Bio-modified magnetic nanoparticles with Terminalia arjuna bark extract for the removal of methylene blue and lead (II) from simulated wastewater

This study reports a greener, cheaper and convenient approach to synthesize Terminalia arjuna bark extract coated magnetite nanoparticles (TA@MNPs) using the co-precipitation method and efficient removal of methylene blue (MB) and lead ions [Pb(II)] from simulated wastewater. The synthesized nanoparticles (NPs) were characterized by various techniques such as DLS, XRD, FTIR, HRTEM, AGM, and TGA. From TGA analysis, TA@MNPs was found to be stable even after 500 °C. Using the batch method, maximum removal was achieved at pH 9.0 for MB and pH 3.0 for Pb(II) solutions, respectively. Adsorption study showed that TA@MNPs followed pseudo-second-order kinetics by both adsorbates while isotherm modeling towards adsorption of Pb(II) and MB exhibited Langmuir and Freundlich isotherm respectively. The maximum adsorption capacity for Pb(II) on TA@MNPs was 210.5 mg g-1. The thermodynamic study proved the spontaneity of the physisorption process. Regeneration studies were also performed using five different eluents for the two adsorbents. Overall, TA@MNPs effectively removed pollutants from wastewater and thus could be potentially useful in providing clean water in a cheaper way.