Kinetic Study of Air Bubbles-Cetyltrimethylammonium Bromide (CTAB) Surfactant for Recovering Microalgae Biomass in a Foam Flotation Column

摘要

Owingto their efficient photosynthesis, microalgae tend to possess superior growthrates and high lipid production, hence their significance to the biofuelsector. The bulk harvesting of microalgae from cultures is a substantial stagein advancing the production of biomass-based fuels. However, a reliable andcost-effective harvesting technology is not yet available. Foam flotation,which is a subcategory of the adsorptive bubble separation process, showsconsiderable promise for the harvesting and enrichment of microalgae biomass.The available literature indicates that virtually no data has been reported onthe flotation kinetics of microalgae. Therefore, tobetter describe the recovery of microalgae by the flotation process, this work studied the flotation kinetics of the freshwatermicroalgae Chlorella vulgaris. The recovery of microalgae cells in abatch foam flotation column over time at different operating conditions wasfitted to nine flotation kinetic models, including first, fractional, andsecond order kinetic models; a first order kinetic model with rectangular,exponential, gamma, and sinusoidal distributions of floatabilities; a secondorder kinetic model with rectangular distribution of floatabilities; a fullymixed reactor; and modified Kelsall flotation kinetic models. Evaluation of thekinetic models showed that the discrete rate constant model (i.e. modifiedKelsall kinetic model) fitted the experimental data best. The modified Kelsallmodel shows the highest values of adjusted R2 (>0.995) and thelowest values of mean squared error (<2.63). Apart from the modified Kelsallmodel, which has discrete rate constants, no single kinetic model, with orwithout a continuous distribution, was sufficient to represent the flotationdata, and the optimal model may vary under different conditions. More work isrecommended using different freshwater and marine microalgae species.