Inorganic acids such as HF, HCl, HNO 3, H 2SO 4, and CH 3COOH are widely used in semiconductor or photoelectric manufacturing factories (or fabs) for wafer cleaning and wet-etching processes resulting in the emission of gaseous inorganic acidic pollutants from the stacks, which need to be treated to meet the emission standard of Taiwan Environment Protection Agency. The excellent long-term performance of the HWS warrants its potential applications in many areas in which liquid absorption is the preferred treatment method and the theoretical equations can facilitate the design of the HWS. Additionally, the predicted height and removal efficiencies of the HWS were very close to the experimental data. With water jet cleaning of the honeycomb modules once per year, the pressure drop of the HWS remained to be low at 0.5–0.8 cm H 2O, indicating minimal scaling in the HWS. Results showed that the removal efficiency for the mixed gases emitted from the fab always maintained as high as > 95% for HF, CH 3COOH, HCl, HNO 3, HNO 2, and H 2SO 4 with the inlet concentrations ranging from supper-ppmv to sub-ppmv, during a 3.5-yr period. In this study, the HWS scaled up to operate at a 100 CMM flow rate was tested for removing mixed acidic gases at a semiconductor fab for a very long period of 3.5 yr. A laboratory scale, 1.0 CMM (m 3 min − 1) wet scrubber packed with water-absorbing honeycomb material (HWS) with a very large geometric surface area of 480 m 2 m − 3 and a low pressure drop developed in our previous study was shown to achieve a very high removal efficiency for acidic gases but there were no long-term test data.
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