Solar assisted cell wall disruption of indigenously isolated microalgae strains: process optimization

Rigid cell wall of microalgae is a serious obstacle in commercialization of microalgae biofuels. Conventional cell wall rupturing techniques require organic solvents and are not so efficient. In this research work, TiO2 photocatalyst was used to rupture the cell walls of two different indigenously isolated microalgae strains; Scenedesmus and Chlorella. Cell wall rupturing was monitored by the amount of malondialdehyde (MDA) formed in reaction mixture which is an important secondary metabolite of lipid peroxidation. Different important influencing parameters like calcination temperature, catalyst synthesis pH, catalyst dose, algae media pH, stirring speed and sunlight exposure time were optimized during this study. Maximum MDA concentration of 2.839 nM ml−1 from Scenedesmus and 1.697 nM ml−1 from Chlorella was achieved by using catalyst synthesized at 600 °C calcination temperature and pH 3 by 5 h of sunlight exposure. The synthesized catalyst was immobilized to check out its recycling capability. The catalyst with maximum catalytic activity was characterized by SEM, XRD and FT-IR analysis. Kinetic study for lipid oxidation was also performed and overall study results indicated that TiO2 has good capability to rupture microalgae cell wall for lipid release and this method is cost effective as it does not require the involvement of organic solvents.