No abstract

The use of agricultural biomass residues as an alternative of fossil derivatives have been extensively investigated in the last years due to environmental concerns. In this context, the liquefaction appears as an alternative to use these renewable sources to produce green materials. The present work aims to synthesize polyols from the cassava peels (CP), lemon bagasse (LB) and rice husk (RH) in order to obtain biopolyols suitable to produce polyurethane foams and add value to these residues. Besides the production of the green foams, this work has also the objective to evaluate how composition of the biomass (e.g.: solid, lignin and holocellulose content) can be related to the process yield and the characteristics of the biopolyol (e.g: hydroxyl number). The polyols were synthesized from the biomass liquefaction, using crude glycerol as solvent (a by-product of biodiesel industry) and sulfuric acid as catalyst. The liquefaction was performed using an autoclave, operated at 125 °C and 1.84 atm. Liquefaction yield varied from 38 to 91 %, according to biomass and process parameters used. It was observed that CP, which has the higher volatile solids content and the lower lignin plus holocellulose content, had the higher liquefaction yield. Polyol's hydroxyl number from RH had the lowest values and lower variation, according to process parameters. Liquefaction yield and hydroxyl number from LB presented great response to process parameters used.

O uso da biomassa para a produção de produtos químicos denominados “bioprodutos” tem sido investigado para a produção de biomateriais e biocombustíveis, a fim de substituir a matéria-prima sintética oriunda dos compostos do petróleo. Nesse contexto, a liquefação surge como um processo promissor para transformar matéria orgânica em poliol e aumentar a densidade da biomassa. O presente trabalho investigou o processo de liquefação de três resíduos lignocelulósicos (casca de mandioca, bagaço de limão e casca de arroz), em temperaturas moderadas (100, 150 e 200 ºC) e em três tempos (30, 60 e 90 minutos). Os polióis foram sintetizados a partir da liquefação da biomassa nas condições: razão 2: 1 entre solvente (glicerol) e biomassa e 7 % em massa de ácido sulfúrico concentrado (catalisador). A partir deste trabalho observou-se que as condições de processo e a composição da biomassa influenciaram no rendimento da liquefação. Em condições de temperatura moderada, os valores de rendimento de liquefação do bagaço de limão foram acima de 80 % em massa. Para a casca da mandioca, os rendimentos alcançaram valores acima de 77 % em massa, nas corridas experimentais a 100 ºC e em todos os intervalos de tempo. A liquefação da casca de arroz obteve valores de rendimento abaixo de 54 % em massa para todas as condições de processo. Esses resultados podem ser devidos ao maior teor de cinzas e lignina na casca de arroz. De acordo com os resultados, as biomassas em estudo apresentam potencial para a produção de poliol, por meio do processo de liquefação.

Two biopolyol-based foams derived from banana leaves (BL) or stems (BS) were produced, and their compression mechanical behavior and 3D microstructure were characterized. Traditional compression and in situ tests were performed during 3D image acquisition using X-ray microtomography. A methodology of image acquisition, processing, and analysis was developed to discriminate the foam cells and measure their numbers, volumes, and shapes along with the compression steps. The two foams had similar compression behaviors, but the average cell volume was five times larger for the BS foam than the BL foam. It was also shown that the number of cells increased with increasing compression while the average cell volume decreased. Cell shapes were elongated and did not change with compression. A possible explanation for these characteristics was proposed based on the possibility of cell collapse. The developed methodology will facilitate a broader study of biopolyol-based foams intending to verify the possibility of using these foams as green alternatives to the typical petrol-based foams.