of Bio-Oil Samples Obtained from Freshwater Algae and Microbial Treated Algae

Pyrolysis experiments of two types of algal biomass (Spirogyra) freshwater Algae (FWA) and microbial treated algae (MTA) were carried out in an electrically heated stainless steel reactor to determine the effects of pyrolysis temperature, pyrolysis product yields and bio-oil properties. After pyrolysis two types of bio-oil were produced, freshwater algae bio-oil (FWAB) and microbial treated algae bio-oil (MTAB). Gas chromatography/mass spectrometry (GC-MS) analysis and Fourier transform infrared spectroscopy (FTIR) has been done of both types of bio-oil samples and also a comparison is shown between these two samples and explained it with the help of graphs and tables. The bio-oil was obtained from pyrolysis in which temperature of the system was kept 25°C and then increased up to 650°C time by time. After pyrolysis the obtained bio-oil was introduced to distillation and then analyzed by GC-MS technique and FTIR, which show different peaks and results of different compounds and functional groups present in both bio-oil samples and a noticeable difference is shown between these two bio-oil samples on the basis of hydrocarbons as well as other compounds.