Application of nanofiltration membranes for removal of surfactants from water solutions

Wroclaw University of Science and Technology, Faculty of Environmental Engineering, Wybrzeże S. Wyspiańskiego 27, 50-370 Wrocław

^* Corresponding author: aleksandra.klimonda@pwr.edu.pl

Abstract

The objective of the study was to compare effectiveness of nanofiltration (NF) process for treatment aqueous solutions containing various types of surfactants (anionic, cationic and non-ionic). The experiments were conducted with the use of Microdyn-Nadir® nanofiltration membranes (NP010 and NP030). The effect of surfactant type, its concentration and membrane cut-off on the process parameters (retention coefficient and permeate flux) was assessed. The experiments showed that separation of anionic and cationic surfactants depended on their concentration in the feed solutions. The retention coefficient of anionic surfactant ranged from 54 to 81% (NP010) and from 64 to 80% (NP030), while rejection of cationic surfactant varied from 48 to 85% (NP010) and from 51 to 88% (NP030). The values of retention coefficient of non-ionic surfactant were in the range of 69-77% and 79-88% for NP010 and NP030, respectively; and to a much lesser extent were depended on its concentration in the feed solutions in comparison with anionic and cationic compounds. Membrane characterized by smaller value of cut-off (NP030) allowed to obtain higher retention coefficients of surfactants. The membrane permeability deterioration was observed with the increase of surfactants concentration in the treated solutions. In all experiments, a sharp decline of the permeate flux was noticed for concentration below the CMC values.