Regeneration of process water containing surfactants by nanofiltration--investigation and modelling of mass transport.
The mechanisms in nanofiltration of aqueous solutions of different anionic surfactants and of mixture solutions of surfactants and NaCl are investigated. The surfactants used are sodium dodecylether sulfate, sodium dodecyl sulfate and sodium alkyl benzene sulfonate. High retentions in the range of 95% up to 99.9% referring to the feed concentration are found to depend on the solvent flux. If additional salt is present in the solution, the permeate quality is deteriorating because of lower solvent flux and of mass transfer due to the electrical potential. The experimental results show that convective mass transfer of surfactant through the nanofiltration membrane occurs. Consequently, an extended solution-diffusion model is used for modelling of the process. Depending on the feed composition, concentration polarisation has to be considered in the model. The calculated surfactant flux through the membrane is in good agreement with the experimental results.
D004058:Diffusion; D005374:Filtration; D008962:Models, Theoretical; D012965:Sodium Chloride / Q000737:chemistry; D013501:Surface-Active Agents / Q000032:analysis* / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*
D013501:Surface-Active Agents; D012965:Sodium Chloride