An inorganic-organic hybrid optical sensor for heavy metal ion detection based on immobilizing 4-(2-pyridylazo)-resorcinol on functionalized HMS.

Tongge Liu, Gang Li, Na Zhang, Yongying Chen

Index: J. Hazard. Mater. 201-202 , 155-61, (2012)

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Abstract

A novel and low-cost optical sensor for heavy metal ion detection has been prepared by immobilizing 4-(2-pyridylazo)-resorcinol (PAR) on the functionalized hexagonal mesoporous silica (HMS) via N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMAC). The successful fabrication of this optical sensor is confirmed by extensive characterizations using FT-IR, low angle X-ray diffraction (XRD), UV-vis spectroscopy and N(2) sorption, meanwhile its colorimetric properties, selectivity, sensitivity and reversibility are also investigated. The optical sensor responds selectively to heavy metal ions, such as Fe(3+), Cd(2+), Ni(2+), Zn(2+), Pb(2+), Co(2+), Hg(2+) and Cu(2+) with a color change from yellow to orange or purple in alkaline solutions, while it shows a color change only for Cu(2+) under strongly acidic conditions. At pH 12.0, this optical sensor has a high sensitivity that makes it possible to detect Cu(2+) in aqueous solution with the detection limit as low as 40ppb by naked-eye. This optical sensor also shows excellent reversibility and regeneration by treatment with a solution of EDTA.Copyright © 2011 Elsevier B.V. All rights reserved.