Removal of phenol and chlorophenols from water by new ozone generator

Abstract

Presence of phenol in river water occasionally disturbs the production of drinking water. Phenol often originated from coal power plants or pesticides. New ozone generator [Kuraica et al., Vacuum, 73 (2004) 705] was used for removal of phenol and chlorophenols from water. The ozone generator was based on coaxial dielectric-barrier-discharge and operated in the air at an atmospheric pressure. Flowing water was one of dielectric layers. Ozone and ozonized water were generated in the same volume of the discharge. This type of ozone generator has considerable advantages in comparison with the classical ones. In this paper five experiments were described, three with bidistilled water and two with different water samples from river Danube. In all cases, 5 L of water containing 6 mg/L of corresponding phenol was passed once through the ozonizer. The concentration of dissolved ozone in water was 7-40 mg/L. The ozonization lasted 1 h, but the total contact time was up to 94 h. In all cases, before and after the treatment of water with ozone, the concentration of corresponding phenol [Standard Methods for Examination of Water and Wastewater, method 510 13, Chloroform Extraction Method, American Public Health Association, Washington, 1985, p. 558], dissolved and residual ozone [Standard Methods for Examination of Water and Wastewater, Methods 2-41, 2-42 (dissolved ozone) Iodometric Method; method 4-104 (ozone residual) Indigo Colorimetric Method, American Public Health Association, Washington, 1995] were determined by standard methods. In experiments with distilled water most of the phenol was removed during ozonization (89.5%). After 24 and 96 h the percentage of removed phenol increased to 93.3 and 98.9%, respectively. With 4-chlorophenol and 2,4-dichlorophenol, 99.8 and 98.9% of corresponding phenols were removed. In experiments with two different water samples from Danube, the phenol was also mostly removed during ozonization, 76.7 and 80.0%, respectively.