Efficient removal of tetracycline and Cu2+ by honeycomb derived magnetic carbon: Adsorption mechanism and advanced oxidation regeneration mechanism.

The honeycomb magnetic carbons (xFe@HCNs) were prepared by sacrificial template method novelty using polyacrylamide resin (PAAS) as template and ammonium pyrrolidine dithioate/Fe3+ complex (APDC-Fe) as carbon skeleton and metal source. Tetracycline (TC) and copper (Cu2+) as target pollutants were used to investigate the adsorption properties of xFe@HCNs in single or binary TC and Cu2+ systems. The adsorption capacity sequence for TC among the adsorbents was (mmol·g-1): 2Fe@HCNs (0.088) > 8Fe@HCNs (0.061) > HCNs (0.054) > RC (0.036), and for Cu2+ was (mmol·g-1): 2Fe@HCNs (1.120) > 8Fe@HCNs (1.026) > RC (0.792) > HCNs (0.681). 2Fe@HCNs demonstrated notable affinity for adsorbing both TC and Cu2+. Additionally, the influence of hydrochemical factors (i.e., cation species, anion species, and pH) on the adsorption properties of 2Fe@HCNs. Combined with advanced oxidation technology, the regeneration methods of magnetic adsorbent were explored using oxidizing agents (e.g., H2O2 and peroxymonosulfate) as eluents which could increase the adsorption sites of magnetic carbon adsorbents during the regenerating process, which was the novelty of the study. Furthermore, the regeneration mechanisms of H2O2 as eluent were investigated. This study discussed the application and regeneration methods of magnetic adsorbents in water treatment, offering new insights into environmental remediation using magnetic materials.

Confined Co@NCNTs as highly efficient catalysts for activating peroxymonosulfate: free radical and non-radical co-catalytic mechanisms.

A series of transition metal (Co, Ni, Fe) nanoparticles were confined in N-doped carbon nanotubes (NCNTs) prepared (Co@NCNTs, Ni@NCNTs, and Fe@NCNTs) by the polymerization method. The structure and composition of catalysts were well characterized. The catalytic activity of catalysts for activating peroxymonosulfate (PMS) was conducted via acid orange 7 (AO7) degradation. Among the catalysts, Co@NCNTs performed the best catalytic activity. Additionally, Co@NCNTs performed good catalytic activity in pH values of 2.39-10.98. Cl- and SO42- played a promoting roles in AO7 degradation. NO3- presented a weak effect on the catalytic performance of Co@NCNTs, while HCO3- and CO32- significantly suppressed the catalytic performance of Co@NCNTs. Both non-radical (1O2 and electron transfer) and free-radical (·OH and SO4·-) pathways were detected in the Co@NCNTs/PMS system. Notably, 1O2 was identified to be the main active specie in this study. The catalytic activity of Co@NCNTs gradually decreased after cycle reuse of Co@NCNTs. Finally, the toxicity of the AO7 degradation solution in the study was evaluated by Chlorella pyrenoidosa.

Investigation of In Vitro Cytocompatibility of Zinc-Containing Coatings Developed on Medical Magnesium Alloys.

In a neutral solution, we investigated the effects of Na2[ZnEDTA] concentrations at 0, 6, 12, 18, and 24 g/L on surface morphology, chemical composition, degradation resistance, and in vitro cytocompatibility of micro-arc oxidation (MAO) coatings developed on WE43 (Mg-Y-Nd-Zr) magnesium alloys. The results show that the enhanced Na2[ZnEDTA] concentration increased the Zn amount but slightly decreased the degradation resistance of MAO-treated coatings. Among the zinc-containing MAO samples, the fabricated sample in the base solution added 6 g/L Na2[ZnEDTA] exhibits the smallest corrosion current density (6.84 × 10-7 A·cm-2), while the sample developed in the solution added 24 g/L Na2[ZnEDTA] and contains the highest Zn content (3.64 wt.%) but exhibits the largest corrosion current density (1.39 × 10-6 A·cm-2). Compared to untreated WE43 magnesium alloys, zinc-containing MAO samples promote initial cell adhesion and spreading and reveal enhanced cell viability. Coating degradation resistance plays a more important role in osseogenic ability than Zn content. Among the untreated WE43 magnesium alloys and the treated MAO samples, the sample developed in the base solution with 6 g/L Na2[ZnEDTA] reveals the highest ALP expression at 14 d. Our results indicate that the MAO samples formed in the solution with Na2[ZnEDTA] promoted degradation resistance and osseogenesis differentiation of the WE43 magnesium alloys, suggesting potential clinic applications.

Novel Mg-Incorporated Micro-Arc Oxidation Coatings for Orthopedic Implants Application.

In this study, Ti-6Al-4V alloy samples were processed by micro-arc oxidation (MAO) in phytic acid (H12Phy) electrolytes with the addition of different concentrations of EDTA-MgNa2 (Na2MgY) and potassium hydroxide (KOH). The surface characterization and cytocompatibility of MAO-treated samples were evaluated systematically. H12Phy is a necessary agent for MAO coating formation, and the addition of Na2MgY and KOH into the electrolytes increases the surface roughness, micropore size and Mg contents in the coatings. The MAO coatings are primarily composed of anatase, rutile, MgO and Mg3(PO4)2. Magnesium (Mg) ions in the electrolytes enter into MAO coatings by diffusion and electromigration. The MAO coatings containing 2.97 at% Mg show excellent cell viability, adhesion, proliferation, alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion, but the cytocompatibility of the MAO coatings containing 6.82 at% Mg was the worst due to the excessively high Mg content. Our results revealed that MAO coatings with proper Mg contents improve the cytocompatibility of the Ti-6Al-4V alloys and have large potential in orthopedic applications.

Investigation of Zinc and Phosphorus Elements Incorporated into Micro-Arc Oxidation Coatings Developed on Ti-6Al-4V Alloys.

In order to clarify the mechanism that zinc and phosphorus elements entering the micro-arc oxidation (MAO) coatings developed on Ti-6Al-4V alloys, anodic coatings containing different zinc and phosphorus were fabricated using an orthogonal experiment of four factors with three levels in an electrolyte containing EDTA-ZnNa2, KOH, and phytic acid. Surface morphology, element composition, chemical state and phase structure of MAO coatings were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The concentrations of zinc and phosphorus in the electrolyte were analyzed by an inductively coupled plasma optical emission spectrometry (ICP-OES). The results show that zinc and phosphorus elements in MAO coatings exist in the form of Zn3(PO4)2. Phytic acid is the most important factor on both zinc and phosphorus contents of MAO coatings. With the increase of phytic acid concentration or the decrease of KOH concentration, the contents of zinc and phosphorus in MAO coatings present a similarly increasing tendency. Our results indicate that phosphorus takes part in coating formation mainly by diffusion, while zinc enters into MAO coatings with phosphorus from phytic acid.