Historical Pigment Exhibiting Ammonia Gas Capture beyond Standard Adsorbents with Adsorption Sites of Two Kinds

Abstract

Prussian blue is a historical pigment synthesized for the first time at the beginning of 18th century. Here we demonstrate that the historical pigment exhibits surprising adsorption properties of gaseous ammonia. Prussian blue shows 12.5 mmol/g of ammonia capacity at 0.1 MPa, whereas standard ammonia adsorbents show only 5.08-11.3 mmol/g. Dense adsorption was also observed for trace contamination in atmosphere. Results also show higher adsorption by Prussian blue analogues with the optimization of chemical composition. The respective capacities of cobalt hexacyanocobaltate (CoHCC) and copper hexacyanoferrate (CuHCF) were raised to 21.9 and 20.2 mmol/g, the highest value among the recyclable adsorbents. Also, CoHCC showed repeated adsorption in vacuum. CuHCF showed regeneration by acid washing. The chemical state of the adsorbed ammonia depends on the presence of the water in atmosphere: NH3, which was stored as in the dehydrated case, was converted into NH4(+) in the hydrated case.

A Switch in the Hydrophobic/Hydrophilic Gas‐Adsorption Character of Prussian Blue Analogues: An Affinity Control for Smart Gas Sorption

“…[21,22] In contrast, PBA have been much less investigated for gas adsorption [23] despite an excellent hydrothermal stabilitya nd high adsorption capacities observedf or the adsorption of water, [24,25] CO 2 , [26][27][28] or ammonia. [29] In this frame,K awamoto et al highlighted the potential of PBAs for gas storage using different strategies, but to the best of our knowledge,t heir surface properties, in terms of hydrophobicity and hydrophilic character have never really been clarified up to now. [24] Recently,w er eported on as eries of lipophilicP BA materials, highly efficient for the separation of different vapors, such as water and hydrocarbons.…”

Interpretation of the Role of Composition on the Inclusion Efficiency of Monovalent Cations into Cobalt Hexacyanoferrate

“…The powder XRD profiles of all nine compositions of NaCoHCF are given in Figure . In general, the profiles are found to match those of the PBA . However, as the number of Na and water varied with vacancy, the impact of this change on the lattice environment becomes clear.…”

“…In addition, as the concentration of Cs in environmental water is comparatively negligible, the absolute selectivity of PBAs for this ion may not hinder their application for NH 4 uptake. As expected, in recent years, the separation or decontamination related studies of PBAs have expanded to other environmental causes such as the adsorption of dissolved or gaseous ammonia . NH 4 removal and recovery is usually faced with selectivity problems because the application area often contains chemical fertilizer or biomass matrices, making selectivity an extremely important factor when choosing the adsorbent .…”

Structural and Gas Retention Changes Induced by Ozonization of Cobalt(II) and Manganese(II) Hexacyanocobaltates(III)

“…That is why the vast majority of them are obtained with polar molecules in their frameworks. Polar solvents interact strongly with the framework, which is beneficial for the retention of some gases, such as ammonia, at trace level [29]. However, it becomes a high energy-consuming process when framework degassing is required.…”