Polyaniline (PANI), a conducting polymer, can be modified to become a useful sensor for acidic dyes1 .
Researchers have doped PANI with two organic compounds. The modified PANI selectively binds to acidic dyes sparing basic dyes. Acid dyes exhibit the highest toxicity level. Dyes including acidic ones have the ability to induce sensitization in humans. Acidic dyes are used in various industries including textile.
Using two doping agents p-toluenesulfonic acid (PTSA) and camphorsulfonic acid (CSA), the researchers modified PANI and studied its efficacy with various acidic dyes.
They found that the doped PANI selectively adsorbs acidic dyes and does not adsorb cationic (basic) dyes. The adsorbed dyes were desorbed from the polymer by using a basic aqueous solution. The adsorption of acidic dyes causes the variation in electrical conductivity of PANI. This indicates its potential as a conductometric sensor for these dyes at very low concentration.
The authors of this work are from: Solid State and Structural Chemistry Unit and Department of Chemical Engineering, Indian Institute Science, Bangalore, and Polymer and Engineering, National Chemical Laboratory, Pune.
