An Innovative Bioremediation Approach to Heavy Metal Removal: Combined Application of Chlorella vulgaris and Amine-Functionalized MgFe2O4 Nanoparticles in Industrial Wastewater Treatment

The removal of heavy metals from industrial wastewater remains a major environmental challenge, demanding efficient, sustainable solutions. This study explores the combined use of Chlorella vulgaris and amine-functionalized magnesium ferrite (MgFe2O4-NH2) nanoparticles to remove cobalt ions from battery effluents. The research aims to explore the capacity of C. vulgaris to adsorb heavy metals, followed by their separation using magnetic nanoparticles. Cobalt adsorption by C. vulgaris was facilitated through the interaction of metal ions on the cell wall, achieving a removal efficiency of 96.44% within 30 min, which increased to 98.78% over 10 h. Amine-functionalized MgFe2O4 nanoparticles, synthesized and characterized using HRTEM, FTIR, and VSM, displayed high surface reactivity due to the presence of -NH2 and -OH groups. At neutral pH, zeta potential measurements revealed a slightly negative charge (−5.6 ± 4.3 mV), while protonation at lower pH levels enhanced electrostatic interactions with the negatively charged algal biomass. Magnetic separation of the cobalt-adsorbed biomass achieved efficiencies ranging from 94.9% to 99.2% within 60 s, significantly outperforming conventional sedimentation methods. SEM and FTIR analyses confirmed the binding of nanoparticles to algal cell walls. The even distribution of MgFe2O4 nanoparticles on algal surfaces was further validated by TEM imaging, and the strong magnetic properties of the nanoparticles enabled rapid and efficient separation under an external magnetic field.