Ricerc@Sapienza

Manganese oxides are important geomaterials, used in a large number of applications. For instance, as pigments in art works or in the treatment and removal of heavy metals from drinking water. Particularly, ramsdellite [Mn4+O2] and groutellite [(Mn0.54+,Mn0.53+)O1.5(OH)0.5], because of their 2 × 1 frameworks that enable proton diffusion, are very important cathode materials. Manganese oxides commonly occur as crypto-crystalline and very fine mixtures of different Mn-phases, iron oxides, silicates and carbonates. Thus, proper characterization can be a difficult task using XRPD.

In the energy transition from fossil to clean fuels, hydrogen plays a key role. Proton-exchange membrane fuel cells (PEMFCs) represent the most promising hydrogen application, but they require a pure hydrogen stream (CO < 10 ppm). The steam iron process represents a technology for the production of pure H2, exploiting iron redox cycles. If renewable reducing agents are used, the process can be considered completely green. In this context, bio-ethanol can be an interesting solution that is still not thoroughly explored.

Lead is a highly toxic element and can cause serious illnesses, as a consequence of this, stringent limits have been set for this element, especially regarding drinking water. In this paper, the potential of manganese oxides (MnOx) as adsorbents for the removal of lead (as Pb II) from synthetically contaminated water was investigated. These oxides were recovered from alkaline batteries by a bio-hydrometallurgical process through potassium permanganate (KMnO4) precipitation.