(378w) Design and Fabrication of High-Performance Hollow Fiber Membrane Devices for Direct Contact Membrane Distillation

Membrane Distillate (MD) is an emerging water desalination technology that can allow for desalination of saline water using low-grade thermal energy. However, currently, there are no commercial membrane devices that are designed for water desalination through the membrane distillation process. This is mostly due to the lack of high-performance membranes and modules. Hollow fiber membrane modules are the most attractive candidates from the design perspective. In our recent modeling studies¹, we showed that the packing configuration of hollow fibers in a module plays an important role performance of modules. To validate our modeling studies, we fabricated Polyvinylidene Fluoride (PVDF) hollow fiber membranes using Nonsolvent Induced Phase Inversion (NIPS) process and packaged them into a module using custom-made spacers. We made spacers using additive manufacturing approach. Similar to the result of our modeling work, the experimental results showed that the close-packed configuration of membranes in the module provides about 13% more water flux compared to that of a randomly packed module. The average values for the permeate flux obtained from the experimental studies were 25±5 kg m^-2 h^-1 when the feed and distillate temperatures were set to 70 and 20 °C, respectively. Furthermore, we modified the outer surface of the hollow fiber membranes and deposited a thin coat of polytetrafluoroethylene (PTFE) through initiated chemical vapor deposition (iCVD) process. This coating imparted super-hydrophobicity to the surface of the membrane, rendering them self-cleaning. The result of our accelerated scaling experiment showed a significant reduction of salt scaling on the surface of the modified hollow fiber membranes.

References

(1) Mohammadi Ghaleni, M.; Bavarian, M.; Nejati, S. Model-Guided Design of High-Performance Membrane Distillation Modules for Water Desalination. J. Memb. Sci. 2018, 563, 794–803.