Development of dopamine-based magnetite nanocomposite for effective harvesting of Chlorella sorokiniana Kh12 biomass

Using dopamine-coated magnetite nanocomposite, a novel harvesting method for lutein-rich Chlorella sorokiniana Kh12 microalgae has been developed. Microalgae harvesting can be achieved using various techniques, but existing methods are energy-intensive, time-consuming, and costly. However, advancement in the conventional harvesting approach is required to achieve cheaper, faster, and environmentally friendly biomass harvesting. Nanoparticle-based flocculation is an exciting and novel method for harvesting microalgae among existing harvesting processes. It is an effective strategy due to its characteristics such as modest processing costs, energy savings, and speedy separation. For effective binding to anionic algal cells, magnetic nanoparticles can be further enhanced by fixing a relatively positive functional group. The present study focused on developing a novel dopamine-coated magnetite nanocomposite with an average size of 10.89 nm for microalgae biomass harvesting. Moreover, reusing synthesized nanocomposite can significantly reduce the overall processing cost of the microalgal bioprocess. The designed nanocomposite was characterized using TEM, Zeta analyzer, and FTIR. The maximum harvesting efficiency of the designed nanocomposite on Chlorella sorokiniana Kh12 was >99% at pH 3 with a reaction and contact time of 10 and 5 min respectively. The nanocomposite was removed from microalgae by shifting the pH to alkaline and was reused for up to 5 cycles with a harvesting efficiency of >93%. There is a novel, efficient, and competent commercial method that could soon fill a major bottleneck concerning high-cost microalgae harvesting for algal biorefineries.