Green synthesis of iron and silver nanoparticles from aqueous extract of buckwheat husk waste: antibacterial, cytotoxic, and dye decolorization properties

Iron oxide (BHFeNP) and silver nanoparticles (BHAgNP) were produced using a green synthesis method through the extract of buckwheat husk (BH) waste to remove dye pollutants from water bodies in this study. The BHFeNP and BHAgNP were characterized by TEM, SEM, XRD, EDX, and FTIR techniques. Then, the methylene blue (MB) removal performance of the synthesized nanoparticles (NPs) was investigated. MB adsorption experiments showed that BHFeNPs were more dependent on temperature, adsorbent amount, and pH, while BHAgNPs notably depended on adsorbent amount, initial MB concentration, and pH. BHAgNPs had higher adsorption rates than BHFeNPs, and the Langmuir isotherm was more suitable for the adsorption process. BHAgNP and BHFeNP were shown to have the maximum adsorption capacities of 96.3 and 53.4 mg/g at pH 8 and 25 °C, respectively, in the presence of 0.25 g/L NP. Kinetic and thermodynamic calculations revealed that MB adsorption was spontaneously endothermic and supported the pseudo-second-order kinetic model. The antibacterial potentials of BHFeNPs and BHAgNPs were investigated against two gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two gram-positive (Enterococcus faecalis and Staphylococcus aureus) bacterial strains. BHAgNPs exhibited a higher antibacterial activity against the strains used. In cytotoxicity studies with ARPE-19, A549, HeLa, and DU-145 cell lines, it was observed that BHAgNP had a greater cell growth inhibition effect than BHFeNP and BH extract. Examining the morphological changes in the cells exhibited that BHAgNP significantly inhibited A549 and ARPE-19. Reusability studies of the generated NPs revealed MB removal capabilities of 92.5% and above after the fifth stage. The present study demonstrates that BHAgNP and BHFeNPs are viable nanoadsorbents for the elimination of environmental pollution due to their excellent removal performances and stable adsorbent characteristics.