One-step generation of S and N co-doped reduced graphene oxide for high-efficiency adsorption towards methylene blue

S and N co-doped reduced graphene (S-N-rGO) nanohybrids were prepared by a one-step oil bath heating process using glutathione (GSH) as a green and mild co-reduction agent and a S and N source. It can be applied in the field of adsorption for the removal of methylene blue (MB) from aqueous solutions. The efficient adsorption rate of S-N-rGO hybrids for MB (50 mg L^-1) was observed with the best even within 2'07'' from blue solutions into colorless (the mass ratio GO : GSH = 60 : 200). Under this mass ratio, the effects of initial solution pH, temperature, initial concentration and contact time on adsorption towards MB were explored systematically. The results indicated that the adsorption capacity at 275 K could reach up to 598.8 mg g^-1, the adsorption behavior followed the pseudo-second-order kinetic model and the equilibrium adsorption data fitted the Langmuir isotherm well. Thermodynamic and kinetic analyses revealed that adsorption is an exothermic, spontaneous and physisorption process.