Green Synthesis of Nickel and Copper Nanoparticles Doped with Silver from <i>Hammada scoparia</i> Leaf Extract and Evaluation of Their Potential to Inhibit Microorganisms and to Remove Dyes from Aqueous Solutions

Hammada scoparia (Pomel) is a powerful plant with important biological properties. In this study, we report on the green synthesis of silver-doped nickel and copper nanoparticles (NPs) in the presence of H. scoparia leaf extract using a self-propagating sol–gel autocombustion process. The synthesized NiO, CuO, Ag-NiO, and Ag-CuO NPs were characterized with Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Afterward, they were tested for their antimicrobial activity as well as their potential to remove dyes from aqueous solutions using adsorption processes for malachite green (MG) and photocatalytic degradation for methylene blue (MB). Our results showed that the mass of the adsorbent had a significant effect on the adsorption rate, which increased to reach a maximum value of 98%. The Ag-CuO NP showed the best final conversion of MB (97.95%) compared to NiO, CuO, and Ag-NiO. In addition, we noted that the NPs doped with silver had the best performance in the removal of dyes. These results indicated that the photocatalytic performance was significantly improved after the addition of silver. Moreover, the antimicrobial activity showed that the studied NPs had moderate activity against the tested bacteria and a weak activity or were ineffective against Candida albicans. Therefore, the green synthesis of NPs from H. scoparia leaf extract is considered a sustainable alternative to removing dyes from aqueous solutions. However, further investigation should be performed on the other dyes to understand the overall effectiveness of these NPs