A novel method for removing NOx from simulated marine exhaust gas in wet absorption system using Na2SO3/THS composite solution.

Since it is difficult to deal with high‐concentration nitrates in scrubbed wastewater onboard vessels, the application of traditional wet denitration technology is limited to some extent. Here a novel method for removing pre‐oxidized NOx by using Na2SO3/THS composite solution is proposed with the aim to obtain high NOx absorption efficiency and low nitrate concentration in scrubbed wastewater simultaneously. The effects of Na2SO3 concentration, THS concentration, NOx oxidation degree, coexistence of SO2 and O2 in flue gas, initial pH value and temperature of absorption solution on denitration performance were discussed in detail. The results showed Na2SO3 could reduce NOx to nitrate, nitrite, and N2. The addition of THS could promote NOx absorption greatly by forming complexes with SO32−. When initial NOx concentration was 1000 ppm with a NOx oxidation degree of 50%, O2 concentration was 8%, Na2SO3 and THS concentrations were 25 and 20 mmol/L, a NOx absorption efficiency of 87% could be achieved, while nitrate and nitrite concentrations were 32.97 and 14.19 mg/L, respectively. [ABSTRACT FROM AUTHOR]