Brahim Chafik El Idrissi

In the present paper, graphitic carbon nitride (g-C3N4) was prepared using a conventional hydrothermal process. Several characterization methods were applied to analyze the resulting g-C3N4 sample, such as: X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectrophotometry, attenuated total reflectance -Fourier-transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The pollutant selected to measure the g-C3N4 photocatalytic performance was methylene blue (MB). Using response surface methodology (RSM), the pH solution effects, photocatalyst dose (mg/L), and irradiation period (min) were examined and adjusted. The optimal conditions, which included 1.3g/L of g-C3N4 photocatalyst, solution pH = 10.83, and irradiation time = 119.3 min, resulted in a degradation efficiency of 86.58%. The principal active species involved in photocatalytic degradation have been identified and a potential mechanism has also been provided. Additionally, the degradation kinetics were monitored and obtained to follow pseudo-second order kinetics.

We have synthesized a new composition of calcium phosphate bone cements (CPCs) and silver loaded calcium phosphate bone cements (Ag-CPCs) based on α–tricalcium phosphate, brushite, and hydroxyapatite phases. Cement powders with an atomic ratio of Ca/P equal to 1.38 and Ag/Ca = 0 and 0.05 were used in this study. The silver was introduced into the cement matrix by means of Ag₃PO₄ powder, already prepared. The significant effects of the introduction of silver in the solid phase as silver phosphate on setting time, morphology, and phase composition of the final cements were evaluated. With the addition of silver, the final setting time increased by ̴ 25%. XRD shows that the crystalline composition of cement changes and the cement pattern demonstrates peaks of whitlockite for silver loaded cement samples. FTIR spectroscopy shows the presence of the pyrophosphate phase. Graphical Abstract

The present work reports the synthesis of pure hydroxyapatite and HAp supported Ag3PO4 (Ag3PO4/HAp composites) with varying amounts of silver ions Ag+ with a facile in-situ ion exchange method. XRD results of Ag3PO4/HAp composite reveal the peaks characteristic of pure HAp with additional peaks of silver ions which suggest the deposit of silver particles on the support surface (HAp). The nano-composites Ag3PO4/HAp samples show good adsorption and improved photocatalytic activities in methylene blue MB degradation (more than 70%). Antibacterial study of Ag3PO4/HAp nano-composites showed that the HAp dried at 90°C possesses some antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. Also, compared to HAp sample, deposition of Ag3PO4 nanoparticles on HAp surface improves the antibacterial performance of the composites.

In this paper, the synthesis of nanosized powders β -Tricalcium phosphate β -Ca3(PO4)2 was studied by the wet chemical method at different values of reaction temperature, initial concentration of diammonium hydrogen phosphate (NH4)2HPO4, calcium nitrate tetrahydrate Ca(NO3)2·4H2O addition rate, pH of reaction and aging time. All these parameters have a great impact on the properties of the resulting β-TCP nano powders. Analysis results of morphology, structure of TCP powder from infrared (IR) spectra, X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the synthesized TCP powder had spherical crystal shape with crystallite size, calculated by XRD method, less than 60 nm, mono and biphasic structure composed of βTCP with pyrophosphate calcium or hydroxyapatite. The variation of the synthesis conditions did not affect the morphology, but it affect the size of crystallites and particles.

The stoichiometric hydroxyapatite, Ca10(PO4)6(OH)2 is prepared by an aqueous precipitation method at room temperature, the main reactants were Ca(OH)2 and H3PO4 without addition of ammonia solution. The sample was analyzed by Fourier transformed infrared spectroscopy (FTIR) which reveals the presence of a small amount of carbonate due to absorbance of carbon dioxide from the air during synthesis process. The crystal structure was carried out by X-ray powder diffraction data and the Rietveld method using FullPROF software. We confirmed that this material has a hexagonal structure (space group P63/m; Z = 1). Unit-cell parameters with higher precision (a = b = 9.4159(4) Å , c = 6.8819(3) Å, α = β = 90°; and γ = 120°).