ABSTRACT
Spherical particles with tunable anisotropic structures enabled by multiple surface functionalities have garnered interest for their potential applications in adsorption technologies. The presence of diverse functional groups in the surface layer, exhibiting varying acidity and hydrophilicity, can lead to unique characteristics in terms of surface structure and behaviour. In this study, the particles were synthesised using a two-step approach involving surface functionalisation of previously synthesised SiO2 Stöber particles. This was achieved by employing 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS) in a toluene-in-water emulsion. The resulting particles were found to be nonporous, with a specific surface area of 8 m2 g-1. Their sizes were determined to be up to 350 nm through photon cross-correlation spectroscopy. Moreover, the particles exhibited a high net content of functional groups (both amino and mercapto) of 2 mmol g-1. The organisation of the particles during synthesis was observed through SEM images, providing insights into their structural characteristics. Additionally, the study of Eu(iii), Au(iii), and Ag(i) ions and fluorescein adsorption demonstrated varying interactions on the surface, highlighting the potential applications and versatility of these functionalised particles.
ABSTRACT
The demand for new renewable energy sources, improved energy storage and exhaust-free transportation requires the use of large quantities of rare earth (REE) and late transition (LTM, group 8-12) elements. In order to achieve sustainability in their use, an efficient green recycling technology is required. Here, an approach, a synthetic route and an evaluation of the designed bio-based material are reported. Cotton-derived nano cellulose particles were functionalized with a polyamino ligand, tris(2-aminoethyl) amine (TAEA), achieving ligand content of up to ca. 0.8 mmol g-1. The morphology and structure of the produced adsorbent were revealed by PXRD, SEM-EDS, AFM and FTIR techniques. The adsorption capacity and kinetics of REE and LTM were investigated by conductometric photometric titrations, revealing quick uptake, high adsorption capacity and pronounced selectivity for LTM compared to REE. Molecular insights into the mode of action of the adsorbent were obtained via the investigation of the molecular structure of the Ni(II)-TAEA complex by an X-ray single crystal study. The bio-based adsorbent nanomaterial demonstrated in this work opens up a perspective for tailoring specific adsorbents in the sequestration of REE and LTM for their sustainable recycling.
Subject(s)
Metals, Rare Earth , Renewable EnergyABSTRACT
In recent years, Zr-based metal-organic frameworks (MOFs) have been developed that facilitate catalytic degradation of toxic organophosphate agents, such as chemical warfare agents (CWAs). Because of strict regulations, experiments using live agents are not possible for most laboratories and, as a result, simulants are used in the majority of cases. Reports that employ real CWAs are scarce and do not cover the whole spectrum of agents. We here present a comparative study in which UiO-66-NH2, NU-1000, MOF-808, and PCN-777 are evaluated for their effectiveness in the degradation of paraoxon and the chemical warfare agents tabun, VX, and soman, in N-ethylmorpholine buffer (pH 10) as well as in pure water. All MOFs showed excellent ability to degrade the agents under basic conditions. It was further disclosed that tabun is degraded by different mechanisms depending on the conditions. The presence of an amine, either as part of the MOF structure (UiO-66-NH2) or in the agent itself (VX, tabun), is the most important factor governing degradation rates in water. The results show that MOFs have great potential in future protective applications. Although the use of simulants provides valuable information for initial screening and selection of new MOFs, the use of live agents revealed additional mechanisms that should aid the future development of even better catalysts.