Detection of Azo Dyes Using Carbon Dots from Olive Mill Wastes

Azo dyes are widely spread in our day life, being heavily used cosmetics, healthcare products, textile industries, and as artificial food colorants. This intense industrial activity, which inherently includes their own production, inexorably leads to uncontrolled release of into the environment. As emerging pollutants, detection, particularly water systems, is a priority. Herein, fluorescence-based method was employed for sensitive selective detection anionic neutral azo dyes. Carbon dots (CDs) synthesized from wet pomace (WP), an abundant semi-solid waste olive mills, were probes. An outstanding capability methyl orange (MO) red (MR) aqueous solutions disclosed, reached limit (LOD) 151 ppb MO. The selectivity WP-CDs dye established through competitive experiments with other dyes, either (indigo carmine) or cationic (fuchsin, methylene blue, rhodamine 6G); perchlorate salts transition metal cations (Cu(II), Co(II), Fe(II), Fe(III), Hg(II), Pb(II)); sodium common anions (NO3−, CO32−, Cl−, SO42−). Evidence has been collected that supports static quenching main transduction event underlying observed probe’s fluorescence, combined dynamic resonance energy transfer (RET) mechanism at high MO concentrations.