The removal of phenol and its derivatives from aqueous solutions by adsorption on petroleum asphaltene

This research describes the adsorption of phenol and o-substituted phenols and xylenol isomers on petroleum asphaltenes from aqueous solution. the results revealed that the adsorption equilibrium data were best fitted with the generalized and freundlich isotherms. for o-substituted phenols,it was found that electron-withdrawing groups increase the adsorption capacity. the uptake of these phenols decreases in the order: o-nitrophenol > o-chlorophenol > o-aminophenol > o-cresol > phenol,while the adsorption of xylenol isomers decreases in the order: 2,6-xylenol > 2,5-xylenol > 3,5-xylenol > 3,4-xylenol. batch equilibrium results at different temperatures suggest that the adsorption of 2,6-xylenol and 3,5-xylenol onto asphaltene is an endothermic process,δg values obtained were positive indicating a nonspontaneous process with increasing randomness at the solid-solution interface. the influence of solution ph on the adsorption of 3,5-xylenol on asphaltenes was also investigated. the adsorption process was found to be independent on the solution ph. the adsorption capacity of 3,5-xylenol was found to increase with the decrease in particle size of the adsorbent. © 2013 omer el-amin ahmed adam and ammar hani al-dujaili.