Simultaneous detection of aqueous aluminum(III) and chromium(III) using Persea americana reduced and capped silver nanoparticles

There is a significant interest to develop sensing devices that detect water toxins, especially heavy metal ions. Although there have already been numerical reports on detecting toxic heavy metal ions, the use of adaptable devices could enable a broader range of sensing applications. Here, we used fresh peel extract (PeA) and dried peel extract (DPeA) of Persea americana (Avocado) as a reducing and capping agent to synthesize and stabilize AgNPs. The dimensions of NPs were controlled by tuning pH, temperature, and volume of the reducing agent. The sensitivity and selectivity of the AgNPs toward various metal ions viz. Ni(II), Cd(II), Al(III), Hg(II), Cr(III), Ba(II), Pb(II), Zn(II), Co(II), Mn(II), Cu(II), Ca(II), Mg(II), and K(I) were studied. The detection probe was found to be selective and sensitive toward Al(III) and Cr(III) ions with the detection limit of 0.04 ppm and 0.05 ppm, respectively. High-resolution transmission electron microscope (HRTEM), ultraviolet-visible (UV-Vis) spectroscopy, and dynamic light scattering (DLS) analysis results confirm an agglomeration-based mechanism for sensing both metal ions. This method can be exploited for the colorimetric detection of toxic heavy metals in real water samples. Novelty statement This is the first study to report the use of avocado peel extract to synthesize AgNPs in sensing aqueous Al(III) and Cr(III) at trace level concentration.