Pure and Mg-doped manganese oxide thin films were synthesized on heated glass substrates using the spray pyrolysis technique. The surface chemical composition was investigated by the use of X-ray photoelectron spectroscopy (XPS). Structural and morphological properties were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM). Optical properties were characterized by UV-visible spectroscopy. XPS spectra showed typical Mn (2p3/2), (2p1/2) and O (1s) peaks of Mn3O4 with a slight shift attributed to the formation of different chemical states of manganese. XRD analysis revealed the tetragonal phase of Mn3O4 with a preferred (211) growth orientation that improved with Mg-doping; likewise, grain size is observed to increase with the Mg doping. SEM images of Mn3O4 films showed rough surfaces composed of uniformly distributed nanograins whose size decreases with the Mg-doping. The manganese oxide films surface observed in AFM show a textured, rough and porous surface. The combination of transmittance and absorption data in the UV-visible range allowed determining the energy values of the Eg band gap (1.5–2.5 eV). The decrease of the band gap with the Mg-doping increase is attributed to the influence of the greater size of the Mg2+ ion in the manganese oxide lattice.

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Abstract:In this research, a detailed study for energy consumption levels evaluation and environmental impacts assessment in the fertilizers production sector in Algeria was achieved. An analysis of the various inputs and outputs to the process to identify different sources of pollution throughout the life cycle of fertilizer was used. One product is making the subject in this study; CAN 27% N. The flows of material and energy for each phase of the life cycle were counted and the associated environmental problems were identified. The analysis was conducted according to the LCA standards ISO (International Standard Organization) 14040 series and the impacts categories studied are Global Warming Potential, Acidification Potential, Troposphere Ozone Precursor Potential, and Resources use. The results show that Cumulative Energies Requirement and GHG emission in Algerian fertilizers production process are significant. Ammonia plant use 82% of total natural gas that is consumed by fertilizer manufactory. Production of ammonia per year requires 4,506.107MJ of electricity and 2,059.108of natural gas and generates 1.82 T CO2 eq. (equivalent).