Waste citrus fruit peels for removal of Hg(II) ions

Abstract

Abstract: Mercury is considered as a highly toxic and hazardous pollutant even in trace concentration. Severe consequence of mercury poisoning was observed as Minamata disease in Japan in 1956. Amongst the various techniques used for removal of Hg(II) ions from polluted waters, adsorption demonstrates most promising results. This paper focuses on adsorption of mercury using citrus fruit peels waste from Phyllanthus emblica (Indian gooseberry/amla), Citrus sinensis (orange), Mangifera indica (raw mango) and Citrus limetta (sweet lime). The citrus peels were naturally shade dried, powdered to an average particle diameter of 150–200 μ and used without any chemical modification. The impact of solution pH, Hg(II) ion concentration and initial Hg(II) concentration was evaluated in batch adsorption process. The order of Hg(II) adsorption was found to be as: P. emblica > C. sinensis > C. limetta > M. indica. Langmuir and Freundlich isotherm describes the equilibrium adsorption condition. The adsorption of Hg(II) followed the pseudo-second-order kinetic mechanism. The thermodynamic investigation showed that the adsorption is a spontaneous process. © 2013 Balaban Desalination Publications. All rights reserved.