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Hydration of LiOH and LiCl─Near-Infrared Spectroscopic Analysis
ACS Omega ( IF 3.7 ) Pub Date : 2021-11-24 , DOI: 10.1021/acsomega.1c05379 Masato Takeuchi 1 , Ryo Kurosawa 2 , Junichi Ryu 2 , Masaya Matsuoka 1
ACS Omega ( IF 3.7 ) Pub Date : 2021-11-24 , DOI: 10.1021/acsomega.1c05379 Masato Takeuchi 1 , Ryo Kurosawa 2 , Junichi Ryu 2 , Masaya Matsuoka 1
Affiliation
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The hydration behavior of LiOH, LiOH·H2O, and LiCl was observed by near-infrared (NIR) spectroscopy. Anhydrous LiOH showed two absorption bands at 7340 and 7171 cm–1. These NIR bands were assigned to the first overtone of surface hydroxyls and interlayer hydroxyls of LiOH, respectively. LiOH·H2O showed two absorption bands at 7137 and 6970 cm–1. These NIR bands were assigned to the first overtone of interlayer hydroxyls and H2O molecules coordinated with Li+, respectively. The interlayer OH– and the coordinated H2O of LiOH·H2O were not modified even when the LiOH·H2O was exposed to air. In contrast, anhydrous LiOH was slowly hydrated for several hours, to form LiOH·H2O under ambient conditions (RH 60%). Kinetic analysis showed that the hydration of the interlayer OH– of LiOH proceeded as a second-order reaction, indicating the formation of intermediate species─[Li(H2O)x(OH)4]3– (x = 1 or 2). However, the hydration of the LiOH surface did not follow a second-order reaction because the chemisorption of H2O molecules onto the defect sites of the LiOH surface does not need to crossover the energy barrier. Furthermore, we succeeded in observing the hydration of deliquescent LiCl, including the formation of LiCl solution for several minutes by NIR spectroscopy.
中文翻译：
LiOH和LiCl的水合反应─近红外光谱分析
通过近红外（NIR）光谱观察LiOH、LiOH·H 2 O和LiCl的水化行为。无水LiOH在7340和7171 cm –1处有两个吸收带。这些 NIR 谱带分别归属于 LiOH 的表面羟基和层间羟基的第一泛音。 LiOH·H 2 O在7137和6970 cm –1处显示出两个吸收带。这些NIR谱带分别归属于与Li +配位的层间羟基和H 2 O分子的第一泛音。即使当LiOH·H 2 O暴露在空气中时，LiOH·H 2 O的层间OH -和配位的H 2 O也没有发生改变。相比之下，无水LiOH在环境条件（RH 60%）下缓慢水合几个小时，形成LiOH·H 2 O。动力学分析表明，LiOH层间OH –的水合为二级反应，表明形成了中间物种─[Li(H 2 O) x (OH) 4 ] 3– ( x = 1 or 2) 。然而，LiOH表面的水合并不遵循二级反应，因为H 2 O分子在LiOH表面缺陷位点上的化学吸附不需要跨越能垒。此外，我们成功地观察到了潮解性 LiCl 的水合，包括通过近红外光谱在几分钟内形成 LiCl 溶液。
更新日期：2021-12-07
中文翻译：
LiOH和LiCl的水合反应─近红外光谱分析
通过近红外（NIR）光谱观察LiOH、LiOH·H 2 O和LiCl的水化行为。无水LiOH在7340和7171 cm –1处有两个吸收带。这些 NIR 谱带分别归属于 LiOH 的表面羟基和层间羟基的第一泛音。 LiOH·H 2 O在7137和6970 cm –1处显示出两个吸收带。这些NIR谱带分别归属于与Li +配位的层间羟基和H 2 O分子的第一泛音。即使当LiOH·H 2 O暴露在空气中时，LiOH·H 2 O的层间OH -和配位的H 2 O也没有发生改变。相比之下，无水LiOH在环境条件（RH 60%）下缓慢水合几个小时，形成LiOH·H 2 O。动力学分析表明，LiOH层间OH –的水合为二级反应，表明形成了中间物种─[Li(H 2 O) x (OH) 4 ] 3– ( x = 1 or 2) 。然而，LiOH表面的水合并不遵循二级反应，因为H 2 O分子在LiOH表面缺陷位点上的化学吸附不需要跨越能垒。此外，我们成功地观察到了潮解性 LiCl 的水合，包括通过近红外光谱在几分钟内形成 LiCl 溶液。
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