Colorimetric sensing of cyanide anions in aqueous media based on functional surface modification of natural cellulose materials

The synthesis of two new water soluble azo dyes and their optical response to different anions is reported herein. Solution studies in water indicate that cyanide induces a colour change in these dyes, whereas no changes are observed in the presence of other anions, such as CH3COOH−,HSO4−,ClO3−,ClO4−,Cl−,Br−,H2PO4−,S2O3−,F−,NO3−,I−,NO2−,SO32−,S2−,C2O42−,SO42−,N3−,SCN−,F−,CO32−,HCO32−. In the second part of the paper, we report the incorporation of one of these dyes onto cellulosic fibres. The dye-sensitized cellulose materials were immersed in solutions of different anions and their response studied. The material is able to detect cyanide about 0.01-0.07 μM in aqueous solution with high selectivity over other anions.