Using graphene oxide as a superior adsorbent for the highly efficient immobilization of Cu(II) from aqueous solution

The uptake of Cu(II) on graphene oxide (GO) by an adsorption process as a function of solution pH and ionic strength in the absence and presence of humic acid (HA) or fulvic acid (FA) was studied by using a batch technique. The results indicated that the uptake of Cu(II) on GO was clearly dependent on solution pH but independent on ionic strength. A positive effect of HA or FA on Cu(II) uptake on GO was found at low pH, whereas a negative effect of HA or FA on Cu(II) uptake on GO was observed at high pH. The adsorption isotherms of Cu(II) on GO can be described better by the Langmuir model than by the Freundlich model. The thermodynamic data calculated from temperature-dependent uptake of Cu(II) on GO suggested that the adsorption process was spontaneous and enhanced at higher temperature. Results of this work suggest that GO may be a promising candidate for the efficient immobilization of Cu(II) and related heavy metal ions from aqueous solutions.