Utilization of Tommy Atkins Mango Peel as a Sustainable Biosorbent for the Removal of Pb(II) Ions in Water

The contamination of water resources by heavy metals, such as lead ions, represents a serious environmental and public health problem, requiring effective treatment methods. This study evaluated the adsorptive potential of Tommy Atkins mango peel as a biosorbent for removing lead ions from synthetic aqueous solutions. The mango peels were obtained in the city of Crato, CE, dried in an oven at 313.15 K for 3 days, and then ground to a uniform powder. The material was characterized using x-ray fluorescence, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The fluorescence results indicated that the peel has a high potassium (5.093%) and calcium (2.170%) content, as well as significant incorporation of lead ions (28.882%) after the adsorption process. Infrared analysis identified functional groups such as ─OH, ─CH, ─C═O, and ─C─O, which are crucial for retaining metal ions. Electron microscopy images revealed a fibrous structure and uniform porosity, favoring adsorbent-adsorbate interaction. Kinetic studies showed that the pseudo-first-order model was the most suitable for describing the process, with an adjusted R² of 0.96258. The equilibrium time was reached in 60 min, with an adsorption capacity of 9.65 mg g^-1. Adsorption isotherms revealed that the Sips model provided the best fit to the experimental data, with maximum adsorption capacities of 72.57, 51.44, and 30.92 mg g^-1 at temperatures of 278.15, 298.15, and 318.15 K, respectively, with greater efficiency observed at lower temperatures. Thermodynamic analysis indicated an exothermic process, with ΔH° (-53.97 kJ mol^-1), ΔS° (-0.161 kJ mol^-1K^-1), and negative ΔG° confirming the favorable and spontaneous nature of adsorption, alongside a reduction in system entropy. Tommy Atkins mango peel, therefore, demonstrates promising characteristics as a biosorbent, combining efficiency in the adsorption process with environmental sustainability due to its origin as agricultural waste. This study contributes to the valorization of plant by-products and expands the possibilities of accessible and sustainable solutions for the treatment of water contaminated by heavy metals.