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

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 5min of irradiation time for the UV/H2O2 system when a low concentration (0.01mol/L) of H2O2 was used. The colored solution of benzoquinone can also be observed through the first 5min for the UV/H2O2/Fe+3 system at a high concentration (100ppm) of 4-CP. The experimental results show that the optimum reagents for complete degradation of 4-CP (50ppm) were H2O2=0.005mol/L, Fe+3=0.16x10(-3)mol/L under acidic conditions (pH=3), and irradiation time of 15min for the UV/H2O2/Fe+3 system with a molar ratio of H2O2/Fe+3/4-CP equals 13/0.4/1.