Magnetic hexadecylamine-graphene quantum dots-silver nanoparticle nanocomposite as adsorbents for the removal of phenanthrene and bacteria from aqueous solution

In this study, novel multifunctional magnetic silver nanoparticles complexed with hexadecylamine-functionalized sulfur- and nitrogen-co-doped graphene quantum dots (AgNPs@Fe3O4-C16SNGQDs) were tested for the removal of phenanthrene and as antibacterial agents from an aqueous solution. The resulting materials were successfully applied as adsorbents and antibacterial agents in batch adsorption and disk diffusion tests. An average Brunauer–Emmett–Teller (BET) surface area of 83.7 and 85.3 m2/g was obtained for AgNPs@Fe3O4 and AgNPs@Fe3O4-C16SNGQDs, respectively. Accordingly, adsorption capacity evaluated using the Langmuir adsorption isotherm was found to be 4097.7 and 5965.7 mg/g for AgNPs@Fe3O4 and AgNPs@Fe3O4-C16SNGQDs, respectively, after 24 h mixing time. The modification of AgNPs@Fe3O4 with C16-SNGQDs facilitated higher adsorption performance at ambient temperature, which is more sustainable and cost-effective when considering large-scale use. Furthermore, C16-SNGQDs showed increased antibacterial activity against negatively charged bacterial strains, whereas AgNPs@Fe3O4-C16SNGQDs showed enhanced inhibition against gram-positive bacteria. Hence, multifunctional nanoparticles have the potential for microbial and chemical pollution remediation and could significantly improve current water treatment methods.