Cation exchange hybrid membranes based on PVA for alkali recovery through diffusion dialysis

• Published in: Journal of membrane science Vol. 376; no. 1; pp. 233 - 240
• Main Authors: Wang, Hui, Wu, Cuiming, Wu, Yonghui, Luo, Jingyi, Xu, Tongwen
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2011; Elsevier
• Subjects: acids; alcohols; Alkali recovery; artificial membranes; cation exchange; Cation exchange membrane; Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; dialysis; Diffusion dialysis; diffusivity; Exact sciences and technology; Fourier transform infrared spectroscopy; General and physical chemistry; Hybrid membrane; ions; Membranes; permeability; polyvinyl alcohol; PVA; scanning electron microscopy; sodium hydroxide; temperature; thermal stability; Diffusion dialysis; PVA; Alkali recovery; Hybrid membrane; Cation exchange membrane; Water; Organic cation; Separation; Acrylic acid; Alcohol; Selectivity; Tungstates; Recovery; Thermal stability; Sodium hydroxide; Diffusion; Polymeric membrane; Scanning electron microscopy; Swelling; Chemical structure; Ions; Permeability; Diffusivity; Infrared spectrometry; Inorganic cation; Sodium; Sol gel process; Dialysis; Silane
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2011.04.025

► Cation exchange hybrid membranes are prepared from multi-alkoxy silicon copolymer and PVA. ► The swelling degree can be better suppressed as IEC values increase. ► Despite the low IEC (0.76–0.90 mmol/g), the separation factor ( S) and OH − dialysis coefficients ( U OH) are both high. ► Performances for diffusion dialysis of NaOH + Na 2WO 4 system are excellent. Organic–inorganic cation exchange hybrid membranes have been prepared through sol–gel reaction of poly(acrylic acid-co-methacryloxypropyl trimethoxy silane (poly(AA-co-γ-MPS)) in presence of poly(vinyl alcohol) (PVA). The membranes are characterized by FTIR, SEM, thermal stability and mechanical strength. T d values are in the range of 264–270 °C. TS ranges from 8.4 MPa to 32.2 MPa and E b in the range of 72.1–103.5%. The membranes can remain integrity in 65 °C hot water for more than 12 days and the swelling behavior is better suppressed as poly(AA-co-γ-MPS) content increases. The membranes are tested for recovering sodium hydroxide from the mixture of sodium hydroxide (NaOH) and sodium tungstate (Na 2WO 4) at different temperatures (35–55 °C) through diffusion dialysis (DD). Both permeability and selectivity are excellent despite the low IEC of the membranes and the low diffusivity of OH − ions. The dialysis coefficients of OH − ( U OH) are in the range of 0.010–0.042 m/h, similar to previously reported values for acids ( U H: 0.005–0.055 m/h). The hybrid membrane containing 50 wt% poly(AA-co-γ-MPS) has the highest separation factor of 95.7 at 35 °C. The DD performances have been correlated with the membrane physico-chemical structure, especially the presence of large amount of –OH groups.