Removal of chlorophenols from aqueous solution by fly ash

Fly ash from coal-fired thermal power plants can be used for the removal of 2-chlorophenol (2-CP) and 2,4-dichlorophenol (2,4-DCP) with enthalpy chang es of about -3 kcal/mol. The amounts of 2-CP and 2,3-DCP removed are affect ed by the pH value of the solution. The efficiency of removal improves when the pH value is less than the pK(a) values of 2-CP and 2,4-DCP, respective ly. The adsorbed amount of chlorophenol by fly ash is also affected by part icle diameter, carbon content, and the specific surface area of the ash use d in this study. As expected, more adsorption takes place with fly ash of h igher carbon content and larger specific surface area. Moreover, the adsorb ed amount of chlorophenol is not influenced by the matrix in the wastewater , as shown by studying the removal of 2-CP and 2,4-DCP in wastewater from a synthetic fiber plant. Chlorophenols in the wastewater were also removed e fficiently through a fly ash column, with breakthrough times being inversel y proportional to flow rates. (C) 2000 Elsevier Science B.V. All rights res erved.