This work investigates the efficiency of activated carbon that has undergone surface modification by impregnation with tetrabutylammonium (TBA) and copper in the removal of phthalate. Initially, the adsorption isotherms of phthalate on plain-carbon were measured at different pH values. It was concluded, using Langmuir model, that the adsorption capacity increased upon decreasing pH. To enhance the removal capacity at moderate pH, activated carbons were modified by immobilizing copper or TBA at their surface. The phthalate removal efficiencies of two separate fixed bed columns of Cu- and TBA-impregnated carbons were compared with that of plain activated carbon at pH 4. The results indicated that Cu-impregnated carbon has a removal capacity of nearly two times that of plain carbon. TBA impregnation was also shown to enhance the phthalate adsorption capacity with a factor of 1.7 times that of plain carbon. The observed results were explained in terms of chemisorption by forming Cu(Pht)(2) or electrostatic interaction between positively charged TBA and phthalate anions. The overall phthalate removal is a combination adsorption capacity of plain activated carbon, and the extent of copper metal ions and TBA agent molecules immobilized on the carbon. (C) 2003 Elsevier B.V. All rights reserved.