Nitrogen compounds in liquid fuel are one of themajor sources of air pollutants (NOX) that lead to the production of hazardous haze and acid rain. To prevent air pollution by NOX and their consequent harmful result, it is necessary to remove the nitrogen compounds from the fuel before consumption. 3-(tributylphosphonio) propane-1-sulfonate as phosphonium-based zwitterionic liquid (PZiL) is used as a new extractant agent to eliminate nitrogen compounds from model fuel by liquid/liquid extraction. Unlike most of the reported ionic liquids (ILs)which have been used with the extractant/fuel ratio of 1/1 to 1/10, the utilized PZiL can be usedwith a much lower ratio of 1/100with the same removal efficiency of other ILs. Alsowith PZiL/fuel ratio of 1/1000 the extractant shows good removal efficiency. The introduced PZiL can be used several times for extraction without any treatment. Operating at room temperature and within several minutes can be considered as other advantages. Just by two cycles, deep denitrogenation of 500 ppm indole solution can be achieved with PZiL/fuel ratio of 1/ 100. Interestingly by increasing the concentration of N-compound up to 20,000 ppm, the amount of removed N-compound increases too. Because of the mentioned unique properties of PZiL for denitrogenation of liquid fuel, it can be introduced as a super-extractant for N-compounds from liquid fuel.
