Sequestration potential of bagged agrowaste activated carbon for iron and manganese from aqueous media: isothermic and kinetic modelling

In this study, activated carbons (ACs) from banana stems and ripped plantain peels were used in the mitigation of iron (Fe²⁺) and manganese (Mn²⁺) in aqueous media. The AC were activated by soaking in 20% phosphoric acid (H₃PO₄) at a ratio of 1:5. The AC was calcined at 500 °C and washed till near neutral pH. The ACs were characterized by SEM, FTIR, and BET analysis. Ripped plantain peel AC (RPPAC), and Banana Stem AC (BSAC) were packaged as bagged and unbagged adsorbents. All adsorption experiments were undertaken using 2 g of adsorbent, pH 6 and at room temperature (25 °C). The maximum removal efficiency of bagged BSAC and RPPAC were 99.95% (for both) at 30 minutes for Mn²⁺. The bagged and unbagged BSAC resulted in 72.5% removal efficiency value (at 120 minutes) and 99.1% removal efficiency (at 90 minutes) for Fe²⁺ removal respectively. At a contact time of 30 mins, the unbagged (RPPAC and BSAC) adsorbents had a removal efficiency of 99.95% for both Fe²⁺ and Mn²⁺. Adsorbents were evaluated via Isotherm and kinetic models and were found effective in mitigating Fe and Mn contamination in water.