Organic pollutants exist in industrial wastewater effluent is a critical environmental problem. For instance, Para-nitrophenol is one of the volatile organic compounds (VOC) that can cause a significant harm to biological systems including plants, fish and other organisms due to its toxicity. However, para-nitrophenol can cause technical problems in Condensate Polishing Plant (one part of the wastewater treatment system) such as resins defect in the ion exchange unit. Activated carbon (AC) is commonly used in the carbon filter which is installed before the ion exchange unit. The proposed AC has been modified to extend the resin lifetime which may shorten as a result of fouling due to the organic compounds. Adsorptive removal of organic pollutants can efficiently solve this problem. Surface modification of AC using acidic solution is employed in this research. Scanning Electron Microscope (SEM) is used to study the pore structure of the activated carbon before and after modification. The effect of different controlling parameters was investigated by verification of adsorbate concentration, pH and temperature against the adsorption capacity of both unmodified and modified AC. Whereas UV-vis Spectrophotometer was used to determine the adsorption capacity of AC towards organic pollutant. As the concentration of absorbate increases, adsorption capacity increases. The adsorption reaches its highest point around pH 7, and when the carbonization temperature increases, the adsorption capacity increases as well.