Extraction of total carbohydrates by solvents from the microalgae <em>Chlorella</em> vulgaris and analysis of the influence of NaNO3 and photoperiods on microalgae cell growth

Abstract

The development of new resources for ethanol production has been changing over the years, and microalgae use has become one of the most ecological alternatives. Microalgae are increasingly being used due to their biochemical composition, rich in carbohydrates and proteins, in addition to several properties such as high CO2 absorption capacity. One of the most cultivated and studied microalgae today is Chlorella vulgaris since it has high growth rates and can be cultivated in different environments and conditions. Therefore, microalgae biomass is composed of potential ingredients for the production of biofuels. Considering the above, the objective of this work is to extract the total carbohydrates stored in the cellular structure of the microalgae by the organic solvent extraction method, hexane/ethanol (1:2) and by ionic liquid/ethanol (1:2), evaluating different conditions of microalgae cultivation. For this, 9 experiments were carried out, varying according to the culture medium in which the microalgae were introduced, containing BG-11 medium with different concentrations of NaNO3 (sodium nitrate) and forced aeration, in addition to different cultivation photoperiods. The reading of the results showed that the breakdown of the microalgae cell wall was better with acid hydrolysis and extraction with hexane. Thus, the highest efficiency in the extraction of carbohydrates was with a sodium nitrate concentration of 2300 and a photoperiod of 16 hours, during the entire period evaluated.