Enhancing the Adsorption Performance of 2-Methylisoborneol by Activated Carbon by Promoting Hydrophobic Effects

Powdered activated carbon (PAC) is the most widely used adsorbent for removing odorants like 2-methylisoborneol (MIB) for drinking water purification. The hydrophobicity exhibited by the moieties of the carbon structure is known to be important for the adsorption of activated carbon. Here we propose a novel approach for regulating the hydrophobicity of the carbon surface by rearranging carbon atoms without changing the pore structures markedly through thermal transformation using Fe(NO3)3 as the catalyst. Five different PACs were transformed into hydrophobic porous carbons (HPCs) with 2.47–3.00 times the adsorption capacity and faster adsorption rates, accompanied by the surface free energy being decreased by 26.67–36.40%, the IG2/IG1 representing the degree of order being increased by 17.31–53.68%, the C–C(sp2)/C–C(sp3) being increased by 31.9–49.8%, and the oxygen content being decreased by 4.71–8.63%. The increase in ordered planar crystals dominated by sp2 carbons as well as the decrease in the number of heteroatoms in HPCs might be the main reason for its enhanced adsorption of MIB. Simulation based on reactive force field molecular dynamics indicated that MIB molecules tended to be adsorbed in ordered structures. This study provides a novel angle for improving the surface hydrophobicity of activated carbon, which may lead to the development of high-performance adsorbents.