EVALUATION OF EUCALYPTUS KRAFT PULP LIGNIN THROUGH THE NITROBENZENE OXIDATION, COPPER OXIDE REDUCTION AND ACIDOLYSIS TECHNIQUES

This study aimed to evaluate the sensitiveness of the information obtained for the residual lignin from Eucalyptus grandis kraft pulps analyzed through the nitrobenzene oxidation, copper oxide (CuO) reduction and acidolysis techniques. The chips were cooked, resulting pulps of kappa number 14,5 and 16,9, respectively. Both lignins' pulps were evaluated through three methods (nitrobenzene oxidation, copper oxide oxidation and acidolysis). Then, they were subjected to an oxygen delignification stage. The 16,9 kappa number pulp resulted in higher levels of non-condensed lignin structures by the acidolysis method, higher syringyl/vanillin ratios (S/V) by the nitrobenzene and copper oxide methods and better performance in the oxygen delignification stage. The different methods allowed to differ the residual lignin pulps with kappa number 14,5 and 16,9, and the nitrobenzene oxidation method showed the highest sensitiveness in this study results.

Advanced oxidation process H2O2/UV combined with anaerobic digestion to remove chlorinated organics from bleached kraft pulp mill wastewater

This study investigated the application of an advanced oxidation process combining hydrogen peroxide with ultraviolet radiation (H2O2/UV) to remove recalcitrant compounds from Kraft bleaching effluent. Anaerobic pre-treatment was performed to remove easily degraded organics using a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Bleaching plant effluent was treated in the HAIB reactor processed over 19 h of hydraulic retention time (HRT), reaching the expected removal efficiencies for COD (61 +/- 3%), TOC (69 +/- 9%), BOD5 (90 +/- 5%) and AOX (55 +/- 14%). However, the anaerobic treatment did not achieve acceptable removal of UV254 compounds. Furthermore, there was an increase of lignin, measured as total phenols. The H2O2/UV post-treatment provided a wide range of removal efficiencies depending on the dosage of hydrogen peroxide and UV irradiation: COD ranged from 0 to 11%, UV254 from 16 to 35%, lignin from 0 to 29% and AOX from 23 to 54%. All peroxide dosages applied in this work promoted an increase in the BOD5/COD ratio of the wastewater. The experiments demonstrate the technical feasibility of using H2O2/UV for post-treatment of bleaching effluents submitted to anaerobic pre-treatment.

Cellulose micro/nanofibres from Eucalyptus kraft pulp: Preparation and properties

There is growing interest in cellulose nanofibres from renewable sources for several industrial applications. However, there is a lack of information about one of the most abundant cellulose pulps: bleached Eucalyptus kraft pulp. The objective of the present work was to obtain Eucalyptus cellulose micro/nanofibres by three different processes, namely: refining, sonication and acid hydrolysis of the cellulose pulp. The refining was limited by the low efficiency of isolated nanofibrils, while sonication was more effective for this purpose. However, the latter process occurred at the expense of considerable damage to the cellulose structure. The whiskers obtained by acid hydrolysis resulted in nanostructures with lower diameter and length, and high crystallinity. Increasing hydrolysis reaction time led to narrower and shorter whiskers, but increased the crystallinity index. The present work contributes to the different widespread methods used for the production of micro/nanofibres for different applications. (C) 2012 Elsevier Ltd. All rights reserved.

Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production

Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. High cellulose content, low content of non-cellulosic material, high brightness, a uniform molecular weight distribution and high cellulose reactivity are the key features that determine the quality of a dissolving pulp. The first part of this work was an optimization study regarding the application of selected enzymes in different stages of a new purification process recently developed in Novozymes for purifying an eucalypt Kraft pulp into dissolving pulp, as an alternative to the pre-hydrolysis kraft (PHK) process. In addition, a viscosity reduction was achieved by cellulase (endoglucanase) treatment in the beginning of the sequence, while the GH11 and GH10 xylanases contributed to boost the brightness of the final pulp. The second part of the work aimed at exploring different auxiliary enzyme activities together with a key xylanase towards further removal of recalcitrant hemicelluloses from a partially bleached Eucalypt Kraft pulp. The resistant fraction (ca. 6% xylan in pulp) was not hydrolysable by the different combinations of enzymes tested. Production of a dissolving pulp was successful when using a cold caustic extraction (CCE) stage in the end of the sequence O-X-DHCE-X-HCE-D-CCE. The application of enzymes improved process efficiency. The main requirements for the production of a dissolving pulp (suitable for viscose making) were fulfilled: 2,7% residual xylan, 92,4% of brightness, a viscosity within the values of a commercial dissolving pulp and increased reactivity.

Lignocellulosic polysaccharides and lignin degradation by wood decay fungi: the relevance of nonenzymatic Fenton-based reactions

The brown rot fungus Wolfiporia cocos and the selective white rot fungus Perenniporia medulla-panis produce peptides and phenolate-derivative compounds as low molecular weight Fe(3+)-reductants. Phenolates were the major compounds with Fe(3+)-reducing activity in both fungi and displayed Fe(3+)-reducing activity at pH 2.0 and 4.5 in the absence and presence of oxalic acid. The chemical structures of these compounds were identified. Together with Fe(3+) and H(2)O(2) (mediated Fenton reaction) they produced oxygen radicals that oxidized lignocellulosic polysaccharides and lignin extensively in vitro under conditions similar to those found in vivo. These results indicate that, in addition to the extensively studied Gloeophyllum trabeum-a model brown rot fungus-other brown rot fungi as well as selective white rot fungi, possess the means to promote Fenton chemistry to degrade cellulose and hemicellulose, and to modify lignin. Moreover, new information is provided, particularly regarding how lignin is attacked, and either repolymerized or solubilized depending on the type of fungal attack, and suggests a new pathway for selective white rot degradation of wood. The importance of Fenton reactions mediated by phenolates operating separately or synergistically with carbohydrate-degrading enzymes in brown rot fungi, and lignin-modifying enzymes in white rot fungi is discussed. This research improves our understanding of natural processes in carbon cycling in the environment, which may enable the exploration of novel methods for bioconversion of lignocellulose in the production of biofuels or polymers, in addition to the development of new and better ways to protect wood from degradation by microorganisms.

Optimal Mechanical PulpingProcesses for Eucalyptus, Acacia and Birch

Tässä diplomityössä tutkittiin ja vertailtiin eukalyptuksen, akaasian ja koivun kemimekaanista kuiduttamista ja valkaisua. Yleensä näitä puulajeja käytetään sellun keittoon. Puulajit eroavat toisistaan kasvupaikan ja kuiturakenteen osalta. Eukalyptus ja akaasia ovat niin sanottuja trooppisia lehtipuita, kun taas koivu kasvaa pohjoisilla vyöhykkeillä. Koivulla on kookkaimmat kuidut ja akaasialla pienimmät kuidut. Myös näiden lajien putkilot eroavat toisistaan. Koivun putkilot ovat pitkiä ja kapeita, kun taas eukalyptuksen ja akaasian putkilot ovat lyhyitä ja leveitä. Prosessiksi valittiin kaksivaiheinen APMP-prosessi. Koeajot tehtiinKeskuslaboratorio Oy:ssä. Massoille asetettiin seuraavat tavoitteet: freeness 150-200 ml ja vaaleus 80 %ISO. Eukalyptukselle ja koivulle tehtiin kaksi erilaista impregnointisarjaa, mutta akaasialle vain yksi. Jauhatuksen viimeisessä vaiheessa kokeiltiin myös jauhinvalkaisua. Jauhatuksen energiankulutus oli korkea varsinkin eukalyptuksella ja akaasialla. Jotta energiankulutus saataisiin pienemmäksi, tulisi käyttää enemmän lipeää, mutta se johtaa alkalitummumiseen. Lopuksi massat valkaistiin laboratoriossa. Eukalyptus ja koivu pystyttiin valkaisemaan vaaleuteen 80 %ISO, mutta eukalyptuksen valkaisu vaati enemmän peroksidia kuin koivun valkaisu. Akaasian lähtövaaleus oli niin alhainen, ettei siinä päästy tavoitevaaleuteen. Eukalyptuksella on parempi valonsironta ja paremmat lujuusominaisuudet kuin koivulla. Kemimekaanista massaa voidaan käyttää hienopaperissa parantamassa jäykkyyttä, bulkkia ja valonsirontaa, mutta usein ongelmana on alhainen vaaleus ja huono vaaleuden pysyvyys. Kemimekaanista massaa voidaankäyttää missä tahansa mekaanisissa painopapereissa. Mekaanisissa painopapereissa kemimekaanisella lehtipuumassalla voidaan korvata mekaanista havupuumassaa. Akaasia on niin tummaa, ettei sitä voida käyttää korkeavaaleuksisiin papereihin. Eukalyptus ja koivu ovat vaaleampia ja helpompia valkaista kuin akaasia, mutta myös niillä on niin huono vaaleudenpysyvyys että käyttö hienopapereissa on rajoittunutta. Mekaanisille eukalyptus ja koivumassoille hienopaperia parempi käyttökohde on mekaaniset painopaperit, kuten MWC-paperi.

Kuitujen kiharuuteen vaikuttavia tekijöitä sulfaattiselluloosan valmistuksessa

Diplomityön tarkoituksena oli selvittää kuitujen kihartuvuuden profiili koivu- ja havusellulinjalla prosessivaiheiden suhteen. Profiilin perusteella pyrittiin selvittämään kuitulinjojen prosessista kuitujen kiharuuteen voimakkaimmin vaikuttavia tekijöitä. Työn kirjallisuusosassa käsiteltiin kuitujen ominaisuuksia sekä teollisen sellun valmistusprosessin kuituihin aiheuttamia kuituvaurioita ja niiden mahdollisia syitä. Lisäksi käytiin läpi kuituvaurioiden analysointimenetelmiä ja kuituvaurioiden kanssa korreloivia sellun laatuarvoja. Työn kokeellinen osa suoritettiin kuitulinjojen normaalin tuotannon ohessa. Kokeellisen osan massanäytteitä otettiin varsin moninaisista tuotantotilanteista mahdollisimman kattavan kiharuusprofiilin aikaansaamiseksi. Koivusellulinjalla vuokeittimen tuotantotaso vaikutti suuresti valmistettavan sellun ominaisuuksiin. Kuituvaurioiden syntyyn voimakkaimmin vaikuttavaksi tekijäksi osoittautui keittimen pohja-alueen, puskun ja massan pesuvaiheen sakeus. Tämän alueen sakeus muuttui tuotantotason mukaan, tuotantotason kasvun myötä alueen sakeus laski. Sakeuden lasku vähensi kuitujen kiharuutta sekä massan venymää ja paransi vetojäykkyyttä. Tuotantotason kasvu paransi myös keittimestä otettujen massanäytteiden vetojäykkyyspotentiaalia. Havusellulinjalla käytetyn Lo-Solids –keittomallin ja konventionaalisen keittomallin kesken esiintyi varsin merkittäviä laadullisia eroja. Lo-Solids –keittomallilla keitetyt sellukuidut kihartuivat konventionaalisella keittomallilla keitettyjä sellukuituja enemmän. Lo-Solids –keittomallilla keitetyn sellun vetojäykkyys oli konventionaalisella mallilla keitetyn sellun vetojäykkyyttä heikompi.

Hydrolysis of xylans by enzyme systems from solid cultures of Trichoderma harzianum strains

Xylanase activity was isolated from crude extracts of Trichoderma harzianum strains C and 4 grown at 28oC in a solid medium containing wheat bran as the carbon source. Enzyme activity was demonstrable in the permeate after ultrafiltration of the crude extracts using an Amicon system. The hydrolysis patterns of different xylans and paper pulps by xylanase activity ranged from xylose, xylobiose and xylotriose to higher xylooligosaccharides. A purified ß-xylosidase from the Trichoderma harzianum strain released xylose, xylobiose and xylotriose from seaweed, deacetylated, oat spelt and birchwood xylans. The purified enzyme was not active against acetylated xylan and catalyzed the hydrolysis of xylooligosaccharides, including xylotriose, xylotetraose and xylopentaose. However, the enzyme was not able to degrade xylohexaose. Xylanase pretreatment was effective for hardwood kraft pulp bleaching. Hardwood kraft pulp bleached in the XEOP sequence had its kappa number reduced from 13.2 to 8.9 and a viscosity of 20.45 cp. The efficiency of delignification was 33%.

Influência das principais commodities agropecuárias e de variáveis macroeconômicas sobre os preços da terra agrícola no Brasil

Este trabalho tem como proposta investigar como o preço de terras de uso rural no Brasil é afetado pelos preços e exportações das principais commodities agropecuárias, bem como por variáveis macroeconômicas, como taxa básica de juros, taxa de câmbio, taxa de inflação e disponibilidade de crédito agrícola. Para tal foram consideradas as produções agrícola de algodão, café, cana-de-açúcar (e seus principais produtos açúcar e etanol), milho e soja, a produção pecuária de carne bovina e a produção industrial de celulose de fibra curta com foco em sua principal matéria prima, os plantios reflorestados de eucalipto. Em linha com estudos anteriores, foi encontrada evidência empírica de que o preço da terra possui cointegração com algumas das variáveis agrícolas, pecuárias e florestais citadas, em especial em estados com maior vocação agropecuária e/ou para silvicultura. Quanto às variáveis macroeconômicas, apenas a taxa básica de juros apresentou cointegração com o preço de terras para todos os estados avaliados, taxa de câmbio e disponibilidade de crédito rural não aparecem como variáveis estatisticamente significantes. Conclui-se que, para estados com notável participação na balança comercial brasileira de produtos agrossilvipastoris, é possível obter um modelo de equilibro de longo prazo entre o preço da terra de uso rural e as variáveis destacadas acima, de modo que investidores do setor possam utilizá-lo como ferramenta de projeção no auxílio da tomada de decisão além de avaliar potenciais impactos no valor de seus ativos A inovação do presente estudo está em testar as hipóteses de cointegração para cada um dos estados da federação.

The Chemical Mechanism of a Brown-Rot Decay Mimtic System and its Application in Paper Recycling Processes

This work is aimed at improving our current knowledge of the non-enzymatic inecl~anisins involved in brown-rot decay, as well as the exploration of potential applications of a brown-rot mimetic model system in paper recycling processes. The study was divided into two parts. The first part focussed on the chemical mechanisms involved in chelation and reduction of iron by a low molecular weight chelator (isolated from the brown-rot fungus Gloeophyllz~m tmbeum) and its model compound 2,3- dihydroxybenzoic acid (2,3-DHBA). Chelation as well as free radical generation mediated by this system were studied by ESR measurement. The results indicate that the effects of the chelator/iron ratio, the pH, and other reaction parameters on hydroxyl radical generation by a Fenton type system could be determined using ESR spin-trapping techniques. The results also support the hypothesis that superoxide radicals are involved in the chelator-mediated Fenton process. In the second part of the study, the effect of a chelator-mediated Fenton system for the improvement of deinking efficiency and the n~odification of fiber and paper properties was studied. For the deinking study, copy paper was laser printed with an identical standard pattern. Then repulping and flotation operations were performed to remove ink particles. Under properly controlled deinking conditions, the chelator mediated treatment (CMT) resulted in a reduction in dirt count over that of conventional deinking procedures with no significant loss of pulp strength. To study the effect of the chelator system treatment on the quality of pulp with different fines content, a fully bleached hardwood kraft pulp was beaten to different freeness levels and treated with the chelator-mediated free radical system. The result shows that virgin fiber and heavily beaten fiber respond differently to the free radical treatment. Unbeaten fibers become more flexible and easier to collapse after free radical treatment, while beaten fibers show a reduction in fines and small materials after mild free radical treatment.

Additional revenue opportunities in pulp mills and their impacts on the kraft process

Although the concept of multi-products biorefinery provides an opportunity to meet the future demands for biofuels, biomaterials or chemicals, it is not assured that its implementation would improve the profitability of kraft pulp mills. The attractiveness will depend on several factors such as mill age and location, government incentives, economy of scale, end user requirements, and how much value can be added to the new products. In addition, the effective integration of alternative technologies is not straightforward and has to be carefully studied. In this work, detailed balances were performed to evaluate possible impacts that lignin removal, hemicelluloses recovery prior to pulping, torrefaction and pyrolysis of wood residues cause on the conventional mill operation. The development of mill balances was based on theoretical fundamentals, practical experience, literature review, personal communication with technology suppliers and analysis of mill process data. Hemicelluloses recovery through pre-hydrolysis of chips leads to impacts in several stages of the kraft process. Effects can be observed on the pulping process, wood consumption, black liquor properties and, inevitably, on the pulp quality. When lignin is removed from black liquor, it will affect mostly the chemical recovery operation and steam generation rate. Since mineral acid is used to precipitate the lignin, impacts on the mill chemical balance are also expected. A great advantage of processing the wood residues for additional income results from the fact that the pulping process, pulp quality and sales are not harmfully affected. For pulp mills interested in implementing the concept of multi-products biorefinery, this work has indicated possible impacts to be considered in a technical feasibility study.

Production of Ethanol from Hardwood

Diminishing crude oil and natural gas supplies, along with concern about greenhouse gas are major driving forces in the search for efficient renewable energy sources. The conversion of lignocellulosic biomass to energy and useful chemicals is a component of the solution. Ethanol is most commonly produced by enzymatic hydrolysis of complex carbohydrates to simple sugars followed by fermentation using yeast. C6Hl0O5 + H2O −Enxymes→ C6H12O6 −Yeast→ 2CH3CH2OH + 2C02 In the U.S. corn is the primary starting raw material for commercial ethanol production. However, there is insufficient corn available to meet the future demand for ethanol as a gasoline additive. Consequently a variety of processes are being developed for producing ethanol from biomass; among which is the NREL process for the production of ethanol from white hardwood. The objective of the thesis reported here was to perform a technical economic analysis of the hardwood to ethanol process. In this analysis a Greenfield plant was compared to co-locating the ethanol plant adjacent to a Kraft pulp mill. The advantage of the latter case is that facilities can be shared jointly for ethanol production and for the production of pulp. Preliminary process designs were performed for three cases; a base case size of 2205 dry tons/day of hardwood (52 million gallons of ethanol per year) as well as the two cases of half and double this size. The thermal efficiency of the NREL process was estimated to be approximately 36%; that is about 36% of the thermal energy in the wood is retained in the product ethanol and by-product electrical energy. The discounted cash flow rate of return on investment and the net present value methods of evaluating process alternatives were used to evaluate the economic feasibility of the NREL process. The minimum acceptable discounted cash flow rate of return after taxes was assumed to be 10%. In all of the process alternatives investigated, the dominant cost factors are the capital recovery charges and the cost of wood. The Greenfield NREL process is not economically viable with the cost of producing ethanol varying from $2.58 to $2.08/gallon for the half capacity and double capacity cases respectively. The co-location cases appear more promising due to reductions in capital costs. The most profitable co-location case resulted in a discounted cash flow rate of return improving from 8.5% for the half capacity case to 20.3% for the double capacity case. Due to economy of scale, the investments become more and more profitable as the size of the plant increases. This concept is limited by the amount of wood that can be delivered to the plant on a sustainable basis as well as the demand for ethanol within a reasonable distance of the plant.

Sisal organosolv pulp as reinforcement for cement based composites

The present work describes non-conventional sisal (Agave sisalana) chemical (organosolv) pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP) fibres were produced by the slurry de-watering and pressing method as a crude simulation of the Hatschek process. Composites were evaluated at 28 days of age, after exposition to accelerated carbonation and after 100 soak/dry cycles. Composites containing organosolv pulp presented lower mechanical strength, water absorption and apparent porosity than composites reinforced with kraft pulp. The best mechanical performance after ageing was also achieved by samples reinforced with kraft pulp. The addition of PP fibres favoured the maintenance of toughness after ageing. Accelerated carbonation promoted the densification of the composites reinforced with sisal organosolv + PP fibres.

High-yield kraft pulping of Eucalyptus grandis Hill ex Maiden biotreated by Ceriporiopsis subvermispora under two different culture conditions

In the present study, it was evaluated how two different culture conditions for the biotreatment of Eucalyptus grandis by Ceriporiopsis subvermispora affect a subsequent high-yield kraft pulping process. Under the varied culture conditions investigated, different extracellular enzyme activities were observed. Manganese-peroxidase (MnP) secretion was 3.7 times higher in cultures supplemented with glucose plus corn-steep liquor (glucose/CSL) as compared to non-supplemented (NS) cultures. The biotreated samples underwent diverse levels of wood component degradation as losses of weight and lignin were increased in glucose/CSL cultures. Mass balances for lignin removal during kraft pulping showed that delignification was facilitated when both biotreated wood samples were cooked. Delignification efficiency did not correlate positively with MnP levels in the cultures. On the other hand, biopulps from NS and glucose/CSL cultures saved 27% and 38% beating time to achieve 288 Schopper-Riegler freeness during refining, respectively. Biopulps disposed of decreased tensile and tear resistances, thus easier refining of the biokraft pulps seems to be a consequence of less resistant fiber walls. Improved beatability of biopulps was tentatively related to short fibers and fines formation during refining. We suggest that to some extent polysaccharide depolymerization occurred during the biotreatment, which also resulted in diminished pulp yields in the case of glucose/CSL cultures.

Toxicity and recalcitrant compound removal from bleaching pulp plant effluents by an integrated system: anaerobic packed-bed bioreactor and ozone

Effluents originated in cellulose pulp manufacturing processes are usually toxic and recalcitrant, specially the bleaching effluents, which exhibit high contents of aromatic compounds (e.g. residual lignin derivates). Although biological processes are normally used, their efficiency for the removal of toxic lignin derivates is low. The toxicity and recalcitrance of a bleached Kraft pulp mill were assessed through bioassays and ultraviolet absorption measurements, i.e. acid soluble lignin (ASL), UV(280), and specific ultraviolet absorption (SUVA), before and after treatment by an integrated system comprised of an anaerobic packed-bed bioreactor and oxidation step with ozone. Furthermore, adsorbable organic halides (AOX) were measured. The results demonstrated not only that the toxic recalcitrant compounds can be removed successfully using integrated system, but also the ultraviolet absorption measurements can be an interesting control-parameter in a wastewater treatment.