Removal of nitrate from water by bulk liquid membrane

A bulk liquid membrane (BLM) containing dimethyldioctadecylammonium chloride (DODMAC) as the carrier reagent was developed for the removal of nitrate from water. DODMAC was found to be an efficient carrier for the nitrate transport through a solvent membrane containing 10 vol% chloroform and 90 vol% n-hexane. The optimum conditions of operation were found as: concentrations of feed, carrier and strip reagents of 0.00145, 0.012 and 0.8 M, respectively, and stirring speed of agitation of 250 rpm. At optimum conditions the extraction reached 99% after 7 h of operation while the stripping was also 97%. The latter reveals the high efficiency of the stripping phase in releasing the carrier. The long-term performance of the developed system was also appropriate where after 60 h of operation the extraction of nitrate was more than 92%. Effects of other parameters including the feed/ membrane and membrane/strip phase ratios (v/v), nitrate salt, and type of strip reagent on the mass transfer of membrane system were also studied. The small amounts of remained chloroform in water were removed using air stripping method. Comparison between this work and other BLM works confirms the priority of developed system in removing nitrate from contaminated water.