No_x removal from air through super hydrophobic hollow fiber membrane contactors

NO_x, a generic term for nitrogen oxides, is an air pollutant that can causes damage to the ozone layer, and produces greenhouse effects, acid rain and photochemical smog. It is mainly produced by diesel engine exhaust due to the reaction between nitrogen and oxygen, especially at elevated temperatures. NO_x needs to be reduced from flue gas in order to fulfil environment regulations due to its hazardous nature. This study aims to remove NO_x from air through absorption using a mixture of H₂O₂ and HNO₃ solutions as an absorbent in the membrane contactors. In the experiment, the feed gas and the absorbent were flowed in the shell side and the lumen fibers, respectively. The flow rates of absorbent and feed gas, as well as the fiber number the membrane contactor, greatly influence the efficiency of NO_x removal, mass transfer coefficients and fluxes. The highest values of NO_x removal efficiency, mass transfer coefficient and flux achieved in the study were 47%, 8.7×10^-5 cm.sec^-1, and 3.1×10^-5 mmole.cm^-2.sec^-1, respectively.