New Chitosan鈥揟hiomer: An Efficient Colorimetric Sensor and Effective Sorbent for Mercury at Ultralow Concentration
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- 作者：Kalpana Chauhan ; Prem Singh ; Rakesh Kumar Singhal
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2015
- 出版时间：December 2, 2015
- 年：2015
- 卷：7
- 期：47
- 页码：26069-26078
- 全文大小：654K
- ISSN：1944-8252
文摘
This paper describes an innovative procedure for the fabrication of a facile colorimetric sensor in one step with thiol functional group for Hg2+ detection at trace level. The sensor was successfully synthesized via chitosan isothiouronium salt intermediate with innocuous low cost thiourea reagent under microwave irradiation. It is an innovative green approach to achieve thiol functionalization with a high degree of substitution. Thiomer was characterized by titrimetry, FTIR, 1H NMR, elemental analysis (CHNS), and EDX for extent of modification with detail structure. The synthesized and well characterized thiomer was screened for sensor application. The sensing solution of thiomer resulted in an instantaneous sharp color change from colorless, yellow, to brown with increase in Hg2+ concentration. Chitosan thiomer also exhibited high sensitivity and selectivity for Hg2+ over other possible interfering ions in aqueous media. The sensing responses were visualized quantitatively with quick response, good selectivity, high sensitivity, and a low detection limit of 鈭?.465 ppb by the naked eye. The same was tested with a paper strip method for technological applications. Furthermore, the as-prepared sensors also exhibited exceptional sorption potential for Hg2+ even from ultralow concentration aqueous solution and reduced the Hg2+ concentration from 10 ppb to the extremely low level of 鈭?.04 ppb as studied by cyclic voltammetry. Thus, the proposed method is simple, promising, and rapid without any complicated modifying step and is an economical alternative to traditional Hg2+ sensors for rapid sensor application in environmental water samples at ppb levels.