Synthesis of l-cysteine stabilized zero-valent iron (nZVI) nanoparticles for lead remediation from water

Abstract

l-Cysteine (l-cyst) stabilized zero-valent iron (nZVI) nanoparticles were synthesized by chemical reduction method using ferric chloride as a reducer and l-cyst as a stabilizing agent under nitrogen atmosphere. The l-cyst-nZVI energy band gap of 2.5eV was obtained using UV absorption spectra. The zeta potential of bare nZVI and l-cyst-nZVI were +24.0 and −35.0mV, respectively. The surface charge reversal from positive to negative confirmed the l-cyst presence onto the nZVI surface. The biocompatibility study of l-cyst-nZVI was performed using MTT assay on MDCK-2 as model cell lines. Aqueous Pb2+ sorption studies were conducted at different initial pHs (2.0–7.0), contact time (5–45min), temperatures (5–45°C), l-cyst-nZVI dosage (1.0–5.0g/L) and initial Pb2+ concentration (10–50mg/L). Almost 100% of lead was removed from a 50mg/L lead solution within 25min. A pseudo-second-order rate equation best described the Pb2+ sorption kinetics. Separation of exhausted l-cyst-nZVI NPs from aqueous system using a simple magnet was also demonstrated. l-cyst-nZVI nanoparticles may be used to remediate Pb2+ from aqueous solutions.