Green synthesis of NaP1 zeolite from MSWI fly ash and silica-rich solid waste with superior Cu(II) removal efficiency

Yang, Daokui; Kow, Kien-Woh; Meredith, Will; Peng, Yaqi; Wang, Lei; Li, Xiang; Zhang, Guanlin; Zhang, Jiazheng; Chen, Guifang; Li, Jingwei; Wang, Xujiang; Wang, Wenlong; Mao, Yanpeng; Xu, Mengxia

Abstract

Microwave hydrothermal treatment provides a promising strategy for detoxifying and valorizing municipal solid waste solid waste incineration fly ash (MSWI-FA) into zeolite materials. However, the intrinsically low Si/Al ratio of MSWI-FA often results in reduced zeolite purity. To address this issue, an alkali fusion-assisted microwave hydrothermal method was developed to synthesize NaP1 zeolite directly from MSWI-FA, employing silica-rich solid waste as an eco-friendly alternative to conventional sodium silicate (Na2SiO3). The resultant MSWI-FA-based zeolite (IFA-NaP1) was comprehensively evaluated for its Cu(II) adsorption characteristics. Among the silica-rich solid waste investigated (i.e., silica fume, rice husk ash, and waste glass), silica fume-derived IFA-NaP1 exhibits the most favorable properties, achieving a cation exchange capacity of 2.46 meq∙g−1, 11% higher than that of its Na2SiO3-based counterpart. Mechanistic analysis reveals distinctive silica source-dependent pathways: Na2SiO3 induces multinuclear competition and sequential transformations, whereas silica fume enables a direct sequential transformation. Leaching assessments of IFA-NaP1 confirm its effective immobilization of Pb, Zn, and Cd, with Cr and Cu levels remaining within regulatory thresholds. The silica fume-derived IFA-NaP1 synthesized at 140 °C exhibits superior Cu(II) removal, achieving a maximum adsorption capacity of 123 mg∙g−1, 13% higher than Na2SiO3-derived material. Thermodynamic analysis shows Cu(II) adsorption is endothermic and entropy-driven, involving mechanisms such as electrostatic attraction, ion exchange, silyl radical reduction, surface complexation, and precipitation. This work highlights a sustainable strategy for converting MSWI-FA into efficient zeolite adsorbents, advancing hazardous waste detoxification and heavy metal remediation.

Citation

Yang, D., Kow, K.-W., Meredith, W., Peng, Y., Wang, L., Li, X., Zhang, G., Zhang, J., Chen, G., Li, J., Wang, X., Wang, W., Mao, Y., & Xu, M. (2025). Green synthesis of NaP1 zeolite from MSWI fly ash and silica-rich solid waste with superior Cu(II) removal efficiency. Chemical Engineering Journal, 522, Article 167475. https://doi.org/10.1016/j.cej.2025.167475

• Journal Article Type: Article
• Acceptance Date: Aug 19, 2025
• Online Publication Date: Aug 23, 2025
• Publication Date: 2025-10
• Deposit Date: Aug 29, 2025
• Publicly Available Date: Aug 29, 2025
• Journal: Chemical Engineering Journal
• Print ISSN: 1385-8947
• Electronic ISSN: 1873-5606
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 522
• Article Number: 167475
• DOI: https://doi.org/10.1016/j.cej.2025.167475
• Keywords: MSWI fly ashNaP, 1 zeolite, Silica fume, Synthesis mechanism, Cu(II) adsorption
• Public URL: https://nottingham-repository.worktribe.com/output/53377264
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S1385894725083147?via%3Dihub
• Additional Information: This article is maintained by: Elsevier; Article Title: Green synthesis of NaP1 zeolite from MSWI fly ash and silica-rich solid waste with superior Cu(II) removal efficiency; Journal Title: Chemical Engineering Journal; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.cej.2025.167475; Content Type: article; Copyright: © 2025 The Authors. Published by Elsevier B.V.