Metal–organic
frameworks (MOFs) offer great promise in a
variety of gas- and liquid-phase separations. However, the excellent
performance on the lab scale hardly translates into pilot- or industrial-scale
applications due to the microcrystalline nature of MOFs. Therefore,
the structuring of MOFs into pellets or beads is a highly solicited
and timely requirement. In this work, a general structuring method
is developed for preparing MOF–polymer composite beads based
on an easy polymerization strategy. This method adopts biocompatible,
biodegradable poly(acrylic acid) (PAA) and sodium alginate monomers,
which are cross-linked using Ca2+ ions. Also, the preparation
procedure employs water and hence is nontoxic. Moreover, the universal
method has been applied to 12 different structurally diverse MOFs
and three MOF-based composites. To validate the applicability of the
structuring method, beads consisting of a MOF composite, namely Fe–BTC/PDA,
were subsequently employed for the extraction of Pb and Pd ions from
real-world water samples. For example, we find that just 1 g of Fe–BTC/PDA
beads is able to decontaminate >10 L of freshwater containing highly
toxic lead (Pb) concentrations of 600 ppb while under continuous flow.
Moreover, the beads offer one of the highest Pd capacities to date,
498 mg of Pd per gram of composite bead. Furthermore, large quantities
of Pd, 7.8 wt %, can be readily concentrated inside the bead while
under continuous flow, and this value can be readily increased with
regenerative cycling.
This article explains the need for energy-efficient large-scale CO2 capture and briefly mentions the requirements for optimal solid sorbents for this application.
Wet-chemical methods involving the coreduction of HAuCl 4 and AgNO 3 have been proven particularly suitable for producing stable Au−Ag alloy NPs with controllable structure−property relationship. However, very poor-solubility of AgCl in aqueous medium and intrinsically different surface energies of Au and Ag remained detrimental-factors in synthesizing so-called "alloy" NPs above the solubility-product of AgCl. Here, we report a robust coreduction procedure for producing citrate-stabilized "homogeneously alloyed" Au−Ag NPs of average size sub-10 nm at room-temperature upon simultaneously overcoming the detrimental factors by a simple reagent NH 4 OH. The alloy NPs revealed a high-degree of crystallinity, composition-tunable surface plasmon resonance (SPR) behavior, controlled-catalysis, biocompatibility, surface enhance Raman scattering (SERS) activity and high-chemical stability. The alloy NPs could withstand corrosive chemical environment and be easily transferred from aqueous medium to various organic media. Fusion of NPs under high-energy electron-beam suggested an inertial coalescence. Our method may lead to the developments of metallic and bimetallic alloy NPs in the fulfillment of various applications in the future.
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