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Here, we report the synthesis and study of new orange‐red (OR) colour‐emitting phosphors Na2ZnP2O7:xTb3+ (x = 1, 1.25, 1.5, and 1.75 mol%) using a conventional solid‐state reaction. The sample crystallographic structures and their room temperature photoluminescence properties were measured using X‐ray powder diffraction, excitation and emission spectra, as well as emission decay curves. X‐ray diffraction analysis showed an isostructural tetragonal structure for all the doped materials with no impurities. Several colour emissions corresponding to 5D4→7F6 (blue), 5D4→7F5 (green), 5D4→7F4 (orange) and 5D4→7F3,2,0 (red) intraconfigurational transitions were observed and investigated. These colours were dominated by the OR colours. 5D4 energy level lifetime was independent of Tb3+ concentration. Various radiative and luminescence parameters, such as experimental branching ratio, radiative decay rate, and luminescence quantum efficiencies, were calculated and discussed. Chromaticity diagram calculations illustrated an orange emission for all the studied materials.

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The aim of this work is the removal of phosphates from an aqueous solution by adsorption on a new, inexpensive adsorbent, calcium oxide. We have also shown interest in the choice of removal method, which is adsorption. The kinetic study of the removal of phosphate ions by adsorption on calcium oxide allowed us to calculate the value of adsorption capacity as a function of the parameters affecting adsorption: Amount of adsorbent, initial concentration of phosphate ion solution, pH of the mixture and temperature. The study of adsorption isotherms showed that the Freundlich model is the most appropriate for the phenomenon of phosphate ion adsorption. Modeling of the kinetic data by the pseudo-first order and pseudo-second order equations shows that the adsorption process is best described by the second order equation. Thermodynamic parameters such as enthalpy ΔH°, entropy ΔS° and free enthalpy ΔG° were also evaluated to determine the nature of adsorption. The results show that the adsorption process is a spontaneous and endothermic physisorption.