Ruan W, Wu H, Qi Y, Yang H. Removal of Hg
2+ in wastewater by grafting nitrogen/sulfur-containing molecule onto Uio-66-NH
2: from synthesis to adsorption studies.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023;
30:15464-15479. [PMID:
36169833 DOI:
10.1007/s11356-022-23255-7]
[Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
The remediation of heavy metal deserves to be on the agenda, with the adsorbent design bearing the brunt of it. In this study, the molecule (4, 6-diamino-2-mercaptopyrimidine, DMP) containing thiol (-SH) and amino (-NH2) functional groups was grafted onto Uio-66-NH2, and a composite metal-organic framework nanomaterial (Zr(NH2)-DMP) was synthesized via a facile post-modification scheme. The morphological characteristics and structural features of the modified adsorbent were characterized by XRD, FT-IR, FE-SEM, EDS, BET, and XPS. The characterization results verified that the post-modification scheme was successfully achieved. The adsorption experiments were carried out to investigate the removal performance of the Zr(NH2)-DMP towards Hg2+ under different influencing parameters. The maximum adsorption capacity of 389.4 mg/g was obtained, and the adsorption equilibrium was achieved within 30 min at pH 6 at room temperature. Adsorption thermodynamic study indicated that the adsorption process was exothermic and spontaneous. The Zr(NH2)-DMP exhibited excellent selectivity for Hg2+, and also has the potential to remove Cu2+, Fe2+, and Zn2+ ions. The introduction of Cl- inhibited the removal of Hg2+ due to the formation of mercuric chlorides (removal efficiency reduced from 97.8 to 95.6%). The removal efficiency of up to 86.7% was obtained after four cycles. The Langmuir isotherm and Pseudo-second kinetic were more suitable for fitting the adsorption process of Hg2+ by Zr(NH2)-DMP. The main removal mechanism could be attributed to the chelation between Hg2+ (soft acid) and nitrogen/sulfur (soft base) elements. These findings convinced that the successful synthesis of Zr(NH2)-DMP provides an option for Hg2+ removal from wastewater.
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