Redox-Responsive Copper(I) Metallogel: A Metal鈥揙rganic Hybrid Sorbent for Reductive Removal of Chromium(VI) from Aqueous Solution

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• 作者：Sougata Sarkar ; Soumen Dutta ; Partha Bairi ; Tarasankar Pal
• 刊名：Langmuir
• 出版年：2014
• 出版时间：July 8, 2014
• 年：2014
• 卷：30
• 期：26
• 页码：7833-7841
• 全文大小：423K
• ISSN：1520-5827

文摘

Herein, we report a new strategy to remove toxic Cr(VI) ion from aqueous solution using metal鈥搊rganic hybrid gel as sorbent. The gel could be easily synthesized from the commercially available organic ligand 2-mercaptobenzimidazole (2-MBIm) and copper(II) chloride in alcoholic medium. The synthesis involves one-electron reduction of Cu(II) to Cu(I) by 2-MBIm, and then gel formation is triggered through Cu(I)鈥搇igand coordination and extensive hydrogen-bonding interactions involving the 鈥溾€揘H鈥?protons (of 2-MBIm ligand), solvent molecules, and chloride ions. The gel shows entangled network morphology. Different microanalytical techniques (FTIR, powder XRD, FESEM, TEM, rheology etc.) have been employed for complete characterizations of the gel sample. Both Cu(I) (in situ formed) and Cl^{鈥?/sup> ions trigger the gel formation as demonstrated from systematic chemical analyses. The gel also exhibits its stimuli-responsive behavior toward different interfering chemical parameters (pH, selective metal ions and anions, selective complexing agents, etc.). Finally the gel shows its redox-responsive nature owing to the distinguished presence of Cu(I) metal centers throughout its structural backbone. And this indeed helps in the effective removal of Cr(VI) ions from aqueous solution. Reduction of Cr(VI) to Cr(III) ions and its subsequent sorption take place in the gel matrix. The reductive removal of Cr(VI) has been quantitatively interpreted through a set of different kinetic measurements/models, and the removal capacity of the gel matrix has been observed to be 331 mg g鈥? at pH 2.7, which is admirably higher than the commonly used adsorbents. However, the capacity decreases with the increase in pH of the solution. The overall removal mechanism has been clearly demonstrated. Again, the gel could also be recycled. Thus, the low-cost and large-scale fabrication of the redox-active metallogel makes it an efficient matrix for the toxic ion removal and hence indicates the high promise of this new generation hybrid material for environmental pollution abatement.}