Sensor for the evaluation of dielectric properties of sulfur-containing heteroatomic hydrocarbon compounds in petroleum based liquids at a microfluidic scale

Desulfurization of hydrocarbons is an important step in the processing of petroleum products, which requires an accurate and robust method for the sulfur-containing component evaluation. On the other hand, sulfur-containing heteroatomic hydrocarbon additives are harmful for people and the environment. Therefore, it is advantageous to conduct laboratory tests at low volumes to reduce doses of exposure of sulfur-containing vapors to the personnel. Microfluidics is an emerging platform that provides an advantage to operate with low volumes. The microfluidic dielectric spectroscopy approach is proposed in the current contribution as a platform for determination of the concentration of polar heteroatomic components in binary mixtures. The presence of heteroatomic components in petroleum products leads to a perceptible change in the dielectric properties of the blend. This paper shows the technological aspects for the microfluidic sensor chip design. It was successfully used to determine the concentration of thiophene (as a typical sulfur-containing hydrocarbon) in gasoline. We compare the commercially available solution with the developed microfluidic sensor. We demonstrate the developed microfluidic sensor chip that has a comparable sensitivity as a macroscopic commercial measurement cell but at the microscale. It is able to operate at 103 times reduced volume of liquid analyte, providing stable control of the sulfur-containing additive concentration. The obtained results are intended to be applied for lab monitoring of sulfur-containing components in petroleum products.