Search

The objective of this work was to evaluate the types of hydrothermal pretreatments on elephant grass using sodium hydroxide and hydrogen peroxide at different temperatures on lignin and cellulose contents. For this, an experimental arrangement was set up to evaluate the effects of temperature and alkaline elements, as well as their interaction on the final concentrations of cellulose and lignin. The tests were performed in triplicate, as well as comparisons of means two to two for the answers obtained, by means of statistical tests. According to the results obtained, the average contents of cellulose for pretreatment with NaOH at temperatures of 80 and 120 °C were 56.94% and 57.01% respectively and for peroxide (H2O2) were 53.85% and 53.73%. The average lignin contents at temperatures of 80 and 120 °C treated with NaOH were 16.09% and 18.40% respectively, and for the pretreatment with H2O2 the contents were 12.13% and 15.00% respectively. With a focus on obtaining fermentable sugars by enzymatic hydrolysis of the pretreated elephant grass, it was concluded that the best option would be the alkaline pre-treatment with NaOH at 80 °C, generating energy savings and considerable cellulose content.

The increasing energy demand and reduction in the availability of nonrenewable energy sources, allied with an increase in public environmental awareness, have stimulated a search for alternative energy sources. The present study was aimed at producing biomass from the microalga Spirulina platensis and at assessing in situ synthesis of alkyl esters via acid transesterification/esterification of biomass to produce biodiesel. Two alcohols (ethanol and methanol) and two cosolvents (hexane and chloroform) were tested, at different temperatures (30, 45, 60, 75, and 90°C) and reaction times (10, 20, 30, 60, and 120 min). The factorial analysis of variance detected an interaction between the factors (): temperature, reaction time, alcohol, and cosolvent. The best yields were obtained with the combination ethanol and chloroform at 60°C, after 30 min of reaction, and with hexane at 45°C, after 10 min of reaction. In situ transesterification/esterification of alga biomass to form esters for biodiesel production adds unconventional dynamics to the use of this feedstock.