João C. Diniz da Costa

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This work reports the remarkable effect of reversible gas molecular sieving for high temperature gas separation from cobalt doped ethoxy polysiloxane (CoES40) membranes. This effect stemmed from alternating the reducing and oxidising (redox) state of the cobalt particles embedded in the ES40 matrix. The reduced membranes gave the best H2 permeances of 1 ×(More)
Graphene oxide-iron oxide (GO-Fe3O4) nanocomposites were synthesised by co-precipitating iron salts onto GO sheets in basic solution. The results showed that formation of two distinct structures was dependent upon the GO loading. The first structure corresponds to a low GO loading up to 10 wt%, associated with the beneficial intercalation of GO within Fe3O4(More)
The functionality or oxidation state of cobalt within a silica matrix can be tailored through the use of cationic surfactants and their halide counter ions during the sol-gel synthesis. Simply by adding surfactant we could significantly increase the amount of cobalt existing as Co3O4 within the silica from 44% to 77%, without varying the cobalt precursor(More)
Finite control of pore size distributions is a highly desired attribute when producing porous materials. While many methodologies strive to produce such materials through one-pot strategies, oftentimes the pore structure requires post-treatment modification. In this study, modulation of pore size in cobalt-silica systems was investigated by a novel,(More)
This work shows the preparation of silica membranes by a two-step sol-gel method using tetraethyl orthosilicate in ethanolic solution by employing nitric acid and ammonia as co-catalysts. The sols prepared in pH 6 resulted in the lowest concentration of silanol (Si-OH) species to improve hydrostability and the optimized conditions for film coating. The(More)
This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation(More)
This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a(More)
A ternary phase-separation investigation of the ethyl silicate 40 (ES40) sol-gel process was conducted using ethanol and water as the solvent and hydrolysing agent, respectively. This oligomeric silica precursor underwent various degrees of phase separation behaviour in solution during the sol-gel reactions as a function of temperature and H2O/Si ratios.(More)
An innovative concept is proposed to recover ammonia from industrial wastewater using a molecular sieve silica membrane in pervaporation (PV), benchmarked against vacuum membrane distillation (VMD). Cobalt and iron doped molecular sieve silica-based ceramic membranes were evaluated based on the ammonia concentration factor downstream and long-term(More)
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