Modified Thin-Film Composite Membranes for Enhanced Reverse Osmosis
Opportunity
Reverse osmosis (RO) has received unprecedented attention owing to its simplicity and efficiency, while the thin-film composite (TFC) configuration is dominating in RO membrane and desalination market. TFC membranes can be fabricated by interfacial polymerization of amine monomers with acyl monomers to form a polyamide matrix on a porous substrate. Although TFC membranes are well featured at high water permeability and salt rejection, continuous efforts have been given to target better separation performance at a lower energy cost.
Thin-film nanocomposite (TFN) membranes have been intensively investigated because of their outperformance in desalination. The development of nanomaterial paves new ways to design novel thin-film nanocomposite (TFN) membranes by incorporating nanomaterial into the polyamide matrix. Not only can such nanomaterial regulate the physiochemical properties of the TFN membranes, they also endow the membranes with additional water paths through interior or exterior pore architecture. However, in most cases, nanomaterial has to be synthesized in advance before preparing TFN membranes, which is usually both material- and time-consuming.
According to the MarketsandMarkets report, the global membrane market was valued at USD 6.4 billion in 2022 and is projected to reach USD 10.1 billion by 2027, growing at a CAGR of 9.7% from 2022 to 2027.
Technology
This invention relates to a methodology to form TFN membranes directly on TFC membranes, resulting in membranes with enhanced water permeability with little compromise on salt rejection.
By optimizing the preparation process and adjusting the concentrations of nanomaterial precursors, an optimal TFN membrane was achieved with a water permeance of 3.36 liter.m-2.h-1.bar-1 (LMH bar-1) and a salt rejection of 98.22%. This represents an 84% improvement in water permeance compared to the pristine membrane, without sacrificing salt rejection performance. This new method simplifies the process of integrating nanomaterials into TFN membranes, removing the need for tedious and resource-intensive nanomaterial synthesis, and allowing for practical scaling-up and even modification of commercial membranes.
The post-treatment process has also been conducted on a small commercial seawater RO membrane module. After post-treatment, the water permeability increases by 40% while the salt rejection only decreases by 0.2%.
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