Synthesizing cationic polymers and tuning their properties for microalgae harvesting

Area of Science:

• Polymer Chemistry
• Biotechnology
• Environmental Science

Background:

• Microalgae harvesting is crucial for biofuel production and wastewater treatment.
• Efficient and cost-effective flocculation methods are needed to improve microalgae recovery.
• Cationic polymers offer potential for microalgae cell aggregation through charge neutralization.

Purpose of the Study:

• To develop a facile synthesis and tuning method for a cationic polymer, poly(3-acrylamidopropyl)trimethylammonium chloride (PAPTAC).
• To evaluate the efficacy of synthesized PAPTAC for harvesting three microalgae species.
• To compare the performance of PAPTAC with a commercial flocculant.

Main Methods:

• Synthesis of PAPTAC via UV-induced free-radical polymerization.
• Tuning of polymer molecular weight and surface charge by adjusting monomer concentration and UV power.
• Microalgae harvesting experiments using synthesized PAPTAC and a commercial polymer.

Main Results:

• PAPTAC was successfully synthesized and tuned by controlling polymerization parameters.
• PAPTAC exhibited high flocculation efficiency for Scenedesmus sp. and P. purpureum (25 mg-polymer/g dry biomass).
• PAPTAC outperformed a commercial polymer in harvesting Scenedesmus sp. and P. purpureum, attributed to charge neutralization and bridging mechanisms.

Conclusions:

• The synthesized cationic PAPTAC polymer is effective for harvesting specific microalgae species.
• Tuning polymerization conditions allows for optimization of PAPTAC for microalgae flocculation.
• PAPTAC shows promise as an efficient and tunable alternative to commercial flocculants for microalgae harvesting.