Green colorimetric recognition of trace sulfide ions in water samples using curcumin nanoparticle in micelle mediated system

In this paper, green curcumin nanoparticles (CURNs) are introduced for colorimetric sensing of sulfide using micelle mediated cloud point extraction for the first time. CURNs are transferred into non-ionic surfactant phase and show strong surface plasmon absorption intensity. The extraction of CURNs to the surfactant rich phase is suppressed in the presence of Cu2+ but upon addition of sulfide, the extraction of CURNs to the surfactant rich phase is increased again. This increase in the absorbance of surfactant rich phase is related to the sulfide concentration and was used as an analytical signal for the sensing of sulfide. The effect of chemical variables such as pH of the sample solution, concentration of Cu2+, electrolyte and CURNs on the cloud point extraction was studied. Under optimum conditions, the change in absorption intensity was linearly proportional to the concentration of sulfide in the range of 0.5–200.0 ng mL−1 with a detection limit of 0.4 ng mL−1. The relative standard deviations for 10 replicate measurements of 20 ng mL−1 and 175 ng mL−1 of sulfide were 4.1% and 1.4% respectively. The method was successfully applied to the determination of sulfide in different water samples.