Distinctive detection of Fe2+ and Fe3+ by biosurfactant capped silver nanoparticles via naked eye colorimetric sensing

Abstract

Explicit detection of iron as Fe²⁺ and Fe³⁺ in biological and environmental systems using simple materials and methods is crucial. In this study, green synthesized silver nanoparticles (AgNps) capable of distinguishing Fe²⁺ and Fe³⁺ ions with certainty via simple naked eye visualization have been illustrated for the first time. Sapindus mukorossi pericarp extract was used as both a reducing and stabilizing agent for the synthesis of eco-friendly AgNps within 10 min by means of ultrasound assistance. The formation of AgNps was confirmed by visual observation and characterized by UV-vis, FT-IR, XRD, SEM-EDX, TEM and XPS techniques. The proposed AgNps were successfully explored as a potential colorimetric probe for selective, sensitive, and rapid detection and distinction of Fe²⁺ and Fe³⁺ ions over various other metal ions including Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Ba²⁺, Mn²⁺, Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ in an aqueous medium. The method was successfully applied to the determination of Fe²⁺ and Fe³⁺ ions in tap, drinking and river water which indicates the efficiency of the probe in real sample analysis.