Simultaneous removal of NOx and SO2 through polysulfone hollow fiber membrane using NaClO3 and NaOH as absorbents

NOx and SO2 are air pollutants that have triggered off severe environmental problems such as acid rain and photochemical smog, which significantly endanger the ecological environment and disrupt human health. Membrane gas absorption technology is a promising alternative to conventional technologies to mitigate acid gases. This study aims to remove NOx and SO2 simultaneously through a polysulfone hollow fiber membrane contactor by using a combination of NaClO3/NaOH as an absorbent solution. The reaction was carried out on a hollow fiber membrane module with various variations of absorbent concentration, which was set to 0.01 M; 0.05 M; 0.1 M; 0.5 M, and 1 M. The feed gas containing NOx and SO2 is flowed to the membrane tube section, while a combination of solvents will fill the membrane shell section, NaClO3/NaOH, to oxidize the gas simultaneously. The feed gas used in this research is a mixture of NOx and SO2 gases containing 600 ppm and 500 ppm, respectively, and the gas flow rate was set constant at 100 mL/minute. The hollow fiber membrane and solvent activity were tested on the efficiency of NOx and SO2 gas absorption, mass transfer flux, and NOx and SO2 loading. Based on the experimental result, the NOx and SO2 reduction efficiency increased along with the increase of NaClO3 concentration from 76.19% to 91.01%, while for SO2 reduction efficiency stabilized at 97% to 100%. The experiment achieved the highest values of membrane performance defined as NOx and SO2 mass transfer flux, and NOx and SO2 loading were 5.23×10−6 mmole/cm2.s; 4.75×10−6 mmole/cm2.s, and 1.54 mmole NOx/mole NaClO3.s and 1.65 mmole SO2/mole NaClO3.s, respectively.