Optimised phycoerythrin extraction method from Porphyridium sp. combining imidazolium-based ionic liquids

Phycoerythrin (PE) extraction from Porphyridium sp. was studied employing ultrasound-assisted extraction combined with aqueous mixtures of two imidazolium-based ionic liquids (ILs) simultaneously, marking a significant novelty. A face-centred central composite design and response surface optimised PE yield (E_PE), considering the effects of ionic liquid concentration (IL), [Emim][EtSO₄]/[Bmim][EtSO₄] mass ratio (E/B), biomass concentration (BM), and time (t). Improvements in E_PE by 300 % and 115 % were achieved compared to a phosphate buffer solution and the freeze-thaw method, respectively. Temperature and pH effects were examined independently, leading to the determination of optimal operating conditions: BM = 10 mg mL^-1, IL = 18.6 wt%, E/B = 0.78/0.22, t = 10 min, T = 35 °C, and pH = 7.5. Results indicated the potential for reusing the ILs for at least five consecutive extraction cycles, maintaining an E_PE of 94.2 % compared to fresh ones. This underscores the success and innovation of the developed technology in enhancing PE extraction from Porphyridium sp.