Abstract:
Interest in, and the use of, membrane distillation for desalination applications is growing in areas like Wyoming that are grappling with dwindling freshwater supplies and the large volumes of saline water that are generated from the development of our energy resources. Realizing the full potential of membrane distillation hinges on the development of new membrane materials that are tailored for the unique requirements of this process. The overarching goal of our proposed research is the synthesis, characterization, and testing of a new membrane surface coating whose properties can be changed in response to environmental stimuli. The objective is to create a micro-structured surface capable of switchable hydrophobicity for improving the performance of membrane distillation processes in order to make it viable for desalination applications. It is our central premise that a biologically inspired micro-patterned surface manufactured through conventional photolithography techniques using shape-memory polymers, can create a highly hydrophobic surface when erect, while demonstrating dramatically less hydrophobicity when in a relaxed state, as a result of the relationship between surface roughness and hydrophobicity. Such a surface would facilitate easier cleaning of the membrane by backwashing, while maximizing the separation efficiency and permeate flux rate through the membrane. Our rationale for undertaking this research is that new treatment strategies, like membrane distillation, are needed to effectively manage highly saline waters. We will accomplish the overall objective of this proposal by pursuing the following specific aims:
Specific Aim #1 – Synthesize membrane surface treatments from shape-memory polymers having tunable surface structure controlled hydrophobicity. Standard photopolymerization techniques will be used to fabricate micro-patterns, consisting of arrays of vertical micro-pillars, onto micro-porous substrates to form a membrane.
Specific Aim #2 – Assess and evaluate the efficacy of membrane surfaces with tunable surface structure and hydrophobicity. We will characterize the structure and hydrophobicity of the shape-memory polymer structures as a function of environmental parameters relevant to membrane distillation applications and evaluate any changes in polymer structure in terms of their impact on membrane performance.