| The elimination of organic matters and heavy metals in landfill leachate remains a longstanding challenge in wastewater treatment. Due to its relatively large specific surface area and abundant atomic thickness, magnetic graphene oxide(MGO) has attracted great attention of researchers in wastewater treatments. However, the difficulty of its separation limited its application. To improve the separation property, this study prepared magnetic graphene oxide combining magnetic of iron oxide with adsorption property of graphene oxide.In this study, MGO was synthesized using Hummers method and chemical co-precipitation method and investigated to explore the possibility of applying in the simultaneous removal of HA/FA and Pb(Ⅱ) from landfill leachate. Various conditions of adsorption were optimized. The major work and results included four parts.In the first part, MGO were synthesized and characterized. The process of preparation and characteration were mainly introduced. MGO was characterized by Scanning electron microscopy(SEM), Transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS) 、 Fourier transform infrared spectroscope(FTIR) 、 magnetization measurement and zeta potential measurement. The results showed that iron oxides were successfulIy coated on the surface of graphene oxide to produce MGO; the saturated magnetization of MGO was 25.22 emu/g,which was suficient enough to be separated from aqueous solutions using magnet;the isoelectric point of MGO was about 5.0.The second part was preliminary experiment. The experiments were conducted to explore the removal of HA/FA and Pb(Ⅱ) in binary system and the optimized mass ratio of magnetic particles and graphene oxide. The results showed that MGO exhibited excellent removal efficiency of HA/FA and Pb(Ⅱ) in binary system; the optimized mass ratio of magnetic particles and graphene oxide was 1.74.The third part and the fourth part introduced the removal of HA/FA and Pb(Ⅱ) by MGO in binary system. Batch adsorption experiments were carried out to investigate the sorption performance of MGO, including adsorption isotherms, effects of initial pH, Pb(Ⅱ) concernation, HA/FA concernation, contact time, regeneration and reusability. In addition, the performance of MGO to remove HA/FA and Pb(Ⅱ) was also studied. The results indicated that, the sorption isotherm for HA and FA on MGO in single system at 25 ℃ was better described by Freundlich model and the maximum adsorption capacity based on Langmuir models was 98.82 mg/g and 72.38 mg/g, respectively. the isotherm data for Pb(Ⅱ) at 25 ℃ was fitted well Langmuir models and the maximum adsorption capacity was 58.43 mg/g. Weak acid environment enhanced the adsorption of HA/FA and Pb(Ⅱ). In binary system, results showed that TOC removal(both in HA and FA) enhanced with increasing Pb(Ⅱ).. Noticeably, Pb(Ⅱ) removal steeply increased to the maximum(about 87%) with increasing concentration of HA, when HA concentration was less than 110 mg/L, and considerably decreased with increasing concentration of HA, when HA concentration was greater than 110 mg/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.In sum, the synthesized MGO for removal HA/FA and Pb(Ⅱ) in binary system made great contributions in wastewater treatment process and provide theoretical guiding significance in landfill leachate treatment. |
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