Abstract
BackgroundEnergy demand by mankind has become one of the most important aspects of our society. A promising technology that seeks to provide part of the energy demand and to obtain high-value products is the thermochemical conversion of microalgae biomass. Inorganic species presented in microalgae biomass may act as catalysts for thermochemical reactions and are responsible for notorious ash-related issues during thermochemical decomposition.ResultsIn this study, the freeze-dried biomass of Scenedesmus sp. was used to evaluate the lipid extraction methodology regarding a sonication bath as pretreatment technique for cell disruption followed by vortex mixing and n-hexane as solvent. It is also presented the lipid and amino acid profiles for Scenedesmus sp. The freeze-dried biomass was pyrolysed through a TGA (thermogravimetric analysis), with heating rates of 20 °C/min, from 100 to 650 °C. The ash and sulfated ash contents were accurately determined by combustion of biomass in a muffle furnace. The element component of ashes of the freeze-dried, defatted, pyrolysed and sulfated biomasses was determined by means of scanning electron microscope (SEM) fitted with energy dispersive spectroscopy (EDS). The lipid content obtained for Scenedesmus sp. dry biomass was 16.72% (± 0.03). The content of the sulfated ash obtained was 17.81 ± 0.15%. The SEM–EDS technique identified different mineral compounds in ashes, allowing to quantify Mg, P, S, K, Ca, Fe, Co and Br, as well as oxides.ConclusionThe results suggest a possible strategy to evaluate in a semi-quantitative manner the ash composition of freeze-dryed, defatted, sulfated and pyrolysed biomass of Scenedesmus sp. and its feasibility in using Scenedesmus sp. biomass in different thermochemical conversion strategies to achieve processes with positive energy ratio, representing potential use both environmental and energetically.
Highlights
Energy demand by mankind has become one of the most important aspects of our society
Ment component of ashes of the freeze-dried, defatted, pyrolysed and sulfated biomasses was determined by means of scanning electron microscope (SEM) fitted with energy dispersive spectroscopy (EDS)
The lipid content obtained for Scenedesmus sp. dry biomass was 16.72% (± 0.03)
Summary
Energy demand by mankind has become one of the most important aspects of our society. Most of the energy consumed in daily activities comes from non-renewable sources of energy, obtained through fossil fuels (coal, natural gas and oil). De Souza et al Biotechnol Biofuels (2020) 13:63 value of 5523 million tonnes of oil equivalent (Mtoe) in 1971 to 14,034 Mtoe in 2017 [1]. Considering this current scenario, the 2030 Agenda for Sustainable Development [2] and the Brazilian Energy Plan [3], related to climate change and energy security issues, an alternative proposed for the reduction in the use of fossil fuels by the transport sector is the use of biofuels, already implemented in Brazilian energy matrix. The use of raw materials which not demand the use of agricultural areas is necessary to minimize competition for food production [4]
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