Enthalpy of immersion of activated carbons with different oxygen content in organic solvents and water

Interactions between activated carbons with different oxygen content on its surface and solvents classified as volatile organic compounds (VOCs), can be studied from adsorption isotherms and immersion enthalpy. Our Investigation Group have worked for several years in the study of adsorbent-adsorbate interactions through the use of immersion calorimetry in addition to techniques such as the elaboration of N-2, CO2 and different solvents adsorption isotherms, elemental analysis, Scanning electron microscopy, SEM, X-ray diffraction, XRD, Raman spectrometry, Bohem titration and pH at the point of zero charge among others. This study presents some of the most recent results obtained from the modification of activated carbons prepared using coconut shell, through treatments of: 1) impregnation with nitric acid and impregnation with phosphoric acid at 291 K; 2) functionalization of nitric acid pre-oxidized activated carbon with ammonium hydroxide by refluxing and 3) carbonization in nitrogen atmosphere at 1073, 1173 and 1273 K. The immersion enthalpies obtained less than 100 J/g, suggest that the weaker adsorbent-adsorbate interactions promote a more efficient adsorption process.