The influence of surface chemistry on activated carbon adsorption of 2-methylisoborneol from aqueous solution

An activated carbon with a relatively high oxygen content was heated at various temperatures in an argon atmosphere to produce a series of carbons with decreasing oxygen content. A second activated carbon with a relatively low oxygen content was treated with an ozone–oxygen mixture to produce a series of carbons with increasing oxygen content. In both cases, the pore size distribution and pore volume were unaffected by the treatment conditions. Adsorption isotherm and enthalpy of water displacement measurements were made for adsorption of 2-methylisoborneol (MIB) by these carbons in water. Both measurements show the importance of the oxygen content on the adsorption of MIB from aqueous solution. Increasing surface oxygen content at a constant pore volume leads to a decrease in both the amount adsorbed and the enthalpy of adsorption. To test the role of the solvent in this adsorption process, a relatively non-polar solvent, dichloromethane (DCM), was used to make adsorption measurements. Adsorption isotherms show that the amount of MIB adsorbed from DCM solution is independent of the oxygen content. These results indicate that the solvent plays an important role in the control of the adsorption from solution of a sparingly soluble solute.