Functionalized Banana Stalk for Lumefantrine Drug Removal

Functionalized banana stalk (BSAC) was investigated as a potential adsorbent in removing a commonly used pharmaceutical antimalaria drug, Lumefantrine (LUMF). The raw banana stalk was chemically treated with orthophosphoric acid to enhance its adsorptive properties. The effect of LUMF initial concentration, temperature, solution pH and contact time on the adsorption process was studied using the batch equilibrium process. The surface characteristics of the prepared adsorbent were investigated using SEM, FTIR, proximate analysis and the Boehm titration techniques. The FTIR spectra showed notable peaks that are responsible for the adsorptive uptake of LUMF. The micrograph from the SEM showed well-developed pores which can be attributed to the effect of the acid treatment, and results from the proximate analysis showed 73.92% carbon content which is a remarkable percentage for a favorable uptake. The Sips isotherm model best fitted the experimental data with an R^2 = 1, and a maximum adsorption capacity of 102.1 mg g^-1. The closeness of the n values obtained from the Sips isotherm to 1 makes the model approach that of the Langmuir isotherm suggesting a monolayer coverage of LUMF on the BSAC surface. The pseudo-second-order kinetic model best explains the kinetics of adsorption of LUMF onto BSAC with R^2 values ranging from 0.9845-0.9997. The optimum pH recorded for this study was found between 5-7, and the pHpzc for the BSAC was obtained at 4.5. Parameters obtained from the thermodynamic studies suggest that LUMF uptake by BSAC is endothermic, spontaneous, and thermodynamically favored (ΔH° = +46.83 kJ mol^-1, ΔS° = +0.242 kJ K^-1 mol^-1 and ΔG° = -41.66 kJ mol^-1). BSAC was found to be effective in removing LUMF from aqueous solutions.