Removal of trace ammonia by ionic liquids

Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 31057, Taiwan

^* Corresponding author: juliehsu@itri.org.tw

Abstract

Ammonia (NH₃), a critical process gas in semiconductor production, is the second largest air pollution from semiconductor factories as well as one of PM2.5 precursors. NH₃ emission standard will be regulated more strictly from current 2.5 ppm to 0.8 ppm as revealed by the 2025 semiconductor air pollution standard draft. NH₃ emission concentration was controlled using wet scrubber to achieve the regulations by adjusting pH value and increasing the water-recycling rate. However, it resulted in increased water consumption and the NH3 exhaust concentration still above emission standards (1 ppm). The purpose of this project was to develop ionic liquids which have high absorption ability to remove low NH₃ concentration. The results show that IL-1 and IL-5 were both good for NH₃ absorption, which the absorption capacity was greater than water. Among them, the liquid level of IL-1 will increase after the NH₃ absorption test, which indicates that it has good water absorption capacity. It has the dual functions of dehumidification and ammonia removal. Furthermore, IL-5 has the best NH₃ absorption ability which compared at same concentration can maintain the NH₃ outlet concentration at 0 ppm for more than 351 minutes.