Aminoclay-conjugated TiO2 synthesis for simultaneous harvesting and wet-disruption of oleaginous Chlorella sp.

• TiO2 nanoparticles entrapped in aminoclay matrix were synthesized.
• Microalgae harvesting efficiency was achieved ∼85% at 3.0 g/L injection.
• ∼95% of microalgae cells was disrupted by photocatalysis within 3 h.
• Integration of harvesting/lipid-extraction steps was demonstrated.

In microalgae-based biorefinement, the integration of harvesting and lipid extraction steps could reduce the costs of downstream processes. One potential of integrated methods, microalgae harvesting by aminoclay-conjugated TiO2 has been considered. Therein, aminoclay plays an efficient role in microalgae flocculation and direct cell disruption by TiO2 photocatalytic performance under UV-light irradiation. In the present study, two TiO2 photocatalysts, a commercial anatase/rutile bicrystalline (of ∼5 nm diameter) and anatase/brookite bicrystalline (of ∼3.5 nm diameter) by sol–gel reaction at room temperature, were distributed uniformly onto an aminoclay matrix by ultrasound-irradiated TiO2 particles, resulting in aminoclay-conjugated TiO2 composites. Within 10 min, the injection of aminoclay-conjugated TiO2 into the prepared 1.5 g/L-concentration microalgal feedstocks produced an ∼85% harvesting efficiency for oleaginous Chlorella sp. KR-1. Subsequently, the harvested wet-microalgae biomass was UV-irradiated at 365 nm for 3 h, thereby effecting the disruption of ∼95% of cells.

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