Copper nanoparticles of well-controlled size and shape: a new advance in synthesis and self-organization.

International audienceHere, we report a new synthetic route for spherical small copper nanoparticles (CuNPs) with size ranging from 3.5 nm to 11 nm and with an unprecedented associated monodispersity (<10%). This synthesis is based on the reduction of an organometallic precursor (CuCl(PPh3)3) by tert-butylamine borane in the presence of dodecylamine (DDA) at a moderate temperature (50 to 100 °C). Because of their narrow size distribution, the CuNPs form long-range 2D organizations (several μm(2)). The wide range of CuNPs sizes is obtained by controlling the reaction temperature and DDA-to-copper phosphine salt ratio during the synthesis process. The addition of oleic acid (OA) after the synthesis stabilizes the CuNPs (no coalescence) for several weeks under a nitrogen atmosphere. The nature and the reactivity of the ligands were studied by IR and UV-visible spectroscopy. We thus show that just after synthesis the nanoparticles are coated by phosphine and DDA. After adding OA, a clear exchange between phosphine and OA is evidenced. This exchange is possible thanks to an acid-base reaction between the free alkylamine in excess in the solution and OA. OA is then adsorbed on the NPs surface in the form of carboxylate. Furthermore, the use of oleylamine (OYA) instead of DDA as the capping agent allows one to obtain other NP shapes (nanorods, triangles and nanodisks). We get evidence that OYA allows the selective adsorption of chloride ions derived from the copper precursor on the different crystallographic faces during the growth of CuNPs that induces the formation of anisotropic shapes such nanorods or triangles

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

SummaryBackground Azithromycin has been proposed as a treatment for COVID-19 on the basis of its immunomodulatoryactions. We aimed to evaluate the safety and efficacy of azithromycin in patients admitted to hospital with COVID-19.Methods In this randomised, controlled, open-label, adaptive platform trial (Randomised Evaluation of COVID-19Therapy [RECOVERY]), several possible treatments were compared with usual care in patients admitted to hospitalwith COVID-19 in the UK. The trial is underway at 176 hospitals in the UK. Eligible and consenting patients wererandomly allocated to either usual standard of care alone or usual standard of care plus azithromycin 500 mg once perday by mouth or intravenously for 10 days or until discharge (or allocation to one of the other RECOVERY treatmentgroups). Patients were assigned via web-based simple (unstratified) randomisation with allocation concealment andwere twice as likely to be randomly assigned to usual care than to any of the active treatment groups. Participants andlocal study staff were not masked to the allocated treatment, but all others involved in the trial were masked to theoutcome data during the trial. The primary outcome was 28-day all-cause mortality, assessed in the intention-to-treatpopulation. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936.Findings Between April 7 and Nov 27, 2020, of 16 442 patients enrolled in the RECOVERY trial, 9433 (57%) wereeligible and 7763 were included in the assessment of azithromycin. The mean age of these study participants was65·3 years (SD 15·7) and approximately a third were women (2944 [38%] of 7763). 2582 patients were randomlyallocated to receive azithromycin and 5181 patients were randomly allocated to usual care alone. Overall,561 (22%) patients allocated to azithromycin and 1162 (22%) patients allocated to usual care died within 28 days(rate ratio 0·97, 95% CI 0·87–1·07; p=0·50). No significant difference was seen in duration of hospital stay (median10 days [IQR 5 to >28] vs 11 days [5 to >28]) or the proportion of patients discharged from hospital alive within 28 days(rate ratio 1·04, 95% CI 0·98–1·10; p=0·19). Among those not on invasive mechanical ventilation at baseline, nosignificant difference was seen in the proportion meeting the composite endpoint of invasive mechanical ventilationor death (risk ratio 0·95, 95% CI 0·87–1·03; p=0·24).Interpretation In patients admitted to hospital with COVID-19, azithromycin did not improve survival or otherprespecified clinical outcomes. Azithromycin use in patients admitted to hospital with COVID-19 should be restrictedto patients in whom there is a clear antimicrobial indication

Efficient and Rapid Removal of Pb(II) and Cu(II) Heavy Metals from Aqueous Solutions by MgO Nanorods

In this study, the adsorption capability of MgO nanorods for the quick and effective elimination of Cu(II) and Pb(II) heavy metals from wastewater was examined. The MgO nanorods were produced via simple coprecipitation process. Various characterization techniques were used to investigate the morphological and chemical properties of the as-prepared nanomaterial. Moreover, the influences of initial heavy-metal ion concentration, pH, and contact time were investigated to evaluate the removal efficiency of the nanomaterials. The adsorption process followed pseudo-second order and Langmuir adsorption isotherm models, according to kinetics and isotherm investigations, respectively. MgO nanoparticles exhibited a high adsorption capacity for Cu(II) (234.34 mg/g) and Pb(II) (221.26 mg/g). The existence of interfering ions in the aqueous solution leads to a decrease in the adsorption capacity. Surface complexation was determined as the key contributor to the adsorption of Cu(II) and Pb(II) heavy-metal ions onto MgO nanorods. Notably, regeneration experiments demonstrate the potential applicability of MgO nanorods for the elimination of Pb(II) and Cu(II) from aqueous solution

Efficient and Rapid Removal of Pb(II) and Cu(II) Heavy Metals from Aqueous Solutions by MgO Nanorods

In this study, the adsorption capability of MgO nanorods for the quick and effective elimination of Cu(II) and Pb(II) heavy metals from wastewater was examined. The MgO nanorods were produced via simple coprecipitation process. Various characterization techniques were used to investigate the morphological and chemical properties of the as-prepared nanomaterial. Moreover, the influences of initial heavy-metal ion concentration, pH, and contact time were investigated to evaluate the removal efficiency of the nanomaterials. The adsorption process followed pseudo-second order and Langmuir adsorption isotherm models, according to kinetics and isotherm investigations, respectively. MgO nanoparticles exhibited a high adsorption capacity for Cu(II) (234.34 mg/g) and Pb(II) (221.26 mg/g). The existence of interfering ions in the aqueous solution leads to a decrease in the adsorption capacity. Surface complexation was determined as the key contributor to the adsorption of Cu(II) and Pb(II) heavy-metal ions onto MgO nanorods. Notably, regeneration experiments demonstrate the potential applicability of MgO nanorods for the elimination of Pb(II) and Cu(II) from aqueous solution

Uptake of BF Dye from the Aqueous Phase by CaO-g-C₃N₄ Nanosorbent: Construction, Descriptions, and Recyclability

Removing organic dyes from contaminated wastewater resulting from industrial effluents with a cost-effective approach addresses a major global challenge. The adsorption technique onto carbon-based materials and metal oxide is one of the most effective dye removal procedures. The current work aimed to evaluate the application of calcium oxide-doped carbon nitride nanostructures (CaO-g-C3N4) to eliminate basic fuchsine dyes (BF) from wastewater. CaO-g-C3N4 nanosorbent were obtained via ultrasonication and characterized by scanning electron microscopy, X-ray diffraction, TEM, and BET. The TEM analysis reveals 2D nanosheet-like nanoparticle architectures with a high specific surface area (37.31 m2/g) for the as-fabricated CaO-g-C3N4 nanosorbent. The adsorption results demonstrated that the variation of the dye concentration impacted the elimination of BF by CaO-C3N4 while no effect of pH on the removal of BF was observed. Freundlich isotherm and Pseudo-First-order adsorption kinetics models best fitted BF adsorption onto CaO-g-C3N4. The highest adsorption capacity of CaO-g-C3N4 for BF was determined to be 813 mg. g−1. The adsorption mechanism of BF is related to the π-π stacking bridging and hydrogen bond, as demonstrated by the FTIR study. CaO-g-C3N4 nanostructures may be easily recovered from solution and were effectively employed for BF elimination in at least four continuous cycles. The fabricated CaO-g-C3N4 adsorbent display excellent BF adsorption capacity and can be used as a potential sorbent in wastewater purification

Efficient Mesoporous MgO/g-C₃N₄ for Heavy Metal Uptake: Modeling Process and Adsorption Mechanism

Removing toxic metal ions arising from contaminated wastewaters caused by industrial effluents with a cost-effective method tackles a serious concern worldwide. The adsorption process onto metal oxide and carbon-based materials offers one of the most efficient technologies adopted for metal ion removal. In this study, mesoporous MgO/g-C3N4 sorbent is fabricated by ultrasonication method for the uptake Pb (II) and Cd (II) heavy metal ions from an aqueous solution. The optimum conditions for maximum uptake: initial concentration of metal ions 250 mg g−1, pH = 5 and pH = 3 for Pb++ and Cd++, and a 60 mg dose of adsorbent. In less than 50 min, the equilibrium is reached with a good adsorption capacity of 114 and 90 mg g−1 corresponding to Pb++ and Cd++, respectively. Moreover, the adsorption isotherm models fit well with the Langmuir isotherm, while the kinetics model fitting study manifest a perfect fit with the pseudo-second order. The as fabricated mesoporous MgO/g-C3N4 sorbent exhibit excellent Pb++ and Cd++ ions uptake and can be utilized as a potential adsorbent in wastewater purification

High Poisonous Cd Ions Removal by Ru-ZnO-g-C₃N₄ Nanocomposite: Description and Adsorption Mechanism

Ru-ZnO-g-C3N4 nanocomposite was made using a straightforward ultrasonication method and evaluated for its potential to remove Cd ions from aqueous environments. X-ray diffraction analysis confirms composite production with an average crystalline size of 6.61 nm, while transmission electron microscopy results indicate nanosheet-like nanomaterials with uniform elements distribution. Measurements of N2 adsorption–desorption reveal the creation of a mesoporous structure with a BET surface area of approximately 257 m2/g. Fourier converted infrared reveals vibrational modes for O-H, amino groups, triazine, and Ru-ZnO. In contrast, X-ray photoelectron spectroscopy investigation reveals the presence of the elements Ru, Zn, O, N, and C. Ru-ZnO-g-C3N4 nanocomposite has remarkable adsorption efficiency for aqueous Cd ions, achieving 475.5 mg/g in 18 min. This study reveals that the Ru-ZnO-g-C3N4 nanocomposite may be used as an effective and reusable adsorbent for removing Cd ions during wastewater treatment and, possibly, for eliminating other toxic metal ions

Dependency of Crystal Violet Dye Removal Behaviors onto Mesoporous V₂O₅-g-C₃N₄ Constructed by Simplistic Ultrasonic Method

This research examined the production of a V2O5-g-C3N4 nanocomposite to remove organic dyes from wastewater. To generate the V2O5-g-C3N4 nanocomposite, the sonication method was applied. The testing of V2O5-g-C3N4 with various dyes (basic fuchsin (BF), malachite green (MG), crystal violet (CV), Congo red (CR), and methyl orange (MO)) revealed that the nanocomposite has a high adsorption ability towards BF, MG, CV, and CR dyes in comparison with MO dye. It was established that the modification of pH influenced the removal of CV by the V2O5-g-C3N4 nanocomposite and that under optimal operating conditions, efficiency of 664.65 mg g−1 could be attained. The best models for CV adsorption onto the V2O5-g-C3N4 nanocomposite were found to be those based on pseudo-second-order adsorption kinetics and the Langmuir isotherm. According to the FTIR analysis results, the CV adsorption mechanism was connected to π–π interactions and the hydrogen bond

Fabrication of Mesoporous V2O5@g-C3N4 Nanocomposite as Photocatalyst for Dye Degradation

This study investigated the photocatalytic degradation of RB dye by V2O5@g-C3N4 nano-catalysts. The sonication method was utilized to create V2O5@g-C3N4 nano-catalysts. V2O5@g-C3N4 nano-catalysts were characterized using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), high-resolution electron microscopy (TEM), BET-surface area analyzer, X-ray photoelectron spectroscopy (XPS), and ultraviolet spectroscopy. In the meantime, the photocatalytic activity, pH, and photocatalyst dosage are investigated in depth to account for RB dye decolorization. The rate constant for RB dye photodegradation was 0.0517 (min&minus;1) and the decolorization rate was 93.4%. The degrading efficiency of RB dye by V2O5@g-C3N4 nanocatalysts is consistent with pseudo-first-order kinetics. The results of this study demonstrated that V2O5@g-C3N4 nanocatalysts are particularly effective at destroying dyes in water