INTERNATIONAL CONFERENCE ON INTEGRATED MANAGEMENT OF THE ENVIRONMENT - ICIME 2014 Improvement of oxygen-containing functional groups on olive stones activated carbon by ozone and nitric acid for heavy metals removal from aqueous phase Thouraya Bohli 1 & Abdelmottaleb Ouederni 1 Received: 15 December 2014 /Accepted: 5 March 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Recently, modification of surface structure of acti- vated carbons in order to improve their adsorption perfor- mance toward especial pollutants has gained great interest. Oxygen-containing functional groups have been devoted as the main responsible for heavy metal binding on the activated carbon surface; their introduction or enhancement needs spe- cific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes sur- face modifications in gaseous phase using ozone (O 3 ) and in liquid phase using nitric acid (HNO 3 ). The activated carbon samples were characterized using N 2 adsorption–desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The acti- vated carbon parent (COSAC) has a high surface area of 1194 m 2 /g and shows a predominantly microporous structure. Oxidation treatments with nitric acid and ozone show a de- crease in both specific surface area and micropore volumes, whereas these acidic treatments have led to a fixation of high amount of surface oxygen functional groups, thus making the carbon surface more hydrophilic. Activated carbon samples were used as an adsorbent matrix for the removal of Co(II), Ni(II), and Cu(II) heavy metal ions from aqueous solutions. Adsorption isotherms were obtained at 30 °C, and the data are well fitted to the Redlich–Peterson and Langmuir equation. Results show that oxidized COSACs, especially COSAC(HNO 3 ), are capable to remove more Co(II), Cu(II), and Ni(II) from aqueous solution. Nitric acid-oxidized olive stones activated carbon was tested in its ability to remove metal ions from binary systems and results show an important maximum adsorbed amount as compared to single systems. Keywords Surface modification . Oxygen functional groups . Olive stones activated carbon . Heavy metals . Adsorption Nomenclature COSAC Olive stones activated carbon prepared by chemical activation using phosphoric acid COSAC(HNO 3 ) Oxidized olive stones activated carbon with nitric acid COSAC(O 3 ) Oxidized olive stones activated carbon with ozone Ox-COSAC Oxidized olive stones activated carbon ICP-AES Inductively coupled plasma atomic emis- sion spectrometry FTIR Fourier transformed infrared spectroscopy SEM Scanning electron microscope A, B Redlich–Peterson parameters (L/g) and (L/mol) β q Adsorption amount (mmol/g) q binary Adsorption uptake from binary system (mmol/g) q single Adsorption uptake from single solution (mmol/g) K F Freundlich parameter (mmol/L)(L/g) (1/n) n Freundlich constant C Liquid phase concentration of metal ion concentration (mmol/L) K L Langmuir parameter (L/mmol) m The mass of adsorbent (g) V Volume of metal ion solution (L) Responsible editor: Philippe Garrigues * Thouraya Bohli bohlithouraya@gmail.com Abdelmottaleb Ouederni mottaleb.ouederni@enig.rnu.tn 1 Laboratory of Research: Process Engineering and Industrial Systems (LR11ES54), National School of Engineers of Gabes, University of Gabès, 6026 Gabès, Tunisia Environ Sci Pollut Res DOI 10.1007/s11356-015-4330-0