The performance of a microporous activated carbon prepared chemically from olive stones for removing Cu(II), Cd(II) and Pb(II) from single and binary aqueous solutions was investigated via the batch technique. The activated carbon sample was characterized using N 2 adsorption-desorption isotherms, SEM, XRD, FTIR, and Boehm titration. The effect of initial pH and contact time were studied. Adsorption kinetic rates were found to be fast and kinetic experimental data fitted very well the pseudo-second-order equation. The adsorption isotherms fit the Redlich-Peterson model very well and maximum adsorption amounts of single metal ions solutions follow the trend Pb(II) > Cd(II) > Cu(II). The adsorption behavior of binary solution systems shows a relatively high affinity to Cu(II) at the activated carbon surface of the mixture with Cd(II) or Pb(II). An antagonistic competitive adsorption phenomenon was observed. Desorption experiments indicated that about 59.5% of Cu(II) and 23% of Cd(II) were desorbed using a diluted sulfuric acid solution.

Recently, modification of surface structure of activated carbons in order to improve their adsorption performance 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 specific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes surface modifications in gaseous phase using ozone (O3) and in liquid phase using nitric acid (HNO3). The activated carbon samples were characterized using N2 adsorption-desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The activated 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 decrease 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(HNO3), 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.

The present work reports the synergistic and inhibitory adsorption effects involved in the multicomponent adsorption of heavy metal ions (Cu(II), Ni(II), and Cd(II)) from binary systems using chemically olive stone activated carbon (COSAC) as adsorbent. In order to evaluate the adsorption capacity of COSAC to remove studied heavy metals, adsorption of metal ions in single and binary systems were conducted. Kinetics adsorption rates in binary systems are very fast as compared to that in single ones and well represented by the pseudo second-order. Langmuir and Sips model fit mono-solute adsorption isotherms and the maximum adsorption capacity of COSAC decreased in the following order: Cd(II) [ Ni(II) [ Cu(II). In binary equilibrium systems, the effect of initial concentration of interfering metal ions on the removal of target ones was studied. Different mutual interactions between metal ions dealing with the decrease and the enhancement of inhibitory and synergetic effects were detected. Results showed that the effects on the adsorption of the metal ions in binary mixture strongly depend on the initial concentration of both metal ions in the solution. In most of the scenarios studied, the total amount of metal ions adsorbed was higher than the sum of the ones obtained in single solutions, suggesting synergetic interactions between the two metal ions. This study proves that COSAC is an effective adsorbent for the removal of heavy metals from multicomponent solutions.

In this work the ability of olive stone activated carbon (COSAC) to remove Pb(II), Cd(II), Ni(II) and Cu(II) metal ions from aqueous solutions was evaluated. The effect of initial pH, contact time and initial concentration on metal ions adsorption was investigated. The results indicated that pH 5 is the optimum value for metal removal. Adsorption kinetic rates were found to be fast; total equilibrium was achieved after 4 hours. Kinetic experimental data fitted very well the pseudo-second order equation and the values of adsorption rate constants were calculated. The equilibrium isotherms were evaluated in terms of maximum adsorption capacity and adsorption affinity by the application of Langmuir and Freundlich equations. Results indicate that the Langmuir model fits adsorption isotherm data better than the Freundlich model. The removal efficiency of heavy metal ions by COSAC decreases in the order Pb(II) > Cd(II) > Ni(II) ≥ Cu(II).

Activated carbon is prepared with chemical activation of olive stones, by using H 3 PO 4 . Batch adsorption of phenol from aqueous solution was investigated. The adsorptive properties were studied in terms of pH, equilibrium time, initial concentration (C 0 : 25-300 mg/L) and particle sizes (0.125-1.6mm) effects. The experimental kinetic data fitted well the pseudo second order model and the equilibrium isotherm data the Langmuir model. The results indicate that chemical olive stones activated carbon is suitable to be used as an adsorbent material for adsorption of phenol from aqueous solution.