Microalgae aggregation induced by thermoresponsive polymers

Area of Science:

• Biotechnology
• Materials Science
• Chemical Engineering

Background:

• Algal biomass harvesting is a significant barrier to the commercialization of algae-based biorefineries.
• Developing efficient and cost-effective algae harvesting technologies is crucial for sustainable biofuel and bioproduct production.

Purpose of the Study:

• To investigate the potential of thermoresponsive polymers (TRPs), specifically poly(N-isopropylacrylamide) (PNIPAM) and its derivatives, for microalgae harvesting.
• To synthesize and characterize various PNIPAM polymers and evaluate their performance in harvesting Chlorella vulgaris.

Main Methods:

• Synthesis of various PNIPAM polymers with differing charge, molecular weight (MW), and amine content.
• Investigation of the effects of polymer concentration on the lower critical solution temperature (LCST) and phase transition behavior.
• Assessment of microalgae (Chlorella vulgaris) harvesting efficiency using synthesized PNIPAM polymers.

Main Results:

• The LCST of PNIPAM decreased with increasing polymer concentration, with a reduced decline rate observed for high MW polymers.
• Amine content did not significantly impact the LCST of the TRPs.
• PNIPAM-300 kDa achieved approximately 92% harvesting efficiency for Chlorella vulgaris cells, while modified TRPs offered minimal improvements.

Conclusions:

• Thermoresponsive polymers, particularly PNIPAM, are a promising class of materials for efficient microalgae harvesting.
• Optimizing polymer properties like molecular weight is key to enhancing harvesting performance.
• TRPs present a viable technological solution to overcome a critical hurdle in algae biorefinery commercialization.