SYNTHESIS AND OPTIMIZATION OF FUNCTIONALIZED CARBON DOTS FROM UNRIPE PLANTAIN PEELS (UPP) FOR BTEX REMOVAL FROM PRODUCED WATER

This study explores the synthesis, characterization, and optimization of functionalized carbon dots (CDs) derived from unripe plantain peels for the adsorption of BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) from produced water. Unripe plantain peels (UPP) were converted into carbon dots via hydrothermal carbonization, followed by surface functionalization with sodium hydroxide. The resulting functionalized CDs were characterized using photoluminescence (PL), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) surface area analysis. Batch adsorption experiments were performed to evaluate BTEX removal, with the effects of contact time (30–150 min), adsorbent dosage (0.5–2.5 g), and temperature (30–70°C) optimized using Response Surface Methodology. The results showed that PL exhibited green fluorescence, while FTIR confirmed the presence of hydroxyl (-OH) and carbonyl (C=O) groups. XRD revealed semi-crystalline structures, and TEM indicated an average particle size of 6.5 nm. SEM showed a quasi-spherical shape, and EDX revealed 89.65% carbon content. BET analysis indicated a high surface area (990.50 m²/g) and large pore volume (1550.52 cm³/g). A quadratic model explained the process with high determination coefficients (R² = 0.9813), and up to 96% BTEX removal was achieved. Isotherm studies showed that the Temkin and Langmuir model (R² = 0.9723 and 0.9664) best described the adsorption process, indicating monolayer adsorption on a surface with finite sites. The Freundlich model (R² = 0.8311) suggested a multilayer adsorption process. The kinetic model of the adsorption of BTEX follows the second order kinetics with R2 = 1.