Waste upcycling of Sapota peels as a green route for the synthesis of silver nanoparticles and their application as catalytic and colorimetric detection of Co2+ and Hg2+

Biochemical synthesis of nanoparticles (NPs) using plant part extracts as capping and reducing agents has drawn considerable attention in research with a growing focus on green chemistry. The present study utilized Sapota (Manilkara zapota L.) peel extract to synthesize silver nanoparticles (SP-AgNPs) using ultrasonic vibration. Different characterization techniques such as UV-vis spectroscopy, dynamic light scattering, Fourier Transform Infrared Spectroscopy, Field emission scanning electron microscope, High resolution transmission electron microscopy, and X-ray diffraction were employed to check the production of SP-AgNPs. The AgNPs were crystalline in nature and had an average particle size of 27.906 nm. The research primarily focused on two aspects: the catalytic activity of SP-AgNPs in degrading environmental pollutants and their ability to act as colorimetric sensors for toxic metal ions. SP-AgNPs exhibited significant catalytic activity in the decomposition of various pollutants such as Methyl Orange (0.035 +/- 0.090 min-1, 92.89 +/- 1.79%), Crystal Violet (0.1097 +/- 0.1016 min-1, 85.56 +/- 2.21%) and Cosmic Brilliant Blue G-250 (0.0697 +/- 0.0275 min-1, 79.56 +/- 1.80%). The high degradation percentages and reaction rate constants indicate the efficiency of SP-AgNPs in pollutant degradation. Additionally, the study demonstrated the effectiveness of SP-AgNPs as sensors for detecting toxic metal ions, particularly Co2+ and Hg2+ with limits of detection 54.40 +/- 1.43 mu M and 10.70 +/- 0.16 mu M. With impressive sensitivity and low detection limits, SP-AgNPs showed promise in detecting these ions, which are often found in environmental contaminants. Moreover, their plant-based synthesis, low toxicity, and cost-effectiveness make them attractive options for environmental remediation efforts.