Effects of the oxidation degree of graphene oxide on the adsorption of methylene blue.
In this current work, a series of graphene oxides (GO) with different oxidation degrees (OD) was prepared using Hummer method. Fundamental adsorption behavior of the GO series for removal of methylene blue (MB) from aqueous solutions has been studied. The GO series shows an overall fast and pH-independent MB adsorption, which is even capable of removing trace levels of dye completely from very dilute solutions. Furthermore, the effects of the oxidation degree (OD) on MB adsorption behavior have been investigated systematically, indicating that the dye uptakes of GO exponentially increase with the increase of OD. Further study on the adsorption mechanism shows that adsorption behavior of GO would change from a Freundlich-type to a Langmuir-type adsorption as the OD increases. It may be due to both the enhanced exfoliation degree of the carbon planes in graphite caused by oxidation and the production of more active adsorption sites. The binding features of the MB loaded GO gradually change from MB molecule parallel stacking on graphite plane through hydrophobic π-π interaction to vertical standing via electrostatic interaction with increasing OD, resulting in a significant improvement of MB uptakes. In addition, the adsorption capacity of the regenerated GO has little loss until four cycles.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
Han
H
Yan
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
Xue
X
Tao
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
Zhen
Z
Yang
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
Kun
K
Li
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China. Electronic address: yanghu@nju.edu.cn.
Hu
H
Yang
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
Aimin
A
Li
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
Rongshi
R
Cheng
D000327:Adsorption; D006108:Graphite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008751:Methylene Blue / Q000302:isolation & purification*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D012996:Solutions; D055672:Static Electricity; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D012996:Solutions; D014874:Water Pollutants, Chemical; D006108:Graphite; D008751:Methylene Blue
Adsorption mechanism; Graphene oxide; Methylene blue; Oxidation degree