Layered titanate nanofibers can absorb bivalent ions from waste water via an ion exchange process. The sorption induces a considerable deformation of the layered structure, thus trapping the cations in the fibers permanently. Therefore, the fibers are desirable sorbents for the removal of toxic, radioactive Ra(2+) and Sr(2+) ions from water and subsequent safe disposal thereof.
CO 2 -resistant oxygen selective ceramic membranes show potential to be utilized in clean combustion and membrane-based reactions for greener chemical synthesis. In real applications, such membranes should have high mechanical strength as well as high oxygen flux and high stability in a CO 2 -containing atmosphere. In this work, a (La 0.8 Ca 0.2 ) 1.01 FeO 3−δ (LCF) perovskite hollow fiber membrane was developed. Its oxygen permeation behavior was tested in different gas atmospheres, i.e., helium and carbon dioxide. Compared to the typical perovskite hollow fibers such as La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) and Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF), the LCF hollow fiber displayed the highest mechanical strength as well as the largest oxygen fluxes and stability in a CO 2 -containing atmosphere, highlighting its attractiveness in oxyfuel combustion and syngas production from methane.
Oxygen selective membranes with enhanced oxygen permeability and CO2 resistance are highly required in sustainable clean energy generation technologies. Here, we present novel, cobalt-free, SrFe1-x Tax O3-δ (x=0, 0.025, 0.05, 0.1, 0.2) perovskite membranes. Ta-doping induced lattice structure progression from orthorhombic (x=0) to cubic (x=0.05). SrFe0.95 Ta0.05 O3-δ (SFT0.05) showed the highest oxygen flux rates reaching 0.85 mL min(-1) cm(-2) at 950 °C on a 1.0 mm-thick membrane. Surface decoration can increase the permeation rate further. Ta inclusion within the perovskite lattice of SrFeO3-δ (SF) enhanced the CO2 resistance of the membranes significantly as evidenced by the absence of the carbonate functional groups on the FTIR spectrum when exposed to CO2 atmosphere at 850 °C. The CO2 resistance of Ta-doped SF compounds correlates with the lower basicity and the higher binding energy for the lattice oxygen. SFT0.05 demonstrated high stability during long-term permeation tests under 10% CO2 atmosphere.
Ceramic membranes were fabricated by in situ synthesis of alumina nanofibres in the pores of an alumina support as a separation layer, and exhibited a high permeation selectivity for bovine serum albumin relative to bovine hemoglobin (over 60 times) and can effectively retain DNA molecules at high fluxes.
The development of the CO 2 -resistant mixed ionic-electronic conducting membranes can significantly expand their application into many CO 2 involved processes, such as the oxycombustion process and green chemical synthesis in membrane reactors. In this work, the SrCo 0.9 W 0.1 O 3-δ (SCW) hollow fiber membranes were fabricated via a combined phase inversion and sintering method. The oxygen permeation flux of 4.18 mL min À 1 cm À 2 was achieved at 950°C when pure He was used as sweep gas, while this flux can be further improved by 20.81% after Ag modification of outside membrane surface. Furthermore, the oxygen permeation behavior under CO 2 in the sweep gas and surface morphology has been investigated.The oxygen permeation flux experienced a slight decline, then reached a plateau at 2.44 mL min À 1 cm À 2 during permeation evaluation of 70-100 hours at 900°C when swept by 10% CO 2containing gas mixture of 100 mL min À 1 . More interestingly, the oxygen permeation flux only exhibited 9.44% decrease of the original flux value after switching the sweeping gas back to He, which can be attributed to the formation of the porous layer on the inside surface of membrane. The porous layer would reduce the membrane thickness, meanwhile supply more inside membrane surface area, facilitating the oxygen permeation.
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