Designed functionalization of reduced graphene oxide for sorption of Cr(vi) over a wide pH range: a theoretical and experimental perspective

Abstract

The present study illustrates a clear functionalization chemistry for the synthesis of guanidine functionalized reduced graphene oxide (GfG) for sorption of Cr(VI).

A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent

“…As shown in Figure 5, the adsorption energy of Cr(VI) is 290.32 kcal mol −1 , which indicates the presence of strong adsorptive interaction between the GO surface and the Cr(VI). The adsorption energy values are comparable with those found in the previous studies (where a different and a smaller GO model is used) [34]. It is important to observe that as computed by DFT calculation, the preferred adsorption site of the Cr(VI) is also predicted by MC.…”

“…It is important to observe that as computed by DFT calculation, the preferred adsorption site of the Cr(VI) is also predicted by MC. This is associated with the fact that electrostatic interactions can take place at this adsorption site as found previously by Mondal et al [34].…”

Monitoring and Management of Anions in Polluted Aqua Systems: Case Studies on Nitrate, Chromate, Pertechnetate and Diclofenac

“…Using a closely related approach, Nkutha et al [157] have made graphene-based sorbents by modification of graphene oxide with amino-and mercaptosilanes providing materials with -NH2 and -SH functional groups suitable for metal binding. The main outcome of the article is the observation that, analogous to the work by Mondal et al [156], the highest adsorption efficiencies were observed at pH 2. Again, the issue that could be raised here is that neither graphene nor specific silanes are necessarily very cheap; there is thus a need to further transfer these reactions and concepts to cheaper and more readily available carbon materials.…”

“…Interestingly, the surface areas of these materials are below 100 m 2 /g. The materials show an excellent to carbon-based materials such as those discussed above [153][154][155][156][157][158][159], which show high adsorption capacities at low pH but perform rather poorly at high pH.…”

“…Using an approach that may not currently be accessible to mass applications due to high cost, Mondal et al [156] presented an interesting fundamental study on how reduced graphene oxide can be functionalized with guanidine groups to enable Cr(VI) removal, Figure 5. The authors performed an in-depth characterization of the materials and demonstrated that 139 mg/g maximum adsorption capacity in acidic conditions and 51 mg/g can be reached in acid-free conditions.…”