Novel and sustainable green sulfur-doped carbon nanospheres via hydrothermal process for Cd (II) ion removal

Herein, the synthesis, characterization, and adsorption performance of a novel green sulfur-doped carbon nanosphere (S-CNs) is studied to eliminate Cd (II) ions from water effectively. S-CNs were characterized using different techniques including Raman spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), Brunauer–Emmett–Teller (BET) specific surface area analysis and Fourier transform infrared spectrophotometry (FT-IR), were performed. The efficient adsorption of the Cd (II) ions onto S-CNs strongly depended on pH, initial concentration of Cd (II) ions, S-CNs dosage, and temperature. Four isotherm models (Langmuir, Freundlich, Temkin & Redlich Peterson) were tested for modeling. Out of four, Langmuir showed more applicability than the other three models, with a Q_max value of 242.72 mg/g. Kinetic modeling studies suggest a superior fit of the obtained experimental data with the Elovich equation (linear) and pseudo-second-order (non-linear) rather than other linear and non-linear models. Data obtained from thermodynamic modeling indicates that using S-CNs for Cd (II) ions adsorption is a spontaneous and endothermic . The current work recommends using better and recyclable S-CNs to uptake excess Cd (II) ions.