Alkaline earth metal doped nickel ferrites as a potential material for heavy metal removal from waste water

Water pollutants especially heavy metals are very harmful to the ecosystem even at low concentrations. For the effective removal of heavy metals (lead and cadmium), nickel ferrite, and alkaline earth metals doped nickel ferrite were synthesized using the co-precipitation method. The synthesized adsorbents were characterized using XRD, BET, FESEM-EDX, FTIR, VSM, UV–Vis, and XPS analytical techniques. Batch adsorption studies were performed with different parameters of adsorption such as pH, contact time, dosage of adsorbent, and concentration of heavy metal ions solution for a period of 60 min at room temperature. Removal percentage of Pb(II) and Cd(II) ions is 83% and 45% in case of nickel ferrite and reached to 97% and 80% for doped nickel ferrites. Isothermal studies were conducted using linear and non-linear equations of Langmuir and Freundlich isotherm models. The adsorption isotherm data was better fitted in linear Langmuir model (correlation coefficient, R2 = 0.99446 for Pb(II) and 0.96682 for Cd(II) ions) than Freundlich model (R2 = 0.85171 for Pb(II) and 0.73917 for Cd(II) ions). The kinetics studies for Pb(II) and Cd(II) ions adsorption were conducted using nonlinear pseudo-first-order, second-order, and intraparticle diffusion models. The process of adsorption of heavy metals can be adequately described by a pseudo-second order model with correlation coefficient (R2) of 0.98823 and 0.98248 for Pb(II) and Cd(II) ions. The findings revealed that prepared mesoporous ferrites (as per BET analysis) act as an efficient adsorbents to remove heavy metals from wastewater along with good recyclability and easy separation under the influence of an external magnetic field.