Enhancement of Biofuel Production from Microalgae

Abstract

Global warming is rising excessively due to the tremendous use of fossil fuels, polluting the newlineatmosphere and giving rise to health issues. It is very important to reduce our dependence on newlineconventional fuels and opt for renewable biofuels to save the Earth. Renewable biofuels for newlinetransportation mainly include bioethanol and biodiesel, which contributes over 16 billion newlinegallons globally and India s share is only 1%. The first and second generation includes food newlinecrops and non food crops, whereas the third generation biofuels include algae which provide newlineinnumerable benefits compared to first and second generation biofuels. newlineHence, in this study, two microalgal species Chlorella minutissima and Chlorella pyrenoidosa newlinewere studied for improving the harvesting, lipid productivity and transesterification of biofuel newlineproduction. Harvesting was done using iron oxide nanoparticles (IONPs). These were newlinesynthesized using iron chloride salts by chemical co-precipitation method, and the IONPs were newlinecharacterized by FTIR, XRD, SEM, VSM and Zeta potential values. 85% Chlorella newlineminutissima and 90% Chlorella pyrenoidosa were successfully harvested in 60 seconds at a newlineconcentration of 600 mg and 500 mg IONPs/L. The harvesting efficiency was attributed to the newlineelectrostatic interactions between charges of the microalgal cell surface and the IONPs. There newlinewas maximum attraction at pH 5 between Chlorella minutissima and the IONPs and the same newlinewas true for Chlorella pyrenoidosa and the IONPs at pH 3. newlineLipid content was improved by changing the carbon-nitrogen ratio and adding excess carbon newlinein the form of salts. Chlorella minutissima and Chlorella pyrenoidosa were provided nitrogen newlinedeficiency with increased carbon in the form of citrate, sodium acetate, sodium carbonate and newlinesodium potassium tartrate to increase the lipid productivity. The maximum lipid of about 23 to 25% was obtained, when both algae were cultivated in medium deprived of nitrogen and enriched with sodium acetate.