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Byline: J. Sunarso, C-Y. Chen, A.T.T. Tran, M.S. Wong, J.C. Diniz Da Costa In this work we investigated the synthesis of composite organic and inorganic membranes for proton conduction. Particles derived from metal alkoxides (M(OR)n) sol-gel processes (Ti, Zr, W with phosphoric acid) were embedded in polymeric matrices of poly-vinyl alcohol, (3-glycidoxypropyl)-trimethoxysilane and ethylene glycol. The structure of the composite membranes was complex as several IR peaks were convoluted, indicating the assignment of several functional groups. However, the peaks assigned to OH groups reduced in intensity in the composite membranes, indicating that cross-linking of hydroxyl groups in the organic and inorganic phases of the membrane may have occurred. The particles allowed for re-arrangement of the polymer matrix, as crystallinity was reduced compared to a polymer blank membrane. The composite membrane process resulted in homogeneous dispersion of nanoparticles into the polymer film. Proton conduction of the inorganic phase was mainly dominated by titania. Binary mixtures of titania phosphate (sample name TiP) resulted in proton conduction of 7.15 x 10−2 S.cm−1, one order of magnitude higher than zirconia phosphate (ZrP). The addition of Zr and W to TiP forming ternary or quaternary phases also led to lower proton conduction as compared to TiP. Similar trends were also observed for the composite membranes, though the TiP composite membrane proton conduction reduced after several hours of testing at 50[degrees]C, which was mainly attributed to acid leaching.

The surge of face mask waste in response to the global pandemic has proven to be a liability to the environment. Microfibers from plastic constituents of the face mask would cause microplastic pollution in the water bodies. Fortunately, these waste could be converted into renewable source of energy via thermochemical method, i.e. pyrolysis. However, the studies on the thermal decomposition of face masks and their kinetic mechanisms are not well-established. The aim of this paper focuses on the prospects of pyrolysis at low to high heating rates ranging from 10 °C min-1 to 100 °C min-1, to cater for the slow pyrolysis and fast pyrolysis modes. Following this, the thermal degradation behaviour of the face mask waste was studied via thermogravimetric analysis which determined the single peak temperature degradation range at 218 to 424 °C at 10 °C min-1, and maximum degradation rate was determined at 172.51 wt.% min-1 at 520 °C, with heating rate of 100 °C min-1. Flynn-Wall-Ozawa (FWO) and Starink method was employed to determine the average activation energy and average pre-exponential factor of the pyrolysis process of face mask waste. i.e., 41.31 kJ mol-1 and 0.9965, 10.43 kJ mol-1 and 0.9901 for FWO and Starink method, respectively.

This work addresses the impact of emulsifier on the physical properties, thermal behavior and microstructure of styrene-butadiene-styrene (SBS) polymer modified bitumen (PMB) using conventional tests, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The results show that emulsifier B demonstrates the best contribution during emulsification of SBS PMB whereas emulsifier C shows nondesirable impact. Emulsifier B improves the thermal stability of SBS PMB while emulsifiers A and C contribute negatively. FTIR results indicate no further chemical reaction on SBS PMB during emulsification with emulsifier A and B and slight physical and chemical change with emulsifier C. [ABSTRACT FROM AUTHOR]

In this work the oxygen reduction reaction on Bi0.5Sr0.5FeO3-8 (BSF) and La0.5Sr0.5FeO3-8 (LSF) as cathodes for intermediate temperature solid oxide fuel cells (600-750°C) is compared in detail. Partial substitution of Sr in SrFeO3-δ with 50 mole % of Bi or La results in the distinct structural features which strongly impact its electrochemical characteristics due to the presence of a lone electron pair in Bi3+, which is not available in La3+ Cubic Structure for BSF favours higher ionic conductivity and enhanced formation of oxygen vacancies relative to rhombohedral structure for LSF. Large oxygen nonstoichiometry for BSF, nevertheless, leads to the dominance of Fe3+ and subsequent low electronic conductivity relative to LSF. It was found that upon cathodic polarization, the oxygen vacancies are created on LSF which helps reducing its interfacial resistance afterward, which is not the case for BSF. Overall, BSF demonstrates good electrochemical performance which can be further optimized by enhancing its electronic conductivity. [ABSTRACT FROM AUTHOR]

Abstract: In this work, perovskite BaBiO3−δ disk membranes were synthesized with the molar ratio (z) of BiO1.5 to BaO between 0.5 and 3 at varying sintering temperatures. Disk membranes with z > 1.33, associated with a lower amount of Bi-rich perovskite phase, showed mechanically weak properties while membranes with z ≤1 showed superior stability at temperatures in excess of 800°C. The best performance was obtained for the z = 0.86 disk membrane, reaching oxygen fluxes of 1.2mlmin−1 cm−2 at 950°C. This was attributed to the higher sintering temperature and the formation of oxygen deficient phase of BaBiO3−δ perovskite. For gas testing temperatures above 800°C, it was found that the oxygen permeation was limited by both bulk diffusion and surface kinetics as oxygen flux did not increase proportionally to the inverse of membrane thickness reduction. Further analysis showed that the activation energy for oxygen ionic transport changed at 800°C, however the z = 1 sample displayed the opposite trend from other compositions, indicating the formation of more oxygen vacancies in the crystal lattice. Mechanically stable disk membranes exposed to thermal cycling tests resulted in crystal structure instability of the pure perovskite (z = 1) and loss of oxygen vacancies while the z < 1 sample was relatively stable. Conversely, z >1 sample showed superior thermal cycling and crystal structure stability. [Copyright &y& Elsevier]

Abstract: Although Nernst observed ionic conduction of zirconia–yttria solutions in 1899, the field of oxygen separation research remained dormant. In the last 30 years, research efforts by the scientific community intensified significantly, stemming from the pioneering work of Takahashi and co-workers, with the initial development of mixed ionic–electronic conducting (MIEC) oxides. A large number of MIEC compounds have been synthesized and characterized since then, mainly based on perovskites (ABO3−δ and A2BO4±δ ) and fluorites (A δ B1−δ O2−δ and A2δ B2−2δ O3), or dual-phases by the introduction of metal or ceramic elements. These compounds form dense ceramic membranes, which exhibit significant oxygen ionic and electronic conductivity at elevated temperatures. In turn, this process allows for the ionic transport of oxygen from air due to the differential partial pressure of oxygen across the membrane, providing the driving force for oxygen ion transport. As a result, defect-free synthesized membranes deliver 100% pure oxygen. Electrons involved in the electrochemical oxidation and reduction of oxygen ions and oxygen molecules respectively are transported in the opposite direction, thus ensuring overall electrical neutrality. Notably, the fundamental application of the defect theory was deduced to a plethora of MIEC materials over the last 30 years, providing the understanding of electronic and ionic transport, in particular when dopants are introduced to the compound of interest. As a consequence, there are many special cases of ionic oxygen transport limitation accompanied by phase changes, depending upon the temperature and oxygen partial pressure operating conditions. This paper aims at reviewing all the significant and relevant contribution of the research community in this area in the last three decades in conjunction with theoretical principles. [Copyright &y& Elsevier]