Abstract
This paper discusses the role played by the mechanical stiffness of porous nanocomposite supports on thin-film composite (TFC) membrane water permeance. Helically coiled and multiwall carbon nanotubes (CNTs) were studied as additives in the nanocomposite supports. Mechanical stiffness was evaluated using tensile tests and penetration tests. While a low loading of CNTs caused macrovoids that decreased the structural integrity, adding higher loads of CNTs compensated for this effect, and this resulted in a net increase in structural stiffness. It was found that the Young’s modulus of the nanocomposite supports increased by 30% upon addition of CNTs at 2 wt %. Results were similar for both types of CNTs. An empirical model for porous composite materials described the Young’s modulus results. The nanocomposite supports were subsequently used to create TFC membranes. TFC membranes with stiffer supports were more effective at preventing declines in water permeance during compression. These findings support the idea that increasing the mechanical stiffness of TFC membrane nanocomposite supports is an effective strategy for enhancing water production in desalination operations.
Highlights
Seawater desalination and water reclamation via reverse osmosis (RO) are processes with high specific energy consumption [1,2]
An annealing process described by Lind et al [32] was used in which the membrane taped to the glass slide was submerged in water at 90 ◦ C for 2 min
Nanocomposite supports for thin-film composite (TFC) membranes made from Matrimid and helically coiled or straight multiwall carbon nanotubes were fabricated via wet phase inversion
Summary
Seawater desalination and water reclamation via reverse osmosis (RO) are processes with high specific energy consumption [1,2]. Showed that increased loading of MWCNTs in the active layer of a TFC RO membrane modified its chemically functionalized carbon nanotubes and incorporated them into the support layer of a TFC structure and led to higher water flux with minimal decreases in the rejection of sodium chloride. This approach led nanotubes to increased hydrophilicity improved organic functionalized carbon and incorporatedand them into the support fouling of the TFC for membrane, due toThis the positive charge of the composite structure. The effect of the mechanical stiffness of the nanocomposite support on TFC membrane water permeance under compression was studied
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