The reverse osmosis membrane technology plays an important role in the supply of pure water. The high water production is always desirable. In this study, a new acid acceptor consisting of the crown ether (18-crown-6)/KOH is used to catalyze the interfacial polymerization reaction for the polyamide reverse osmosis membrane fabrication to increase the membrane flux. The 18- crown-6 and the KOH will form a complex compound, to help the diffusion of the KOH from the aqueous phase to the organic phase, so that the KOH can work more efficiently to catalyze the polymerization. Meanwhile, the 18-crown-6 can effectively inhibit the excess hydrolysis of the TMC from the KOH, preventing a significant deterioration in the ion rejection of the membrane. To verify the above reasoning, the SEM and XPS characterizations are used to show that the membrane has a thin and properly hydrolyzed surface morphology. The membrane performance test shows that the application of the (18-crown-6)/KOH as the acid acceptor can promote the membrane flux better (up to 72% increase) as compared with using only the KOH (38% increase). Moreover, the use of the (18- crown-6)/KOH can help the membrane to maintain a reasonable NaCl rejection of above 90%. That solves the problem of rejection deterioration when only the KOH is used as the acid acceptor with a rejection of below 60%. Although Cs+ has a smaller hydraulic radius than that of Na+, this kind of membrane also enjoys a similarly excellent separation behavior with respect to CsNO3. That means that the (18-crown-6)/KOH catalyst composition is effective and applicable in future.
HUANG Hai
,
LI Ming
,
ZHANG Lin
,
HOU Li'an
. Preparation of polyamide reverse osmosis membrane by using 18-crown-6/KOH complex catalyst[J]. Science & Technology Review, 2015
, 33(14)
: 36
-40
.
DOI: 10.3981/j.issn.1000-7857.2015.14.006
[1] Shannon M A, Bohn P W, Elimelech M, et al. Science and technology for water purification in the coming decades[J]. Nature, 2008, 452 (7185): 301-310.
[2] Kuehne M A, Song R Q, Li N N, et al. Flux enhancement in TFC RO membranes[J]. Environmental Progress, 2001, 20(1): 23-26.
[3] Navarro R, Gonzaleza M P, Saucedo I, et al. Effect of an acidic treatment on the chemical and charge properties of a nanofiltration membrane[J]. Journal of Membrane Science, 2008, 307(1): 136-148.
[4] Raval H D, Trivedi J J, Joshi S V, et al. Flux enhancement of thin film composite RO membrane by controlled chlorine treatment[J]. Desalination, 2010, 250(3): 945-949.
[5] Gorgojo P, Jimenez-Solomon M F, Livingston A G. Polyamide thin film composite membranes on cross-linked polyimide supports: Improvement of RO performance via activating solvent[J]. Desalination, 2014, 344: 181-188.
[6] Xiang J, Xie Z, Hoang M, et al. Effect of ammonium salts on the properties of poly(piperazineamide) thin film composite nanofiltration membrane[J]. Journal of Membrane Science, 2014, 465: 34-40.
[7] Karmakar R, Samanta A. Phase-transfer catalyst-induced changes in the absorption and fluorescence behavior of some electron donoracceptor molecules[J]. Journal of the American Chemical Society, 2001, 123(16): 3809-3817.
[8] 张林, 林赛赛, 魏平, 等. 4-二甲氨基吡啶催化的界面聚合法制备超 支化聚乙烯亚胺复合膜[J]. 催化学报, 2012, 33(10): 1730-1735. Zhang Lin, Lin Saisai, Wei Ping, et al. Preparation of hyperbranched polyethyleneimine composite membrane using interfacial polymerization catalyzed by 4- dimethylamiopryidine[J]. Chinese Journal of Catalysis, 2012, 33(10): 1730-1735.
[9] Kong C, Kanezashi M, Yamomoto T, et al. Controlled synthesis of high performance polyamide membrane with thin dense layer for water desalination[J]. Journal of Membrane Science, 2010, 362(1/2): 76-80.
[10] Duan M, Wang Z, Xu J, et al. Influence of hexamethyl phosphoramide on polyamide composite reverse osmosis membrane performance[J]. Separation and Purification Technology, 2010, 75(2): 145-155.
[11] Kim S H, Kwak S Y, Suzuki T. Positron annihilation spectroscopic evidence to demonstrate the flux-enhancement mechanism in morphology-controlled thin-film-composite (TFC) membrane[J]. Environmental Science &Technology, 2005, 39(6): 1764-1770.
[12] Ghosh A K, Jeong B H, Huang X, et al. Impacts of reaction and curing conditions on polyamide composite reverse osmosis membrane properties[J]. Journal of Membrane Science, 2008, 311(1/2): 34-45.
[13] Cadotte J E. Reverse osmosis membrane: US Patent 4039440[P]. 1977-08-02.
[14] Petersen R J. Composite reverse-osmosis and nanofiltration membranes[J]. Journal of Membrane Science, 1993, 83(1): 81-150.
[15] Grinfeld A A, Artamkina G A, Beletskaya I P. Oxidation of nitrobenzenes by oxygen in a KOH-organic solvent-18-crown-6 ether system[J]. Bulletin of the Academy of Sciences of the Ussr Division of Chemical Science, 1982, 31(11): 2332-2332.
[16] Freger V. Nanoscale heterogeneity of polyamide membranes formed by interfacial polymerization[J]. Langmuir, 2003, 19(11): 4791-4797.
[17] Gurzhiy V V, Tyumentseva O S, Krivovichev S V, et al. Novel type of molecular connectivity in one-dimensional uranyl compounds: K@(18- crown-6)(H2O) (UO2)(SeO4)(NO3), a new potassium uranyl selenate with 18-crown-6 ether[J]. Inorganic Chemistry Communications, 2014, 45: 93-96.
[18] Guida W C, Mathre D J. Phase-transfer alkylation of heterocycles in the presence of 18-crown-6 and potassium tert-butoxide[J]. Journal of Organic Chemistry, 1980, 45(16): 3172-3176.
[19] Zhu L, Zhu L, Jiang J, et al. Hydrophilic and anti- fouling polyethersulfone ultrafiltration membranes with poly(2- hydroxyethyl methacrylate) grafted silica nanoparticles as additive[J]. Journal of Membrane Science, 2014, 451: 157-168.
[20] Tansel B, Sager J, Rector T, et al. Significance of hydrated radius and hydration shells on ionic permeability during nanofiltration in dead end and cross flow modes[J]. Separation and Purification Technology, 2006, 51(1): 40-47.
