{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T10:02:33Z","timestamp":1790071353984,"version":"4.0.1"},"reference-count":38,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T00:00:00Z","timestamp":1790035200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["12405361"],"award-info":[{"award-number":["12405361"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["12405361"],"award-info":[{"award-number":["12405361"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004829","name":"Sichuan Science and Technology Program","doi-asserted-by":"publisher","award":["2026JDHJ0044"],"award-info":[{"award-number":["2026JDHJ0044"]}],"id":[{"id":"10.13039\/501100004829","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Fly ash-based geopolymers are widely used as solidification matrices for intermediate- and low-level radioactive waste liquids. Their performance relies heavily on the adsorption capacity of the primary component, N-A-S-H gels, which directly governs the long-term stability of the solidified waste form. This study prepared N-A-S-H gels using both the sol\u2013gel synthesis and the hydrothermal synthesis method. The effects of the Si\/Al ratio, alkalinity, and NaNO3 on the structure of N-A-S-H gels were analyzed using EDS, FT-IR, and XRD. Additionally, the dynamic adsorption capacity of N-A-S-H gels for Sr2+ under varying solution temperatures and alkaline conditions was evaluated and fitted using the Thomas and Yoon\u2013Nelson models. For sol\u2013gel-synthesized gels, a lower initial Si\/Al ratio led to a higher theoretical maximum Sr2+ adsorption capacity of 121.71 mg\/g at room temperature and neutral pH. For hydrothermally synthesized gels from raw fly ash, the high initial alkalinity reduced the Si\/Al ratio but adversely decreased Sr2+ adsorption capacity. Raising the temperature to 60 \u00b0C improved Sr2+ uptake for all gel samples, with a maximum increase of 28.75 mg\/g. Under alkaline conditions, Sr2+ uptake for all gels decreased significantly, with a minimum theoretical reduction of 31.55 mg\/g. The findings of this study provide a theoretical foundation for understanding the radionuclide migration mechanisms of fly ash-based geopolymer solidification forms in complex geological environments.<\/jats:p>","DOI":"10.3390\/ma19194035","type":"journal-article","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T09:04:17Z","timestamp":1790067857000},"page":"4035","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Synthesis of N-A-S-H Gels via Sol\u2013Gel and Hydrothermal Methods: Composition, Microstructure, and Dynamic Adsorption Characteristics for Sr2+"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8991-5685","authenticated-orcid":false,"given":"Zhao","family":"Zheng","sequence":"first","affiliation":[{"name":"School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China"},{"name":"Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinpeng","family":"Ye","sequence":"additional","affiliation":[{"name":"School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Long","family":"Shi","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China"},{"name":"Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xue","family":"Ma","sequence":"additional","affiliation":[{"name":"School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3401-4238","authenticated-orcid":false,"given":"Luping","family":"Tang","sequence":"additional","affiliation":[{"name":"Division of Building Technology, Chalmers University of Technology, 41296 Gothenburg, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e20131","DOI":"10.1111\/jace.20131","article-title":"Advancements in immobilization of cesium and strontium radionuclides in cementitious wasteforms\u2014A review","volume":"108","author":"Jain","year":"2025","journal-title":"J. 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