Procedure optimisation for green synthesis of silver nanoparticles by Taguchi method

Abstract

This study is dealing with optimisation of the green synthesised silver nanoparticles (AgNPs) using the Taguchi design. Orthogonal array of L9 type was used as an experimental design to detect the optimum conditions for synthesis of AgNPs. AgNPs were synthesised using the extract of Mentha longifolia as a reducing agent. In addition to the colour changes, ultraviolet visible spectroscopy was used to attest the appearance of AgNPs. Meanwhile, yielded AgNPs were characterised by FT-IR, scanning electron microscopy and dynamic light scattering (DLS) technique. UV–visible spectrophotometer showed absorbance peak at 340 nm. DLS analysis showed that the synthesised AgNPs are 21.1 nm in optimum conditions. The optimised condition for the synthesis of AgNPs revealed that silver nitrate concentration was 10 mM, temperature was 60°C, pH was 9 and plant extract concentration was 3%. The results demonstrated that AgNPs can be synthesised by controlling silver nitrate and plant extract concentration, pH and temperature. The minimum diameter predicted by statistical model was 35 nm while the obtained diameter was 21.1 nm which is very close to the experimental designed measure. This indicates that the statistical predicated proposed by Taguchi was correct.