Mass cultivation of microalgae and extraction of total hydrocarbons: A kinetic and thermodynamic study

Abstract

In this present investigation, the biofuel alga Botryococcus braunii (B. braunii) was mass cultivated in 10m2 open raceway pond at batch mode. This study was mainly focused on the kinetics and thermodynamics approach for total lipid and hydrocarbon extraction. At batch mode cultivation the alga produced highest dry biomass of 23gm−2d−1. The algal cells were harvested by autoflocculation method and dried. Different pre-treatment methods, solvents systems and optimization of extraction parameters were carried out in the dry biomass containing moisture less than 1wt%. This reveals ultrasonication combined with chloroform: methanol, extracted maximum of 24.2wt% total lipid and hydrocarbon. Temperature effects (308–338K) on kinetics were investigated. The extraction follows first order kinetics and their rate constants and activation energy were determined as 3.0431s−1and 36.7214kJmol−1 respectively. Thermodynamic activation parameters ΔG≠, ΔH≠ and ΔS≠ were measured, which suggest that the process was endothermic, irreversible and spontaneous.