Graphene oxides for removal of heavy and precious metals from wastewater

Iron, chromium, lead, europium, silver, copper, strontium, cesium, zinc and nickel are some of the most frequently found heavy metal ions in wastewater and can cause serious health problems. Hence, their removal is essential from the environmental point of view. Recent studies show that graphene oxide (GO) can efficiently remove heavy metal ions from wastewater. A great deal of effort has been made to enhance the waste removal performance of GO using a variety of techniques. The performance of GO as an adsorbent agent to remove various organic pollutants, radioactive wastes and dyes has already been reviewed by various authors. However, the capability of GO and its derivatives to remove heavy metal ions has not been reviewed in detail. This paper reviews the wastewater removal efficiency and sorption mechanism of GO, functionalized GO and their composites for five of the most extensively studied heavy metal ions: Cr(III), Cr(VI), Cu(II), Pb(II) and Au(III). The waste removal kinetics of the adsorbents and the condition for the maximum adsorption are analysed for each of these heavy metal ions.