Disruption of microalgal cells for lipid extraction through Fenton reaction: modeling of experiments and remarks on its effect on lipids composition

A novel cell disruption technique, based on the use of Fenton reaction, for the improvement of lipid extraction from microalgae has been recently proposed in the literature. The experimental results have shown that, when disruption is performed under suitable operating conditions, the amount of lipids subsequently extracted from Chlorella vulgaris is greatly increased with respect to the case where no pretreatment was performed. Specifically, the use of Fenton reactant leads to a corresponding increase of the extracted lipids from 6.9 to 17.4%wt/wt. Moreover, it is observed that the treatment provokes a significant improvement of the quality of fatty acids methyl esters (FAMEs) obtained by trans-esterification of extracted lipids. These results, together with the extreme simplicity, low cost and energy consumption of the proposed technique, are very promising in view of its industrial transposition. To this aim, the use of suitable mathematical models might represent a valuable tool to design and control possible industrial size reactors. Along these lines, a simple but exhaustive model to quantitatively describe the effects of contact time and reactants concentration on the amount of lipids extractable from microalgae is proposed in this work. The model takes into account the effect of the OH<sup/> species on both cell wall breakage and lipid peroxidation phenomena. Model results and experimental data are successfully compared in terms of lipids extracted from wet microalgae previously subjected to the disruption treatment under different operating conditions. Furthermore, the possible chemical physical mechanisms underlying the improvement of FAMES composition, observed after the disruption treatment, is discussed. Finally, potential capabilities of the model to contribute to the industrial scale transposition of the proposed technique are presented.