Adsorption of Mn2+ from the Acid Mine Drainage using Banana Peel

The sustainable removal of heavy metals from Acid Mine Drainage (AMD) has become a major challenge to scientists and engineers despite numerous treatment technologies. This is because most of the explored technologies are too expensive and also have significant disposal challenges. Therefore, the need to develop a more effective and affordable technology for the removal of heavy metals from AMD is inevitable. The banana peel, the most abundant fruit that is almost consumed across the world, was explored in this study to evaluate its potential to remove heavy metals under AMD conditions. The adsorption of manganese metal ion (Mn2+) has been studied to investigate the effects of controlling parameters such as particle size, doses, and initial concentration of Mn2+, contact time, pH and selectivity of the banana peel. Synthetic single component solution and actual AMD were used in a batch system. Langmuir and Freundlich isotherms were applied to describe adsorption equilibrium. The maximum amount of Mn2+ metal ions adsorbed, as evaluated by Langmuir isotherm was 6.920 mg.g-1. The adsorption data also fitted the pseudo second order kinetics very well and suggested that the adsorption is characterized by the valence forces through exchange of charges between banana peel powder and heavy metal ion. Continuous fixed bed column studies were conducted by using AMD at room temperature and the effects of various parameters like flowrate and bed depth were investigated. The column bed capacity and saturation time as expected increased with the increase of bed depth and decrease of flowrate. The results show that the column performed well at lowest flowrate. The Thomas model and Bed Depth Service Time (BDST) model were applied to evaluate the breakthrough curves and to analyse the experimental data. The results obtained in this study demonstrated that the banana peel powder can be used for the removal of Mn2+ ions from AMD using batch and fixed bed adsorption system.