Applying Line-and-Groove Patterns to Nanofiltration Membranes

Nanofiltration (NF) membranes are a method of water/wastewater treatment that rejects divalent ions, suspended particles, viruses, and bacteria. NF membranes require a lower operating pressure than reverse osmosis, 3.5-16 bar, making them a less expensive option for the partial desalination of water and water softening. One issue with NF membranes is fouling, which is a solute build up that blocks the pores of the membrane. Membrane fouling decreases the permeance and rejection of the membrane over time. Membrane surface patterning is a method used to reduce membrane fouling. Our project goal was to understand the relationship between foulant size and pattern size and its influence on membrane fouling. This was accomplished by analyzing patterns that are smaller than (300-nm), equal to (10-µm), and larger than (50-µm) the foulant size (10-µm). The membranes were tested in a dead-end cell, and the feed solutions used to test the membranes were: deionized water, 2,000 ppm sodium sulfate, and a n-dodecane brine solution with 2,000 ppm n-dodecane and 35,000 ppm sodium chloride. The results from these experiments demonstrated that the flux recovery ratio was not significantly impacted by patterning, however the smaller than and larger than patterns decreased the rate of fouling by a small margin.