Ultrathin, Multilayered Polyelectrolyte Films as Nanofiltration Membranes

详细信息    查看全文

• 作者：Brian W. Stanton ; Jeremy J. Harris ; Matthew D. Miller ; and Merlin L. Bruening
• 刊名：Langmuir
• 出版年：2003
• 出版时间：August 19, 2003
• 年：2003
• 卷：19
• 期：17
• 页码：7038 - 7042
• 全文大小：65K
• 年卷期：v.19,no.17(August 19, 2003)
• ISSN：1520-5827

文摘

This study shows that alternating polyelectrolyte deposition on porous supports can yield nanofiltrationmembranes that allow high water flux along with selective ion transport. Membranes composed of 4.5-5layer pairs of poly(styrene sulfonate)/poly(allylamine hydrochloride) (PSS/PAH) on porous alumina allowwater fluxes of 1-2 m³ m^-2 day^-1 at 4.8 bar while exhibiting MgSO₄ rejections of 96%. Rejections of CaCl₂and Na₂SO₄ depend on polyelectrolyte deposition conditions and the composition of the outer layer of themembrane. In general, divalent-ion rejection increases when the charge of the outer layer of the membranehas the same sign as the divalent ion being rejected. Increasing the concentration of the supporting electrolytepresent during deposition of the terminating PSS layer of PSS/PAH membranes results in a higher surfacecharge, and hence higher Na₂SO₄ rejections (up to 95%). Nanofiltration with mixed solutions of NaCl andNa₂SO₄ yields Cl^-/SO₄^2- selectivities of about 30 when the top layer of PSS/PAH membranes is depositedfrom a solution of high ionic strength. Capping PSS/PAH films with a layer of PAA increases Cl^-/SO₄^2-selectivities to values as high as 80. Interestingly, Cl^-/SO₄^2- selectivities in mixed solutions are higherthan those determined from single-salt measurements, presumably because diffusion potentials are differentin the two cases. The high selectivities, water fluxes, and ion rejections of PSS/PAH membranes make thempotentially attractive for applications in water and salt purification.