Abstract
Membrane desalination is a leading technology for treating saline waters to augment fresh water supply. The need for high-performance desalination membranes, particularly with high water/salt selectivity, has stimulated research into the fundamental structure-property-performance relationship of state-of-the-art membranes. In this study, we utilize a facile method for tuning properties of a polymeric desalination membrane to shed light on water and salt transport mechanisms of such membranes. A desalination membrane made of cellulose triacetate is treated in a plasticizer solution, followed by water rinsing. The modified membranes exhibit reduced salt flux without compromising water flux, indicating enhanced water/salt selectivity. An inspection of material characteristics using a model film system reveals a plasticizing-extracting process in changing the polymeric structure, which leads to the reduction of crystallite size in the polymer matrix, consequently affecting the transport properties of the membranes. Our findings highlight the potential of the plasticizing-extracting process in fabricating membranes with desired desalination performance.
Highlights
Membrane desalination is a leading technology for treating saline waters to augment fresh water supply
We propose that the reduced crystallite size results in an enlargement of the interfacial area between the crystalline and amorphous regions, which is responsible for the observed enhanced water/salt selectivity
Pristine cellulose triacetate (CTA) membranes were soaked in a p-nitrophenol (PNP) solution, followed by water rinsing to obtain modified membranes
Summary
Membrane desalination is a leading technology for treating saline waters to augment fresh water supply. We demonstrate a facile method to tune the transport properties of a polymeric desalination membrane via a plasticizerinduced swelling and subsequent deswelling process, which results in modification of the internal structure of the polymer material. Compared with the pristine membrane, the modified membrane displays significantly enhanced water/salt selectivity and desalination performance.
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