Enhanced dechlorination of chlorobenzene compounds on fly ash: effects of metals, solvents, and temperature

Abstract

Dechlorination of di-chlorobenzene and tri-chlorobenzene on fly ash was optimized. Solutions of sulfur with alkaline solutions of potassium hydroxide, sodium hydroxide, and calcium hydroxide were applied for dechlorination of chlorobenzene compounds. Higher dechlorination (%) on surface of fly ash was achieved in sulfur and calcium hydroxide mixture, which further was enhanced with the addition of sodium hydroxide. Higher dechlorination (%) was obtained at 90°C, where metals in general, and copper and lead, in particular, enhance the catalytic potential of fly ash for dechlorination by hydrodechlorination and substitution reactions. But at high temperatures (120–170°C), dechlorination process was adversely affected by these metals. Moreover, the fly ash particles provided the surface to accomplish reduction and substitution reactions by adsorbing the chlorinated aromatic compound, hydrogen, hydroxyl, and thiol ions. The effects of water, organic solvents, and temperature were studied and reactions conditions were optimized to get maximum dechlorination.