K Mousapour - Department of Chemistry, Payame Noor University, sari, Iran
S Hajizadeh - Department of Chemistry, Urmia University, Urmia, Iran
K Farhadi - Departments of Chemistry, Urmia University, Urmia, Iran

A simple, rapid, sensitive and selective colorimetric sensor for the determination of Cr (III) in aqueous solution based onbarbituric acid functionalized silver nanoparticles (BA- Ag NPs) has been developed. Cr (III) induces BA- Ag NPsaggregation and color of BA–AgNPs solution changes from yellow to red which is easy to detect by the naked eye. The Cr(III) can be detected rapidly based on the color change of the system. The ratio of UV-Vis absorption intensity at 520 nm toabsorption intensity at 418 nm (A520/A418) is linearly proportional to the concentration of Cr (III) from 0.012 to3.25 ppm.The presence of Cr (III) leads to a marked red-shift of extinction bands, whereas a BA-AgNPs solution does not exhibitcolorimetric response upon the addition of other cations. The mechanism of interaction between BA-AgNPs and Cr (III)was studied by UV-Vis spectrophotometry and transition electron microscopy (TEM). The proposed method has beensuccessfully used for the determination of Cr (III) in petrochemical wastewater.

silver nanoparticles, 2-thio barbituric acid, Cr (III), colorimetric sensor