Search

We report here the structural, FTIR, optical, mechanical, and magnetic properties of Zn1−xFexO with various Fe nanopowder additions (0.00 ≤ x ≤ 0.30). The wurtzite structure and compressive stress are clearly conformed in all samples. Further, the lattice constants, crystallite size, porosity, strains, grain size, Debye temperature, and elastic modulus are increased as x increases to 0.05, followed by a decrease at x = 0.30, but they are higher than those of ZnO. Interestingly, two electronic transitions were observed for all samples corresponding to two values of energy gaps, Eg1 and Eg2. They were decreased from 3.25 and 3.72 eV to 3.00 and 3.60 eV, respectively. In contrast, an enhancement of the lattice constant ϵL, the density of charge carriers (N/m*), and the optical and electrical conductivities as x increases was obtained. For example, ϵL and charge carriers density (N/m*) for x = 0.30 doped sample are, respectively, 10 and 15 times more than those of ZnO. The refractive index (n) increases as x is increased, and a good correlation between n and Eg was obtained. Other parameters, such as the dissipation factor, surface and bulk loss functions, were also controlled by the variation of x. The non-linear optical parameters were also increased by increasing x, indicating not only the interesting optical properties of these materials but also the possibility of their optoelectronic applications. The Vickers hardness Hv is increased by increasing x to 0.30 and applying load to 9.8 N. In contrast, the surface energy γ, elastic indentation de, and resistance pressure decrease as x increases to 0.10, followed by an increase at x = 0.30. A noticeable ferromagnetic behavior with evaluated magnetization parameters is clearly obtained for the x = 0.10 sample. The saturation magnetization Ms is about 250 times greater than that of ZnO, which supports the room temperature ferromagnetic (RTFM) for the Fe-doped sample. These findings indicate that the addition of Fe as nanopowder to ZnO is promising for altering plastic flow region, optoelectronic, high-power operating and spintronic devices, which highlights the present investigation. [ABSTRACT FROM AUTHOR]

An activated carbon (AC) deriving from sludge is used in this research for the adsorption of two water pollutants, namely Reactive Black 5 (RB5) and Green Alizarin (GA) dyes, at different temperatures. The adsorption capacities varied from 277.2 to 312.69 mg/g for GA and from 225.82 to 256.02 mg/g for RB5. Comparatively, this adsorbent presents good performances in removing these dyes from wastewater. The application of physical models to adsorption experiments is advantageous to provide new insights into the dyes' adsorption mechanism. A dedicated physical adsorption model suggests that RB5 and GA dyes are adsorbed in a monolayer. Moreover, the orientation of RB5 and GA dyes on AC resulted in an angled position, determining a multi-molecular process. In addition, both dyes are adsorbed by the occurrence of an aggregation process, forming a dimer. The impact of temperature can be also interpreted, allowing concluding that it plays a relevant role in removing these dyes. The calculation and interpretation of adsorption energies show that the dyes are removed via an endothermic process, and physical forces are involved., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)