Distillation and detection of SO2 using a microfluidic chip

A miniaturized distillation system is presented for separating sulfurous acid (H2SO3) into sulfur dioxide (SO2) and water (H2O). The major components of the proposed system include a microfluidic distillation chip, a power control module, and a carrier gas pressure control module. The microfluidic chip is patterned using a commercial CO2 laser and comprises a serpentine channel, a heating zone, a buffer zone, a cooling zone, and a collection tank. In the proposed device, the H2SO3 solution is injected into the microfluidic chip and is separated into SO2 and H2O via an appropriate control of the distillation time and temperature. The gaseous SO2 is then transported into the collection chamber by the carrier gas and is mixed with DI water. Finally, the SO2 concentration is deduced from the absorbance measurements obtained using a spectrophotometer. The experimental results show that a correlation coefficient of R-2 = 0.9981 and a distillation efficiency as high as 94.6% are obtained for H2SO3 solutions with SO2 concentrations in the range of 100-500 ppm. The SO2 concentrations of two commercial red wines are successfully detected using the developed device. Overall, the results presented in this study show that the proposed system provides a compact and reliable tool for SO2 concentration measurement purposes.