Sensors

Australian Resources Research Centre, Kensington, Perth

Dr Linda Stalker
Linda.Stalker@csiro.au

• A portable infrared attenuated total reflection (IRATR) spectrometer was developed for analyzing CO2 and CH4 in geosequestration scenarios. This infrared-based online sensor system is suitable for monitoring, detecting, and differentiating
  carbon dioxide and methane at different pressures (i.e., up to 11MPa) in saline aquifer and/or synthetic brine environments. The design of the sensor system eliminates the present problems in such measurement scenarios of either portability or capability
  operating at harsh conditions, and especially at elevated pressures for in-field deployment of current available IR systems. It is
  demonstrated that the detection and quantification of dissolved CO2 and CH4 at pressurized conditions is feasible at relevant
  saline downhole conditions present within the piping of the present injection wells serving as an online/in-line monitoring tool.
• The use of mid-infrared sensors based on conventional spectroscopic equipment for oil spill monitoring and fingerprinting in aqueous systems has to date been mainly confined to laboratory environments. This paper presents a portable-based mid-infrared attenuated total reflectance (MIR-ATR) sensor system that was used to quantify a number of environmentally
  relevant hydrocarbon contaminants in marine water. The sensor comprises a polymer-coated diamond waveguide in combination with a room-temperature operated pyroelectric detector, and the analytical performance was optimized by evaluating the influence of polymer composition, polymer film thickness, and solution flow rate on the sensor response. Uncertainties regarding the analytical performance and instrument specifications for dissolved oil detection were investigated using real-world seawater matrices. The reliability of the sensor was tested by exposition to known volumes of different oils; crude oil and diesel samples were equilibrated with seawater and then analyzed using the developed MIR-ATR sensor system. For validation, gas chromatographic measurements were performed revealing that the MIR-ATR sensor is a promising on-site monitoring tool for determining the concentration of a range of dissolved oil components in seawater at ppb to ppm levels.