Abstract A novel method based on a Na2S2O8/urea composite system was used to both synchronously absorb SO2 and NO from marine diesel engine emissions and reduce the nitrate residues in cleaning wastewater. In the Na2S2O8/urea solution, a temperature of over 60 °C and a Na2S2O8 concentration of >0.05 mol/L were found to fully absorb SO2 by overcoming the SO2 release and effectively absorb NO. Urea successfully reduced the residual nitrate concentration and improves NO absorption at a concentration below 2 mol/L. The NO and SO2 removal efficiencies reached 97.8 ± 1.5% and 100%, respectively, at 70 °C in 0.1 mol/L Na2S2O8 and 1.5 mol/L urea solutions. The residual nitrate concentration was 8.12 ± 0.25 mg/L, far below the regulatory limit of 60 mg/L. Acidic conditions (pH ≤ 5.5) could be conducive to absorbing NO and reducing the residual nitrate concentration. Based on the experimental results, this novel method is highly promising for reducing ship emissions.

中文翻译：

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一种同步吸收船用柴油机 SO2 和 NO 的新方法

摘要 采用一种基于Na2S2O8/尿素复合体系的新方法，同步吸收船用柴油机排放的SO2和NO，减少清洗废水中的硝酸盐残留。在 Na2S2O8/尿素溶液中，温度超过 60°C 且 Na2S2O8 浓度 >0.05 mol/L，通过克服 SO2 释放充分吸收 SO2 并有效吸收 NO。尿素在低于 2 mol/L 的浓度下成功降低了残留硝酸盐浓度并提高了 NO 吸收。在 70 °C 下，在 0.1 mol/L Na2S2O8 和 1.5 mol/L 尿素溶液中，NO 和 SO2 去除效率分别达到 97.8 ± 1.5% 和 100%。残留硝酸盐浓度为 8.12 ± 0.25 mg/L，远低于 60 mg/L 的监管限值。酸性条件（pH ≤ 5。5）有利于吸收NO，降低残留硝酸盐浓度。根据实验结果，这种新方法对于减少船舶排放非常有希望。