Real-time detection of naphtha using photothermal cantilever deflection spectroscopy

石脑油是一种稀释剂，用于从油砂中提炼沥青，由低分子量的脂肪族和芳烃组成。其他石脑油成分包括异石蜡和环烷烃。在油砂加工过程中，几乎所有的石脑油都被回收。然而，在优化的工艺条件下，石脑油向尾矿流的损失小于1%是不可避免的。目前，石脑油的监测是通过人工每隔6小时采集一次样品，然后运送到实验室用gc -质谱仪进行分析，这种仪器体积大、价格昂贵，而且需要训练有素的人员。任何可能的石脑油泄漏到尾矿流将不会被发现，直到下一次预定的人工测试。本课题的目标是设计和研制一种能够实时检测尾矿流和尾矿库中石脑油的微型、高灵敏度传感器。石脑油是碳氢化合物的混合物；基于界面化学的传感方法将遭受假阳性。在此，我们提出了一种新型传感器，可以实时提供石脑油的“分子指纹”。该技术将微悬臂梁作为物理（位移）传感器的灵敏度与中红外光谱的选择性相结合。中红外区域通常被称为“分子指纹区”，具有独特的振动峰，没有泛音。该方法克服了悬臂式化学传感平台（缺乏选择性）以及传统中红外光谱技术灵敏度低、体积大、成本低等缺点。所提出的装置将是微型的，高灵敏度的，非常有选择性的，而且便宜。此外，该技术适用于大规模生产和大规模部署，这使得它在工业实现中非常可行。

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.