Simultaneous removal of humic acid/fulvic acid and lead from landfill leachate using magnetic graphene oxide

Abstract

The elimination of organic matters and heavy metals in landfill leachate remains a longstanding challenge in wastewater treatment. In this study, magnetic graphene oxide (MGO) was synthesized and investigated to explore the possibility of applying in the simultaneous removal of HA/FA and Pb(II) from landfill leachate. MGO was characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscope. In single system, the sorption isotherm for FA on MGO at 25°C were better described by Freundlich model than Langmuir and Temkin models with a maximum adsorption capacity of 72.38mg/g. The isotherm data for HA at 25°C was fitted well both Freundlich and Temkin models with a maximum adsorption capacity of 98.82mg/g, while the isotherm data for Pb(II) at 25°C was fitted well both Langmuir and Temkin models with a maximum adsorption capacity of 58.43mg/g. In binary system, results showed that TOC removal (both in HA and FA) enhanced with increasing Pb(II). Furthermore, TOC removal enhancement caused by the increase of Pb(II) in HA-Pb(II) system was greater than that in FA-Pb(II), which was caused by HA possessing more substantial aromatic rings than FA. Noticeably, Pb(II) removal steeply increased to the maximum (about 87%) with increasing concentration of HA, when HA concentration was less than 110mg/L, and considerably decreased with increasing concentration of HA, when HA concentration was greater than 110mg/L. However, Pb(II) removal slightly increased and remained a considerable percentage with a little fluctuation as the FA concentration increased. The regenerated MGO still had high efficiency both for HA/FA and for Pb(II) in the third cycle. The removal efficiencies of Pb(II), HA/FA in real water and in landfill leachate were almost analogues to that in ultrapure water. The successful application of MGO for removing HA/FA and Pb(II) in tap water and landfill leachate provided a possibility of MGO used for real wastewaters treatment.