Nox removal from air through super hydrophobic hollow fiber membrane contactors

Abstract

NOx, 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. NOx needs to be reduced from flue gas in order to fulfil environment regulations due to its hazardous nature. This study aims to remove NOx 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 NOx removal, mass transfer coefficients and fluxes. The highest values of NOx 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.