adsorption of polycyclic aromatic hydrocarbons on activated carbons: kinetic and isotherm curve modeling

the modeling of kinetic and isotherm curves acquired in adsorption of polycyclic aromatic hydrocarbons (pahs) as a model compound (phenanthrene) on activated carbons in the organic solvent. all the runs were carried out in a batch system at atmospheric pressure, process temperature of 24±2°c, and using the 100 ml phenanthrene in cyclohexan. this experimental work was mainly focused on the study of how the variables properties such as adsorbent dosage, the initial phenanthrene concentration, contact time and ph of cyclohexane solutions influence the kinetic and isotherm of the adsorption process. the results indicated that ph did not play a key role in the process of phenanthrene adsorption. the considerable adsorption (8.34 mg/g) was reached at ph 7, adsorbent dosage of 0.3 g/100 ml and agitation time of 11 h on activated carbons. the impact of adsorbent dose on phenanthrene concentration was not important after 0.3 g/100 ml. the results also showed that adsorption capacity became notably greater with an increase in contact time and initial phenanthrene concentration. another important finding was that adsorption processes and equilibrium data well fitted by pseudo-second-order kinetic (r 2 =0.99) and fraundlich adsorption models (r 2 =0.99). it can be concluded that there was a significant positive correlation between adsorption processes and the freundlich isotherm model but langmuir theory showed only a weak association.