The kinetics of the removal of organic pollutants from drinking water by a novel plasma-based advanced oxidation technology

Abstract

The main goal of this study was to examine the oxidation kinetics of four common organic pollutants, Chicago Sky Blue 6B (CSB), Rhodamine B (RhB), phenol, and 4-chlorophenol (4-CP), in drinking water using an advanced oxidation processes (AOP) corona technology. This was achieved by determining the rate constants and by tracking kinetics. In most experiments, a pseudo-first-order kinetics was found. Due to its molecular structure, the constant rate of color removal (K_CSB = 2.3E−3 min⁻¹) was higher than that of the aromatic groups (K_CSB = 3.0E−4 min⁻¹). Hydroxyl radical kinetics was investigated by means of p-chlorobenzoic acid (pCBA) degradation. When 10 mg/l of phenol was added to the water, pCBA degradation decreased (K_pCBA = 3.70E−04 min⁻¹). An experiment carried out under similar conditions, but with an inactive ozone injection system, caused the pCBA rate constant to decrease even more (K_pCBA = 1.60E−04 min⁻¹). The rate constants significantly increased, when the injector operated, since polluted water entered the static mixer at high pressure, where a second encounter occurred with oxidative agents that originated in air enriched with ozone that was drawn from the reactor. The high pressure separates the water into droplets, which allows for a better exposure of pollutants to oxidative agents.

Keywords:

• Corona
• AOP
• Hydroxyl radical
• CSB
• RhB
• Phenol
• 4-CP

Acknowledgments

We would like to thank Prof. Ori Lahav, of the Faculty of Civil and Environmental Engineering, Technion, Haifa, Israel, for providing his professional input and advice. We would also like to thank Dvir Solnik, Itay Even-Ezra, Yuri Shmokler, and Gal Bitan of Aquapure Technologies for the use of the non-thermal plasma pilot unit and for their technical and professional support during the study.