Brazilian sugar cane bagasse ashes from the cogeneration industry as active pozzolans for cement manufacture

For proper management of wastes and their possible recycling as raw materials, complete characterization of the materials is necessary to evaluate the main scientific aspects and potential applications. The current paper presents a detailed scientific study of different Brazilian sugar cane bagasse ashes from the cogeneration industry as alternative cementing materials (active addition) for cement manufacture. The results show that the ashes from the industrial process (filter and bottom ones) present different chemical and mineralogical compositions and pozzolanic properties as well. As a consequence of its nature, the kinetic rate constant (K) states that the pozzolanic activity is null for the bottom ash and very low for the filter ash with respect to a sugar cane bagasse ash obtained in the laboratory under controlled burning conditions (reference). The scarce pozzolanic activity showed by ashes could be related to a possible contamination of bagasse wastes (with soils) before their use as alternative combustibles. For this reason, an optimization process for these wastes is advisable, if the ashes are to be used as pozzolans. (C) 2011 Elsevier Ltd. All rights reserved.

Effects of calcining conditions on the microstructure of sugar cane waste ashes (SCWA): Influence in the pozzolanic activation

in this paper a study of calcining conditions on the microstructural features of sugar cane waste ash (SCWA) is carried out. For this purpose, some microparticles (< 90 mu m) of sugar cane straw ash and sugar cane bagasse ash of samples calcined at 800 degrees C and 1000 are studied by combining the bright field and the dark field images with the electron diffraction patterns in the transmission electron microscopy (TEM). It is appreciated that the morphology and texture of these microparticles change when silicon or calcium are present. Furthermore, it is observed that iron oxide (magnetite Fe(3)O(4)) is located in the calcium-rich particles. The microstructural information is correlated with the results of a kinetic-diffusive model that allows the computing of the kinetic parameters of the pozzolanic reaction (mainly the reaction rate constant). The results show that the sugar cane wastes ash calcined at 800 and 1000 degrees C have properties indicative of high pozzolanic activity. The X-ray diffraction patterns, the TEM images and the pozzolanic activity tests show the influence of different factors on the activation of these ashes. (c) 2008 Elsevier Ltd. All rights reserved.

Study of the pozzolanic reaction kinetics in sugar cane bagasse-clay ash/calcium hydroxide system: kinetic parameters and pozzolanic activity

This paper presents a study of the pozzolanic reaction kinetics between calcium hydroxide and a mixture of sugar cane bagasse with 20 and 30% of clay, burned at 800 and 1000 degrees C (SCBCA) by electrical conductivity measurements. A kinetic-diffusive model produced in previous studies by some of the authors was used. The model was fitted to the experimental data, which allowed the computation of the kinetic parameters of the pozzolanic reaction (reaction rate constant and free energy of activation) that rigorously characterised the pozzolanic activity of the materials. The results show that SCBCA demonstrated reactivity and good pozzolanic qualities in the range 800-1000 degrees C.

Screening for endophytic nitrogen-fixing bacteria in Brazilian sugar cane varieties used in organic farming and description of Stenotrophomonas pavanii sp. nov.

A Gram-negative, rod-shaped, non-spore-forming and nitrogen-fixing bacterium, designated ICB 89(T), was isolated from stems of a Brazilian sugar cane variety widely used in organic farming. 16S rRNA gene sequence analysis revealed that strain ICB 89(T) belonged to the genus Stenotrophomonas and was most closely related to Stenotrophomonas maltophilia LMG 958(T), Stenotrophomonas rhizophila LMG 22075(T), Stenotrophomonas nitritireducens L2(T), [Pseudomonas] geniculata ATCC 19374(T), [Pseudomonas] hibiscicola ATCC 19867(T) and [Pseudomonas] beteli ATCC 19861(T). DNA-DNA hybridization together with chemotaxonomic data and biochemical characteristics allowed the differentiation of strain ICB 89(T) from its nearest phylogenetic neighbours. Therefore, strain ICB 89(T) represents a novel species, for which the name Stenotrophomonas pavanii sp. nov. is proposed. The type strain is ICB 89(T) (=CBMAI 564(T) =LMG 25348(T)).

Enzymatic hydrolysis of pretreated sugar cane bagasse using Penicillium funiculosum and Trichoderma harzianum cellulases

In this study, we investigated the enzymatic hydrolysis of pretreated sugarcane bagasse using eight different enzymatic blends obtained from concentrated crude enzyme extracts produced by Penicillium funiculosum and Trichoderma harzianum as well as from the extracts in combination with a commercial enzymatic cocktail. The influence of different levels of biomass delignification, degree of crystallinity of lignicellulose, composition of enzymatic activities and BSA on enzymatic hydrolysis yields (HYs) was evaluated. Our X-ray diffraction studies showed that crystallinity of lignocellulose is not a key determinant of its recalcitrance toward enzymatic hydrolysis. In fact, under the experimental conditions of our study, an increase in crystallinity of lignocellulosic samples resulted in increased glucose release by enzymatic hydrolysis. Furthermore, under the same conditions, the addition of BSA had no significant effect on enzymatic hydrolysis. The most efficient enzyme blends were obtained by mixing a commercial enzymatic cocktail with P. funiculosum or T. harzianum cellulase preparations (HYs above 97%) followed by the concentrated extract of P. funiculosum alone (HY= 88.5%). Increased hydrolytic efficiencies appeared to correlate with having an adequate level of both beta-glucosidase and xylanase activities in the blends. (C) 2011 Elsevier Ltd. All rights reserved.

Bifurcation analysis of a model for biological control

In this paper we study the Lyapunov stability and Hopf bifurcation in a biological system which models the biological control of parasites of orange plantations. (c) 2007 Elsevier Ltd. All rights reserved.

A preliminary characterization of the mutagenicity of atmospheric particulate matter collected during sugar cane harvesting using the Salmonella/microsome microsuspension assay

During sugar cane harvesting season, which occurs from May to November of each year, the crops are burnt, cut, and transported to the mills. There are reports showing that mutagenic activity and PAH content increase during harvesting season in some areas of Sao Paulo State in comparison with nonharvesting periods. The objective of this work was to preliminarily characterize the mutagenic activity of the total organic extracts as well as corresponding organic fractions of airborne particulate matter (PM) collected twice from two cities, Araraquara (ARQ) and Piracicaba (PRB), during sugar cane harvesting season using the Salmonella/microsome microssuspension assay. One sample collected in Sao Paulo metropolitan area was also included. The mutagenicity of the total extracts ranged from 55 to 320 revertants per cubic meter without the addition of S9 and from not detected to 57 revertants per cubic meter in the presence of S9 in areas with sugar cane plantations. Of the three fractions analyzed, the most polar ones (nitro and oxy) were the most potent. A comparison of the response of TA98 with YG1041 and the increased potencies without S9 indicated that nitro compounds are causing the observed effect. More studies are necessary to verify the sources of the mutagenic activity such as burning of vegetal biomass and combustion of heavy duty vehicles used to transport the sugar cane to the mills. The Salmonella/microsome assay can be an important tool to monitor the atmosphere for mutagenicity during sugar cane harvesting season.

Evaluation of monolithic columns for determination of formaldehyde and acetaldehyde in sugar cane spirits by High-Performance Liquid Chromatography

High-Performance Liquid Chromatography (HPLC) conditions are described for separation of 2,4-dinitrophenylhydrazone (2,4-DNPH) derivatives of carbonyl compounds in a 10 cm long C-18 reversed phase monolithic column. Using a linear gradient from 40 to 77% acetonitrile (acetonitrile-water system), the separation was achieved in about 10 min-a time significantly shorter than that obtained with a packed particles column. The method was applied for determination of formaldehyde and acetaldehyde in Brazilian sugar cane spirits. The linear dynamic range was between 30 and 600 mu g L-1, and the detection limits were 8 and 4 mu g L-1 for formaldehyde and acetaldehyde, respectively.

Physical Vapor Deposited Thin Films of Lignins Extracted from Sugar Cane Bagasse: Morphology, Electrical Properties, and Sensing Applications

The concern related to the environmental degradation and to the exhaustion of natural resources has induced the research on biodegradable materials obtained from renewable sources, which involves fundamental properties and general application. In this context, we have fabricated thin films of lignins, which were extracted from sugar cane bagasse via modified organosolv process using ethanol as organic solvent. The films were made using the vacuum thermal evaporation technique (PVD, physical vapor deposition) grown up to 120 nm. The main objective was to explore basic properties such as electrical and surface morphology and the sensing performance of these lignins as transducers. The PVD film growth was monitored via ultraviolet-visible (UV-vis) absorption spectroscopy and quartz crystal microbalance, revealing a linear relationship between absorbance and film thickness. The 120 nm lignin PVD film morphology presented small aggregates spread all over the film surface on the nanometer scale (atomic force microscopy, AFM) and homogeneous on the micrometer scale (optical microscopy). The PVD films were deposited onto Au interdigitated electrode (IDE) for both electrical characterization and sensing experiments. In the case of electrical characterization, current versus voltage (I vs V) dc measurements were carried out for the Au IDE coated with 120 nm lignin PVD film, leading to a conductivity of 3.6 x 10(-10) S/m. Using impedance spectroscopy, also for the Au IDE coated with the 120 nm lignin PVD film, dielectric constant of 8.0, tan delta of 3.9 x 10(-3)) and conductivity of 1.75 x 10(-9) S/m were calculated at 1 kHz. As a proof-of-principle, the application of these lignins as transducers in sensing devices was monitored by both impedance spectroscopy (capacitance vs frequency) and I versus time dc measurements toward aniline vapor (saturated atmosphere). The electrical responses showed that the sensing units are sensible to aniline vapor with the process being reversible. AFM images conducted directly onto the sensing units (Au IDE coated with 120 nm lignin PVD film) before and after the sensing experiments showed a decrease in the PVD film roughness from 5.8 to 3.2 nm after exposing to aniline.

Amino acids profile of sugar cane spirit (cachaca), rum, and whisky

An analytical procedure for the separation and quantification of 20 amino acids in cachacas has been developed involving C18 solid phase cleanup, derivatization with o-phthalaldehyde/2-mercaptoethanol, and reverse phase liquid chromatography with fluorescence detection. The detection limit was between 0.0050 (Cys) and 0.25 (Ser) mg L-1, whereas the recovery index varies from 69.5 (Lys) to 100 (Tyr)%. Relative standard deviations vary from 1.39 (Trp) to 13.4 (Glu)% and from 3.08 (Glu) to 13.5 (His) for the repeatability and intermediate precision, respectively. From the quantitative profile of amino acids in 41 cachacas, 5 turns, and 12 whisky samples, the following order of amino acids in significant quantities is observed: Gly = Ser < Cys < Ile < His < Pro = Asp < Asn < Tyr for cachaca; Phe < Glu = Gln = Val = Ala < His = Gly Thr = Arg = Tyr < Asn Ser = Lys = Pro < Cys = Asp for rum; and Ala = Asn < Trp < Gln = His = Met = Ile = Cys < Thr < Asp Leu < Phe = Lys < Ser = Gly = Tyr = Val < Glu = Pro < Arg for whisky samples. (C) 2007 Elsevier Ltd. All rights reserved.

Formation of Dextran Deposits in Brazilian Sugar Cane Spirits

The formation of dextran deposits in sugared Brazilian cachaca was studied as a function of the time considering the effects of temperature, molecular weight (M(w)), visible light, pH, and the presence of Ca, Mg, Cu, and Fe ions in the concentrations at which they are usually present in this beverage. At 25 degrees C and pH 4.4, the experimental half-lives (t(1/2)) for precipitation are 73 and 124 days for dextrans with M(w) 5.9 x 10(6) and 2.1 x 10(6) Da, respectively. For dextrans with M(w) 5.0 x 10(5) and 4.0 x 10(4) Da, the experimental t(1/2) values are >180 days. For a dextran with M(w) 2.1 x 10(6) Da a change in pH from 4.4 to 5.5 at 25 degrees C resulted in a t(1/2) decrease from 124 to 25 days. At pH 4.4 the visible light and the presence of metal ions in average concentrations usually found in cachacas do not exhibit noticeable influence on the rate of dextran precipitation.

Taxonomic redescription and biological notes on Diaugia angusta (Diptera,Tachinidae): parasitoid of the palm boring weevils Metamasius ensirostris and M. hemipterus (Coleoptera, Dryophthoridae)

Diaugia angusta Perty, 1833 is a Neotropical species of Tachinidae (Diptera) reported here as a parasitoid of Metamasius ensirostris (Germar, 1824) and M hemipterus (Linnaeus, 1758) (Coleoptera: Dryophthoridae) in Brazil. Several species of Dryophthoridae and Curculionidae cause damage to bromeliad and palm species, and most are regarded as pests. In the present study, the male and female of D. angusta are morphologically characterized and illustrated to provide a means for the identification of this parasitoid. Data obtained from preliminary field research show that natural parasitism of Metamasius pupae by D. angusta varies by year but can reach nearly 30%. A network of parasitoid-host interactions among tachinid parasitoids and coleopteran hosts reported as bromeliad and palm pests (Dryophthoridae and Curculionidae) in the Americas indicates that the species of the tribe Dexiini sensu lam (including D. angusta) might be promising as biological control agents of these pests.

Molecular mass distribution of dextran in Brazilian sugar and insoluble deposits of cachaca

The dextran molecular mass distribution profile in 77 sugar samples from Brazil and twelve insoluble deposits (alcoholic flocks) samples from sugared cachacas (Brazilian sugar cane spirit) is described in terms of number-average molecular mass M,,, weight-average molecular mass M(w), Z-average molecular mass M,, and polydispersity. The analyses were performed by size-exclusion chromatography, using a refractive index detector. In most of the sugar samples, it was possible to identify two major groups of dextrans with Mw averages of 5 x 10(6) and 5 x 10(4) Da. Based on the evaluated parameters, the dextran distribution profile is about the same in samples analyzed over five seasons, and, therefore, it is likely that the Brazilian product pattern will not change very much over the years. In insoluble deposits from sugared cachacas, dextrans with Mw values in the order of the 10(5) Da were the most frequent ones, being present in 58% of the samples. (c) 2008 Elsevier Ltd. All rights reserved.