Co-production of furfural and wood composite products from bio-based processing residues

Soludongwe, Siviwe Mlamli (2020-03)

Thesis (MScFor)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: There is an increased environmental concern to move from a petroleum-based economy to a more bio-based economy. Lignocellulosic materials have been shown to be a good source of building blocks for value-added products such as furfural. The integration of lignocellulosic material in a biorefinery concept proves to be necessary and beneficial in the industry and global context. The lignocellulosic material was sourced locally and included sugarcane (Saccharum officinarum) bagasse, Blue gum (Eucalyptus globulus) and Long-leaved wattle (Acacia longifolia). The lignocellulosic materials were pre-treated with NaOH aimed at enhancing the flexural and physical properties of the manufactured panels as well as extracting hemicelluloses. The effect of the treatment on fibres and resultant by-products were evaluated using wet chemical and instrumental methods, such as high-performance liquid chromatography (HPLC), molecular weight, size-exclusion chromatography (SEM) and Fourier-transform infrared spectroscopy (FTIR). In the present study, the co-production of composite panels and furfural was investigated. The aim was to integrate the biorefinery concept in using biomass waste and alkali pre-treatment to produce furfural. The composite panels were manufactured using untreated and alkaline treated lignocellulosic material, while furfural was produced from the pre-treated by-products. Moreover, this study set out to simultaneously add value to the by-products from pretreated lignocellulosic material by producing furfural, which had not been done previously. In order to produce the furfural, a central composite statistical design (CCD) was used with independent variable temperatures (150-170 °C), time (30-90 min) and the response variable furfural yield, while acidic concentration (2wt%) and solid loading (14wt%) were kept constant. The experimental conditions were sourced with reference to literature to mimic the industrial standards. The interaction of the independent variables and their effect on the produced furfural were evaluated using the Pareto analysis of variance. Response surface models were used to develop and predict the parameters yielding optimum furfural yield. The yields of furfural from the acid hydrolysis of the extracted hemicelluloses was 39, 45 and 44 mol% for sugarcane bagasse, E.globulus and A.longifolia, respectively. These values were slightly lower than the predicted values from the CCD. The low furfural yields led to a Pareto chart showing no confidence of independent variables on the furfural yield. Furthermore, the performance of the treated materials compared to untreated materials were evaluated on the properties of the manufactured composite panels, such as modulus of elasticity (MOE), modulus of rupture (MOR), water absorption and thickness. Based on the results, the treated lignocellulosic materials enhanced the properties of the composite panels as compared to the untreated lignocellulosic materials. In the treated panels the modulus of rupture was 10.42 MPa, 11.13 MPa and 6.4 MPa for sugarcane bagasse, E. globulus and A. longifolia, respectively. The manufactured panels met the minimum requirements and are classified as low density to medium density boards according to ANSI A208.1. These panels prove useful in the wood panel industry as core material for solid doors.

AFRIKAANSE OPSOMMING: Daar is 'n toenemende kommer oor die omgewing om van 'n petroleum-gebaseerde ekonomie na 'n meer bio-gebaseerde ekonomie te beweeg. Lignosellulosiese materiale is 'n goeie bron van boustene vir waardetoevoegende produkte soos furfural. Die integrasie van lignosellulosiese materiaal in 'n bioraffinadery-konsep blyk in die industrie en wêreldwye konteks noodsaaklik en voordelig te wees. Die lignosellulosiese materiaal is plaaslik verkry en bevat suikerriet (Saccharum officinarum) bagasse, bloekom (Eucalyptus globulus) en langblaar-wattel (Acacia longifolia). Die lignosellulosiese materiaal is vooraf behandel met NaOH wat daarop gemik was om die buig- en fisiese eienskappe van die vervaardigde panele te verbeter, asook om hemiselluloses te onttrek. Die effek van die behandeling op vesels en gevolglike neweprodukte is beoordeel met behulp van nat chemiese en instrumentele metodes, soos hoëprestasie vloeistofchromatografie (HPLC), molekulêre gewig, grootte-uitsluitingschromatografie (SEM) en Fourier-transvorm infrarooi spektroskopie (FTIR ). In die huidige studie is die medeproduksie van saamgestelde panele en furfural ondersoek. Die doel was om die bioraffinadery-konsep te integreer in die gebruik van biomassa-afval en voorafbehandeling van alkali om furfural te produseer. Die saamgestelde panele is vervaardig met onbehandelde en alkaliese behandelde lignosellulosiese materiaal, terwyl furfural vervaardig is uit die voorafbehandelde neweprodukte. Verder het hierdie studie beoog om gelyktydig waarde toe te voeg tot die neweprodukte van voorafbehandelde lignosellulosiese materiaal deur furfural te vervaardig, wat nog nie voorheen gedoen is nie. Om die furfural te vervaardig, is 'n sentrale saamgestelde statistiese ontwerp (CCD) gebruik met onafhanklike veranderlike temperature (150-170 ° C), tyd (30-90 min) en die respons veranderlike furfural opbrengs, terwyl die suur konsentrasie (2 gew.%) en vaste belading (14 gew.%) konstant gehou is. Die eksperimentele toestande is verkry met verwysing na literatuur om die industriële standaarde na te boots. Die interaksie van die onafhanklike veranderlikes en hul effek op die geproduseerde furfural is geëvalueer aan die hand van die Pareto variansie-analise. Modelle vir responsoppervlaktes is gebruik om die parameters te ontwikkel en te voorspel wat die optimale fururale opbrengs lewer. Die opbrengste van furfural uit die suurhidrolise van die onttrekte hemiselluloses was onderskeidelik 39, 45 en 44 mol% vir suikerrietbagasse, E. globulus en A. longifolia. Hierdie waardes was effens laer as die voorspelde waardes van die CCD. Die lae furfural opbrengste het gelei tot 'n Pareto-grafiek wat geen vertroue toon in die onafhanklike veranderlikes op die furfural opbrengs nie. Verder is die prestasie van die behandelde materiale in vergelyking met onbehandelde materiale beoordeel aan die hand van die eienskappe van die vervaardigde saamgestelde panele, soos modulus van elastisiteit (MOE), modulus van skeuring (MOR), waterabsorpsie en dikte. Op grond van die resultate het die behandelde lignosellulosiese-materiale die eienskappe van die saamgestelde panele verbeter in vergelyking met die onbehandelde lignosellulosiese-materiale. In die behandelde panele was die modulus van die skeuring onderskeidelik 10,42 MPa, 11,13 MPa en 6,4 MPa vir suikerrietbagasse, E. globulus en A. longifolia. Die vervaardigde panele het aan die minimum vereistes voldoen en word volgens ANSI A208.1 as lae digtheid tot mediumdigtheid borde geklassifiseer. Hierdie panele is nuttig in die houtpaneelbedryf as kernmateriaal vir soliede deure.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/108271
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