International audienceThe aim of this study was to develop synthetic magnetite nanoparticles (nFe3O4) with preferential reactivity for trace elements (TE) for possible environmental applications as adsorbents. The synthetic magnetite materials obtained through the co-precipitation of both Fe 3+ and Fe 2+ ions (Fe 2+ / Fe 3+ = 0.5) were characterized by a set of complementary techniques such as X-ray diffraction, transmission and scanning electron microscopy, Fourier transform infrared and Raman spectroscopy, and BET adsorption method. The resulting nFe3O4 displayed a wide specific surface area (100 m 2 g-1) with particles reaching a size of about 10 nm, smaller than those of the well-crystallized commercial ones (cFe3O4) estimated at 80 nm while showing a BET surface area of 6.8 m² g-1. The adsorption properties of the synthetic nFe304 magnetite nanoparticles were characterized and compared to commercial analogues with the adsorption of both arsenic and copper. The equilibrium adsorption isotherms were properly fitted with Langmuir and Freundlich equation models. The maximum adsorption capacity for the solid phase, qm, obtained for the adsorption of arsenic onto nFe3O4 had an increase of 69.46% comparative to the value obtained for the adsorption of arsenic on cFe3O4. The results suggested that the iron oxide nanoparticle

The aim of the current research work was to study the physicochemical and biological properties of synthesized zinc doped hydroxyapatite (ZnHAp) nanoparticles with Zn concentrationsxZn=0(HAp),xZn=0.07(7ZnHAp), andxZn=0.1(10ZnHAp) for potential use in biological applications. The morphology, size, compositions, and incorporation of zinc into hydroxyapatite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman scattering, and X-Ray Photoelectron Spectroscopy (XPS). In addition, the cytotoxicity of ZnHAp nanoparticles was tested on bothE. colibacteria and human hepatocarcinoma cell line HepG2. The results showed that ZnHAp nanoparticles (HAp, 7ZnHAp, and 10ZnHAp) have slightly elongated morphologies with average diameters between 25 nm and 18 nm. On the other hand, a uniform and homogeneous distribution of the constituent elements (calcium, phosphorus, zinc, and oxygen) in the ZnHAp powder was noticed. Besides, FTIR and Raman analyses confirmed the proper hydroxyapatite structure of the synthesized ZnHAp nanoparticles with the signature of phosphate, carbonate, and hydroxyl groups. Moreover, it can be concluded that Zn doping at the tested concentrations is not inducing a specific prokaryote or eukaryote toxicity in HAp compounds.

Samarium doped hydroxyapatite (Sm:HAp), (PO₄)₆(OH)₂ (HAp), bionanoparticles with different x_Sm have been successfully synthesized by coprecipitation method. Detailed characterization of samarium doped hydroxyapatite nanoparticles (Sm:HAp‐NPs) was carried out using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The biocompatibility of samarium doped hydroxyapatite was assessed by cell viability. The antibacterial activity of the Sm:HAp‐NPs was tested against Gram‐negative bacteria (Pseudomonas aeruginosa and Escherichia coli) and Gram‐positive bacteria (Enterococcus faecalis and Staphylococcus aureus). A linear increase of antimicrobial activity of P. aeruginosa has been observed when concentrations of Sm:HAp‐NPs in the samples with x_Sm = 0.02 were higher than 0.125 mg/mL. For Sm:HAp‐NPs with x_Sm = 0.05 a significant increase of antibacterial activity on E. coli was observed in the range 0.5–1 mg/mL. For low concentrations of Sm:HAp‐NPs (x_Sm = 0.05) from 0.031 to 0.125 mg/mL a high antibacterial activity on Enterococcus faecalis has been noticed. A growth of the inhibitory effect on S. aureus was observed for all concentrations of Sm:HAp‐NPs with x_Sm = 0.02.

The present work reports a simple coprecipitation adapted method for the synthesis of stable Ce substituted to Ca hydroxyapatite (HAp) nanoparticles. The structural and morphological properties of Ce doped hydroxyapatite (Ce:HAp) were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDAX). The optical properties of Ce doped hydroxyapatite were also investigated using Fourier Transform Infrared (FTIR) spectroscopy, FT Raman spectroscopy and photoluminescence analysis. The results of the XRD studies revealed the progressive increase in the a- and c-axes with increasing of Ce concentrations. In the FTIR studies of Ce:HAp powders a similar structure to hydroxyapatite was observed. IR and Raman wavenumbers and the peak strength of the bands associated to the P-O and O-H bonds decreases progressively with the increase of Ce concentration. All the emission maxima could be attributed to the 5d-4f transitions of Ce ions. The displacement of maximum emission bands with the increase of Cerium in the samples is in agreement with the results obtained by XRD studies. The Ce:HAp samples with xCe =0.03 and 0.05 exhibited significant antibacterial activity against Staphylococcus aureus ATCC 6538 and E. coli 714 bacterial strains compared to Ce:HAp samples with xCe =0 (pure HAp) and 0.01.

This review summarizes recent data related to the management of marine plastic litter to promote sustainable development. It discusses the distribution and identification of marine plastic litter, assesses the potential socio-economic and environmental impacts of these pollutants, and explores their recovery strategies, from a circular economy perspective. The main findings indicate that the majority of marine plastic litter originates from land-based sources. Current technologies and approaches for valorizing marine plastic litter include mechanical and chemical recycling, blockchain technologies by providing traceability, verification, efficiency and transparency throughout the recycling process, and public awareness programs and education. The developed policies to prevent marine plastic litter emphasize regulations and initiatives focused toward reducing plastic use and improving plastic waste management. By adopting a holistic and sustainable approach, it is possible to mitigate the environmental impact of marine plastic debris while simultaneously creating economic opportunities.