Maria Lúcia Bianchi

The use of piassava fibers (Attalea funifera) in the preparation of activated carbon

The piassava fiber, residue of the broom industry, was used as precursor for the preparation of activated carbons (AC). AC were prepared by chemical activation with zinc chloride (AC ZnCl(2)) or phosphoric acid (AC H(3)PO(4)) and by physical activation with carbon dioxide (AC CO(2)) or water vapor (AC H(2)O). These materials were characterized by adsorption/desorption of N(2) to determine the BET areas, elemental analysis (CHN), thermogravimetric analysis (TG, DTA) and scanning electron microscopy (SEM). The carbons were tested with respect to their adsorption capacity of methylene blue, reactive red, phenol and metallic ions (Cr(+6), Cu(+2) and Zn(+2)). AC ZnCl(2) presented the highest surface area (1190 m(2)g(-1)) and AC H(3)PO(4), the largest pore volume (0.543 cm(3)g(-1)). AC ZnCl(2) was more efficient in the adsorption of methylene blue, Cr(+6) and Cu(+2) ions. AC H(2)O was the better adsorbent for phenol, while AC CO(2) was better for Zn(+2) ions.

Characterization of residues from plant biomass for use in energy generation

The use of plant residues for energy purposes is already a reality, yet in order to ensure suitability and recommend a given material as being a good energy generator, it is necessary to characterize the material through chemical analysis and determine its calorific value. This research aimed to analyze different residues from plant biomass, characterizing them as potential sources for energy production. For the accomplishment of this study, the following residues were used: wood processing residue (sawdust and planer shavings); coffee bean parchment and coffee plant stem; bean stem and pod; soybean stem and pod; rice husk; corn leaf, stem, straw and cob; and sugar cane straw and bagasse. For residue characterization the following analyses were done: chemical analysis, immediate chemical analysis, calorific value and elemental analysis. All procedures were conducted at the Laboratory of Forest Biomass Energy of the Federal University of Lavras. In general, all residues showed potential for energetic use. Rice husk was found to have higher lignin content, which is an interesting attribute as far as energy production is concerned. Its high ash content, however, led to a reduction in calorific value and fixed carbon. The remaining residues were found to have similar energetic characteristics, with corn cob showing greater calorific value, followed by coffee plant stem, both also containing higher levels of carbon and fixed carbon. A high correlation was found of higher calorific value with volatile materials, carbon and hydrogen contents.

PREPARAÇÃO E CARACTERIZAÇÃO DE CARVÃO ATIVADO PRODUZIDO A PARTIR DE RESÍDUOS DO BENEFICIAMENTO DO CAFÉ

Coffee fruit processing is one of the most polluting activities in agriculture due to the large amount of waste generated in the process. In this work, coffee parchment was employed as precursor for the production of carbons activated with ZnCl2 (CAP). The material was characterized using N2 adsorption/desorption at 77 K, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The material showed a surface area of 521.6 m2 g-1 and microporous structure. CAP was applied as adsorbent for the removal of methylene blue dye in aqueous medium. The adsorption capacity was found to be about 188.7 mg g-1.

Produção de carvão a partir de resíduo de erva-mate para a remoção de contaminantes orgânicos de meio aquoso

In this work we present a new adsorbent material, obtained by mate waste pyrolisis. The resulting charcoal presented high specific area when compared with other pyrolized materials and also high capacity to remove organic contaminants from aqueous solution. The charcoal showed specific area of 344, 191 and ~0.3 m2 g-1 for sample Mate 1, Mate 2 and Mate 3, respectively. According to the corresponding adsorption isotherm these materials present good adsorption capacity for reactive textile and methylene blue dyes and the herbicide atrazine. Adsorption maxima were respectively 16, 230 and 35 mg g-1 for such substances, when sample Mate 1 was used.In this work we present a new adsorbent material, obtained by mate waste pyrolisis. The resulting charcoal presented high specific area when compared with other pyrolized materials and also high capacity to remove organic contaminants from aqueous solution. The charcoal showed specific area of 344, 191 and ~0.3 m g for sample Mate 1, Mate 2 and Mate 3, respectively. According to the corresponding adsorption isotherm these materials present good adsorption capacity for reactive textile and methylene blue dyes and the herbicide atrazine. Adsorption maxima were respectively 16, 230 and 35 mg g for such substances, when sample Mate 1 was used.

Correlações entre as propriedades da madeira e do carvão vegetal de híbridos de eucalipto

Three different ages of . Eucalyptus grandis x . Eucalyptos urophylla wood hybrids were studied, with purpose of evaluating wood and charcoal behavior by temperature rising, and investigating the influence of wood characteristics on charcoal. Wood was analyzed chemically (total extractives, lignin, holocellulose, cellulose, ash and elementary composition) and thermally (thermogravimetry analysis - TG, differential thermal analysis - DTA and differential scanning calorimetry - DSC). Also, basic density and higher heating value were evaluated. Charcoal was produced in muffle furnace with constant heating rate of 1,67 oC min-1 up to 450 oC. In the produced charcoal, immediate analysis were conducted, elementary and thermal. The basic density of wood had positive correlation with C/H relation, and negative correlation with ash, nitrogen, oxygen, sulfur contents and S/G relation. The wood contents of ash, nitrogen, sulfur and S/G had positive correlation among each other, and negative correlation with C/H relation. In charcoal, the fixed carbon content, calorific value, elementary carbon content and C/H relation had positive correlation among each other, and negative correlation with volatiles content. The lignin had positive correlation with gravimetric yield in charcoal (RGC) and negative correlation with fixed carbon.

Qualidade da madeira de cinco espécies de ocorrência no cerrado para produção de carvão vegetal

The aim of this research was to evaluate the quality of wood and charcoal of some species from cerrado mineiro aiming the production of bioenergy and use in steel industry. Five wood species from cerrado located in Minas Gerais state were used. Basic density and lignin, total extractives, holocellulose and ash contents were evaluated. Charcoal and fixed carbon yields, contents of fixed carbon, volatile materials and ashes, higher heating value and apparent relative density were evaluated. An entirely randomized design with four repetitions was used in the evaluation of the experiment. Moreover, multivariate analysis of principle components was used. The species Casearia sylvestris and Luehea divaricata had the highest gravimetric yield of charcoal and fixed carbon, as much as high lignin contents in the wood. Charcoal made from Trema micrantha presented high heating value, but the lowest apparent relative density. The species Guazuma ulmifolia stood out due to high fixed carbon content and great potential for use in the steel industry, together with the specie Casearia sylvestris.

Clones de Eucalyptus versus a produção de polpa celulósica.

The wood quality is defined by combining several intrinsic characteristics of the tree to its use. This research aimed to evaluate some of the wood characteristics of Eucalyptus clones and its performance in kraft pulping. Fifteen clones, 5.8 years-old were used, two trees from each clone, totaling thirty trees. The evaluated wood characteristics were: basic density, fiber dimensions (fiber length, wall thickness, lumen diameter) and chemical composition (cellulose, lignin, hemicelluloses, extractives and ash contents). Four samples were cooked at the laboratory for each tree, using different active alkali, to establish the delignification curve. These alkali loads were selected after exploratory cooking to obtain an eighteen kappa number at the medium point of the curve. In the cooking were appraised the screened, the pulp viscosity and consumed alkali. The yield results varied from 43.4 to 52.0%, the active alkali from 17.5 to 23.4%, the consumed alkali from 15.5 to 20.0% and the pulp viscosity from 19.9 to 61.4 cP.

Renewable hybrid nanocatalyst from magnetite and cellulose for treatment of textile effluents

A hybrid catalyst was prepared using cellulose nanofibrils and magnetite to degrade organic compounds. Cellulose nanofibrils were isolated by mechanical defibrillation producing a suspension used as a matrix for magnetite particles. The solution of nanofibrils and magnetite was dried and milled resulting in a catalyst with a 1:1 ratio of cellulose and magnetite that was chemically and physically characterized using light, scanning electron and transmission electron microscopies, specific surface area analysis, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, catalytic potential and degradation kinetics. Results showed good dispersion of the active phase, magnetite, in the mat of cellulosic nanofibrils. Leaching and re-use tests showed that catalytic activity was not lost over several cycles. The hybrid material produced was tested for degradation of methylene blue dye in Fenton-like reactions resulting in a potential catalyst for use in degradation of organic compounds.

ANÁLISE DAS PROPRIEDADES DA MADEIRA E DO CARVÃO VEGETAL DE HÍBRIDOS DE EUCALIPTO EM TRÊS IDADES

In the present studied was investigated hybrids of Eucalyptus grandis x Eucalyptus urophylla in three different ages. Wood and charcoal characteristics as well as the influence of wood characteristics on the charcoals produced were evaluated. Chemical analyzes (extractives, lignin, ash, elemental analysis), basic density and calorific value - PCS were performed for wood. The charcoals were produced in a muffle type furnace with a heating rate of 1.67 °C.min-1 and an end temperature of 450 °C. Volatile material content, ash content, fixed carbon content, elemental analysis and gravimetric yield of the pyrolysis process were performed for the charcoals. An increase in density values​​, extractives content, carbon content and C/H rate were observed with the maturity of the tree. Other features such as ash content and S/G ratio decreased with the age of the tree. Greater gravimetric yield in charcoal and non-condensable gases were found in more mature materials.

Síntese de acetato de celulose a partir da palha de feijão utilizando N-bromossuccinimida (NBS) como catalisador

In this work, cellulose from beans straw was used to produce a more hydrophobic material (cellulose acetate) for use as oil absorbent. Acetic anhydride was used in the reactions with two catalysts, pyridine (PY) and N-bromosuccinimide (NBS). The materials produced were characterized by infrared spectroscopy, scanning electron microscopy, X-ray diffraction and elemental analysis. NBS proved more efficient than PY, with the resulting materials containing higher number of acetate groups, being more hydrophobic and with higher capacity to absorb soybean oil.