Real-time detection of naphtha using photothermal cantilever deflection spectroscopy

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Naphtha, a diluent, used in processing bitumen from oil sands, consists of low molecular weight aliphatic and aromatics hydrocarbons. Other naphtha constituents include iso-paraffins and naphathenes. During oil sands processing, almost all the naphtha is recovered. However, under optimized processing conditions less than 1% naphtha loss to the tailings stream is inevitable. At present naphtha is monitored by manually collecting samples at 6 hr intervals and transported to a lab for analysis by GC-mass spectrometer, which is bulky, expensive and requires trained personal. Any possible leak of naphtha to the tailings stream will go undetected until the next scheduled manual test. The objective of this proposal is to design and develop a miniature, highly sensitive sensor capable of real-time detection of naphtha in the tailings stream and tailings pond. Naptha is a mixture of hydrocarbons; sensing approaches based on interfacial chemistry will suffer from false positives. Here we propose a novel sensor that can provide "molecular fingerprints" of naphtha in real time. The proposed technique combines the sensitivity of a micro cantilever as a physical (displacement) sensor with the selectivity of mid infrared spectroscopy. Mid infrared region is often called "molecular finger print regime" has unique vibrational peaks that is free from overtones. This approach overcomes the disadvantages of cantilever chemical sensing platform (lack of selectivity) as well as of the conventional mid infrared spectroscopy which includes the lack of sensitivity, bulky, and cost considerations. The proposed device will be miniature, highly sensitive, very selective, and inexpensive. Furthermore, this technique is amenable for mass production and mass deployment which makes it excellently feasible for industrial implementations.