The Li(H2O)n dehydration behavior influences the Li+ ion adsorption on H4Ti5O12 with different facets exposed

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-01, Vol.451, p.138870, Article 138870
• Main Authors: Zhao, Bing, Qian, Zhiqiang, Qiao, Yinjun, Li, Jun, Wu, Zhijian, Liu, Zhong
• Format: Article
• Language: English
• Subjects: adsorption mechanisms; dehydration effect; H4Ti5O12; Li+ adsorbents
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.138870

The adsorption behaviors and adsorption mechanism of HTO-s were systematically investigated by experiments and DFT calculations, which indicates the adsorption performance was influenced by adsorbents surface with different facets and dehydration processes. [Display omitted] •The HTO-OS with dominant (111) facet and HTO-NS with dominant (01-1) facet were synthesized.•The adsorption tests show that HTO-NS possesses faster adsorption rates and more stable recyclability than HTO-OS.•The dehydration processes of Li(H2O)4+ on HTO (01-1) and (111) are partially dehydrated to form Li(H2O)+ and Li(H2O)2+ via DFT calculations.•The study helps to better understand the effect of dehydration behavior on the Li+ adsorption in aqueous lithium resources. In this study, octahedrons assembled nanospheres Li4Ti5O12 (LTO-OS) with dominant (111) facet and nanosheets assembled microspheres Li4Ti5O12 (LTO-NS) with dominant (01-1) facet precursors were synthesized. Then, these corresponding H4Ti5O12 adsorbents (HTO-OS and HTO-NS) were obtained via acid treatment and used to recover lithium from aqueous solutions. The systematic adsorption tests show that HTO-NS possesses higher adsorption uptake (35.5 mg/g) and faster adsorption rate (equilibrium time: < 2 h) than HTO-OS (31.2 mg/g), owing to the role of different dehydration processes and exposed facets. With the help of DFT calculation analyses, the dehydration of Li(H2O)4+ on HTO (01-1) and (111) were partially dehydrated Li(H2O)+ and Li(H2O)2+ in the adsorption process, owing to crystal channel and surface atomic arrangement. In addition, the analysis of the adsorption mechanism indicates that the Li+ exist in the form of hydrated lithium ions in the initial adsorption solution, and the dehydration processes occur during Li(H2O)4+ move to the surface of the adsorbent, then an ion exchange reaction has happened between the dehydrated Li+ and H+. These results reveal the adsorbents with different facets exposed indeed influence the surface dehydration processes and Li+ adsorption behaviors, which are favorable to better understand the interfacial interactions between adsorbents and adsorbates.