Biosynthesis of Ag-Cu-Al Nanoparticles for Efficient Adsorption of Lead, Iron and Chromium from Industrial Wastewater

Abstract

Lack of proper effluent disposal methods in industries has led to an exacerbation of the risk posed by heavy metal contaminants present in industrial wastewater. Several approaches have been explored to mitigate these harmful threats but, most of these approaches have several limitations such as, lacking selectivity, removing essential ions along with heavy metals, high post-treatment cost and generating toxic byproducts which further contaminates the environment. To address these difficulties, nanoparticles have recently been employed to mitigate these limitations. Nanoparticles, owing to their minute size and large surface-to-volume ratio, exhibit enhanced reactivity and adsorption capacities, making them exceptional contenders for heavy metal removal. Furthermore, the synergistic effect of trimetallic nanoparticles has also increased its efficacy as an adsorbent. This study efficiently biosynthesized silver-copper-aluminum trimetallic nanoparticles (Ag-Cu-Al NPs) using aqueous leaves extract of Hierochloe odorata at room temperature. The synergistic effect of the three metals was efficiently harnessed in conjunction with the biologically active components from Hierochloe odorata present in the nanoparticles, to enhance the adsorption affinity of the nanoparticles towards available heavy metal ions present in the wastewater. The biosynthesized Ag-Cu-Al NPs was first confirmed by an obvious color shift from grey to olive green after adding the aqueous leaves extract to the trimetallic salt solution of silver nitrate, copper chloride and aluminum oxide. UV-vis spectroscopy of the nanoparticles presented a distinct peak maximum at 405 nm. The possible secondary metabolites responsible for bio-reduction, capping and homogeneity of the nanoparticles were assessed using FTIR. The crystalline nature and particle size of the NPs were investigated using XRD. SEM-EDS analysis revealed the surface texture and constituent elements of the NPs. Adsorption studies demonstrated that the biosynthesized Ag-Cu-Al nanoparticles acts as a highly efficient nano-adsorbent for the removal of lead, iron and chromium from industrial wastewater.