Maicun Deng

Poly(amide-6-b-ethylene oxide)/SAPO-34 mixed matrix membrane for CO2 separation

Abstract In this paper, poly(amide-6-b-ethylene oxide) (Pebax1657)/SAPO-34 mixed matrix membranes (MMMs) were prepared by solvent-evaporation method with acetic acid as a novel solvent. CO2, N2, CH4 and H2 permeation properties were investigated, and the physical properties of Pebax/SAPO-34 MMMs were characterized by XRD and SEM. At low SAPO-34 content, it was homogeneously distributed in the Pebax matrix, and then precipitated and agglomerated at high SAPO-34 content. The crystallinity of Pebax phase in Pebax/SAPO-34 MMMs decreased initially and then rebounded as a result of phase separation. With the increase of transmembrane pressure difference, CO2 permeability was enhanced due to the effect of pressure-induced plasticization. Owing to the happening of stratification, the CO2 permeability of Pebax/SAPO-34 MMMs (50 wt% SAPO-34) increased to 338 Barrer from 111 Barrer of pristine Pebax, while the selectivities of CO2/CH4 and CO2/N2 were almost unchanged. Compared with the pristine Pebax, the gas separation performances of Pebax/SAPO-34 MMMs were remarkably enhanced.

Polyvinyl acetate/poly(amide-12-b-ethylene oxide) blend membranes for carbon dioxide separation

Abstract In this paper, blend membranes from polyvinyl acetate (PVAc) and block copolymer poly(amide-12-b-ethylene oxide) (Pebax1074) are prepared by solution casting and solvent evaporation method. Although they are homogeneous on a macro-scale, the observations from DSC and SEM indicate micro-phase separation for PVAc/Pebax1074 blend membranes. With the increase of Pebax1074 content, gas permeabilities of CO 2 , H 2 , N 2 and CH 4 all increase greatly. PVAc/Pebax1074 blend membranes with high PVAc content are appropriate for CO 2 /CH 4 separation. The temperature dependence of gas permeability is divided into rubbery region and glassy region. The activation energies of permeation in rubbery region are smaller than those in glassy region, and they all decrease with increasing Pebax1074 content. For N 2 , H 2 and CH 4 , their gas permeation properties are mainly influenced by the dual-mode sorption and hydrostatic pressure effect. But for CO 2 , its permeability increases with the increase of pressure due to CO 2 -induced plasticization effect, which is more obvious for PVAc/Pebax1074 blend membranes with high PVAc content.

Permeation Characteristics of Light Hydrocarbons Through Poly(amide-6-β-ethylene oxide) Multilayer Composite Membranes

Abstract In this paper, poly(amide-6-β-ethylene oxide) (PEBA1657) copolymer was used to prepare multilayer polyetherimide (PEI)/polydimethylsiloxane (PDMS)/PEBA1657/PDMS composite membranes by dip-coating method. Permeation behaviors of ethylene, ethane, propylene, propane, n -butane, methane and nitrogen through the multilayer composite membranes were investigated over a range of operating temperature and pressure. The permeances of light hydrocarbons through PEI/PDMS/PEBA1657/PDMS composite membranes increase with their increasing condensability, and the olefins are more permeable than their corresponding paraffins. For light hydrocarbons, the gas permeances increase significantly as temperature increasing. When the transmembrane pressure difference increases, the gas permeance increases moderately due to plasticization effect, while their apparent activation energies for permeation decrease.

Investigation of photoinduced electron transfer based on immobilized Green microalga Tetraselmis subcordiformis photoanode

A microalga Tetraselmis subcordiformis (synonym: Platymonas subcordiformis) based photoanode was prepared by a novel method developed in our lab. In a three-electrode configuration, photocurrent and photosynthetic oxygen evolution were measured synchronously. The effects of three site-specific inhibitors (CCCP, DCMU and DBMIB) on photocurrent response of microalgal photoanode were investigated and discussed. The results indicated that the electrons of photocurrent originated from the photosynthetic electron transfer chain of microalga. In further discussion on specific roles of CCCP during biohydrogen photoproduction from Tetraselmis subcordiformis, it was estimated that CCCP at 15 uM inhibited about 34% of PS II activity as ADRY agent and about 51% of PS II activity as uncoupler.

Effect of Hydrogen Reduction of Silver Ions on the Performance and Structure of New Solid Polymer Electrolyte PEI/Pebax2533/AgBF4 Composite Membranes

Abstract In this paper, the effect of hydrogen reduction of silver ions on the performance and structure of new solid polymer electrolyte polyetherimide (PEI)/Pebax2533 (Polynylon12/tetramethylene oxide block copolymer, PA12-PTMO)/AgBF 4 composite membranes is investigated. For PEI/Pebax2533/AgBF 4 composite membranes prepared with different AgBF 4 concentration, the permeances of propylene and ethylene increase with the increase of AgBF 4 concentration due to the carrier-facilitated transport, resulting in a high selectivity. But for propylene/propane mixture, the mixed-gas selectivity is lower than its ideal selectivity. The hydrogen reduction strongly influences the membrane performance, which causes the decrease of propylene permeance and the increase of propane permeance. With the increase of hydrogen reduction time, the membranes show a clearly color change from white to brown, yielding a great selectivity loss. The data of X-ray diffraction and FT-IR prove that silver ions are reduced to Ag 0 after hydrogen reduction, and aggregated on the surface of PEI/Pebax2533/AgBF 4 composite membranes.