Graphene oxide mediated carbon foam/CNTs composites for highly efficient adsorption of methylene blue and mechanism insight

The preparation of high performance, low cost and recyclable adsorbents is very important to cope with the increasingly devastating water pollution. As a typical three-dimensional porous carbon material, carbon foam (CF) is expected to be a highly efficient adsorbent to wipe out organic dyes from wastewater. However, the uneven size distribution, and lack of adsorption sites signified by insufficient foaming process limit its wider application in the environmental field. Here, CF/carbon nanotubes/graphene oxide (CF/CNTs/GO) composites (adsorbents) were prepared by press-assisted foaming and carbonization methods using mesophase precursors of coal tar pitch and CNTs followed by impregnation of GO nanosheets. The results highlighted that the addition of CNTs facilitated improvement in pore distribution, porosities, and mechanical properties (20 MPa). After treating with GO nanosheets, the adsorption performances of CF/CNTs/GO adsorbents substantially improved due to the increased active sites in the CF/CNTs and the adsorption rate and capacity of methylene blue (MB) reached 73.1% and 146 mg/g respectively. Further, adsorption isotherms (Langmuir and Freundlich), thermodynamics, quasi-first order and quasi-second order kinetics and intraparticle diffusion models were employed to investigate the adsorption mechanism. This work provides a low-cost fabrication technique for the high-performance CF/ CNTs/GO adsorbent and is expected to provide reference for application in the treatment of contaminated water.