Desalination membranes by deposition of polyamide on polyvinylidene fluoride supports using the automated layer-by-layer technique

ABSTRACT

Thin-film composite (TFC) membranes with a polyamide (PA) active layer are the industry standard in desalination applications. The layer-by-layer (LbL) approach provides more precise control over the properties of this active PA layer. The automated spin-assisted LbL version of this approach then minimizes human error and improves repeatability. To improve durability of these membranes, more robust supports are desired, such as polyvinylidene fluoride (PVDF). The use of the LbL technique on this support requires an interlayer to enable the deposition onto the PVDF. In this case, levodopa was utilized to coat the PVDF prior to deposition of the PA layer. The membranes exhibited moderate permeability and higher selectivity for sodium chloride under typical brackish water conditions compared to commercially available NF membranes. This novel interlayer further expands on the automated spin assisted LbL approach, enabling deposition of PA onto a support.

KEYWORDS:

• Layer-by-Layer (LBL)
• Polyamide (PA)
• Polyvinylidene fluoride (PVDF)
• Levodopa
• Automated LBL
• Desalination

Acknowledgements

This work was supported by Dave C. Swalm School of Chemical Engineering at Mississippi State University. The authors acknowledge the assistance of Josh McCoy and Kyle Mistich in performing preliminary experiments. We would like to thank Dr. Edwin P. Chan of the National Institute of Science and Technology (NIST) for his helpful discussions. Thank you to Dr. Orion Rivers and Dr. Iwei Chu of Mississippi State’s I²AT (Institute for Imaging and Analytical Technologies) for their assistance with and access to the SEM. We also extend our immense gratitude to Dr. Devin Shaffer, Dr. Rahul Shevate, Parisa Taheri, and Pablo Bribiesca at the University of Houston for their support for this work and use of their equipment for characterization and testing.