Kaolinite-supported nanoscale zero-valent iron for removal of Pb2+ from aqueous solution: Reactivity, characterization and mechanism

The use of nanoscale zero-valent iron (nZVI) to remediate contaminated groundwater is limited due to its lack of durability and mechanical strength. To address this issue, 20% (w/w) nZVI was loaded onto kaolinite as a support material (K-nZVI). More than 96% of Pb2+ was removed from aqueous solution using K-nZVI at an initial condition of 500 mg/L Pb2+ within 30 min under the conditions of 10 g/L of K-nZVI, pH 5.10 and a temperature of 30 °C. To understand the mechanism of removal of Pb2+, various techniques were implemented to characterize K-nZVI. Scanning electron microscopy (SEM) indicated that K-nZVI had a suitable dispersive state with a lower aggregation, where the mean specific surface area and average particle size as determined by the BET-N2 method and X-ray diffraction (XRD), were 26.11 m2/g and 44.3 nm, respectively. The results obtained from XRD, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated that a small number of iron oxides formed on the surface of K-nZVI, suggesting that free Pb2+ was adsorbed onto K-nZVI and subsequently reduced to Pb0.

► kaolinite-supported nanoscale zero-valent iron(K-nZVI) used for the removal of Pb2+.
► More than 96% Pb2+ from aqueous solution was removed by K-nZVI.
► Characterizations of K-nZVI were by SEM, BET-N2 method, XRD, XPS and FTIR.
► The adsorbed Pb2+ on K-nZVI were reduced to Pb0.