Around 10% of the worldwide annual
production of gold is used for
manufacturing of electronic devices. According to the European Commission,
waste electric and electronic equipment is the fastest growing waste
stream in the European Union. This has generated the need for an effective
method to recover gold from electronic waste. Here, we report a simple,
effective, and highly selective nylon-12-based three-dimensional (3D)-printed
scavenger objects for gold recovery directly from an aqua regia extract
of a printed circuit board waste. Using the easy to handle and reusable
3D-printed meshes or columns, gold can be selectively captured both
in a batch and continuous flow processes by dipping the scavenger
into the solution or passing the gold-containing solution through
the column. The possibility to optimize the shape, size, and flow
properties of scavenger objects with 3D printing enables the gold
scavengers to match the requirements of any processing plants.
The formation of complexes between hexafluorophosphate (PF ) and tetraisobutyloctahydroxypyridine[4]arene has been thoroughly studied in the gas phase (ESI-QTOF-MS, IM-MS, DFT calculations), in the solid state (X-ray crystallography), and in chloroform solution ( H, F, and DOSY NMR spectroscopy). In all states of matter, simultaneous endo complexation of solvent molecules and exo complexation of a PF anion within a pyridine[4]arene dimer was observed. While similar ternary complexes are often observed in the solid state, this is a unique example of such behavior in the gas phase.
Selective
laser sintering (SLS) 3D printing was utilized to fabricate highly
porous carbonous electrodes. The electrodes were prepared by using
a mixture of fine graphite powder and either polyamide-12, polystyrene,
or polyurethane polymer powder as SLS printing material. During the
printing process the graphite powder was dispersed uniformly on the
supporting polymer matrix. Graphite’s concentration in the
mixture was varied between 5 and 40 wt % to find the correlation between
the carbon content and conductivity. The graphite concentration, polymer
matrix, and printing conditions all had an impact on the final conductivity.
Due to the SLS printing technique, all the 3D printed electrodes were
highly porous. By using polyurethane as the supporting matrix it was
possible to produce flexible electrodes in which the conductivity
is sensitive to pressure and mechanical stress. Physical properties
such as graphite distribution, attachment, and the overall porosity
of the printed electrodes were studied using scanning electron microscopy
(SEM), helium ion microscopy (HIM), and X-ray tomography. The results
show that the combination of chemical design of the printing material
and the utilization of SLS 3D printing enables fabrication of highly
customizable electrodes with desired chemical, physical, mechanical,
and flow-through properties.
Selective laser sintering (SLS) 3d printing was utilized to manufacture a solid catalyst for Suzuki-Miyaura cross-coupling reactions from polypropylene as a base material and palladium nanoparticles on silica (SilicaCat Pd 0 R815-100 by SiliCycle) as the catalytically active additive. The 3d printed catalyst showed similar activity to that of the pristine powdery commercial catalyst, but with improved practical recoverability and reduced leaching of palladium into solution. Recycling of the printed catalyst led to increase of the induction period of the reactions, attributed to the pseudo-homogeneous catalysis. The reaction is initiated by oxidative addition of aryl iodide to palladium nanoparticles, resulting in formation of soluble molecular species, which then act as the homogeneous catalyst. SLS 3d printing improves handling, overall practicality and recyclability of the catalyst without altering the chemical behaviour of the active component.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.