Decontamination of Nitrate Polluted Water

Nitrate can be extracted from water at any pH below 10 by a water-insoluble quaternary ammonium 2, 4, 6-tri-methylphenate or N-benzyl-H-methylbenzenesulfonamidate dissolved in trioctylphosphate (TOP). Membranes were prepared by taking up TOP solutions of the quaternary ammonium bases in porous polypropylene (Celgard R -2400). These membranes were used in a modified dialysis cell to transfer N0 3 − from near-neutral water to stripping solutions of pH, 12-14. Specific rate constants, k, in excess of 10 −4 cm s −1 were observed for nitrate removal under a wide variety of loading and stripping conditions. This is sufficient to project a practical device for the decontamination of nitrate-polluted water. When the hydrodynamic resistances in both the feed and the strip are removed by pumping these solutions through static mixers adjacent to the membrane, K is reduced by making the stripping solution less basic or by increasing its nitrate concentration. These observations suggest that the disassembly of the carrier of the N0 3 − and H + at the stripping interface is a step-wise process, involving energetically unfavorable, charge-separated species.