Lignin has proven to be an effective reducing agent to synthesize spherical silver nanoparticles from silver nitrate with approaching 100% yield under basic conditions. The reaction mechanism and kinetics examined by UV-vis spectroscopy and TEM indicated instantaneous reduction of silver cations by lignin and nanoparticle formation in two stages: rapid growth and slower pseudo-first order kinetics. The overall reaction kinetics were found to be dependent of a combination of pH and temperature whereas the particles sizes and size distribution were influenced by the length of reaction time, lignin/silver ratio and initial total concentration collectively. Under the optimal condition of 2 mmol/L silver nitrate and 0.16wt% lignin at pH 10, silver nanoparticles in bimodally distributed average feret diameters of 7.3�2.2 nm and 14.3�1.8 nm were synthesized in 23/77 proportion. Elucidation of the underlying reaction mechanism and kinetics clearly validated the feasibilities of controlled silver nanoparticle synthesis by naturally occuring polyphenolics such as lignin.

Silver nanoparticles synthesis with lignin as a reducing and capping agent

246th National Meeting (2013)

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