Effect of L-Glutamic Acid on the Composition and Morphology of Nanostructured Calcium Phosphate as Biomaterial.

Calcium phosphate (CaP) with several chemical compositions and morphologies was prepared by precipitation using aqueous solutions of L-Glutamic acid (H2G) and calcium hydroxide, both mixed together with an aqueous solution (0.15 M) of phosphoric acid. Plate-shaped dicalcium phosphate dihydrate (brushite) particles were obtained and identified at a lower concentration of the solution of the reactants. The Ca/P ratio deduced by EDS was ~1, as expected. The nanoscale dimension of carbonate apatite and amorphous calcium phosphate, with variable Ca/P ratios, were revealed by X-ray diffraction (XRD) and scanning electron microscopy and energy dispersive X-ray spectroscopy analysis (SEM-EDS). They were characterized in medium and high concentrations of calcium hydroxide (0.15 M and 0.20 M). The equilibria involved in all the reactions in aqueous solution were determined. The thermodynamic calculations showed a decrease in the amount of chelate complexes with an increase in pH, being the opposite of [CaPO4-] and [CaHG+]. This fluctuation showed an evident influence on the morphology and polymorphism of CaP particles obtained under the present experimental conditions, with potential use as a biomaterial.

Effective removal of cationic dye on activated carbon made from cactus fruit peels: a combined experimental and theoretical study.

This article investigates experimentally and theoretically the adsorption of Basic Red 46 cationic dye (BR46) using activated carbon generated from cactus fruit peels (ACCFP). The prepared adsorbent was characterized by different analytical tools showing a good surface for the uptake of pollutants. A maximum batch adsorption capacity of 806.38 mg g-1 was achieved at optimal conditions. The Freundlich model best represented the equilibrium data, although the pseudo-second-order kinetic model best described the adsorption kinetics. The thermodynamic studies demonstrated that the adsorption process was spontaneous (ΔG° < 0) and endothermic (ΔH° = 32.512 kJ mol-1). DFT descriptors were combined with COSMO-RS and AIM theory to provide a complete picture of the adsorbate/adsorbent system and its molecular interactions. Last, the ACCFP was regenerable up to four times, emphasizing the idea of using it as an adsorbent to treat textile wastewaters.