1-(2-Pyridylazo)-2-Naphthol Entrapped Polyacrylamide Hydrogels: Detection of Copper Ions in Water

Abstract A colorimetric material was prepared and evaluated for simple and rapid detection of copper ion and other toxic metal ions. In this study, a colorimetric 1-(2-pyridylazo)-2-naphthol entrapped polyacrylamide (PAN-PAA) hydrogels was successfully prepared through polymerization and characterized by FT-IR. PAN-PAA hydrogels were evaluated for naked eye detection of Cu(II) ions in water. A yellow colour solution change into pink visual colour was observed within 20 min when hydrogel treated with Cu(II) ions at 300 μg L–1 (ppb). The colour ntensity increased with increasing concentration of Cu(II) ions. The reaction time of colour change observed less time when concentration of metal ion is increasing such as1 mg L–1 (15 min), 2 mg L–1 (10 min) and 3 mg L–1 (5 min). UV-visible spectra of PAN-PAA hydrogel shows absorbance at wavelength 560 nm with copper ions without interference of other metal ions viz. Cd(II), Co(II), Ni(II), Fe(II), Hg(II) and Pb(II). The hydrogels can be regenerated with 1 N HCl after reaction of Cu(II) ions. In conclusion, PAN-PAA hydrogel can be used as a potential colorimetric material for detection of Cu(II) ions in water. Colorimetric methods have their own advantages such as simplicity, high sensitivity and a short response time. In particular, these methods can be monitored by the naked eye and potential application in on-site detection owing to their simplicity and potability.