Biosynthesis and Stabilization of Nanosilver Using Houttuynia Extract for Degradation of Azo Acid and Mordant Dyes

Abstract

Silver nanoparticles (AgNPs) are promising candidates for environmental remediation due to their exceptional catalytic properties. However, their tendency to aggregate during formation undermines their stability, posing challenges for large-scale production. This study presents a one-step biosynthesis method of AgNPs using Houttuynia plant (Houttugniae herba) extract, where the plant biomolecules act as both reducer and stabilizer. The bioreduction kinetics were meticulously optimized using the one-factor-at-a-time (OFAT) approach, establishing the ideal synthesis conditions as follows: 1.0 mM AgNO3, 0.1 ml Houttuynia plant extract, heated at 80 °C for 45 minutes, with the medium at pH 9. Morphological characterization revealed the formation of spherical, well separated, and highly crystalline (d-spacing = 0.237 nm) AgNPs with an average particle size of 7.756 ± 2.372 nm. The synthesized AgNPs exhibited remarkable catalytic activity in reducing azo dyes, achieving degradation rates of approximately 98% for both acid red 1 (AR1) and mordant blue 9 (MB9) within 4 and 20 minutes, respectively. This eco-friendly and cost-effective method can be an excellent alternative for treating industrial effluents.