The adsorption of benzene and methylethylketone onto activated carbon: thermodynamic aspects.

The adsorption of volatile organic compounds (VOCs), exemplified by benzene and methylethylketone (MEK), onto seven different types of activated carbon was investigated. Results show that for benzene adsorption the adsorption characteristic energy, enthalpy, free energy and entropy are in the range 17.12-36.86, -20.8 to -44.7, -11.89 to -16.22 kJ/mole and -29.4 to -85.3 J/mole/K, respectively. For the adsorption of MEK, the adsorption characteristic energy, enthalpy, free energy and entropy are in the range 14.47-32.34, -18.3 to -40.8, -10.78 to -15.56 kJ/mole and -24.8 to approximately -60.3 J/mole/K, respectively. The adsorption enthalpy can be calculated indirectly from statistical thermodynamic method and directly from the immersion enthalpy method. The adsorption characteristic energy is calculated by the Dubinin-Astokhov equation. The free energy is calculated by the measured equilibrium adsorption constant.