An aqueous, paper, and gel-based method by using eco-friendly synthesised silver nanoparticles towards rapid colorimetric sensing of palladium ion

In this study, developments were made for silver nanoparticles(AgNPs) synthesis as a colorimetric sensor that is rapid and selectiveusing a bio-reductant of lemongrass extract. The synthesised AgNPswere designed to detect Pd2+ using aqueous, paper, and gel meth-ods. AgNPs were characterised by UV-Vis, FTIR (Fourier TransformInfrared), TEM (Transmission Electron Microscopy), and XRD spec-troscopic analysis (X-Ray Diffraction). These AgNPs aqueous colori-metric sensors showed a good selectivity towards Pd metal ions,which was characterised by AgNPs SPR (Surface PlasmonResonance) tape shifts at 430 nm wavelengths, with the colourchange from dark yellow to clear greyish within 5 seconds. Thecolour changed from yellow to white for AgNPs paper and darkyellow to bright yellow for the gel colorimetric sensor after 5seconds interaction with Pd2+. The limit of detection for aqueous,paper, and gel were 48.635 ppb, 5 ppm and 5 ppm, respectively.Method validation has been conducted, and these AgNPs sensorswere applied for monitoring the Lake Sasak, South Tangerang,water samples and the accuracy and precision of the sensor weretested. This sensor is expected to establish an alternative techniquefor in situ Pd2+ detection and lake water monitoring.