The Effect Of Graphene Oxide On Heavy Metals And Antibiotics In Aqueous Solution: Adsorption And Transport Study

Nowadays, the health and ecological safety risks caused by water contamination had received great attention. As far as the current state of water environment contamination, the treatment of heavy metals and antibiotic pollutants have become one of the top priority of water contamination prevention. As graphene oxide not only has larger specific surface area, wide distribution of pore structure and stable chemical properties, but also has a large amount of surface active functional groups, it was at present considered as the most applicable adsorption materialin the field of the sewage treatment.In this study, graphene oxide (GO), heavy metals (Pb2+, Cu2+), antibiotics (LEV, TC) were selected as the main experimental materials. This work studied the effects of water chemistry conditions (ionic strength (IS) and pH) on the adsorption of Pb2+, Cu2+, LEV and TC on GO by adsorption experiments and the effects of GOon the transport of Pb2+, LEV in saturated porous media by quartz sand column experiments.The main conclusions of the batch adsorption experimentsare:(1) The adsorption rate of heavy metals on GO was veryhigh and reached equilibrium at about 15min. Water chemistry conditions (pH, ionic strength) showed strong effect on the sorption ability of GO. At solution pH of 5.0, the best adsorption efficiency was reached. Both NaCl and CaCl2 decreased heavy metals adsorption onto GO and CaCl2 showed high efficiency even at low ionic strength. Experimental and modeling results showed that GO effectively sorbed Pb2+ with maximum sorption capacity of 142.86 mg/g, by contrast, the adsorption ability of Cu2+ on GO is poorer, with maximum adsorption capacity of 31.25mg/g; (2) The adsorption rate of antibiotics on GO was very high and reached equilibrium at about 48h; Water chemistry conditions showed strong effect on the sorption ability of GO. The best adsorption efficiency was reached at solution pH of 5.0. Both NaCl and CaCl2 decreased antibiotics adsorption onto GO; Experimental and modeling results showed that GO can be used as an effective adsorbents to removal LEV and TC from water, with the maximum sorption capacity of 176.71 mg/g and 87.71mg/g, respectively. (3) The results also showed that GO has the high adsorption capacity of Pb2+ and LEV compared to quartz sand.The main conclusions of the quartz sand column experiments results showed that: (1) Pb2+(10 mg/L) almost all adsorbed on sand column during transport process. (2) The mobility of Pb2+ in sand column enhanced with the presence of GO (10 mg/L) in the solution. (3) The experimental result found that when GO solution was introduced to flush the sand column which polluted by Pb2+, the previously adsorbed Pb2+ could be reactivated and flowed out from the sand column along with the GO particles. Meanwhile the quantity of the reactivated Pb2+ increased with the increasing concentration of the introduced GO solution. (4) The study also found that GO showed high mobility in saturated porous medium, but lower mobility with the presence of Pb2+. (5) LEV (1 mg/L) all adsorbed on sand column during transport process. When GO solution was introduced to flush the sand column which polluted by LEV, the previously adsorbed LEV could also be reactivated and flowed out from the sand column along with the GO particles.The research results could considerably contribute to promoting GO as an adsorption material in removing heavy metals and antibiotics from water system.