Synthesis and assessment of fenugreek carbon quantum dots as novel green scale inhibitor

Novel Fenugreek Carbon Quantum dots were synthesized by One-step pyrolysis and characterized by FTIR, TEM, XRD, and XPS. The FTIR "Fourier Transform Infrared Spectroscopy" spectrum of FCQDs displayed multiple peaks at different wavenumbers indicating that the FCQDs have a significant presence of nitrogen, oxygen functional groups, and unsaturated double bonds on their surface. TEM analysis of FCQDs molecules reveals that they are nearly uniform spherical nanoparticles, typically measuring around 5–6 nm in diameter. The XPS spectra were conducted to further confirm the chemical composition and bonding in FCQDs, aligning with the results obtained from FTIR. The inhibition behavior and efficiency of the synthesized FCQDs for precipitation of CaCO₃ scale were investigated using the conductivity and chronoconductivity methods and the results of both gave similar results of 65% inhibition at 300 mg/L FCQDs. The inhibition mechanism of CaCO₃ precipitation by FCQDs was investigated by SEM, XRD. Langmuir, Flory–Huggins isotherm, and the Kinetic-thermodynamic model were applied to fit the experimental results of the adsorption of FCQDs at CaCO₃ microcrystals. The results indicated that the adsorption behavior of the carbon dots molecules at the surface of scale microcrystals is (physical/ chemical) type with ∆G°_ads of − 24.5 kJ/mole.