Oil extraction by aminoparticle-based H₂O₂ activation via wet microalgae harvesting

In this study, we demonstrated the synthesis of novel aminoparticles with Fe³⁺, Mn²⁺, and Cu²⁺ placed in active metal centers by means of a sol-gel reaction with 3-aminopropyltriethoxysilane (APTES) as a precursor, thereby forming -O(CH₂)₃NH₂ organo-functionalities on cationic metals. The protonated amine groups led to the efficient flocculation of microalgae which occurred within as little as 5 min. To our surprise, the aminoparticles exhibited a Fenton-like activity when 1% hydrogen peroxide (H₂O₂) was introduced. Just like any Fenton-like reaction, it is plausible that •OH radicals are produced through the activation of H₂O₂ by the metal atoms embedded in the aminoparticles, bringing about cell damage and effectively releasing internal lipids from wet microalgae biomass. The efficiency of lipid extraction with the Fe-aminoparticle in the presence of 1% H₂O₂ was 26.70% and nearly 100% of the extracted oil was converted to biodiesel. It is believed that our multiple-functionality aminoparticles represent a promising means of substantially reducing the unit cost of microalgal biorefineries in general and microalgae-based biodiesel production in particular.