Magnetically recyclable L-cysteine capped Fe3O4 nanoadsorbent: A promising pH guided removal of Pb(II), Zn(II) and HCrO4- contaminants

• DOI: 10.1016/j.jece.2021.105880
• Publication Date: 2021-06-16T03:49:39Z
• Authors: Arshid Bashir; Altaf Hussain Pan...; Lateef Ahmad Malik; Aaliya Qureashi; Firdous Ahmad Ganaie; Ghulam Nabi Dar
• Keywords: Carboxylate

Abstract The removal of potentially toxic metal ions such as Pb(II), Zn(II), and Cr(VI) has drawn immense attention because of their persistence and acute toxicological effects. In the present work, we report the preparation of a biocompatible L -cysteine capped Fe3O4 nanoparticles (Fe3O4@ L -Cys) under sonochemical conditions and evaluate its efficiency as an adsorbent for the removal of Pb(II), Zn(II), and Cr(VI) ions from the contaminated water. The adsorbent material displays promising results for decontamination of Pb(II) and Cr(VI) ions present in water samples collected from Dal Lake. Intriguingly, Fe3O4@ L -Cys depicts a pH-guided removal of cationic (Pb2+ and Zn2+) and anionic (HCrO4-) pollutants under competitive and non-competitive optimum batch conditions. We performed density functional theory (DFT) to gain more insight into the pH-dependent site preference for the uptake of Zn(II), Pb(II), and HCrO4- ions. At pH = 3.5, HCrO4- ions interact electrostatically with protonated amine (NH3+) groups, while at pH = 6.5 Zn(II), Pb(II) ions coordinates with carboxylate and amine groups. We first time demonstrated the in-depth interaction of HCrO4- with Fe3O4@ L -Cys using DFT and X-ray photoelectron spectroscopic studies and the results confirm the reduction of HCrO4- to Cr(III) ions. The batch experimental data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model with maximum monolayer capacity (qm) of 243.14, 237.37, and 170.63 mg g−1 for Pb(II), Zn(II), and HCrO4- ions respectively. The Fe3O4@ L -Cys nanoparticles show excellent stability and reusability over multiple cycles of sorption. We strongly believe that the present study will serve as a good guiding star for future research developments in water research and technology.