Mohammed Bettach

Composite materials are commonly employed because of their superior mechanical and electrical properties, as well as their lower density compared to metals. In this research, ceramic waste from the Casablanca region (Morocco) was incorporated into a composite material by combining it with finely ground ceramic fragments (CB) in an unsaturated polymer (UP) resin. The study objectives include the characterization of ceramic waste, evaluation of the mechanical stiffness, influenced by CB content and specimen thickness, and the assessment of its hydric behavior and erosion resistance in aggressive chemical environments. This valorization approach includes a baseline assessment of unmodified ceramic waste and UP’s compatibility and systematic documentation of geometry-dependent stiffness in short-cylinder compression tests. Several methods were used to characterize the material, including XRD, optical microscopy, FTIR-ATR, erosion testing, hydric behavior analysis, surface area measurement, and Young’s modulus. The results showed increased tensile strength and stiffness compared to the starting materials through the evolution of Young’s modulus, demonstrating the enhanced mechanical quality of the composite. Additionally, the material properties changed with the CB content and thickness of the sample, which indicated the potential for optimization. These findings advocate for the reuse of Moroccan industrial ceramic waste as a viable mineral filler for semi-structural polymer composites, supporting the circular economy, environmental sustainability, and public health.

The objective of this work is to study the electrical/dielectric and optical properties of new pyrophosphates LixCu2-x/2P2O7 (x = 0, 0.05 and 0.1) prepared by the ceramic method. The desired phases are identified by X-ray diffraction (XRD) and by IR spectroscopy. All compounds crystallize in the monoclinic system with space group C2/c. Infrared spectroscopy shows all the expected bands in particular those of the P2O74- groups. The study of electrical and dielectric properties is carried out at room temperature by impedance spectroscopy. The Nyquist diagram shows a high frequency arc corresponding to grain effects and a medium frequency arc relating to grain boundary effects, followed by a straight line at a low frequency attributed to the effects of electrode polarization. Modeling of experimental data by an equivalent electrical circuit, allows us to determine the electrical parameters of these pyrophosphates. The evolution of the conductivity (σac) of these phases is adjusted by Jonscher's double power law. The insertion of Lithium improves the conductivity of the LixCu2-x/2P2O7 pyrophosphates. Indeed, the σac passes from 1.14.10-6 S/m for 0% Li to 1.07.10-5 S/m for 10% Li. Thus, the insertion of lithium increases the permittivity at low frequency. Conductivity values are characteristic of semiconductors. These compounds are also characterized by UV spectroscopy, which confirmed that the three compounds are semiconductors with a decrease in the energy gap, which shifted from 3.91 to 3.86 eV when the lithium rate increases from 0 to 10%.

Phosphogypsum (PG) is an acidic by-product generated during the production of phosphoric acid. Usually this by-product is stockpiled or dumped into water bodies, which causes several environmental pollution problems. The aim of this work is to reduce this environmental risk by producing CaCO₃ and Li₂SO₄.H₂O from the conversion of PG by Li₂CO₃. To optimize the reaction conditions, four parameters have been investigated such as the initial concentration of the reagents, the reaction duration, the temperature and the gypsum purity. In addition, the nature of the resulting products was proved principally by X-ray diffraction technic. The obtained results show that the initial concentration of the reagents and the reaction duration are the most influential parameters, while the temperature has no significance effect on this reaction. Also, the acidity and the presence of impurities into PG induce its reactivity compared than commercial gypsum. The purity of the formed CaCO₃ and Li₂SO₄.H₂O at the optimum conversion of PG is 96.08 and 98.71% respectively.

The production of phosphoric acid generates an enormous amount of phosphogypsum with emission of toxic fluorine acid gas. To remedy these environmental problems, a novel and a simple procedure permits converting phosphogypsum waste by recycled fluorine acid into valuable products. The obtained results confirm the efficiency of this procedure, which synthesises at room temperature the calcium fluoride in the form of nano-crystalline powder and the ammonium bisulphate salt from the exact stoichiometric proportions of phosphogypsum, hydrofluoric acid and ammonia. The total conversion of phosphogypsum is achieved after reaction time equal to one hour and a half. Generally, this novel procedure offers not only a solution for reducing phosphogypsum waste and fluorine gas emission, but also gives rise to valuable products, useful to industry and agriculture.

The phosphoric acid production in Morocco generates a large amount of phosphogypsum (PG) which is a significant source of environmental contamination. In this work, PG has been characterized by different analysis techniques that allow to study the effect of the impurities on its physical and chemical properties. Thus, a method to purify the PG from phosphates and fluorides was proposed in order to improve its quality and to make it usable in plaster and cement. The purification process consists to sieve PG under 200 μm and to treat it by sulfuric acid to dissolve the insoluble impurities. The obtained results show that the treatment of PG by sulfuric acid 20 and 50% at 60 °C for 2 h is sufficient to make it suitable for used in the plaster and the cement respectively.

The valorization of phosphogypsum (PG) into valuable products by aqueous solution is very interesting on the economic and environmental side. This paper proposes a simple and efficient procedure which allows converting PG waste into calcite and lithium sulfate monohydrate. This last is recommended in lithium batteries, while the calcite can be used in several industries and in the environment. The optimum conditions of PG conversion obtained at room temperature with exact stoichiometric proportions of PG and Li₂CO₃ and for concentration limit equal to 0.3 mol/l. The PG conversion is total after 1.5 h under these conditions.