Use of mushroom extract for the synthesis of copper nickel bimetallic nanoparticles: chemical functionalization with polyethyleneimine polymer, characterization, and application to the adsorption of anionic dyes from water

In the current work, a biological extract of mushroom was used to synthesize copper nickel bimetallic nanoparticles (CuNi). The prepared CuNi bimetallic nanoparticles were then functionalized with polyethyleneimine polymer. The prepared nanocomposites (CuNi/PEI) were characterized using several analytical techniques including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA). FT-IR showed that several phyto-constituents could act as reducing and stabilizing agents for CuNi. Some nanoparticles looked spherical and some others were nano-rods. The XRD sharp peak, at 2<i>θ</i> = 25.4°, indicated the crystalline nature of CuNi bimetallic nanoparticles. The crystallinity of CuNi was not significantly affected after surface functionalization with polyethyleneimine. The prepared nanocomposites were thermally less stable than CuNi. Further, the nanocomposites were used for the adsorption of two anionic dyes namely Acid Blue 25 (AB25) and Naphthol blue black B (NBBB). At optimum conditions, the highest adsorption capacities of AB25 and NBBB using CuNi/PEI nanocomposites were 198 and 152 mg/g, respectively. However, the adsorption abilities of AB25 and NBBB using CuNi bimetallic nanoparticles were only 35 and 24 mg/g, respectively. The adsorption mechanism was exothermic, nonspontaneous, and fitted well to the pseudo-second order kinetic model and Langmuir isotherm. Overall, the green approach, facile synthesis, and adsorption performance suggested that the prepared CuNi/PEI nanocomposite could be used as an excellent candidate in decolorization processes.