Manganese,as a transition metal with various valences (0~+7),is abundant and widely spread.Manganese (Ⅲ)[Mn (Ⅲ)] can act as both electron acceptor and electron donor.Soluble Mn (Ⅲ) has long been overlooked due to the easy disproportionation and difficulty in detection.However,recent studies show that Mn (Ⅲ) can spread widely in pore water and sediment oxic/anoxic interfaces,playing important roles in biogeochemical redox processes.Further,Mn (Ⅲ) with/without ligands show promises in oxidation of contaminants.Therefore,this review summarizes:(1) the presence of Mn (Ⅲ) in aquatic environment and its generation routes,illustrates the involvement of ligands and biological activities;(2) the methods of preparing Mn (Ⅲ) with/without ligands in lab and quantifying the concentration of Mn (Ⅲ);(3) the hydrolysis constants,disproportionation properties,and redox potentials of Mn (Ⅲ);(4) the environmental significance and possible application of Mn (Ⅲ).Finally,the research needs are proposed.
Contents
1 Introduction
2 Generation of Mn(Ⅲ)
2.1 Mn(Ⅲ) generation in nature
2.2 Mn(Ⅲ) preparation and detection in laboratory
3 Some aspects of chemistry of soluble Mn(Ⅲ)
3.1 Common Mn(Ⅲ) complexes
3.2 Stability constants of Mn(Ⅲ) complexes
3.3 Hydrolysis constants of Mn(Ⅲ)
3.4 Absorption spectra of Mn(Ⅲ)
3.5 Redox potentials of Mn(Ⅲ)
4 Environmental significance of Mn(Ⅲ)
5 Application of Mn(Ⅲ) in water treatment
6 Conclusion