Removal of Ni(II) ions from wastewater by micellar-enhanced ultrafiltration

The feasibility in the use of a sodium dodecyl sulfate anionic surfactant and nonionic monoalkylphenol polyetoxilate to purify contaminated waters of Ni(II) ions has been studied. Both the retention coefficients and the transmembrane fluxes have been determined at purification of the different systems containing Ni(II) ions, anionic, and nonionic surfactants. A choice has been made of the most effective ultrafiltration membrane for its following use in the micellar-enhanced ultrafiltration process. An optimum value of the operating pressure has been determined. As has been shown on an example of the Ni(II) ions, micellar-enhanced ultrafiltration may make use of purified wastewaters from heavy metal ions. The most effective application of this process to remove the heavy metal ions from wastewaters takes place when concentration of the surfactants (both ionic and nonionic ones) is equal to the critical concentration of micelle formation and/or it is lower than that.

Fig. 3. Dependence of the retention coefficient of Ni(II) ions by the UPM-20 membrane (a) and the volume flux across it (b) vs. the OP-10 concentration at an operating pressure of 400 kPa and the different concentration of SDS, g/l: 1.0 (1), 2.34 (2), and 5.0 (3). in the OP-10 concentration does not actually influence the volume flux. This fact might be explained as follows. An addition of OP-10 at its concentration lower than 0.1 g/l increases to great extent the viscosity of a system, and thus the volume flux declines. When that concentration surpasses 0.1 g/l, the viscosity of a system varies a little only and, as a result, there occurs a minor variation in the volume flux. 3.4. Features in the retentivity of Ni(II) ions in the Ni(II)/SDS/OP-10 system Addition of the OP-10 nonionic surfactant into the SDS/Ni(II) system gave results shown in Fig.