The synthesis and study of carboxymethyl cellulose from water hyacinth biomass stabilized silver nanoparticles for a colorimetric detection sensor of Hg( <scp>ii</scp> ) ions

This study aims to synthesize silver nanoparticles, using carboxymethyl cellulose from water hyacinth biomass by a direct synthesis method, for the detection of Hg²⁺, which is a hazardous heavy metal that pollutes the environment. The successful synthesis of carboxymethyl cellulose from water hyacinth biomass to stabilize silver nanoparticles (CMC-AgNPs) was confirmed by UV-vis spectroscopy with a surface plasmon resonance band at 410 nm. CMC-AgNPs were then identified using UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and zeta potential, before the study of Hg²⁺ detection. When the CMC-AgNPs solution comes into contact with mercury, a redox reaction occurs between mercury and CMC-AgNPs, resulting in a color change from yellow to colorless. The effects of different parameters, such as CMC-AgNPs concentration, reaction time and pH for detecting Hg²⁺, were studied, and the limit of detection (LOD) and limit of quantitation (LOQ) in this study were 3.14 μM and 10.45 μM, respectively. Moreover, CMC-AgNPs were used to prepare Hg²⁺ detection films to enhance the convenience of measurement.