Adsorption of a cationic dye from aqueous solution on mesoporous carbon-based honeycomb monolith

A carbon-based honeycomb monolith was prepared using dip-coating method. The carbon-based monolith was then used to remove a cationic dye (methylene blue [MB]) from aqueous solution. Surface chemistry studies demonstrated that acidic functionality (0.567 mmol g(-1)) dominated as compared to basic functionality (0.019 mmol g(-1)). N-2 adsorption/desorption revealed a mesoporous structure. The Brunauer-Emmett-Teller surface area was approximately 352 m(2) g(-1) and the mesoporous volume devoted about 67% the total pore volume. The effects of different parameters (such as initial pH, initial dye concentration, temperature, and contact time) on MB removal were investigated in batch mode. The maximum adsorption capacity is around 121.3 mg g(-1) at optimum pH = 10. An increase in adsorption capacity was observed via increasing MB concentration, with equilibration time ranged between 3,200 and 4,000 min. Both the Langmuir and the Redlich-Peterson models were found to describe well the equilibrium data. Kinetic studies showed better fitting for the pseudo-second-order model. The intraparticle diffusion model showed multilinearity, indicating two or more steps were involved to describe the adsorption process. Regeneration studies showed that the adsorption capacity of the adsorbent was reduced by about 20% after six cycles.