Optical Properties and Kinetic Behavior of Chlorine in Pure Water and Swimming Pool Water using Surface Plasmon Resonance Technique

W.Y.W Yusmawati,W Mahmood Mat Yunus

doi:10.3844/ajassp.2007.1024.1028

Abstract

An optical sensor based on surface plasmon resonance phenomenon for detection of chlorine in pure water and swimming pool water is presented. The measurement was carried out at room temperature using Kretschmann surface plasmon resonance technique. When the air medium outside the metal film is changed to chlorine solution, the resonance angle shifted to the higher value. The shift of resonance angle (∆θ) increases linearly with chlorine concentration in which the detection limit and sensor sensitivity could be quantified. In this work, the sensitivity of the detection was estimated to be 0.11°/ppm and 0.12°/ppm for Calcium Hypochlorite (G70) and Trichloroisocyanuric Acid (G90), respectively. The detection limit of this sensor is better than 0.1 ppm for chlorine samples and capable to monitor the chlorine concentration in swimming pool. We observed that the shift in the resonance angle (∆θ) decreases with time due to reducing amount of chlorine in the solution. Result from real-time measurement of swimming pool water was compared with simulation result carried out in the laboratory. Both have shown that the resonance angle decreases with time due to releasing of chlorine gas to the atmosphere.

Highlights

Swimming pool water needs to be disinfected to prevent swimmer from being infected by microbial pathogen[1]
Surface plasmon resonance technique has emerged as a powerful technique for a variety of chemical and biological sensor applications
We report the surface plasmon resonance technique as an effective optical sensor for monitoring the chlorine concentration level in swimming pool

Summary

Introduction

Swimming pool water needs to be disinfected to prevent swimmer from being infected by microbial pathogen[1]. By maintaining a free chlorine residual of not less than 1.5 ppm, algae infestation can be prevented. It is paramount to maintain free residual chlorine at a level adequate enough to disinfect bacteria and virus that may be brought into the swimming pool water by swimmer, air dust, rain and other sources. Surface plasmon resonance (SPR) spectroscopy is a surface-sensitive technique that has been used to characterize the thickness and/or index of refraction of dielectric medium at noble metal surface. Surface plasmon resonance sensors have been extensively studied[2]. Surface plasmon resonance technique has emerged as a powerful technique for a variety of chemical and biological sensor applications. In the 1983, Liedberg et al.[3] first demonstrated the exploitation of SPR as chemical sensing

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Results

Conclusion