Batch Adsorption Of Manganese (II) Ions Using Fruit Peels: Equilibrium And Kinetic Studies

Abstract

Manganese (Mn) is recognized as a potent neurotoxin, known to elicit severe health implications such as hallucinations, learning impairments, and Mn-induced parkinsonism in both adults and children. In 2021, the World Health Organization (WHO) established a provisional guideline of 0.08 mg/L Mn compared to 0.4 mg/L in 2004 due to mounting evidence underscoring Mn neurotoxicity. Over the years, numerous conventional methods have been explored to address this pressing concern. This study, however, explores an innovative approach focusing on the adsorption process employing waste fruit peels (LOLAC), which are from orange, lemon, and langsat, to remove Mn (II) ions. The primary objective is to ascertain the optimal conditions for manganese adsorption utilizing LOLAC. Parameters influencing Mn (II) ions biosorption, including pH, biosorbent dosage, initial adsorbate concentration, and contact time, were investigated. Batch mode was adopted for its inherent controllability, while UV-Vis spectrophotometry facilitated initial and final Mn (II) ion concentration measurements. Subsequently, the percentage of Mn (II) ions removed was computed to elucidate adsorption equilibrium and kinetics. Experimental outcomes unveiled orange peels as the most efficacious, achieving a remarkable 96.3% removal of manganese under conditions of pH 6, 0.8 g/100ml biosorbent dosage, 100 ppm initial adsorbate concentration, and a contact time of 90 minutes. The Langmuir isotherm model and pseudo-second order kinetics exhibited commendable fitting with the data of Mn adsorption onto LOLAC, indicating a monolayer adsorption mechanism with a second-order reaction rate on the adsorbent. Consequently, activated carbon from orange peel emerges as a promising, cost-effective biosorbent for the remediation of manganese ions from wastewater, outperforming its langsat and lemon peel counterparts.