In Situ Sensing of Volatile Organic Compounds in Groundwater: First Field Tests of a Mid-Infrared Fiber-Optic Sensing System

2003 ◽  
Vol 57 (6) ◽  
pp. 607-613 ◽  
Author(s):  
H. Steiner ◽  
M. Jakusch ◽  
M. Kraft ◽  
M. Karlowatz ◽  
T. Baumann ◽  
...  
Keyword(s):  
Real World ◽  
Fiber Optic ◽  
Silver Halide ◽  
Field Tests ◽  
Reference Analysis ◽  
Mid Infrared ◽  
Sensor Head ◽  
Aquifer System ◽  
Volatile Organic

A prototype mid-infrared sensor system for the determination of volatile organic pollutants in groundwater was developed and tested under real-world conditions. The sensor comprises a portable Fourier transform infrared spectrometer, coupled to the sensor head via mid-infrared transparent silver halide fiber-optic cables. A 10 cm unclad middle section of the 6-m-long fiber is coated with ethylene propylene copolymer in order to enrich the analytes within the penetration depth of the evanescent field protruding from the fiber sensor head. A mixture of tetrachloroethylene, dichlorobenzene, diethyl phthalate, and xylene isomers at concentrations in the low ppm region was investigated qualitatively and quantitatively in an artificial aquifer system filled with Munich gravel. This simulated real-world site at a pilot scale enables in situ studies of the sensor response and spreading of the pollutants injected into the system with controlled groundwater flow. The sensor head was immersed into a monitoring well of the aquifer system at a distance of 1 m downstream of the sample inlet and at a depth of 30 cm. Within one hour, the analytes were clearly identified in the fingerprint region of the IR spectrum (1300 to 700 cm−1). The results have been validated by head-space gas chromatography, using samples collected during the field measurement. Five out of six analytes could be discriminated simultaneously; for two of the analytes the quantitative results are in agreement with the reference analysis.

Quantitative in Situ Monitoring of an Elevated Temperature Reaction Using a Water-Cooled Mid-Infrared Fiber-Optic Probe

1996 ◽  
Vol 68 (7) ◽  
pp. 1116-1123 ◽  
Author(s):  
Paul MacLaurin ◽  
Nicholas C. Crabb ◽  
Ian Wells ◽  
Paul J. Worsfold ◽  
David Coombs
Keyword(s):  
Elevated Temperature ◽  
Fiber Optic ◽  
In Situ Monitoring ◽  
Temperature Reaction ◽  
Fiber Optic Probe ◽  
Mid Infrared ◽  
Optic Probe

Online sensing of volatile organic compounds in groundwater using mid-infrared fibre optic evanescent wave spectroscopy: a pilot scale test

2003 ◽  
Vol 47 (2) ◽  
pp. 121-126 ◽  
Author(s):  
H. Steiner ◽  
K. Staubmann ◽  
R. Allabashi ◽  
N. Fleischmann ◽  
A. Katzir ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Pilot Plant ◽  
Pilot Scale ◽  
In Situ Monitoring ◽  
Fibre Optic ◽  
Sensor Head ◽  
Sensing System ◽  
Volatile Organic

A prototype sensing system for in-situ monitoring of volatile organic compounds in contaminated groundwater was tested at a pilot scale plant. The sensor consists of a commercially available Fourier transform infrared spectrometer, connected to a 6 m long infrared transparent silver halide fibre optic cable. A 10 cm long core-only section at the centre of the fibre is mounted on a sensor head and coated with a hydrophobic polymer layer, while the remaining fibre is protected by Teflon tubing and thus not in contact with the surrounding media. The sensor head was immersed into the monitoring wells of the pilot plant testing the sensor system under circumstances close to field conditions and typical for in-situ measurements. The pilot plant consists of a 1 m3 cubic tank filled with gravel. A pump is used to circulate water horizontally through the tank, simulating a natural aquifer. The evolution of the concentration of analytes injected into the system is monitored with time using the developed prototype sensing system. The results are validated by corresponding sampling and analysis with headspace gas chromatography.

New Frontiers for Mid-Infrared Sensors: Towards Deep Sea Monitoring with a Submarine FT-IR Sensor System

2003 ◽  
Vol 57 (6) ◽  
pp. 591-599 ◽  
Author(s):  
Martin Kraft ◽  
Michael Jakusch ◽  
Manfred Karlowatz ◽  
Abraham Katzir ◽  
Boris Mizaikoff
Keyword(s):  
Fiber Optic ◽  
Field Tests ◽  
Pollution Monitoring ◽  
Fiber Optic Sensor ◽  
Sensor System ◽  
Modular System ◽  
Remotely Operated Vehicle ◽  
Sensor Head ◽  
Optic Sensor ◽  
Ft Ir

A sub-sea deployable fiber-optic sensor system for the continuous determination of a range of environmentally relevant volatile organic compounds in seawater has been developed. The prototype of a robust, miniaturized Fourier transform infrared (FT-IR) spectrometer for in situ underwater pollution monitoring was designed, developed, and built in our research group. The assembled instrument is enclosed in a sealed aluminium pressure vessel and is capable of maintenance-free operation in an oceanic environment down to depths of at least 300 m. The whole system can be incorporated either in a tow frame or a remotely operated vehicle (ROV). A suitable fiber-optic sensor head was developed, optimized in terms of sensitivity and hydrodynamics, and connected to the underwater FT-IR spectrometer. Due to a modular system design, various other sensor head configurations could be realized and tested, ensuring facile adaptation of the instrument to future tasks. The sensor system was characterized in a series of laboratory and simulated field tests. The sensor proved to be capable of quantitatively detecting a range of chlorinated hydrocarbons and monocyclic aromatic hydrocarbons in seawater down to the low ppb (μg/L) concentration range, including mixtures of up to 6 components. It has been demonstrated that varying amounts of salinity, turbidity, or humic acids, as well as interfering seawater pollutants, such as aliphatic hydrocarbons or phenols, do not significantly influence the sensor characteristics. In addition, the sensor exhibits sufficient long-time stability and a low susceptibility to sensor fouling.

Mid-Infrared Fiber-Optic Attenuated Total Reflection Spectroscopy of the Solid—Liquid Phase Transition of Water

2005 ◽  
Vol 59 (4) ◽  
pp. 460-466 ◽  
Author(s):  
Arnon Millo ◽  
Yosef Raichlin ◽  
Abraham Katzir
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Fiber Optic ◽  
Silver Halide ◽  
Attenuated Total Reflection ◽  
Isosbestic Point ◽  
Mid Infrared ◽  
Liquid Phase Transition ◽  
New Information ◽  
Solid Liquid

Measurements of mid-infrared (MIR) absorption spectra of water and heavy water were carried out by fiber-optic evanescent wave spectroscopy, using silver halide (AgClBr) infrared fibers. Such measurements were performed for the first time on one sample, during the solid–liquid phase transition. From the variation of the spectra with temperature we found a new isosbestic point (at 3280 cm−1 for H2O or at 2475 cm−1 for D2O) and we identified five components of the O–H (O–D) stretch band. These phenomena have provided new information about the molecular structure of water.

New IR Fiber-Optic Chemical Sensor for in Situ Measurements of Chlorinated Hydrocarbons in Water

1993 ◽  
Vol 47 (9) ◽  
pp. 1484-1487 ◽  
Author(s):  
R. Krska ◽  
K. Taga ◽  
R. Kellner
Keyword(s):  
Evanescent Wave ◽  
Chemical Sensor ◽  
Fiber Optic ◽  
Silver Halide ◽  
Chlorinated Hydrocarbons ◽  
Sensor System ◽  
Absorption Bands ◽  
Relative Standard ◽  
Polycrystalline Silver

In this work the development and validation of a new MIR fiber-optic physicochemical sensor system for the continuous in situ analysis of chlorinated hydrocarbons (CHCs) in water is described. This study took advantage of the selectivity and sensitivity of fiber evanescent wave spectroscopy (FEWS) and the recent development of polycrystalline silver halide fibers. Since these fibers are transparent up to 20 μm, it was possible for the first time to develop a fiber-optic sensing system for CHCs, which have their strongest absorption bands > 10 μm. The silver halide fibers were coated with low-density polyethylene (LDPE) to enrich the CHC within the evanescent wave and to exclude the IR absorbing water from the measurement. For the quantitative in situ FEWS measurements, the coated silver halide fibers were coupled to a Fourier transform infrared (FT-IR) spectrometer using an off-axis parabolic mirror and a fiber-detector coupling system. This setup enabled the simultaneous in situ detection of the most common chlorinated hydrocarbons in concentrations between 1 to 50 mg/L in water by employing a fiber sensing part only 10 cm in length. A comparative analysis of waste water samples under participation of two experienced head space-gas chromatography (HSGC) laboratories showed good agreement of this continuous sensor system with the established standard techniques. The resulting working curve for tetrachloroethylene showed a correlation coefficient of r2 = 0.968 and a relative standard deviation of 17% in the range from 1 to 10 ppm.

scholarly journals Mid-infrared fiber-optic evanescent field spectroscopy for in situ monitoring of tetrahydrofuran hydrate formation and dissociation

The Analyst ◽  
2017 ◽  
Vol 142 (5) ◽  
pp. 740-744 ◽  
Author(s):  
M. Schwenk ◽  
A. Katzir ◽  
B. Mizaikoff
Keyword(s):  
Fiber Optic ◽  
Hydrate Formation ◽  
Evanescent Field ◽  
In Situ Monitoring ◽  
Clathrate Hydrates ◽  
Mid Infrared ◽  
Field Spectroscopy ◽  
Monitoring Technique

Mid-infrared fiber-optic evanescent field spectroscopy (MIR-FEFS) has been applied as an in situ monitoring technique for THF containing clathrate hydrates.

The Distribution of Volatile Organics in a Leachate Plume, Gloucester, Ontario

1987 ◽  
Vol 22 (1) ◽  
pp. 49-64 ◽  
Author(s):  
J.F. Devlin ◽  
W.A. Gorman
Keyword(s):  
Organic Contaminants ◽  
Source Area ◽  
Unconfined Aquifer ◽  
High Concentration ◽  
Organic Contamination ◽  
Aquifer System ◽  
Aquifer Systems ◽  
Volatile Organic ◽  
Volatile Organic Contaminants ◽  
Aquifer Sediments

Abstract The Gloucester Landfill is located near Ottawa, Ontario, on a northeast trending ridge of Quaternary age. The ridge comprises outwash sediments which make up two aquifer systems. A confined system exists next to bedrock, and is overlain by a silty-clayey stratum (the confining layer) which is, in turn, overlain by an unconfined aquifer system. Two independent volatile organic plumes have previously been identified at the landfill: the southeast plume, which has penetrated the confined aquifer system, and the northeast plume which is migrating in the unconfined aquifer. The distribution of volatile organic contaminants at the northeast plume site appears to be a function of two factors: (1) heterogeneities in the aquifer sediments are causing the channeling of contaminants through a narrow path; (2) the low fraction of organic carbon in the unconfined aquifer sediments at the northeast site is resulting in little retardation of the contaminants there, relative to those at the southeast site. Acetate was the only volatile fatty acid detected in the leachate. It was measurable only in areas where the volatile organic contamination was significant. Although methane was detected in the contaminated sediments, suggesting that microbial activity was present, the high concentration of acetate (>1000 ppm) which was detected down-gradient from the source area indicates that any biodegradation which is occurring is proceeding at a very slow rate.

Sign in / Sign up

Export Citation Format

Share Document