A new compound Mn 5 P 4 O 20 H 8 achieving efficient heavy metal removal to the ppb level through a dual chemisorption–ion exchange pathway

• Published in: Environmental science. Nano Vol. 9; no. 3; pp. 1146 - 1155
• Main Authors: Deng, Mingxia, Liu, Weijing, Liu, Qian, Sun, Du, Huang, Fuqiang
• Format: Journal Article
• Language: English
• Published: 17.03.2022
• ISSN: 2051-8153; 2051-8161
• DOI: 10.1039/D1EN00928A

Effective removal of heavy metal ions down to the mark of tolerance concentration (parts per billion level) from drinking water remains a great challenge. Metal oxide-related materials have emerged as promising candidates for next-gen high performance adsorbents owing to their flexibility in tuning the chemical composition and surface structure. Herein, we have successfully synthesized a new compound Mn 5 P 4 O 20 H 8 through a facile one-pot solvothermal process, which has a lattice structure with a three-dimensional network crosslinked by [PO 4 ] tetrahedra and [MnO 6 ] octahedra. A synergistic pathway of surface hydroxyl group trapping and lattice ion-exchange endows the obtained Mn 5 P 4 O 20 H 8 with superior removal efficiency (>99%) for Pb 2+ , Cr 3+ , and Fe 3+ from relatively high concentration (∼5 parts per million, μg L −1 ) to parts per billion levels (40, 1, and 1 parts per billion for Cr 3+ , Fe 3+ , and Pb 2+ , respectively), much lower than the WHO permitted level for drinking water. The maximum adsorption capacities for Pb 2+ , Cr 3+ , and Fe 3+ are 1510, 201, and 300 mg g −1 , respectively. In addition, the as-prepared Mn 5 P 4 O 20 H 8 adsorbent exhibits excellent reusability without significant degradation. These results make the Mn 5 P 4 O 20 H 8 material a great adsorbent for the application in remediation of heavy metal polluted water. This work sheds light on extending the design of adsorbent nanomaterials for water treatment to a broader library of synthetic toolboxes and mechanistic ideas.