Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-08-10T20:55:24Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese rogerio fagundes.pdf: 3973057 bytes, checksum: 8fe99e859aad91ef3ff737d09df30b91 (MD5) / Made available in DSpace on 2016-08-10T20:55:24Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese rogerio fagundes.pdf: 3973057 bytes, checksum: 8fe99e859aad91ef3ff737d09df30b91 (MD5) Previous issue date: 2016-02-02 / CNPQ / As ligninas estão entre as macromoléculas mais abundantes biosintetizadas da Terra. São obtidas como subproduto da indústria do papel e celulose, sendo utilizadas principalmente, como combustíveis. Suas composições, muito variadas, limitam o desenvolvimento de aplicações de mais alto valor agregado; contudo, devido à sua abundância e origem sustentável, existe um crescente interesse em utilizá-las como matéria-prima e na substituição de derivados do petróleo, por exemplo, na produção de fibras de carbono de baixo custo. Para um uso mais amplo em biorefinarias, processos precisam ser estudados e padronizados, visando obter ligninas com propriedades físicas mais homogêneas e maior solubilidade. Neste trabalho, o fracionamento com solventes foi utilizado com este objetivo. O fracionamento da lignina usando solventes é um processo simples, com bons resultados, e que foi utilizado neste estudo para fracionar uma lignina de bagaço de cana (L1) quase insolúvel e de difícil processamento. As frações obtidas foram caracterizadas por FTIR, UV-VIS, Maldi-TOF, análise térmica e reometria de suas soluções, para avaliar seus aspectos estruturais relevantes para a produção de fibras. L1 foi fracionada até o esgotamento com o uso de quatro solventes: tolueno (E1), etanol (E2), metanol (E3) e dimetilsulfóxido (DMSO, E4). As frações E2, E3 e E4 são similares em massa molar e distribuição de massa molar, mas têm importantes diferenças em suas características estruturais, térmicas e na processabilidade. As frações mostraram diferentes temperaturas de transição vítrea e seguem diferentes rotas de degradação térmica, indicando que suas composições químicas apesar de similares, como demonstrado por FTIR, não são exatamente iguais. Propriedades reológicas das soluções utilizadas para a eletrofiação, incluindo a formação de microestruturas como fase gel, apresentaram diferenças significativas, especialmente entre as frações E2 e E3. A solução da fração E2 apresentou homogeneidade e isotropia muito maiores que a lignina L1. A eletrofiação da fração E2 resultou na produção de nanofibras com diâmetros entre 60 e 120 nm. A fração E3 originou nanoesferas com diâmetros entre 90 e 350 nm, nas mesmas condições de eletrofiação. A fração E4 somente recobriu uma superfície com eletrospray. Estes resultados mostram a possibilidade de desenvolver aplicações de mais alto valor agregado usando as frações da lignina, de uma mesma biomassa ou de misturas de biomassas diversas. / Lignins are the second most abundant biosynthesized macromolecules on Earth. They are obtained as byproducts from the paper industry and used mostly as fuel. Their variable composition has been an obstacle to the development of high added-value applications; however, because of their abundance and sustainable origin, there is growing interest in using lignin as a raw material and as a replacement for oil derivatives, such as low cost carbon fibers. In order to use lignins in biorefineries, their physical properties should be standardized and their solubility improved. In this study, sugarcane bagasse lignin (L1) was fractionated with solvents and the fractions were characterized by FTIR, UV-VIS, Maldi-TOF, thermal analysis and solution rheometry to evaluate structural aspects that are relevant for the production of fibers. L1 was sequentially extracted with four solvents: toluene (E1), ethanol (E2), methanol (E3), and dimethyl sulfoxide (DMSO, E4). Fraction E1 was composed mainly of low molecular weight residues. Fractions E2, E3, and E4 were lignins presenting only slightly different molar masses and molar mass distributions, nonetheless relevant differences in their structural characteristics and processability were observed. Thermal and rheological properties of fractions showed significant differences. The fractions presented different glass transition temperatures. Their thermal degradation routes were not similar, which suggest structural differences among them. Rheological properties of the solutions used for electrospinning, including the formation of gel phase microstructures, were significantly different, particularly those of E2 and E3. Fraction E2 presented more isotropic and homogeneous behavior than L1. Electrospinning of E2 resulted in the production of nanofibers with diameters between 60 and 160 nm. E3 produced nanospheres with diameters between 90 and 350 nm while E4 only covered a surface with electrospray. These results show the possibility of developing high added-value applications using fractions of a single lignin or fractions of mixtures of lignins from distinct biomasses.

Lignin is one of the most abundant natural polymers on Earth, and a valuable resource. Despite being widely available, only a small amount of the produced lignin is currently utilized to make high-value goods, with the majority being used for pulp mills to recover energy. However, the possibility to convert lignin into commercially viable products is presented by the rising need for sustainable and renewable resources. In the past, research has mostly concentrated on converting lignin into chemicals, materials, and biofuels; nevertheless, there has not been much advancement in practical applications. Lignin is difficult to depolymerize due to its intricate structure and resistance to degradation. To separate lignin from lignocellulosic biomass, a number of techniques have been developed, such as kraft and sulfite pulping. These techniques, though, result in lignin with various characteristics. As a result, improved lignin isolation methods are required in order to produce high-quality, pure lignin. Due to its capacity to solubilize lignocellulosic biomass and extract lignin, ionic liquid-based lignin isolation has attracted interest. Ionic liquids are environmentally friendly since they may be recycled and used again. There are still issues with toxicity, physicochemical data, and industrial-scale recovery, though. Lixea is a startup company that specializes in sustainable technology, especially lignin. They have created a novel method of fractionating lignocellulose known as Dendronic® that uses inexpensive ionic liquids to separate lignin and cellulose from biomass. Potentially, this process could result in renewable products, such as chemicals and biofuels on a large scale. Filtration of the lignin is one of the main bottlenecks operations at Lixea`s pilot plan. In this paper two different strategies; Maturing of the lignin suspension through temperature cycling and using previously isolated lignin filter cake as precipitation and filtration aid, have been tested out at the lab scale to improve the lignin filtration speed. Based on the observations in this work the heat treatment strategy is the most promising one, therefore it is recommended to test it the pilot plant to confirm the lab-scale experiments and improve the plant operation. Overall, further research and development are needed to unlock the full potential of lignin as a flexible and sustainable resource.