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Title: A carbon nanotube based resettable sensor for measuring free chlorine in drinking water

Free chlorine from dissolved chlorine gas is widely used as a disinfectant for drinking water. The residual chlorine concentration has to be continuously monitored and accurately controlled in a certain range around 0.5–2 mg/l to ensure drinking water safety and quality. However, simple, reliable, and reagent free monitoring devices are currently not available. Here, we present a free chlorine sensor that uses oxidation of a phenyl-capped aniline tetramer (PCAT) to dope single wall carbon nanotubes (SWCNTs) and to change their resistance. The oxidation of PCAT by chlorine switches the PCAT-SWCNT system into a low resistance (p-doped) state which can be detected by probing it with a small voltage. The change in resistance is found to be proportional to the log-scale concentration of the free chlorine in the sample. The p-doping of the PCAT-SWCNT film then can be electrochemically reversed by polarizing it cathodically. This sensor not only shows good sensing response in the whole concentration range of free chlorine in drinking water but is also able to be electrochemically reset back many times without the use of any reagents. This simple sensor is ideally suited for measuring free chlorine in drinking water continuously.
Authors:
 [1] ; ;  [2] ;  [1] ;  [3]
  1. School of Biomedical Engineering, McMaster University, Hamilton L8S 4L8 (Canada)
  2. Department of Chemistry and Chemical Biology, McMaster University, Hamilton L8S 4L8 (Canada)
  3. (Canada)
Publication Date:
OSTI Identifier:
22412619
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ABUNDANCE; ANILINE; CARBON NANOTUBES; CHLORINE; CONCENTRATION RATIO; DOPED MATERIALS; DRINKING WATER; ELECTRIC CONDUCTIVITY; ELECTROCHEMISTRY; FILMS; MONITORING; OXIDATION; REAGENTS; SENSORS