Removal of 4-chlorophenol from wastewater using a pilot-scale advanced oxidation process

Abstract

Advanced oxidation processes utilizing both UV/H₂O₂ and photo-Fenton UV/H₂O₂/Fe⁺³ systems were investigated using pilot-scale experiments for the degradation and mineralization of 4-chlorophenol (4-CP). The experiments were conducted by using a photoreactor, which consists of three UV lamps fixed in staggered form. Three baffles were fixed vertically at the reactor side walls. These baffles reduce the presence of low radiation zones near the reactor walls. The study shows that the photo-Fenton process was the most effective treatment process under acidic conditions pH = 3, and produced a higher rate of degradation of 4-CP at a very short irradiation time. The reaction was found to follow the first order through both systems. A colored solution of benzoquinone can be observed through the first 5 min of irradiation time for the UV/H₂O₂ system when a low concentration (0.01 mol/L) of H₂O₂ was used. The colored solution of benzoquinone can also be observed through the first 5 min for the UV/H₂O₂/Fe⁺³ system at a high concentration (100 ppm) of 4-CP. The experimental results show that the optimum reagents for complete degradation of 4-CP (50 ppm) were H₂O₂ = 0.005 mol/L, Fe⁺³ = 0.16 × 10⁻³mol/L under acidic conditions (pH = 3), and irradiation time of 15 min for the UV/H₂O₂/Fe⁺³ system with a molar ratio of H₂O₂/Fe⁺³/4-CP equals 13/0.4/1.

Keywords:

• 4-chlorophenol
• Advance oxidation process
• Fenton process
• Photo-Fenton process
• UV photolysis