Equilibrium and kinetics of adsorption of Mn2+ by Haloarchaeon Halobacterium sp GUSF (MTCC3265)

Abstract

The coastal waters of countries bordering on an ocean show increases in manganese pollution due to runoff from mining activity and from industries dealing with production of ferroalloys, steel, iron, petrochemicals, and fertilizers. One gram of dried cells of haloarchaeon Halobacterium sp. GUSF (MTCC3265) adsorbed 99 percent Mn2+ in 60 min at pH 6.8 and 30 degrees C on contact with 109.54 mg Mn2+ per liter in saline solution. Adsorbed Mn2+ was quantified by atomic absorption spectrometry and demonstrated on the cell surface by SEM-EDX. Mn2+ adsorbed to functional groups of the adsorbent was studied by FTIR. The adsorption process of Mn2+ showed saturation and followed pseudo-second-order kinetics; was consistent with the homogeneity of the Langmuir model (R2 of 0.99); exhibited a Qmax of 62.5 mg g-1 and a binding energy of 0.018 L mg-1. The Mn2+adsorption was also consistent with the heterogeneity of the Freundlich model by exhibiting a Kf of 1.0 mg g-1 with an n value of 1.1. Adsorption efficiency of 99 percent was retained even after a third adsorption-desorption cycle. This is the first report on metal ion adsorption, using Mn2+ as an example, by the haloarchaeon Halobacterium sp. GUSF (MTCC3265) in the domain Archaea.