Biogenic nano-silver doped grapefruit peels biocomposite for biosorptive photocatalytic degradation of organic pollutants

In the present study a novel biogenic nano-silver doped grapefruit peels biocomposite (GFP@Ag) has been synthesized in a single-step procedure. The GFP@Ag nano-biocomposite was characterized using UV Visible spectrophotometer, Fourier Transform infrared (FTIR), scanning electron microscopy (SEM), (EDS), Thermogravimetric analysis (TGA), Proton nuclear resonance (¹HNMR), and N₂ adsorption desorption isotherm (BET). A combined approach of photocatalysis and biosorption is involved for the Toluidine blue O (TO), Crystal violet (CV), and brilliant green (BG) cationic dyes utilizing GFP@Ag biocomposite at pH (4-8). The investigated dye concentration was (100-200 ppm) with contact time (20-120 min) and 0.005 g of GFP@Ag at 25 °C under visible sunlight. The maximum degradation-biosorption capacities were 194.8 mg/g, 390.6 mg/g, and 306 mg/g for TO, CV, and BG, respectively. It was concluded that the TO, CV, and BG experimental data matched the pseudo-2nd -order (PSO) and Langmuir models from the kinetic and isotherm studies, respectively. The GFP@Ag was successfully applied to remove TO, CV, and BG multi systems (binary & tertiary). It was concluded that from the thermodynamics investigation, the current photocatalytic-biosorption processes are spontaneous and endothermic. The investigation was extended to estimate a straightforward and environmentally friendly method of producing silver nanoparticles that was able to overcome the drawbacks of alternative methods. Moreover, the evaluation of the applicability of GFP@Ag for the TO, CV, and BG removal in water samples was obtained. The GFP@Ag can be regenerated after the TO removal. The mechanism of the degradation-biosorption of the pollutants under study is elucidated.