Related Experiment Video
Updated: Aug 29, 2026

Three-Dimensionally Printed Microfluidic Cross-flow System for Ultrafiltration/Nanofiltration Membrane Performance Testing
Published on: February 13, 2016
Factors influencing flux decline during nanofiltration of solutions containing dyes and salts
Ismail Koyuncu1, Dincer Topacik, Mark R Wiesner
1Faculty of Civil Engineering, Department of Environmental Engineering, Istanbul Technical University, 80626, Maslak, Istanbul, Turkey. koyuncu@rice.edu
Abstract:
In this paper, factors influencing the flux decline of nanofiltration membranes for the treatment of dye bath wastewaters were investigated. Experiments were performed with synthetic wastewaters. Synthetic solutions were prepared in different dye and salt concentrations at laboratory conditions. Operating conditions including cross-flow velocity and pH were changed to observe the effects of interactions between NaCl, dyes and the membrane. Cake formation rate of dye molecules on membrane surface with time was investigated by using linearized forms of cake filtration equations. The results suggest that cake layer formation of dye molecules on membrane surface, especially at low salt concentrations was the principal cause of flux decline. Operating conditions had a strong influence on permeate flux. Effects of cross-flow velocity on permeate flux were more pronounced at low NaCl concentrations. Furthermore, the lowest permeate flux values were obtained at the alkaline conditions due to increased dye hydrophobicity at high pH values.
Related Concept Videos
Factors Affecting Solubility
Osmosis and Osmotic Pressure of Solutions
Dialysis
Factors Affecting Dissolution: Particle Size and Effective Surface Area
Colloidal precipitates
Factors Affecting Renal Clearance: Drug's Physicochemical Properties and Plasma Levels
One important factor is the drug's molecular size. The kidneys readily excrete smaller molecules below 300 Daltons (Da). On the other hand, molecules weighing between 300 and 500 Da are excreted through both urine and bile. Larger molecules above 500 Da tend to be excreted less...

