BIOADSORBENT FROM ORANGE PEEL FOR THE REMOVAL OF MANGANESE (II) ION FROM AQUEOUS SOLUTION

Abstract

Advisor: Shibiru Yadeta (PhD) Manganese ions occur most commonly in the water and an excess amount of this ion may be dangerous due to its high toxicity and bioaccumulation within the food chain. In this study, orange peel was used as a bio-sorbent to extract manganese ions from aqueous solutions. To quantify the manganese ion, the ion was complexed with dithizone, whose absorbance of metal ion increases with an increase in concentration of the ion. The initial concentration of manganese ions, duration of contact, pH, and amount of adsorbent used all had a significant effect on the tendency of Mn2+ ions to bio-sorb onto orange peel. Since pH was a major factor in bio-sorption, it was determined that pH 6 was the optimal pH for the metals under study. Utilizing Fourier transform infrared (FTIR) spectroscopy, the functional groups of orange peel adsorbent that participated in Mn2+ adsorption were identified. The adsorption equilibrium was achieved with in 40ppm initial concentration, 120 min time, and 1.2g adsorbent dose. At these optimum conditions a maximum removal efficiency of (91.73%, 92.63% and 94.04% respectively) was achieved. The adsorption isotherm of Manganese more fitted with Freundlich model because (R2= 0.9614). Pseudo first order and pseudo second order kinetic models were described for manganese, with pseudo second order (PSO) showing the best fit. The current study's findings suggest that orange peel can effectively remove manganese from aqueous solutions as an adsorbent.
Key words: Manganese ion, orange peel, bio-adsorbent, adsorption isotherms, adsorption