Biosorption of Manganese Using Moringa oleifera Seed Pods: A Sustainable Approach to Water Treatment

Manganese can be considered an emerging contaminant, as it is present at levels exceeding those established by authorities in various environments worldwide. Its presence is due to both anthropogenic activities and natural processes. Although it is a natural health promoter, at high levels it can cause damage to humans and the environment. Therefore, this study aimed to utilize the Moringa oleifera seed pod, a byproduct of its production, as a biosorbent for removing Mn from water containing an excess of this ion, thereby contributing to water treatment and reducing environmental liabilities. The biosorbents were prepared from Moringa oleifera raw pods and chemically modified using NaOH and HCl, demonstrating their ability to remove Mn(II) from the tested water. EDS, SEM, and FTIR were used to characterize the biosorbents. The experimental data were kinetically analyzed, and it was found that the biosorption of the three different adsorbents followed pseudo-second-order kinetics, with an equilibrium time of 30 minutes. The most efficient biosorbent for manganese removal was the basic-treated pod, achieving a 94% removal rate. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm models, yielding a maximum adsorption capacity of 7.64 mg g-1 for the pods with basic treatment and 6.00 mg g-1 for the pods in their natural state. The thermodynamic properties were also evaluated, confirming the spontaneous nature of the reaction and the feasibility of the bioremediation process using the pods. The results show that the adopted process is viable, as it removes manganese from contaminated water and provides sustainability for processing waste from Moringa oleifera oilseed.