Silver nanoparticle synthesis using lignin as reducing and capping agents: A kinetic and mechanistic study

Area of Science:

• Materials Science
• Nanotechnology
• Green Chemistry

Background:

• Silver nanoparticles (AgNPs) possess unique optical, electrical, and antimicrobial properties.
• Traditional synthesis methods often involve harsh chemicals and complex procedures.
• Alkali lignin (ALls), a byproduct of the paper industry, presents an opportunity for sustainable nanomaterial synthesis.

Purpose of the Study:

• To develop a green and efficient method for synthesizing AgNPs using ALls.
• To investigate the influence of pH on the synthesis mechanism and characteristics of AgNPs.
• To optimize synthesis parameters for high yield and controlled nanoparticle size.

Main Methods:

• Synthesis of AgNPs from silver nitrate (AgNO3) and ALls in aqueous solution.
• Investigation of pH-dependent reaction kinetics and mechanisms.
• Characterization of AgNP size, size distribution, and morphology using established techniques.
• Optimization of ALls concentration, temperature, and reaction time.

Main Results:

• AgNP synthesis was significantly influenced by pH, with distinct mechanisms observed under neutral, acidic, and alkaline conditions.
• Under optimal conditions (pH 10, 85°C, 30 min), near 100% yield of AgNPs was achieved.
• The synthesized AgNPs exhibited bimodal size distribution, with populations centered at 7.3 nm and 14.3 nm (Feret diameter).
• ALls acted as both a reducing and capping agent, facilitating nanoparticle formation and stability.

Conclusions:

• Alkali lignin is a viable, eco-friendly agent for the green synthesis of silver nanoparticles.
• pH control is crucial for directing the synthesis mechanism and achieving desired AgNP characteristics.
• The optimized method provides a scalable route for producing well-defined AgNPs with potential applications in various fields.