Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan.
Molecules. 2022 Dec 13;27(24):8840. doi: 10.3390/molecules27248840.
Prussian blue analogs (PBAs) have been reported as promising ammonia (NH) adsorbents with a high capacity compared to activated carbon, zeolite, and ion exchange resins. The adsorbed NH was desorbed by heating and washing with water or acid. Recently, we demonstrated that desorption was also possible by washing with a saturated ammonium hydrogen carbonate solution (sat. NHHCO) and recovered NH as an NHHCO solid by introducing CO into the washing liquid after desorption. However, this has only been proven for copper ferrocyanide and the relationship between the adsorption/desorption behavior and metal ions in PBAs has not been identified. In this study, we investigated the adsorption/desorption behavior of PBAs that are complexes of first row transition metals with hexacyanometalate anions. Six types of PBAs were tested in this study and copper ferricyanide exhibited the highest desorption/adsorption ratio. X-ray diffraction results revealed high structural stability for cobalt hexacyanocobaltate (CoHCC) and nickel ferricyanide (NiHCF). The Fourier transform infrared spectroscopy results showed that the NH adsorbed on the vacancy sites tended to desorb compared to the NH adsorbed on the interstitial sites as ammonium ions. Interestingly, the desorption/adsorption ratio exhibited the Irving-Williams order.
普鲁士蓝类似物 (PBAs) 已被报道为具有高容量的有前途的氨 (NH) 吸附剂，与活性炭、沸石和离子交换树脂相比。吸附的 NH 通过加热和用水或酸洗涤来解吸。最近，我们证明通过用饱和碳酸氢铵溶液 (sat. NHHCO) 洗涤也可以解吸，并在解吸后将 CO 引入洗涤液中，将 NH 回收为 NHHCO 固体。然而，这仅在铜亚铁氰化物中得到证明，并且 PBAs 中金属离子的吸附/解吸行为之间的关系尚未确定。在这项研究中，我们研究了具有六氰合金属阴离子的第一行过渡金属的配合物的 PBAs 的吸附/解吸行为。在这项研究中测试了六种类型的 PBAs，其中铜铁氰化物表现出最高的解吸/吸附比。X 射线衍射结果表明六氰合钴酸钴 (CoHCC) 和镍铁氰化物 (NiHCF) 具有高结构稳定性。傅里叶变换红外光谱结果表明，与间隙位吸附的 NH 相比，空位位吸附的 NH 更倾向于作为铵离子解吸。有趣的是，解吸/吸附比表现出 Irving-Williams 顺序。
