Abstract
This study presents the development and characterization of a polymer-immobilized silver nanoparticle (AgNP) composite for potential application in water remediation and metal recycling. AgNPs were synthesized by ultrasonic spray pyrolysis (USP) using silver nitrate as a precursor and polyvinylpyrrolidone (PVP) as a stabilizing agent, followed by incorporation into a sodium alginate matrix to form separable alginate/AgNP beads. The nanoparticles were characterized by scanning and transmission electron microscopy (SEM, TEM), energy-dispersive X-ray spectroscopy (EDS), selected-area electron diffraction (SAED), dynamic light scattering (DLS), and zeta-potential measurements. The AgNPs were predominantly spherical and crystalline, with a TEM observed average diameter of approximately 90 nm and most particles between 50 and 125 nm. A PVP surface layer of up to approximately 10 nm was observed. DLS measurements showed a hydrodynamic diameter of 159.6 nm. AgNP incorporation into the alginate matrix was confirmed by microscopy and elemental analysis. AgCl formation inside parts of the composite was observed, indicating chemical transformation of silver and the possibility of affected stability and performance due to interactions with the surrounding environment. The dried composite exhibited a low specific surface area of 0.05 m²/g and a pore size of approximately 2 nm, indicating limited accessible porosity. Results indicate a required further optimization of AgNP loading and alginate structure, with preliminary tests of microplastic (MP) interactions with alginate/AgNP beads showing a limited interaction under the tested conditions. The developed composite provides a basis for multifunctional water treatment materials targeting microbial, metallic, organic, and MP contaminants and subsequent metal recycling.