Rapid assembly of polyelectrolyte multilayer membranes using an automatic spray system

Abstract

in Wiley Online Library (wileyonlinelibrary.com).The layer-by-layer (LbL) assembly of polyelectrolyte multilayers on to a porous supporting membrane is able to create various new composite membranes. However, the low efficiency and long time required for such procedures limit practical applications. In this study, an automatic spray system has been constructed for the rapid assembly of polyelectrolyte multilayers on to nanoporous supporting membranes. The compounds polyacrylic acid and poly(ethyleneimine), used as a model polyelectrolyte pair, were alternately sprayed on to a polyacrylonitrile ultrafiltration membrane. Experiments proved that the composite membrane obtained in this way had a good pervaporation dehydration performance. In addition, the process times were dramatically decreased, by as much as 80 folds, when compared with classical dip-LbL methods. Such an automated system can easily be converted to the assembly of various organic species. Therefore, it is a versatile and highly efficient system for manufacturing composite multilayer membranes for many separation applications.(a) 0.25 wt % PEI aqueous solution (100Â). (b) 0.5 wt % PEI aqueous solution (100Â). (Preparative conditions for spray-LbL assembly: t 1 ¼ 3s, t 2 ¼ 3s, t 3 ¼ 3s, t 4 ¼ 27s, and t 5 ¼ 30 min; 0.025 wt % PAA aqueous solutions; 25 C).

Functionalized assembly of solid membranes for chiral separation using polyelectrolytes and chiral ionic liquid

“…As shown in Figure 6, the PAN membrane showed alkyl and ester groups at a wave number of 1736 cm 21 while the hydrolyzed PAN membrane exhibited the carboxy vibration at 1568 cm 21 . This is because, in certain concentrations of NaOH solution, the ACN group in the PAN molecular chain can react to form a COO -group, due to the hydrolysis.…”

“…Previously, it has been demonstrated that LbL assembled composite membranes can function for a wide range of uses, such as pervaporation, gas separation, nanofiltration, reverse osmosis and forward osmosis. [20][21][22][23][24][25][26] However, no previous work has dealt with the assembly of chiral selectors into PEMMs for chiral separation.…”

“…This is because, in certain concentrations of NaOH solution, the ACN group in the PAN molecular chain can react to form a COO -group, due to the hydrolysis. [20][21][22] The positively charged PEI was easily immobilized on to the negatively charged membrane. After applying the PEI coating, the 2244 cm 21 21 formamide peaks appeared.…”

“…[20][21][22] The positively charged PEI was easily immobilized on to the negatively charged membrane. After applying the PEI coating, the 2244 cm 21 21 formamide peaks appeared. These changes provide evidence that a large number of PEI were assembled on to the PAN substrate membrane.…”

“…The polyacrylonitrile (PAN) membranes were first immersed in 2M NaOH aqueous solution for 60 min at 65 C. 20,21 The membrane obtained a negatively charged surface through alkaline hydrolysis. The membrane was then washed repeatedly with deionized water until the flushing solution was neutral.…”