Repeated use of Cyperus esculentus tubers, toward sustainable Green synthesis of silver Nanoparticles

For green synthesis to be a sustainable approach for preparing nanoparticles, efforts must go into the search of methods
that can guarantee effective and efficient use of bio resources. Most conventional approaches require fresh bio-reducing and
stabilizing agents for every synthesis cycle. This study demonstrates that Cyperus esculentus tubers can serve as efficient
bio-reducing and stabilizing agents’ source for multiple syntheses of silver nanoparticles. The simple approach for extracting
reducing agent from Cyperus esculentus tubers reported in this study offers the possibility to reuse the tubers for multiple
syntheses. Reductants from Cyperus esculentus were obtained by soaking the tubers in deionized water for 24 hours, with-
out the need of crushing. Addition of silver ions to the extract resulted in a rapid formation of silver nanoparticles. Effects
of sunlight exposure, temperature, and pH on the formation of silver nanoparticles were studied. Silver nanoparticles were
obtained in seconds under sunlight exposure, minutes at basic conditions, and hours under room and elevated temperatures.
In addition, the Cyperus esculentus tubers could be used multiple times for the preparation of silver nanoparticles, thus
serving as a sustainable bio reducing and stabilizing agents’ source for the preparation of silver nanoparticles. The results
from this study offers a simple, convenient, and economical approach for sustainable green synthesis of silver nanoparticles.
Keywords Silver nanoparticles · Cyperus esculentus tubers · Green synthesis · Tigernut · Bio-reductant