Synthesis of uniform-sized and microporous MIL-125(Ti) to boost arsenic removal by chemical adsorption. (1st March 2021)

• Record Type: Journal Article
• Authors: Liu, Zhongmin; Wang, Cong; Wu, Yongchuan; Geng, Longlong; Zhang, Xiuling; Zhang, Dashuai; Hu, Hui; Zhang, Yongzheng; Li, Xin; Liu, Wei; Na, Ping
• Is Part Of: Polyhedron. Volume 196(2021)
• Publication Date: 2021-03-01
• Subjects: MIL-125(Ti) -- Chemical adsorption -- Arsenic removal -- Structure reforming; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2020.114980
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: The structure reforming of MIL-125(Ti) plays a key role for chemical adsorption: As(III) or As(V) can successfully replace certain organic linker in MIL-125(Ti) and organic linker transform into terephthalic acid. Highlights: The microporosity of MIL-125(Ti) can be enhanced by increasing the mixing degree of the reactants in the synthesis process. Adsorption kinetics models and characterizations manifested the chemical adsorption of arsenic on microporous MIL-125(Ti). Mechanism of structure reforming is verified by experimental and simulation study. Abstract: The adsorption behavior of arsenic on adsorbent have been researched widely, but chemical adsorption of arsenic is uncommon. In this work, a kind of microporous metal-organic framework (MIL-125(Ti)) with columnar morphology and uniform size was solvothermally synthesized, and its chemical adsorption behavior and mechanism of arsenic were firstly investigated by experimental and simulation study. Remarkably, ultra-fast adsorption behavior and excellent arsenic removal capability was achieved. It takes only 20 min to rapidly remove 5 mg L −1 arsenic with 0.2 g L −1 MIL-125(Ti), which is far superior to the previously reported materials. Both experimental and simulation study results show that the adsorption of arsenic obeys a new chemical adsorption mechanism. Both As(III) and As(V) can easily replace the terephthalic acid ligand via competitive coordination and bind to the Ti active site of MIL-125(Ti). In addition, the reaction energy barriers for ligand substitution by H2 O, As(III) and As(V) are 0.46, 0.33 and 0.15 eV, respectively, which further confirming that structure reforming of MIL-125(Ti) plays a key role for chemical adsorption. The study solves the difficulty of removing low concentration of arsenic and provides molecular-level understanding of the chemical adsorption mechanism of arsenic on MIL-125(Ti).