The objective of this work was to study the effect of some operating conditions on the simultaneous
removal of NOx and SO2 from simulated NO–SO2–air flue-gas mixtures in a scrubber column. The gaseous
components were absorbed into 6 M HNO3 electrolyte in the scrubber in a counter-current mode, and
were oxidatively removed by the Ag(II) mediator oxidant electrochemically generated in an electrochemical
cell set-up. The integration of the electrochemical cell with the scrubber set-up ensured continuous
regeneration of the Ag(II) mediator and its repeated reuse for NOx and SO2 removal purpose, thereby
avoiding: (1) the usage of chemicals continuously for oxidation and (2) the production of secondary
waste. The influences of packing material (raschig glass rings, raschig poly(vinylidene) fluoride rings, Jaeger
tri-pack perfluoroalkoxy spheres), feed concentrations of NO and SO2 (100–400 ppm NO and 100–
400 ppm SO2), superficial gas velocity (0.061–0.61 m s�1) and liquid velocity (0.012–0.048 m s�1) were
investigated. The raschig glass rings with high surface area provided highest NO removal efficiency.
NO and NOx showed decreasing abatement at higher feed concentrations. The removal of nitrogen components
was faster and also greater, when SO2 co-existed in the feed. Whereas the gas flow rate decreased
the removal efficiency, the liquid flow rate increased it for NO and NOx. The flow rate effects were analyzed
in terms of gas/liquid residence time and superficial liquid velocity/superficial gas velocity ratio.
SO2 removal was total under all conditions