Highly Efficient Adsorption of Copper Ions by a PVP-Reduced Graphene Oxide Based on a New Adsorptions Mechanism

Abstract

Polyvinylpyrrolidone-reduced graphene oxide was prepared by modified hummers method and was used as adsorbent for removing Cu ions from wastewater. The effects of contact time and ions concentration on adsorption capacity were examined. The maximum adsorption capacity of 1689 mg/g was observed at an initial pH value of 3.5 after agitating for 10 min. It was demonstrated that polyvinylpyrrolidone-reduced graphene oxide had a huge adsorption capacity for Cu ions, which was 10 times higher than maximal value reported in previous works. The adsorption mechanism was also discussed by density functional theory. It demonstrates that Cu ions are attracted to surface of reduced graphene oxide by C atoms in reduced graphene oxide modified by polyvinylpyrrolidone through physisorption processes, which may be responsible for the higher adsorption capacity. Our results suggest that polyvinylpyrrolidone-reduced graphene oxide is an effective adsorbent for removing Cu ions in wastewater. It also provides a new way to improve the adsorption capacity of reduced graphene oxide for dealing with the heavy metal ion in wastewater.