(320aj) Adsorption and Desorption Characteristics of Some Chlorinated Herbicides Onto Activated Carbon

We are exposed to various chemical species present in the environment. Among these compounds, Chlorinated herbicides are very important because of their wide distribution and extensive use as plant growth regulators. When applied, they are easily transferred to surface and ground waters due to their polar nature and relatively high solubility. Although the decomposition rates of these herbicides in the presence of oxygen are relatively fast, they are persistent under reductive conditions, so that their extended use can lead to pollution of surface and ground waters. The treatment methods aimed at the removal of anthropogenic pollutants from the environment have become the subject of increased interest. In wastewater treatment, activated carbon is a powerful adsorbent because it has large surface area and pore volume, which remove liquid-phase contaminants, including organic compounds, heavy metal ions and coloring matters. In order to design effective activated carbon adsorption units and to develop mathematical models which can accurately describe their operation characteristics, sufficient information on both the adsorption and the desorption of individual pollutions under different operating conditions is required. The main purpose of this work is to study adsorption characteristics of 2-methyl-4-chlorophenoxyacetic acid (MCPA), para-chlorophenoxyacetic acid (P-CPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) from aqueous solution onto a granular activated carbon, experimentally as well as theoretically.