NANOSTRUCTURED CARBON DOT FROM MUSA PARADISIACA PEELS FOR THE REMOVAL OF METALS (CR, CU & MN) FROM PRODUCED WATER

This study investigated the use of nanostructured carbon dots (CDs) synthesized from Musa paradisiaca (plantain) peels for the removal of heavy metals, lead (Pb²⁺), copper (Cu²⁺), and iron (Fe²⁺), from produced water. The CDs were synthesized through a simple hydrothermal process and thoroughly characterized using Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and Transmission Electron Microscopy (TEM). These techniques were applied to determine the surface morphology, elemental composition, key functional groups, thermal stability, and structural properties of the synthesized adsorbent. Adsorption experiments were conducted to evaluate the performance of the CDs under different operational conditions. Specifically, the effect of contact time was studied at 30, 60, 90, 120, and 150 minutes, while the effect of adsorbent dosage was examined using 0.5, 1.0, 1.5, 2.0, and 2.5 g of CDs. The results indicated that removal efficiency increased consistently with both higher dosage and longer contact time. Optimal adsorption performance was recorded at 2.5 g dosage and 150 minutes contact time, where removal efficiencies greater than 99% were achieved for all three metals. Kinetic studies using pseudo-first-order (PFO) and pseudo-second-order (PSO) models revealed that the PFO model provided a better fit for the adsorption of Pb²⁺, Cu²⁺, and Fe²⁺, with R² values of 0.8791, 0.7303, and 0.8241 respectively. This suggests that the adsorption process was primarily governed by physical interactions. Additionally, isotherm analysis showed that the Langmuir model best described the equilibrium data, for Fe²⁺, (R² = 0.9924) Fe²⁺, Pb²⁺ (0.8975) and Cu²⁺ (0.8145), indicating monolayer adsorption on a uniformly distributed active surface. Furthermore, the study utilized Central Composite Design (CCD) under Response Surface Methodology (RSM) to model and optimize the adsorption process. The design evaluated the interaction of contact time and adsorbent dosage on removal efficiency, and identified optimal conditions (53.46 minutes, 2.80 g dosage) that yielded high desirability (1.000) and near-complete metal removal. This work demonstrates that carbon dots derived from plantain peels are highly efficient, cost-effective, and environmentally friendly adsorbents suitable for heavy metal remediation in produced water. Their excellent performance shows their potential for advancing sustainable wastewater treatment technologies.