Effective utilization of lignocellulosic waste generated from food processing centers towards removal of nitrate from water

Abstract

This study investigates the use of chemically modified Musa paradisiaca (banana fruit) peels (BPD) as an adsorbent for nitrate removal, representing a food waste management application of this agricultural waste material. This innovative approach addresses waste management challenges while offering a cost-effective and sustainable solution for water treatment. The research evaluates the effectiveness of BPD in a batch system and optimizes the process using Response Surface Methodology (RSM). Detailed characterization of the adsorbent was performed using advanced techniques including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Point of Zero Charge (pHzpc), Brunauer–Emmett–Teller (BET) surface area analysis, and Fourier Transform-Infrared Spectroscopy (FTIR). Isotherm analysis revealed that the Langmuir model provided an excellent fit (R² = 0.994), with a maximum adsorption capacity of 47.619 mg/g for BPD. Kinetic studies indicated that the pseudo-second-order model was most appropriate (R² = 0.969). Thermodynamic analysis showed that nitrate removal is more favorable at lower temperatures, with an increase in free energy at 313 K and a negative enthalpy value (-28.873 kJ/mol). Optimization via RSM identified optimal conditions: initial nitrate concentration of 83.92 mg/L, pH 3.57, contact time of 38.37 minutes, and temperature of 42.29 ℃, achieving a desirability score of 1.0. Furthermore, Density Functional Theory (DFT) analysis elucidated the adsorption mechanism, highlighting the predominance of C-O interactions in the ligand exchange process, with an electrophilicity index (ω) of −1.331 eV. These findings suggest that lignocellulosic materials from food processing waste, Musa paradisiaca peels, hold significant promise for mitigating nitrate contamination in drinking water.