Efficient removal of phenol and p-nitrophenol using nitrogen-doped reduced graphene oxide

Graphene-based materials with a conjugated π region possess unique advantages for treating wastewater contaminated with phenolic compounds. To investigate the interaction mechanisms and optimize the removal efficiency of phenol and p-nitrophenol, nitrogen-doped reduced graphene oxide (N-RGO) with an enlarged conjugated π region and increased hydrophobicity was prepared by annealing a composite of chitosan exfoliated and anchored in a graphene oxide matrix. Results showed that the equilibrium adsorption capacity of N-RGO for phenol and p-nitrophenol was 155.82 and 80.60 mg/g, respectively, at an initial concentration of 200 mg/L, pH of 6, and contact temperature of 30 °C. The optimized removal efficiency was attributed to robust π-π and hydrophobic interactions. Furthermore, regeneration experiments showed that N-RGO could retain a high removal efficiency (> 80 %) over five cycles of reuse. These findings suggest that N-RGO is a promising technique for the removal of phenolic compounds from wastewater using an efficient and recyclable adsorbent.