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Nitric oxide and sulfur dioxide from the exhaust gases of marine diesel engines are harmful for the environment and human health. Environmentally friendly sodium persulfate, which satisfies the requirements of ships and navigation, was used as the main absorbent for the simultaneous removal of SO2 and NO in a self-designed bubble column reactor with an industrial gas distributor in this work. The focus of this work was the absorption of the insoluble NO. The influences of various parameters including the reaction temperature, Na2S2O8 concentration, NO concentration, pH value of the solution, and presence of coexisting gases on NO absorption were comprehensively and systematically studied according to the different working conditions of marine diesel engines. Furthermore, experiments for simultaneously removing SO2 and NO were conducted. Different from the previous studies, the new experimental results showed that the increase of NO concentration and the pH value of 12 were not conducive to the NO absorption; the highest removal efficiency of NO was at pH of 9; the existence of sulfur dioxide weakened the absorption of nitric oxide; the final products of the simultaneous absorption were sulfate and nitrate according to the product detection results. However, the SO2 and NO in simulated exhaust gases (900 ppm SO2, 1000 ppm NO, 15% O2 and 5% CO2) from marine diesel engines were completely absorbed under nonoptimal conditions (at 70 °C and in a 0.15 mol/L sodium persulfate solution), which indicated that sodium persulfate is promising for use in wet emission control technologies for marine diesel engines.

The increasing frequency with which organic pollutants can be found in global surface water poses a formidable threat to both our environment and its creatures. While the problem has attracted adequate attention, current water treatment tools such as commercially available active carbon still cannot satisfy the remediating necessity due to its unfavorable rate of uptake and high regenerating cost. Moreover, water-insoluble pollutant adsorbents typically suffer from poor processability, effectively decreasing their potential for increased point-of-use versatility. Herein, we report a solution processable poly-lipoic ester-based material that readily undergoes simple coacervation upon ultrasonic solution processing. This material exhibits excellent removal efficiencies (>90%) and material recyclability for the uptake of highly concentrated typical pollutants including a plastic component bisphenol A (BPA), a pharmaceutical residue valsartan, and an industrial dye fluorescein from water. The polymer is conveniently accessible by a solvent-free, thermally initiated disulfide exchange ring-opening polymerization of a lipoic ester derivative and is postfunctionalized with an amphiphilic, π-electron-deficient bipyridinium-based side chain. Solution processing of this material facilitated the development of a pollutant sponge, which operates via a dip-remove-squeeze action, with an adsorption rate constant for BPA ∼85 times greater than its progenitor and achieving 80% removal efficiency in 30 s. This approach is particularly promising for quick point-of-use treatment of wastewater with high chemical oxygen demand. These results highlight the importance for material processability in the development of water-insoluble molecular adsorbents and establish poly-lipoic ester-based materials as contending precursors for application-driven soft matter development.

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