Chemical sensors chlorine

R. Tauler, A.K. Smilde, J.M. Henshaw, L.W. Burgess and B.R. Kowalski, Multicomponent determination of chlorinated hydrocarbons using a reaction-based chemical sensor. 2 Chemical speciation using multivariate curve resolution. Anal. Chem., 66 (1994) 3337-3344. 

Tauler R., Smilde A.K., Hemshaw J.M., Burgess L.W., Kowalski B.R., Multicomponent Determination of Chlorinated Hydrocarbons Using a Reaction-based Chemical Sensor. Part 2. Chemical Speciation Using Multivariate Curve Resolution, Anal. Chem. 1994 66 3337-3344. 

Fluorinated polymers, especially polytetrafluoroethylene (PTFE) and copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene (HFP) and perfluorinated alkyl vinyl ethers (PFAVE) as well as other fluorine-containing polymers are well known as materials with unique inertness. However, fluorinated polymers with functional groups are of much more interest because they combine the merits of pefluorinated materials and functional polymers (the terms functional monomer/ polymer will be used in this chapter to mean monomer/polymer containing functional groups, respectively). Such materials can be used, e.g., as ion exchange membranes for chlorine-alkali and fuel cells, gas separation membranes, solid polymeric superacid catalysts and polymeric reagents for various organic reactions, and chemical sensors. Of course, fully fluorinated materials are exceptionally inert, but at the same time are the most complicated to produce. 

Chemical sensors that can be used to identify potential threats to process water and industrial wastewater systems include inorganic monitors (e.g., chlorine analyzer), organic monitors (e.g., total organic carbon analyzer), and toxicity meters. Radiological meters can be used to measure concentrations of several different radioactive species. 

On-wafer membrane deposition and patterning is an important aspect of the fabrication of planar, silicon based (bio)chemical sensors. Three examples are presented in this paper amperometric glucose and free chlorine sensors and a potentiometric ISRET based calcium sensitive device. For the membrane modified ISFET, photolithographic definition of both inner hydrogel-type membrane (polyHEMA) and outer siloxane-based ion sensitive membrane, of total thickness of 80 pm, has been performed. An identical approach has been used for the polyHEMA deposition on the free chlorine sensor. On the other hand, the enzymatic membrane deposition for a glucose electrode has been performed by either a lift-off technique or by an on-chip casting. 

Krska R, Taga K, Kellner R. 1993. New IR fiber-optic chemical sensor for in situ measurements of chlorinated hydrocarbons in water. Applied Spectroscopy 47(9) 1484-1487. 

Small but environrrientallyjnendly. The Chemical Engineer, March 1993 Huge increases in technology in the past distributed manufacturing in small-scale plants miniaturization of processes domestic methanol plant point-of-sale chlorine simpler and cheaper plants economy of plant manufacture process control and automation start-up and shut-down sensor demand [145],... 

In this manner, a nearly universal and very nonselective detector is created that is a compromise between widespread response and high selectivity. For example, the photoionization detector (PID) can detect part-per-billion levels of benzene but cannot detect methane. Conversely, the flame ionization detector (FID) can detect part-per-billion levels of methane but does not detect chlorinated compounds like CCl very effectively. By combining the filament and electrochemical sensor, all of these chemicals can be detected but only at part-per-million levels and above. Because most chemical vapors have toxic exposure limits above 1 ppm (a few such as hydrazines have limits below 1 ppm), this sensitivity is adequate for the initial applications. Several cases of electrochemical sensors being used at the sub-part-per-million level have been reported (3, 16). The filament and electrochemical sensor form the basic gas sensor required for detecting a wide variety of chemicals in air, but with little or no selectivity. The next step is to use an array of such sensors in a variety of ways (modes) to obtain the information required to perform the qualitative analysis of an unknown airborne chemical. 

The single largest application for ECTEE has been as primary insulation and jacketing [62] for voice and copper cables used in building plenums [63]. In automotive applications, ECTEE is used for jackets of cables inside fuel tanks for level sensors, for hookup wires, and in heating cables for car seats. Chemically foamed ECTEE is used in some cable constructions [64]. In the chemical process industry, it is often used in chlorine/caustic environment in cell covers, outlet boxes, lined pipes (Eigure 4.26), and tanks. 

Several studies of phthalocyanines in the presence of strong oxidants, such as chlorine, ozone, and nitrogen dioxide, attribute the primary electronic sensor response to the Sc term (2) where the strong chemical oxidant gasses accept an electron as in (3)-(5) [38, 99, 105-125],... 

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