Hydrogen peroxide bleaching of cellulose pulps obtained from brewer`s spent grain

Brewer`s spent grain (BSG) was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositions were produced by soda pulping: one from the original raw material and the other from material pretreated by dilute acid. Both of them were bleached by a totally chlorine-free sequence performed in three stages, using 5% hydrogen peroxide in the two initial, and a 0.25 N NaOH solution in the last one. Chemical composition, kappa number, viscosity, brightness and yield of bleached and unbleached pulps were evaluated. The high hemicellulose (28.4% w/w) and extractives (5.8% w/w) contents in original BSG affected the pulping and bleaching processes. However, soda pulping of acid pretreated BSG gave a cellulose-rich pulp (90.4% w/w) with low hemicellulose and extractives contents (7.9% w/w and < 3.4% w/w, respectively), which was easily bleached achieving a kappa number of 11.21, viscosity of 3.12 cp, brightness of 71.3%, cellulose content of 95.7% w/w, and residual lignin of 3.4% w/w. Alkaline and oxidative delignification of acid pretreated BSG was found as an attractive approach for producing high-purity, chlorine-free cellulose pulp.

Swine deep bedding ashes as a mineral additive for cement based mortar

The sustainability of intensive swine production demands alternative destinations for the generated residues. Ashes from swine rice husk-based deep bedding were tested as a mineral addition for cement mortars. The ashes were obtained at 400 to 600ºC, ground and sieved through a 325 mesh sieve (# 0.045 mm). The characterization of the ashes included the determination of the index of pozzolanic activity with lime. The ashes were also tested as partial substitutes of Portland cement. The mortars were prepared using a cement:sand proportion of 1:1.5, and with water/cement ratio of 0.4. Three percentages of mass substitution of the cement were tested: 10, 20 and 30%. Mortar performances were assessed at 7 and 28 days determining their compressive strength. The chosen condition for calcinations at the laboratory scale was related to the maximum temperature of 600ºC since the resulting ashes contained vitreous materials and presented satisfactory values for the pozzolanic index under analysis. The pozzolanic activity indicated promising results for ashes produced at 600ºC as a replacement of up to 30% in cement masses.

Carcass quality of feedlot finished steers fed yeast, monensin, and the association of both additives

To evaluate the effects of the supplementation of feed additives on carcass quality in beef cattle, 72 Nellore steers (339.5kg, 20-month old) were feedlot finished and fed for 91 days one of the following diets: 1) control with no additives; or added of 2) live yeast culture; 3) monensin; or 4) the association of both additives. After slaughter, renal, pelvic, and inguinal fat and hot carcass weights were recorded and carcass was split into muscle, bone, and trimmable fat. Carcass Longissimus muscle area and subcutaneous fat thickness at the 12th rib were measured and steaks of Longisimus muscle were taken to determine meat color, shear force, drip, and cooking losses. Yeast increased carcass dressing percentage but there were no effects on hot carcass weight, Longissimus area, subcutaneous fat thickness, percentage and weight of retail cut yield and trimmings. Feed additives had no effect on carcass pH, meat color, fat content, shear force, and drip losses. Supplementation of yeast, monensin or the association of both additives had no important effects on carcass traits and on meat quality of feedlot finished steers.

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Cellulose acetates with different degrees of substitution (DS, from 0.6 to 1.9) were prepared from previously mercerized linter cellulose, in a homogeneous medium, using N,N-dimethylacetamide/lithium chloride as a solvent system. The influence of different degrees of substitution on the properties of cellulose acetates was investigated using thermogravimetric analyses (TGA). Quantitative methods were applied to the thermogravimetric curves in order to determine the apparent activation energy (Ea) related to the thermal decomposition of untreated and mercerized celluloses and cellulose acetates. Ea values were calculated using Broido's method and considering dynamic conditions. Ea values of 158 and 187 kJ mol-1 were obtained for untreated and mercerized cellulose, respectively. A previous study showed that C6OH is the most reactive site for acetylation, probably due to the steric hindrance of C2 and C3. The C6OH takes part in the first step of cellulose decomposition, leading to the formation of levoglucosan and, when it is changed to C6OCOCH3, the results indicate that the mechanism of thermal decomposition changes to one with a lower Ea. A linear correlation between Ea and the DS of the acetates prepared in the present work was identified.

Some aspects of acetylation of untreated and mercerized sisal cellulose

We report here on some aspects of the acetylation in LiCl/N,N-dimethylacetamide, DMAc, of untreated and mercerized sisal cellulose, hereafter designated as sisal and M-sisal, respectively. Fiber mercerization by NaOH solution has resulted in the following changes: 29.9% decrease in the index of crystallinity; 16.2% decrease in the degree of polymerization and 9.3% increase in α-cellulose content. A light scattering study of solutions of sisal, M-sisal, microcrystalline and cotton celluloses in LiCl/DMAc has shown that they are present as aggregates, with (an apparent) average aggregation numbers of 5.2, 3.2, 9.8, and 35.3, respectively. The presence of these aggregates affects the accessibility of cellulose during its functionalization. A study of the evolution of the degree of substitution, DS, of cellulose acetate as a function of reaction time showed an increase up to 5 h, followed by a decrease at 7 h. Possible reasons for this decrease are discussed. As expected, M-sisal gave a higher DS that its untreated counterpart.

Hybrid layer-by-layer assembly based on animal and vegetable structural materials: multilayered films of collagen and cellulose nanowhiskers

Layer-by-layer (LBL) assembly was used to combine crystalline rod-like nanoparticles obtained from a vegetable source, cellulose nanowhiskers (CNWs), with collagen, the main component of skin and connective tissue found exclusively in animals. The film growth of the multilayered collagen/CNW was monitored by UV-Vis spectroscopy and ellipsometry measurements, whereas the film morphology and surface roughness were characterized by SEM and AFM. UV-Vis spectra showed the deposition of the same amount of collagen, 5 mg m(-2), in each dipping cycle. Ellipsometry data showed an increment in thickness with the number of layers, and the average thickness of each bilayer was found to be 8.6 nm. The multilayered bio-based nanocomposites were formed by single layers of densely packed CNWs adsorbed on top of each thin collagen layer where the hydrogen bonding between collagen amide groups and OH groups of the CNWs plays a mandatory role in the build-up of the thin films. The approach used in this work represents a potential strategy to mimic the characteristics of natural extracellular matrix (ECM) which can be used for applications in the biomedical field.

Sisal cellulose acetates obtained from heterogeneous reactions

In the present work, cellulose obtained from sisal, which is a source of rapid growth, was used. Cellulose acetates were produced in heterogeneous medium, using acetic anhydride as esterifying agent and iodine as catalyst, to check if the procedure described in the literature for commercial cellulose also is adequate to sisal cellulose. The results indicated that iodine is an excellent catalyst to obtain sisal cellulose acetates, but the reaction is so fast as described in the literature when, instead of sisal, lower average molar weight cellulose (microcrystalline) is used. The crystallinity index (I(c)) of sisal cellulose acetates diminished compared to sisal cellulose, but there was no direct correlation between their degree of substitution (DS) and I(c). Probably acetyl groups were introduced more homogeneously along the short chains of microcrystalline cellulose, when compared to sisal cellulose, and then for microcrystalline cellulose acetates the Ic decreases as DS increases. Using the linear correlation that was found between degree of substitution (DS) and time reaction is possible to control the DS of sisal cellulose acetates, considering a large interval of degrees of substitution (0.3-2.8).

Sugarcane bagasse cellulose/HDPE composites obtained by extrusion

Natural fibers used in this study were both pre-treated and modified residues from sugarcane bagasse. Polymer of high density polyethylene (HDPE) was employed as matrix in to composites, which were prodUced by mixing high density polyethylene with cellulose (10%) and Cell/ZrO(2)center dot nH(2)O (10%), using an extruder and hydraulic press. Tensile tests showed that the Cell/ZrO(2)center dot nH(2)O (10%)/HDPE composites present better tensile strength than cellulose (10%)/HDPE composites. Cellulose agglomerations were responsible for poor adhesion between fiber and matrix in cellulose (10%)/HDPE composites. HDPF/natural fibers composites showed also lower tensile strength in comparison to the polymer. The increase in Young`s modulus is associated to fibers reinforcement. SEM analysis showed that the cellulose fibers insertion in the matrix Caused all increase of defects, which were reduced When modified cellulose fibers were Used. (C) 2008 Elsevier Ltd. All rights reserved.

The effect of agitation speed, enzyme loading and substrate concentration on enzymatic hydrolysis of cellulose from brewer`s spent grain

Brewer`s spent grain components (cellulose, hemicellulose and lignin) were fractionated in a two-step chemical pretreatment process using dilute sulfuric acid and sodium hydroxide solutions. The cellulose pulp produced was hydrolyzed with a cellulolytic complex, Celluclast 1.5 L, at 45 degrees C to convert the cellulose into glucose. Several conditions were examined: agitation speed (100, 150 and 200 rpm), enzyme loading (5, 25 and 45 FPU/g substrate), and substrate concentration (2, 5 and 8% w/v), according to a 2(3) full factorial design aiming to maximize the glucose yield. The obtained results were interpreted by analysis of variance and response surface methodology. The optimal conditions for enzymatic hydrolysis of brewer`s spent grain were identified as 100 rpm, 45 FPU/g and 2% w/v substrate. Under these conditions, a glucose yield of 93.1% and a cellulose conversion (into glucose and cellobiose) of 99.4% was achieved. The easiness of glucose release from BSG makes this substrate a raw material with great potential to be used in bioconversion processes.

Effect of hemicellulose and lignin on enzymatic hydrolysis of cellulose from brewer`s spent grain

Enzymatic hydrolysis of brewer`s spent grain in three different forms: original (untreated), pretreated by dilute acid (cellulignin), and pretreated by a sequence of dilute acid and dilute alkali (cellulose pulp), was studied to verify the effect of hemicellulose and lignin on cellulose conversion into glucose. The hydrolysis was carried out using a commercial cellulase concentrate (Celluclast 1.5 L) in an enzyme/substrate ratio of 45 FPU/g, 2% (w/v) substrate concentration, 45 degrees C for 96 h. According to the results, the cellulose hydrolysis was affected by the presence of hemicellulose and/or lignin in the sample. The cellulose conversion ratio (defined as glucose yield + cellobiose yield) from cellulignin was 3.5-times higher than that from untreated sample, whereas from cellulose pulp such value was 4-times higher, correspondent to 91.8% (glucose yield of 85.6%). This best result was probably due to the strong modification in the material structure caused by the hemicellulose and lignin removal from the sample. As a consequence, the cellulose fibers were separated being more susceptible to the enzymatic attack. It was concluded that the lower the hemicellulose and lignin contents in the sample, the higher the efficiency of cellulose hydrolysis. (C) 2007 Elsevier Inc. All rights reserved.

Cellulose modified fibres in cement based composites

The objective of the present work is to evaluate the effect of surface modification of cellulose pulp fibres on the mechanical and microstructure of fibre-cement composites. Surface modification of the cellulose pulps was performed with Methacryloxypropyltri-methoxysilane (MPTS) and Aminopropyltri-ethoxysilane (APTS) in an attempt to improve their durability into fibre-cement composites. The surface modification showed significant influence on the microstructure of the composites on the fibre-matrix interface and in the mineralization of the fibre lumen as seen by scanning electron microscopy (SEM) with back-scattered electron (BSE) detector. Accelerated ageing cycles decreased modulus of rupture (MOR) and toughness (TE) of the composites. Composites reinforced with MPTS-modified fibres presented fibres free from cement hydration products, while APTS-modified fibres presented accelerated mineralization. Higher mineralization of the fibres led to higher embrittlement of the composite after accelerated ageing cycles. These observations are therefore very useful for understanding the mechanisms of degradation of fibre-cement composites. (C) 2009 Elsevier Ltd. All rights reserved.

Effect of Antioxidants and Corrosion Inhibitor Additives on the Quenching Performance of Soybean Oil

Cooling curve analysis was used to evaluate the effect of corrosion inhibitor additives and antioxidants on the quenching properties of soybean oil. The results showed that addition of corrosion inhibitors provided significant changes in the cooling curve behavior and of the yellow metal corrosion inhibitors evaluated tolyltriazole exhibits the greatest rate acceleration of heat transfer. However, the presence of antioxidants did not exhibit a significant effect on quenching properties of soybean oil. (C)2010 Journal of Mechanical Engineering. All rights reserved.

Combination of an anaerobic process with O(3), UV and O(3)/UV for cellulose pulp bleaching effluent treatment

Recent studies have shown that partial oxidation by advanced oxidation processes (AOP) is able to transform hard-to-degrade compounds and increase their biodegradability. In this work, anaerobic treatment was followed by ozonation, UV radiation and ozonation in the presence of UV radiation, to treat bleaching effluents from a cellulose kraft Pulp plant. The anaerobic reactor (horizontal anaerobic immobilized Sludge bed, HAISB) was Used as a pretreatment to reduce the efficient organic load before applying ACIP. The ozone treatments were applied in three different pH environments (3, 8 and 10) with retention times of 10, 30, 45 and 60 min. COD and adsorbable organic halogens (AOX) removal efficiencies at the HAISB were approximately 50%, while the BOD removal efficiency reached 80%. Ozonation promoted further removal of AOX and COD so that the combined efficiency reached 96% for AOX and 70% for COD. In the oxidation process, BOD was either removed in small quantities or actually increased, as intended, so that a second biological treatment would be able to complete the treatment. The maximum increase in the BOD(5)/COD ratio (biodegradability indicator) Occurred at pH 8, reaching 104% for ozonation at a dosage of 1540 mg(O3).L(-1). Applying UV radiation alone resulted in lower values: a 34% increase ill the BOD(5)/COD ratio and a 76% AOX removal efficiency. These results indicate that the combination of anaerobic treatment with ozonation or ozonation/UV radiation improves the treatability of cellulose pulp bleaching efficients and that the resulting wastewater is suitable for further biological treatment under aerobic conditions with a low level of toxic compounds from the halogenated family.

Biodeterioration of painted mortar surfaces in tropical urban and coastal situations: Comparison of four paint formulations

Four different architectural acrylic paint formulations were tested by exposure to weathering for 7 years in the urban site of Sao Paulo and the coastal site of Ubatuba, South-East Brazil. Surface discolorations and detachment of coatings were assessed and the components of the biofilms were identified by standard microbiological methods. The painted surfaces of the mortar panels were much more discolored in Ubatuba, where major components of the biofilms were the cyanobacteria Gloeocapsa and Scytonema. In two of the four paint films, a pink coloration on the surface at this coastal site, caused mainly by red-pigmented Gloeocapsa, produced high discoloration ratings, but low degradation (as measured by detachment). Biofilms in Sao Paulo contained the same range of phototrophs, but in lesser quantity. However, fungal numbers, as determined by plating, were higher. Detachment ratings in this urban site were only slightly lower than in Ubatuba. The matt paint performed worst of the four, with silk and semi-gloss finishes giving lowest biodeterioration ratings. The matt elastomeric paint performed well at both sites, apart from becoming almost 100% covered by the pink biofilm in Ubatuba. Unpainted mortar panels became intensely discolored with a black biofilm, showing that all the paints had achieved one of their objectives, that of surface protection of the substrate. The value of PVC (pigment volume content) as an indicator of coatings biosusceptibility, is questioned. (C) 2011 Elsevier Ltd. All rights reserved.

Bond strength and transversal deformation aging on cement-polymer adhesive mortar

Polymer-modified mortar is widely used to set ceramic tiles used as external finishing for high rise buildings in countries such as Brazil, Israel, Singapore and Portugal, mainly because it shows better bond strength and flexibility as compared to the traditional ones. Despite this, the results in the literature already published concerning the long-term performance of those composite mortars are is not conclusive. This paper, based on a laboratory program, compared the performance over time of four commercial polymer-modified adhesive mortars exposed to a typical Brazilian outdoor aging environment and to an indoor environment in terms of mortar flexibility and the bond strength to porcelain tiles. The results show that under laboratory condition, the mortars are more flexible and have higher bond strength than under external condition, and that there is an important correlation between the transversal deformability and the bond strength. (C) 2008 Elsevier Ltd. All rights reserved.