High tough and highly porous graphene/carbon nanotubes hybrid beads enhanced by carbonized polyacrylonitrile for efficient dyes adsorption

Abstract

Abstract Dyes pollution poses severe threat to ecological system and presents a great challenge for global sustainability. High efficient adsorbent for dyes pollution is urgently demanded. Herein, highly porous graphene/carbon nanotubes hybrid beads (HPGCB) with strong mechanical stability are developed as high efficient adsorbent, in which the synthesis involves three steps: (1) emulsifying and self-assembling the graphene/carbon nanotubes into spherical hydrogel, (2) coating of polyacrylonitrile (PAN) and (3) KOH activated carbonization. As for the proposed strategy, while the carbonized PAN layer strengthens effectively the mechanical stability and cyclic resilient property of HPGCB, the KOH activation creates lots of nanopores (0.8–2 nm) on graphene network and offers large specific surface area (1270 m2/g). By adsorption evaluation, HPGCB reaches maximum adsorption capacity of 521.5 mg/mL for methylene blue (MB), which is superior to other similar adsorbents. The adsorption kinetics of MB on HPGCB is analyzed by both pseudo second-order and intra-particle diffusion models, which confirm its fast adsorption rate for dyes adsorption. Taken together these properties, the proposed HPGCB has great potential in the remediation of water pollution.