Self-assembled poly(N-methylaniline)-lignosulfonate spheres: from silver-ion adsorbent to antimicrobial material

Self-assembled poly(N-methylaniline)-lignosulfonate (PNMA-LS) composite spheres with reactive silver-ion adsorbability were prepared from N-methylaniline by using lignosulfonate (LS) as a dispersant. The results show that the PNMA-LS composite consisted of spheres with good size distribution and an average diameter of 1.03-1.27 μm, and the spheres were assembled by their final nanofibers with an average diameter of 19-34 nm. The PNMA-LS composite spheres exhibit excellent silver-ion adsorption; the maximum adsorption capacity of silver ions is up to 2.16 g g(-1) at an adsorption temperature of 308 K. TEM and wide-angle X-ray results of the PNMA-LS composite spheres after absorption of silver ions show that silver ions are reduced to silver nanoparticles with a mean diameter of about 11.2 nm through a redox reaction between the PNMA-LS composite and the silver ions. The main adsorption mechanism between the PNMA-LS composite and the silver ions is chelation and redox adsorption. In particular, a ternary PNMA-LS-Ag composite achieved by using the reducing reaction between PNMA-LS composite spheres and silver ions can be used as an antibacterial material with high bactericidal rate of 99.95 and 99.99% for Escherichia coli and Staphylococcus aureus cells, respectively.