An overwhelmingly selective colorimetric sensor for Ag+ using a simple modified polyacrylonitrile fiber.

A carboxymethyl-dithiocarbamate immobilized polyacrylonitrile fiber colorimetric sensor has been synthesized. This fiber sensor exhibits excellent selectivity and sensitivity for Ag + in aqueous solution with a remarkable color change from light pink to red–brown over a wide pH range of 2–12. The sensor responds selectively to Ag + in the presence of other ions, including Mg 2+ , Al 3+ , Ca 2+ , Cr 3+ , Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ . The colorimetric sensor has an extremely fast response time (10 s) and a low visual limit of detection (5.53 × 10 −12 mol/L). The fiber sensor also undergoes an obvious color change in the presence of Ag + solutions containing EDTA, NaCl or NaBr. Density functional theory optimization reveals that the sensor and Ag + interact via a seven-membered ring complexation mechanism. [ABSTRACT FROM AUTHOR]