Direct synthesis of lemongrass (Cymbopogon citratus L.) essential oil-silver nanoparticles (EO-AgNPs) as biopesticides and application for lichen inhibition on stones

Lemongrass essential oil (Cymbopogon citratus L.) is used directly to kill lichens and has many disadvantages such as being less effective, volatile, and inefficient. Lichens are a type of microbe that grows in rocks and cause biodeteriorations of rock material because they are highly erosive. Therefore, this research aims to investigate the direct synthesis of lemongrass (Cymbopogon citratus L.) essential oil-silver nanoparticles (EO-AgNPs) as biopesticides and application for lichens inhibition on stones. This was carried out in order to improve the performance and effectiveness of biopesticides which is excellent in killing lichens on stone surfaces. However, it has several disadvantages, such as not being economical, slow performance, and high volatility. The EO-AgNPs nanoparticles were produced by adding AgNO(3) powder directly to lemongrass essential oil. They were then observed to know the effect of variations in storage time on material stability and AgNO(3) concentration. The synthesized material was characterized by UV-Vis Spectrophotometer, FTIR, particle size analyzer (PSA), and SEM-EDX before being tested for its effectiveness in killing lichens directly on stones and inhibition activity. The results showed that the EO-AgNPs had been successfully synthesized as indicated by the color of the clear dark brown solution in the wavelength range of 430 nm. Furthermore, after it was analyzed using PSA and SEM-EDX, EO-AgNPs had a particle size of 332 nm and were spherical with Ag, C, O content of 27.28, 57.98, and 14.74%, respectively. The antifungal activity for killing lichens based on the diameter of inhibition zone (DIZ) using EO and EO-AgNO(3) was 14.7 mm and 20.3 mm, respectively. This shows that EO-AgNPs nanoparticles are capable of killing lichens on rock surfaces and also have a better inhibition activity than EO.