Metal-organic frameworks (MOFs) are versatile materials that incorporate metal centers along with organic linkers in highly ordered, intricate structures. MIL-53 is a MOF that exhibits a "breathing effect," where the pore size and MOF topology are profoundly influenced by the identity and binding mechanism of guest molecules. This phenomenon renders MIL-53 a promising candidate for sensing applications. In this report, the adsorption of various organic compounds within MIL-53 is investigated using a combination of complementary techniques. Thermal gravimetric analysis experiments confirm loading of the guest molecules and yield insight into adsorption interactions and strengths. Significant guest-induced changes in the crystal structure of MIL-53 are revealed by powder X-ray diffraction experiments; specific unique phases of MIL-53 are related to the identity of the guest molecule and its binding mechanism to the framework. 27 Al and 13 C solid-state NMR experiments probe the interaction between guest molecules and MIL-53. The relationship between the nature of the guest, the structure of MIL-53, and 27 Al NMR parameters is explored. 27 Al NMR parameters are sensitive to the host-guest binding mechanism (i.e., hydrogenbonding or -stacking interactions) and yield valuable information regarding the influence of the adsorbates on the local aluminum environment. This combination of physical characterization techniques is a useful probe of guest adsorption and the breathing effect within MIL-53 and should prove useful for investigation of related MOFs. Résumé: Les réseaux métallo-organiques (MOF, acronyme anglais pour Metal-Organic Frameworks) sont des matériaux polyvalents où des centres métalliques sont incorporés dans un réseau organique formant des structures complexes et hautement ordonnées. Le MIL-53 est un réseau métallo-organique présentant un « effet de respiration », dont la taille des pores et la topologie du réseau métallo-organique dépendent fortement de l'identité et du mécanisme de liaison des molécules invitées. Ce phénomène fait du MIL-53 un candidat prometteur pour des applications dans le domaine des capteurs. Dans les présents travaux, nous avons étudié l'adsorption de divers composés organiques au MIL-53 à l'aide d'un ensemble de techniques complémentaires. Des analyses thermogravimétriques confirment la charge de molécules invitées et fournissent un aperçu des interactions et des forces d'adsorption. Des expériences de diffraction des rayons X sur poudre ont permis de révéler des modifications importantes de la structure cristalline du MIL-53 induites par l'invité; des phases uniques propres au MIL-53 sont liées à l'identité de l'invité et à son mécanisme de liaison au réseau. Des expériences de RMN 27 Al et 13 C à l'état solide ont permis d'explorer les interactions entre les molécules invitées et le MIL-53. Nous avons étudié la relation entre la nature de l'invité, la structure du MIL-53 et les paramètres RMN 27 Al. Ces derniers sont sensibles au mécanisme de liaison hôte-invité (c.-à -d. les l...

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Waste of Electrical and Electronic Equipments (WEEE) is one of the fastest growing waste streams in the world. The treatment of WEEE with high content of precious metals (Au in particular) has received the most attention due to their high economic potential. The development of simple, environmentally friendly and cost-effective methods for the recovery of metals from “low-value” WEEE (e.g., <100 g/t Au) is important from the circular economy perspective. In this study, the separation of base (Cu) and precious (Ag) metals from scrap TV boards (STVBs) by using a zig-zag air separator was investigated. Size-reduced scrap STVBs (-1 mm) were subjected to separation tests after the removal of the fine fraction (-0.1 mm). The sized scrap material (-1 +0.1 mm) was determined to have a metal content of 15.4% Cu, 47 g/t Ag and 0.05% Fe, with no gold. In the air separation tests, the effect of air flow rate (4-16 m/s) on the recovery of metals was studied. Increasing the air flow rate resulted in low metal recoveries with concurrent high metal grades in the concentrate. Separation efficiency (%) calculations showed that the most efficient separation is obtained at the highest air flow rate of 16 m/s. At this flow rate, 15.4% of the material was recovered in the concentrate which contains 62.3% Cu and 198 g/t Ag with recoveries of 63.3% Cu and 73.9% Ag. The findings indicated that zig-zag air separators can be used to obtain a metal-rich fraction under suitable conditions of the flow regime.