{
  "abstract": "Nanoscale confinement can reorganize water molecules and alter ionic hydration, offering a potential route to separating chemically similar ions. We use molecular dynamics simulations with the MACE-MH-1 foundation machine-learning interatomic potential to investigate the hydration of eight trivalent lanthanide ions (Ln 3+ : La 3+ , Pr 3+ , Nd 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Tm 3+ , and Lu 3+ ) in carbon nanotubes (CNTs) with diameters of 1.09–1.49 nm. We first evaluate MACE-MH-1 for Ln 3+ hydration in bulk solution. The OMOL model of MACE-MH-1 reproduces the reported Ln–O distances and coordination-number trends and is therefore used for the CNT simulations. The hydration factor, which measures first-shell orientational order, varies nonmonotonically with CNT diameter and reaches a minimum in CNT(9,9), which also accommodates the most first-shell water molecules. This minimum coincides with the emergence of a central water population and reflects two combined effects: difference in preferred orientation between first-shell and surrounding water molecules and increased hydrogen-bond coupling between them. However, different Ln 3+ ions respond similarly to confinement, suggesting that CNT confinement alone may offer limited selectivity for their separation.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Biosystems and Agricultural Engineering",
    "University of Kentucky",
    "Department of Chemical and Materials Engineering"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Kailong Zhang",
      "orcid": "0000-0002-9476-9552"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Jian Shi"
    },
    {
      "affs": [
        2,
        1
      ],
      "name": "Qing Shao"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4nt5py63sbprd.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15009104/v1",
  "fulltext_url": null,
  "id": "4nt5py63sbprd",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009104/v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2204|Nanopore and Nanochannel Transport Studies"
    ]
  ],
  "openalex": "W7213872660",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-20",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/4nt5py63sbprd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:19Z",
      "native_id": "10.26434/chemrxiv.15009104",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009104/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "source:chemrxiv",
      "subfield": "general"
    }
  ],
  "title": "Water Layering and Orientation Modulate Lanthanide Hydration in Carbon Nanotubes",
  "title_text": "Water Layering and Orientation Modulate Lanthanide Hydration in Carbon Nanotubes",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:19Z",
  "url": "https://research.draconitic.com/paper/4nt5py63sbprd",
  "venue": "ChemRxiv",
  "versions": []
}