Metal‐organic frameworks (MOFs) have raised a lot of interest, especially as adsorbing materials, because of their unique and well‐defined pore structures. One of the main challenges in the utilization of MOFs is their crystalline and powdery nature, which makes their use inconvenient in practice. Three‐dimensional printing has been suggested as a potential solution to overcome this problem. We used selective laser sintering (SLS) to print highly porous flow‐through filters containing the MOF copper(II) benzene‐1,3,5‐tricarboxylate (HKUST‐1). These filters were printed simply by mixing HKUST‐1 with an easily printable nylon‐12 polymer matrix. By using the SLS, powdery particles were fused together in such a way that the structure of the printed solid material resembles the structure of a powder bed. The MOF additive is firmly attached only on the surface of partially fused polymer particles and therefore remains accessible to fluids passing through the filter. Powder X‐ray analysis of the printed object confirmed that printing did not have any negative impact on the structure of the MOF. CO2‐adsorption studies also showed that the activity of the MOF was not affected by the printing process. SLS offers a straightforward and easy way to fabricate tailor‐made MOF‐containing filters for practical applications.
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.
Selective laser sintering (SLS) 3D printing is used to fabricate highly macroporous ion scavenger filters for recovery of Pd and Pt from electronic waste. The scavengers are printed by using a mixture of polypropylene with 10 wt% of type‐1 anion exchange resin. Porosities and the flow‐through properties of the filters are controlled by adjusting the SLS printing parameters. The cylinder‐shaped filters are used in selective recovery of Pd and Pt from acidic leachate of electronic waste simply by passing the solution through the object. Under such conditions, the scavenger filters are able to capture Pd and Pt as anionic complexes with high efficiency from a solution containing mixture of different metal ions. By using the Pd/Pt scavenger together with previously reported, highly selective nylon‐based Au scavenger, precious metals, i.e., Au, Pd, and Pt could all be recovered from the electronic waste leachate in a single flow‐through process. One of the main advantages of the printed scavengers is that all recovered metals can be easily extracted from the filters as separate fractions by using aqueous solutions of thiourea or diluted nitric acid. After removal of the captured metals, the scavengers are reusable without significant loss of their ion‐capturing performance.
Three-dimensional
selective laser sintering printing was utilized
to produce porous, solid objects, in which the catalytically active
component, Pd/SiO
2
, is attached to an easily printable
supporting polypropylene framework. Physical properties of the printed
objects, such as porosity, were controlled by varying the printing
parameters. Structural characterization of the objects was performed
by helium ion microscopy, scanning electron microscopy, and X-ray
tomography, and the catalytic performance of the objects was tested
in the hydrogenation of styrene, cyclohexene, and phenylacetylene.
The results show that the selective laser sintering process provides
an alternative and effective way to produce highly active and easily
reusable heterogeneous catalysts without significantly reducing the
catalytic efficiency of the active Pd/SiO
2
component. The
ability to control the size, porosity, mechanical properties, flow
properties, physical properties, and chemical properties of the catalyst
objects opens up possibilities to optimize devices for different reaction
environments including batch reactions and continuous flow systems.
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