Synthesis of hierarchical hollow MIL-53(Al)-NH 2 as an adsorbent for removing fluoride: experimental and theoretical per
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RESEARCH ARTICLE
Synthesis of hierarchical hollow MIL-53(Al)-NH2 as an adsorbent for removing fluoride: experimental and theoretical perspective Lei Huang 1 & Zhihui Yang 1,2 & Xiaorui Li 1 & Lanjing Hou 1 & Sikpaam Issaka Alhassan 1 & Haiying Wang 1,2,3 Received: 24 May 2020 / Accepted: 21 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The MIL-53(Al)-NH2 was designed to remove fluoride with hierarchical hollow morphology. It was used as an adsorbent for fluoride removal at a wide pH range (1–12) due to the positive zeta potential of MIL-53(Al)-NH2. The pH did not significantly influence the fluoride adsorption into MIL-53(Al)-NH2. However, the adsorbent indicated good adsorption capacity with maximum adsorption of 1070.6 mg g−1. Different adsorption kinetic and thermodynamic models were investigated for MIL-53(Al)NH2. The adsorption of fluoride into MIL-53(Al)-NH2 followed the pseudo-second-order model and a well-fitted Langmuir model indicating chemical and monolayer adsorption process. When mass transfer model was used at initial concentrations of 3− 100 ppm and 1000 ppm, the rates of conversion were 8.4 × 10−8 and 4.7 × 10−8 m s−1. Moreover, anions such as SO2− 4 , PO4 , − − − NO3 , Cl , and Br also had less effect on the adsorption of fluoride. Also, experimental and theoretical calculations on adsorption mechanism of MIL-53(Al)-NH2 revealed that the material had good stability and regenerative capacity using alum as regenerant. In a nutshell, the dominant crystal face (1 0 1) and adsorption sites Al, O, and N combined well with F−, HF, and HF2− through density functional theory. It opens a good way of designing hollow MOFs for adsorbing contaminants in wastewater. Keywords Metal organic frameworks . Adsorption . Fluoride . MIL-53(Al) . Density functional theory
Introduction Excess fluoride in natural waters has been demonstrated as a health problem that includes calcification of the bones and teeth, Alzheimer’s syndrome, arthritis, brain damage, thyroid disorder, and infertility (Abtahi et al. 2019). This kind of wastewater is primarily produced by some industrial plants. In China, zinc metallurgy, copper metallurgy, aluminum Responsible Editor: Tito Roberto Cadaval Jr Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-10975-x) contains supplementary material, which is available to authorized users. * Haiying Wang [email protected] 1
School of Metallurgy and Environment, Central South University, Changsha 410083, People’s Republic of China
2
Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Changsha 410083, People’s Republic of China
3
Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China
metallurgy, and ferrous metallurgy produce substantial amount of water containing fluoride (Choong et al. 2020; Gao et al. 2020). Effluents produced from these factories contain high concentrations of fluoride (at more than 100 ppm). As a result, ma
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