Efeito do intemperismo artificial em quatro madeiras tropicais monitorado por espectroscopia de infravermelho (DRIFT)

Four tropical woods, were investigated to compare their performance and natural resistances to artificial weathering using the diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). The species were garapeira (Apuleia leiocarpa), itaúba (Mezilaurus itauba) and tauari (Couratari sp.), woods traditionally indicated for exterior uses, and marupá (Simarouba amara), that served as reference. The samples were submitted to cycles of UV radiation (350 nm) and water until 2,000 h. The photodegradation processes of woods surfaces were accomplished monitoring the changes in the intensities associated to lignin (1508 cm-1) and carbonyl group (1736 cm-1) absorptions. The results have shown that lignin was the first component to be photodegradated, resulting in surfaces mainly composed by cellulose, after 2,000 h of UV irradiation. The processes of formation and lixiviation of carbonyl compounds were different for each species. The experimental conditions used in this work were too severe to evaluate the wood density and extractives content influences during the treatment.

Aplicações de fibras lignocelulósicas na química de polímeros e em compósitos

The use of lignocellulosic fibers and their constituents, as raw materials in the production of polymeric and composite materials, represent an exceptional opportunity of sustainable technological development. In the present report works that discuss promising alternatives of obtaining and use of materials such as cellulose, hemicellulose, lignin, cellulose nanocrystals and biocomposites were revised. The advance in the use of biomass can be, in a near future, capable of going beyond the application difficulties of these vast materials, especially in relation to the economical unviability, by the production of high performance polymeric and composite materials. This advance would represent a higher profitability to some areas of agrobusiness, especially the sector of biofuels, which produces elevated amounts of biomass waste.

Validação de metodologia para a caracterização química de bagaço de cana-de-açúcar

In this work, a methodology for the characterization of sugar cane bagasse was validated. Bagasse pre-treated with steam in a 5000 L reactor at a pressure of 15.3 kgf/cm², during 7 min, was used to test the methodology. The methodology consisted of the hydrolysis of the material with H2SO4 at 72% v/v, for the quantification of carbohydrates, organic acid, furfural and hydroxymethylfurfural by HPLC; insoluble lignin and ash by gravimetry; and soluble lignin by spectrophotometry. Linearity, repeatability, reproducibility and accuracy of the results obtained in two Research Laboratories were determined, and were considered to be suitable for the validation of the methodology.

Uma visão sobre a estrutura, composição e biodegradação da madeira

Wood is the main raw material used in the pulp and paper industry. It is a material that presents heterogeneous structure and complex composition, which results in a relatively resistant material to the biodegradation process. In the present review, we attempted to summarize the structural characteristics of wood and describe the chemical nature of its major components to, afterwards, comment about its biodegradation. The role of the enzyme manganese peroxidase in the lignin degradation by a selective white-rot fungus, Ceriporiopsis subvermispora, was highlighted.

Interferência da lignina na quantificação de radicais livres no processo de compostagem

In this work was studied composts and their humic acids (HA) to evaluate the use of EPR in the monitoring of the humification. It was observed increase in the concentration of organic free radical (OFR) in all the composts, but in L1 the increase was more significant than L2 and L3. Research more detailed of L1 showed that the lignin is main source of OFR. Then determination of these radicals in material in nature that contains high amount of lignin isn't a good indicator to monitor the humification process in the composting and yes the fraction HA of the composts.

Determinação de constituintes químicos em madeira de eucalipto por Pi-CG/EM e calibração multivariada: comparação entre redes neurais artificiais e máquinas de vetor suporte

Multivariate models were developed using Artificial Neural Network (ANN) and Least Square - Support Vector Machines (LS-SVM) for estimating lignin siringyl/guaiacyl ratio and the contents of cellulose, hemicelluloses and lignin in eucalyptus wood by pyrolysis associated to gaseous chromatography and mass spectrometry (Py-GC/MS). The results obtained by two calibration methods were in agreement with those of reference methods. However a comparison indicated that the LS-SVM model presented better predictive capacity for the cellulose and lignin contents, while the ANN model presented was more adequate for estimating the hemicelluloses content and lignin siringyl/guaiacyl ratio.

Uso de aditivos na biodegradação de madeira pelo fungo Ceriporiopsis subvermispora: efeito na peroxidação de lipídios dependente de manganês-peroxidase

Ceriporiopsis subvermispora is a selective fungus in the wood delignification and the most promising in biopulping. Through the lipid peroxidation initiated by manganese peroxidase (MnP), free radicals can be generated, which can act in the degradation of lignin nonphenolic structures. This work evaluated the prooxidant activity (based in lipid peroxidation) of enzymatic extracts from wood biodegradation by this fungus in cultures containing exogenous calcium, oxalic acid or soybean oil. It was observed that MnP significant activity is required to promote lipid peroxidation and wood delignification. Positive correlation between prooxidant activity x MnP was observed up to 300 IU kg-1 of wood.

Ligniinin määrän ja ligniinin modifioinnin vaikutus kuusen puuaineen ominaisuuksiin ja lahonkestoon

Seloste väitöskirjasta: The effect of lignin content and lignin modification on Norway spruce wood properties and decay resistance. Dissertationes Forestales 68.

EFEITO DOS TRATAMENTOS SUPERFICIAIS NAS PROPRIEDADES DO BAGAÇO DA FIBRA DE PIAÇAVA Attalea funifera Martius

The aim of this study was to investigate the effect of surface treatment on the properties of waste piassava fiber with the goal of aggregating additional business value. The fiber surface was subjected to four different treatments. In the present work, it was found that washing the fibers with water partially removed impurities from the surface rendering it rougher. Alkaline treatment removed impurities from the surface, hemicellulose and lignin, improving the flexibility of the fibers. Increasing the concentration of washing agents, times and temperature of treatment promoted intense defibrillation on the fiber surface, reducing its strength.

PARÂMETROS TERMODINÂMICOS DA CASCA DE LARANJA DESIDRATADA

The global energy scenario is currently a widely discussed topic, with growing concern about the future supplies. Thus, much attention has been dedicated to the utilization of biomass as an energy resource. In this respect, orange peel has become a material of great interest, especially to Brazil, which generates around 9.5 million tons of this waste per year. To this end, the authors studied the kinetics of the thermal processing of dried orange peel in inert and oxidizing atmosphere. The thermodynamic parameters were determined by the Ozawa-Flynn-Wall method for the global process observed during heating from the 25°C up to 800°C. The thermal analysis in air and nitrogen showed 3-2 stages of mass loss, respectively, with approximately 20% residual mass under a nitrogen atmosphere. The increase in the values of activation energy for the conversion points between 20% and 60% for thermal effects in air and nitrogen atmosphere was observed. The activation energy obtained in an oxidizing atmosphere was higher than that obtained under a nitrogen atmosphere. The fourier-transform infrared spectroscopy and X-ray diffraction analysis showed that the material has a high level of complexity with the presence of alkali and alkaline earth groups as well as phosphate, plus substances such as pectin, cellulose and lignin.

PYROLIGNEOUS LIQUOR PRODUCED FROM ACACIA MEARNSII DE WILD WOOD UNDER CONTROLLED CONDITIONS AS A RENEWABLE SOURCE OF CHEMICALS

Acacia mearnsii de Wild (black wattle) is one of the most important trees planted in Southern Brazil for tannin extraction and charcoal production. The pyrolysis of the black wattle wood used for obtaining charcoal is performed in brick ovens, with the gas fraction being sent directly into the environment. The present study examines the condensable compounds present in the liquor produced from black wattle wood at different thermal degradation conditions, using gas chromatography coupled with mass spectrometry (GC/MS). Branches of black wattle were thermally degraded at controlled ambient and temperature conditions. Overall, a higher variety of compounds were obtained under atmospheric air pressure than under synthetic air pressure. Most of the tentatively identified compounds, such as carboxylic acids, phenols, aldehydes, and low molecular mass lignin fragments, such as guayacol, syringol, and eugenol, were products of lignin thermoconversion. Substituted aromatic compounds, such as vanillin, ethyl vanillin, and 2-methoxy-4-propeny-phenol, were also identified. At temperatures above 200 ºC, furan, 2-acetylfuran, methyl-2-furoate, and furfural, amongst others, were identified as polysaccharide derivatives from cellulose and hemicellulose depolymerization. This study evidences the need for adequate management of the condensable by-products of charcoal production, both for economic reasons and for controlling their potential environmental impact.

Hemiselluloosien erotus ja in situ -modifiointi

Hemiselluloosat kuuluvat selluloosan ja ligniinin ohella puun ja muiden kasvimateriaalien päärakenneaineksiin. Hemiselluloosan kemiallisessa koostumuksessa on eroja kasvilajien välillä, mikä tekee ryhmästä hyvin monimuotoisen. Lehtipuiden pääasiallinen hemiselluloosa on glukuroniksylaani. Ksylaaneja esiintyy laajasti myös muissa kasveissa erilaisina rakenteina. Havupuiden yleisin hemiselluloosa on puolestaan galaktoglukomannaani. Arabinogalaktaani on erityisesti lehtikuusesta runsaana löytyvä hemiselluloosa, jota muissa puulajeissa on vain vähän. Luonnon polymeerejä tutkitaan jatkuvasti muun muassa vaihtoehtojen löytämiseksi raakaöljypohjaisille tuotteille. Aiemmin hemiselluloosia on pääosin hyödynnetty sellaisenaan tai jalostettu esimerkiksi sokereiksi. Selluloosan ja tärkkelyksen tavoin ne voivat kuitenkin toimia myös kemiallisen, fysikaalisen tai entsymaattisen muokkauksen lähtöaineena. Hemiselluloosien käyttöä rajoittaa usein se, että niiden eristäminen kasvimateriaalista hyvällä saannolla on vaikeaa. Useimmiten hemiselluloosa erotetaan biomassasta ligniinin poiston jälkeen uuttamalla erilaisilla reagensseilla, kuten emäksillä. Arabinogalaktaanin erottamiseen ei kuitenkaan vaadita ankaria olosuhteita, vaan yleisimmin siihen riittää uutto vedellä. Kalvosuodatus puolestaan on hyvä keino hemiselluloosan talteenottoon uuttoliuoksista. Tässä työssä tarkasteltiin arabinogalaktaanin erotusta siperianlehtikuusesta uuttokokein. Saadut uuttoliuokset konsentrointiin ja puhdistettiin kalvosuodatusmenetelmillä. Lisäksi tutkittiin eristetyn arabinogalaktaanin käyttöä kemiallisen muokkauksen lähtöaineena, missä pyrkimyksenä oli etenkin in situ -modifiointi suoraan uuttoliuoksessa oleville yhdisteille. Uuttokokeilla saatiin kuitenkin vain pieni osa lehtikuusen arabinogalaktaanista erotetuksi. Myös kalvosuodatusvaiheen aikana menetettiin osa uuttoliuosten arabinogalaktaanista. Koska arabinogalaktaanipitoisuus uuttoliuoksissa jäi hyvin alhaiseksi, in situ -modifiointeja oli vaikea saada onnistumaan. Uutto-olosuhteiden lisätutkimuksella sekä kiinnittämällä erityistä huomiota suodatuskalvojen valintaan voitaneen pitoisuutta nostaa ja saada lisämateriaalia kemiallista muokkausta varten.

The intrinsic mechanisms of softwood fiber damage in brown stock fiber line unit operations Lappeenranta 2010

The effects of pulp processing on softwood fiber properties strongly influence the properties of wet and dry paper webs. Pulp strength delivery studies have provided observations that much of the strength potential of long fibered pulp is lost during brown stock fiber line operations where the pulp is merely washed and transferred to the subsequent processing stages. The objective of this work was to study the intrinsic mechanisms which maycause fiber damage in the different unit operations of modern softwood brown stock processing. The work was conducted by studying the effects of industrial machinery on pulp properties with some actions of unit operations simulated in laboratory scale devices under controlled conditions. An optical imaging system was created and used to study the orientation of fibers in the internal flows during pulp fluidization in mixers and the passage of fibers through the screen openings during screening. The qualitative changes in fibers were evaluated with existing and standardized techniques. The results showed that each process stage has its characteristic effects on fiber properties: Pulp washing and mat formation in displacement washers introduced fiber deformations especially if the fibers entering the stage were intact, but it did not decrease the pulp strength properties. However, storage chests and pulp transfer after displacement washers contributed to strength deterioration. Pulp screening proved to be quite gentle, having the potential of slightly evening out fiber deformations from very deformed pulps and vice versa inflicting a marginal increase in the deformation indices if the fibers were previously intact. Pulp mixing in fluidizing industrial mixers did not have detrimental effects on pulp strength and had the potential of slightly evening out the deformations, provided that the intensity of fluidization was high enough to allow fiber orientation with the flow and that the time of mixing was short. The chemical and mechanical actions of oxygen delignification had two distinct effects on pulp properties: chemical treatment clearly reduced pulp strength with and without mechanical treatment, and the mechanical actions of process machinery introduced more conformability to pulp fibers, but did not clearly contribute to a further decrease in pulp strength. The chemical composition of fibers entering the oxygen stage was also found to affect the susceptibility of fibers to damage during oxygen delignification. Fibers with the smallest content of xylan were found to be more prone to irreversibledeformations accompanied with a lower tensile strength of the pulp. Fibers poor in glucomannan exhibited a lower fiber strength while wet after oxygen delignification as compared to the reference pulp. Pulps with the smallest lignin content on the other hand exhibited improved strength properties as compared to the references.

Pretreatment in membrane filtration of wood hydrolysate

Interest in recovery of valuable components from process streams has increased in recent years. Purpose of biorefinery is to utilize components that otherwise would go to waste. Hemicelluloses, for example, could be utilized in production of many valuable products. One possible way to separate and fractionate hemicelluloses is membrane filtration. In the literature part of this work membrane fouling in filtration processes of pulp and paper process- and wastewaters was investigated. Especially purpose was to find out the possible fouling compounds, after which facilities to remove or modify such components less harmful were studied. In the experimental part different pretreatment methods, mainly to remove or degrade lignin from wood hydrolysate, were studied. In addition, concentration of hemicelluloses and separation from lignin were examined with two ultrafiltration membranes; UFX5 and RC70PP. Changes in feed solution, filtration capacity and fouling of membranes were used to evaluate the effects of pretreatment methods. Changes in hydrolysate composition were observed with different analysis methods. Filtration of hydrolysate proved to be challenging, especially with the UFX5 membrane. The more hydrophilic RC70PP membrane did not seem to be fouled as severely as the UFX5 membrane, according to pure water flux measurements. The UFX5 membrane retained hemicelluloses rather well, but problems arose from rapid flux decline resulting from concentration polarization and fouling of membrane. Most effective pretreatment methods in the case with the UFX5 membrane proved to be prefiltration with the RC70PP membrane, activated carbon adsorption and photocatalytic oxidation using titanium dioxide and UV radiation. An additional experiment with PHW extract showed that pulsed corona discharge treatment degraded lignin quite efficiently and thus improved filtration capacity remarkably, even over six times compared to the filtration with untreated extract.

Taivekartongin sävytys ja jälkikellertyminen

Taivekartongilta vaaditaan nykyisin korkealaatuista ja tasaista ulkonäköä. Pakkauksen tehtävänä on parantaa myyntiä hyvällä ulkonäöllä ja siisteydellä sekä antaa informaatiota ja käyttöohjeita. Tässä diplomityössä tutkittiin taivekartongin sävyttämistä, optisia ominaisuuksia sekä vaaleuden ja sävyjen pysyvyyttä. Kirjallisuusosassa käsiteltiin paperin ja kartongin optisia ominaisuuksia sekä esiteltiin Kubelka-Munkin teoria. Teoriaa voidaan käyttää mm. monikerroskartongin vaaleuden ja sävyjen mallintamisessa. Esillä oli paljon eri prosessitekijöitä, massoja ja kemikaaleja, jotka vaikuttavat kartongin vaaleuteen ja sävyyn. Työssä kärsiteltiin myös keinoja vaikuttaa kartongin sävyyn sävytyksellä ja sävytyksen eri tapoja. Toisaalta vaaleuden ja sävyn pysyvyyteen vaikuttaa kartongin jälkikellertyminen. Työssä tarkasteltiin jälkikellertymisen mekanismeja ja siihen vaikuttavia tekijöitä sekä esitettiin keinoja ennalta ehkäistä ja estää kellertymistä. Kokeellisessa osassa käsiteltiin massan ja päällystyspastan värjäyksen vaikutuksia ulkonäköön ja optisiin ominaisuuksiin. Sinertävillä tai violeteilla sävyväreillä voidaan pienentää mekaanisten massojen luonnollista kellertyvyyttä, jolloin valkoisuuden vaikutelma lisääntyy. Värien lisääminen heikentää vaaleutta, koska värien lisäys nostaa valon absorptiota. Tämän takia on tärkeää lisätä väri mielellään siihen kerrokseen, jossa kellertävä massa on, joka on tyypillisesti kartongin keskikerros. Pintakerrokset ovat valkaistua sellua ja niillä on tärkeä merkitys kartongin vaaleudelle, joten värin lisäys pintaan alentaisi vielä merkittävämmin kartongin kokonaisvaaleutta. Pastan värjäyksellä saadaan tasaisuutta värjäykseen, mutta sävyn säätö on tehtävä edelleen massavärjäyksellä. Pigmenttivärien käytöllä pystytään lisäämään mm. valonkestoa kartongille. Kartongin ja paperituotteiden valonkeston tutkimiseen ei ole olemassa standardia. Työssä tutkittiin laboratorio-olosuhteissa ja huonevalossa vanhentuneiden kartonkinäytteiden vertailtavuutta. Materiaalivalinnoilla pystytään vaikuttamaan valon-kestoon. Siihen vaikuttavat mm. massan laatu, lateksivalinta sekä pigmenttivärin käyttö. Mekaanista massaa sisältävät tuotteet kellertyvät pääasiassa ligniinin takia. Ligniini sisältää paljon UV-säteilyyn reagoivia ryhmiä, jotka muuttuvat värilliseksi lisäten kellertymistä. Valkaistujen sellujen vanhentuminen on suhteessa mekaaniseen massaan erittäin vähäistä. SA-lateksin havaittiin suojaavan vaaleuden menetykseltä ja lisäävän sävyn pysyvyyttä paremmin kuin SB-lateksi.