Mineral matrix deposition of MC3T3-E1 pre-osteoblastic cells exposed to silicocarnotite and nagelschmidtite bioceramics: In vitro comparison to hydroxyapatite.

This work presents the effect of the silicocarnotite (SC) and nagelschmidtite (Nagel) phases on in vitro osteogenesis. The known hydroxyapatite of biological origin (BHAp) was used as a standard of osteoconductive characteristics. The evaluation was carried out in conventional and osteogenic media for comparative purposes to assess the osteogenic ability of the bioceramics. First, the effect of the material on cell viability at 24 h, 7 and 14 days of incubation was evaluated. In addition, cell morphology and attachment on dense bioceramic surfaces were observed by fluorescence microscopy. Specifically, alkaline phosphatase (ALP) activity was evaluated as an osteogenic marker of the early stages of bone cell differentiation. Mineralized extracellular matrix was observed by calcium phosphate deposits and extracellular vesicle formation. Furthermore, cell phenotype determination was confirmed by scanning electron microscope. The results provided relevant information on the cell attachment, proliferation, and osteogenic differentiation processes after 7 and 14 days of incubation. Finally, it was demonstrated that SC and Nagel phases promote cell proliferation and differentiation, while the Nagel phase exhibited a superior osteoconductive behavior and could promote MC3T3-E1 cell differentiation to a higher extent than SC and BHAp, which was reflected in a higher number of deposits in a shorter period for both conventional and osteogenic media.

Production of activated carbon from agave residues and its synergistic application in a hybrid adsorption-AOPs system for effective removal of sulfamethazine from aqueous solutions.

Tequila production in Mexico generates large quantities of agave bagasse (AB), a waste that could be used more efficiently. AB has a high cellulose, hemicellulose, and lignin content, which allows its use as a precursor for synthesizing carbonaceous materials. In the present work, the synthesis of activated carbon impregnated with Fe2+ (AG-Fe-II) and Fe3+ (AG-Fe-III) was carried out and evaluated in a hybrid adsorption-AOP (advanced oxidation process) methodology for sulfamethazine removal (SMT). The materials were characterized before and after the process to determine their morphological, textural, and physicochemical properties. Subsequently, the effect of the main operational variables (pH, initial SMT concentration, mass, and activator dosage) on the hybrid adsorption-degradation process was studied. The Fenton-like reaction was selected as the AOP for the degradation step, and potassium persulfate (K2S2O8) was used as an activating agent. The main iron crystallographic phases in AG-Fe-II were FeS, with a uniform distribution of iron particles over the material's surface. The main crystallographic phase for AG-Fe-III was Fe3O4. The hybrid process achieved 61% and 78% removal efficiency using AG-Fe-II and AG-Fe-III samples, respectively. The pH and initial SMT concentration were the most critical factors for removing SMT from an aqueous phase. Finally, the material was successfully tested in repeated adsorption-degradation cycles.

Performance of novel Ca-biocomposites produced from banana peel and eggshell for highly efficient removal and recovery of phosphate from domestic wastewater.

Using biowaste-based adsorbents to remove phosphorus (P) from wastewater offers significant benefits concerning eutrophication mitigation and addressing waste management challenges. In this work, Ca-biocomposites were prepared by pyrolysis (700 °C) of a mixture of banana peel (BP) and eggshell (ES). The mass ratio of BP to ES was varied in 2:1, 1:1, and 1:2 ratios. Among the tested mixtures, the BPES-1:2 sample exhibited excellent P removal performance, reaching a maximum P adsorption capacity (Qmax) of 214 ± 5 mg P/g. The adsorption process fitted well with the Avrami order kinetic model (R2 > 0.996) and the Liu isotherms model (R2 > 0.997). The excellent fit of the experimental data to the Avrami model suggests that chemisorption is the dominant interaction mechanism, leading to precipitation through the formation of calcium phosphates. Additionally, the Liu model anticipates that the energetic characteristics of the adsorbent's active sites cannot be identical. This is in agreement with the presence of Ca(OH)2 and CaCO3 in the adsorbent material, where the Ca(OH)2 active sites are preferred by the adsorbate molecules (PO43-) for occupation. Furthermore, thermodynamic analysis revealed that P adsorption is a spontaneous process of exothermic nature (ΔH° < 0). The calculated activation energy for the process (72.81 kJ/mol) suggests the P adsorption mechanism involves strong chemical bonding between the adsorbent and P species. In addition, precipitation of apatite (Ca5(PO4)3OH), a vital component in fertilizer production, was observed during the adsorption process. In tertiary treated wastewater applications, the BPES-1:2 biocomposite demonstrated a P removal efficiency of 90%. The solubility of P in a 2% formic acid solution was 100%, while the water-soluble P content was measured at 5.6%. These findings highlight the product's sustainable and environmentally beneficial nature by demonstrating its potential as a slow-release fertilizer, contributing to the application of the 3R slogan: Reduce, Reuse, Recycle. This value-added product is promising in supplying nutrients to plants over an extended period while minimizing the risk of nutrients leaching into the environment.

Porous carbonaceous materials simultaneously dispersing N, Fe and Co as bifunctional catalysts for the ORR and OER: electrochemical performance in a prototype of a Zn-air battery.

Infiltration of the mesoporous structure of SBA-15 silica as a hard template with phenanthroline complexes of Fe3+ and Co2+ allowed the simultaneous dispersion of nitrogen, iron and cobalt species on the surface of the obtained carbonaceous CMK-3 silica replica, with potential as bifunctional heterogeneous catalysts for the cathodic oxygen reduction and evolution reactions (ORR and OER). The textural properties and mesopore structure depended on the composition of the material. The carbonaceous FeCoNCMK-3 (1/1), obtained with an Fe/Co molar ratio of 1/1, exhibited an ordered cylindrical mesoporous structure with a high mesopore volume, a rather homogeneous composition in terms of total and surface concentrations of iron and cobalt, and a balanced presence of pyridinic-, pyrrolic- and graphitic-N species. FeCoNCMK-3 (1/1) could improve the ORR kinetics by adsorption and reduction of O2 through the 4-electron mechanism with a current density of -17.37 mA cm-2, Eonset of 1.13 V vs. RHE and E1/2 of 0.75 V when compared to metal-free, monometallic or bimetallic electrocatalysts with a higher amount of cobalt than that of iron. In addition, FeCoNCMK-3 (1/1) exhibited activity for the OER, presenting lower values of Eonset (1.52 V), Ej10 (1.78 V) and the Tafel slope (76.3 mV dec-1) with respect to other catalysts. When evaluated as a cathode in a prototype of a Zn-air battery, FeCoNCMK-3 (1/1) exhibited a high open circuit voltage of 1.41 V, a peak power density of 66.84 mW cm-2, a large specific capacity of 818.88 mA h gZn-1, and cycling for 20 h but with deactivation upon cycling.

Sargassum macroalgae from Quintana Roo as raw material for the preparation of high-performance phosphate adsorbent from aqueous solutions.

Currently, the large volumes of Sargassum biomass (Sgs) arriving on Caribbean coasts are a problem that must be solved quickly. One alternative is to obtain value-added products from Sgs. In this work, Sgs is demonstrated to be a high-performance Ca - bioadsorbent for phosphate removal by a heat pretreatment at 800 °C that produces biochar. According to XRD analysis, calcined Sgs (CSgs) have a composition of 43.68%, 40.51%, and 8.69% of Ca(OH)2, CaCO3, and CaO, making CSgs a promising material for phosphate removal and recovery. Results demonstrated that CSgs have a high capacity to adsorb P over a wide range of concentrations (25-1000 mg P/L). After P removal, at low P concentration, the adsorbent material is rich in apatite (Ca5(PO4)3OH), and at high P concentration, brushite (CaHPO4•2H2O) was the main P compound. The CSg reached a Qmax of 224.58 mg P/g, which is higher than other high-performance adsorbents reported in the literature. The phosphate adsorption mechanism was dominated by chemisorption, followed by precipitation according to the pseudo-second-order kinetic model. The solubility of P (74.5 wt%) in formic acid solution and the water-soluble P (24.8 wt%) for CSgs after P adsorption indicated that the final product presents the potential to be used as fertilizer for acid soils. This biomass's processability and high phosphate adsorption performance for P removal make CSgs a potential material for wastewater treatment, and subsequent use of these residues as fertilizer offers a circular economy solution to this problem.

Unraveling the Ca-P species produced over the time during phosphorus removal from aqueous solution using biocomposite of eggshell-palm mesocarp fiber.

Phosphorus (P) adsorption from aqueous solutions is usually evaluated by monitoring the P concentration and employed kinetic models. In this work, three adsorbents obtained from eggshell (ES) and eggshell mixed with palm mesocarp fiber (ESF-1:1 and ESF-1:10) at different Ca(OH)2/CaCO3 compositions were evaluated, and the Ca-P species formed monitored as a function of time deconvoluting Fourier Transform Infrared (FTIR) spectra. At 0.25 h the ESF-1:10 (Ca(OH)2: 26.2 wt%) exhibited better adsorption performance of 35 mgg-1 while ESF-1:1 and ES (Ca(OH)2: 2.8 and 3.0 wt%) showed 26 and 4 mgg-1, respectively. Characteristic PO43- bands in apatite were corroborated by XRD and FTIR. It was found that the role of Ca(OH)2 in the adsorption ends before 0.25 h, and thereafter CaCO3 becomes the phase responsible for the removal of orthophosphate H2PO4-/HPO42-/PO43- ions. The results indicate a direct ligand exchange of CO32- for PO43- that takes place while increasing the apatite crystallinity. On the other hand, the P adsorption process is also dependent on P concentration. At low P concentrations, characteristic bands of PO43- in apatite were observed in FTIR, while at high concentrations, characteristic bands for adsorbed HPO42- were obtained. The obtained results give a relevant role to CaCO3 in P adsorption. Kinetic analysis for Ca-based biocomposites showed that the Avrami order kinetic model fits better for the adsorbents. For P adsorption isotherm process the Langmuir's isotherms showed a good fit, with a maximum adsorption capacity of 90.8, 134.0, and 67.9 mgg-1 for ES, ESF-1:1, and ESF-1:10, respectively.

Comparative Study of Ferroelectric and Piezoelectric Properties of BNT-BKT-BT Ceramics near the Phase Transition Zone.

We report a comprehensive comparative study of ferroelectric and piezoelectric properties of BNT-BKT-BT ceramics through the MPB (morphotropic phase boundary) zone, from the rhombohedral to the tetragonal phases in the system (97.5-x)(Bi0.5Na0.5)TiO3 + x(Bi0.5K0.5)TiO3 + 2.5(BaTiO3), where x = 0 to 24.5 mol %. The structural transitions were studied by XRD patterns and Raman spectra. The MPB was confirmed between x = 10 and 12.5 mol % BKT. The dielectric/ferroelectric/piezoelectric properties of the BNT-BKT-BT system are maximized in the MPB region exhibiting a dielectric constant of 1506, a remanent polarization of 34.4 µC/cm², a coercive field = 36.9 kV/cm, and piezoelectric values of d33 = 109 pC/N, kt = 0.52, and kp = 0.24. Changes in microstructure as a function of BKT content are also presented and discussed.

Synthesis, Characterization and In Vitro Study of Synthetic and Bovine-Derived Hydroxyapatite Ceramics: A Comparison.

The physicochemical properties and biological behavior of sintered-bovine-derived hydroxyapatite (BHAp) are here reported and compared to commercial synthetic-HAp (CHAp). Dense ceramics were sintered for 2 h and 4 h at 1200 °C to investigate their microstructure-structure-in-vitro behavior relationship for both HAp ceramics. Densification was directly proportional to sintering time, showing a grain coarsening behavior with a greater effect on BHAp. Lattice parameters, crystallite size, cell volume and Ca/P ratio were determined by Rietveld refinement of X-ray diffraction (XRD) patterns using GSAS®. Ionic substitutions (Na⁺, Mg2+, CO32-) related to BHAp structure were associated with their position changes in the vibrational modes and correlated with the structural parameters obtained from the XRD analysis. Variations in the structural parameters and surface morphology were also evaluated after different soaking periods in simulated body fluid, which is associated with the formation of bone-like apatite layer and thus bioactivity. Mitochondrial activity (MTS) and lactate dehydrogenase (LDH) assays showed that the material released by the ceramics does not induce toxicity after exposure in human fetal osteoblastic (hFOB) cells. Furthermore, no statistically significant differences were found between the HAp obtained from different sources. These results show that BHAp can be used with no restrictions for the same biomedical applications as CHAp.