Removal of chlorophenols using industrial wastes

Development of inexpensive adsorbents from industrial wastes for the treatment of wastewaters is an important area in environmental sciences. Blast furnace slag, dust and sludge from steel plants, and carbon slurry from fertilizer plants after their treatment have been utilized as inexpensive adsorbents for the removal of phenols, which are an important class of pollutants as they are highly toxic. The characterization of the four adsorbents prepared has shown that the carbonaceous adsorbent prepared from carbon slurry possesses high porosity and maximum surface area (380 m2/g) as compared to the other three adsorbents (4-28 m2/g). The adsorption of four phenols (phenol, 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol) on these adsorbents is parallel to their porosity and surface area order. The uptake of the phenols on carbonaceous adsorbent is substantial and found to be 17.2, 50.3, 57.4, and 132.5 mg/g for phenol, 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol, respectively. The detailed adsorption studies on carbonaceous adsorbent have indicated that the adsorption process follows the Langmuir isotherm, is first order, and is pore diffusion controlled. As adsorption of phenols on prepared carbonaceous adsorbent is significant, its performance has been evaluated with respect to standard activated charcoal. The results indicate that the phenols removal efficiency of carbonaceous adsorbent is about 45% to that of a standard activated charcoal sample. Thus, the carbonaceous adsorbent can be used for the removal of phenols as a low-cost alternative (approximately 0.1 U.S. dollars/kg) to activated charcoal.