Surface modification effects on CNTs adsorption of methylene blue and phenol

This study compares the adsorption capacity of modified CNTs using acid and heat treatment. The CNTs were synthesized from acetone and ethanol as carbon sources, using floating catalyst chemical vapor deposition (FC-CVD) method. energy-dispersive X-ray spectroscopy (EDX) and Boehm method revealed the existence of oxygen functional group on the surface of CNTs. Heat modification increases the adsorption capacity of as-synthesized CNTs for methylene blue (MB) and phenol by approximately 76% and 50%, respectively. However, acid modification decreases the adsorption capacity. The equilibrium adsorption data fitted the Redlich-Peterson isotherm. For the adsorption kinetic study, the experimental data obeyed the pseudo-second-order model. Both modifications methods reduced the surface area and pore volume. The studies show that the adsorption of MB and phenol onto modified CNTs is much more influenced by their surface functional group than their surface area and pore volume.