Distillation and detection of SO2 using a microfluidic chip

Abstract

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 H₂Ovia 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 R² = 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.