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 <i>Chlorella vulgaris</i> and amine-functionalized magnesium ferrite (MgFe₂O₄-NH₂) nanoparticles to remove cobalt ions from battery effluents. The research aims to explore the capacity of <i>C. vulgaris</i> to adsorb heavy metals, followed by their separation using magnetic nanoparticles. Cobalt adsorption by <i>C. vulgaris</i> 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.