Avaliação do ciclo de vida da produção de nanocristais de celulose a partir das fibras da prensagem do mesocarpo do dendê

Abstract

In the search for more sustainable production and in order to add value to biofuel chain, palm fibers present as a potential source of crystalline nanocellulose (NCC), which have physicochemical properties promising for application in new materials . The objective of this study is to evaluate the environmental impacts of obtaining 1g of NCC, in laboratory scale, palm pressed fiber (FPMD). The study was conducted based on the Life Cycle Assessment, according to the ISO 14041 and 14044 standards, and assess scenarios for impact mitigation and to compare their environmental performance with other fibers and perform error analysis of the results. The method used was the ReCiPe hierarchical midpoint to assess the following impact categories: climate change (MC), terrestrial acidification (AS), water depletion (DH), human toxicity (TH), marine eutrophication (EM) and freshwater (EAD). The production of NCC palm covers the processes of grinding, pulping acetosolv with acetic acid catalyzed with hydrochloric acid, bleaching with hydrogen peroxide, sulfuric acid hydrolysis, centrifugation and dialysis. In addition to these proceedings related to NCC extraction, also integrated this analysis the following processes: production of palm bunches, mesocarp pressing, and production inputs (pesticides, energy and chemicals). It was observed that the bleaching processes of the FPMD and centrifuging the solution NCC are most impactful, mainly due to energy demand. In the power generation mix in Brazil, the energy obtained from coal results in the emission of sulfur and nitrogen compounds, contributing to the categories AS, TH, EM and EAD. The production of hydroelectric power is the factor that most influences in the category MC due to emissions of methane and carbon dioxide generated by the breakdown of organic matter in flooded areas. In pursuit of environmental performance improvements of NCC production, were assessed the following alternative scenarios NCC production: A) reducing the bleaching time of 2.5 to 2 hours; B) reduction of peroxide concentration from 30 to 20%; C) reduction of the 3 pulping time for 1.5h and use of peroxide 20%. It was concluded that all of these scenarios led to reduction of impacts, with greater relevance to the scenario C, which resulted in greater reduction in EAD (15.5%) and TH (19.9%). Comparing the impacts of the NCC of palm oil produced in scenario C with NCCs obtained from other sources such as coconut husk (CCV) and cotton lint (LA), it is observed that the NCC palm showed greater environmental impact mainly due to increased consumption and less energy yield, calculated as the ratio between the mass and mass NCC LDCF (6%). The impacts analyzed for the NCC CCV were smaller, due to the better yield (11%) and using physical treatment (ultrasound), rather than acid hydrolysis. As for the NCC LA, the best results are mainly due to processes involved summarizing by acid hydrolysis, since the raw material has little lignin. It follows that the research of new production alternatives is necessary to make the NCC production process from the FPMD attractive in terms of environmental performance, such as the use of mechanical route, rather than chemical for cellulose hydrolysis