Copper Loading Research Articles

Three-Dimensional Assemblages of Metal Silicate for Catalytic CO2 Conversion to Methanol and Adsorptive Pollutant Removal

Morphological transformation was performed on Stöber silica nanospheres (ca. 270 nm in diameter) and transmuted into either ZnSiO (zinc silicate) nanoflowers or MgSiO (magnesium silicate) nanoflowers (600–800 nm in diameter) through a facile hydrothermal process. The zinc silicate materials were then chosen for incipient wetness impregnation to imbue them with different levels of Cu and Zn doping due to the well-established elemental synergy of Cu and Zn toward methanol synthesis via CO2 hydrogenation. Characterization results concur that zinc silicate nanoflowers loaded with copper(II) oxide were formed after incipient wetness impregnation. Three as-synthesized catalyst candidates with different copper loadings were then evaluated for CO2 hydrogenation and compared against an industrial catalyst. After the reaction, high-resolution transmission electron microscopy (HRTEM) with energy-dispersive X-ray (EDX) elemental mapping reveal that petite Cu nanoparticles formed on the petals of the impregnated zinc silicate nanoflowers. Experimental results show that all catalyst materials have an exceptional high methanol selectivity, with overall performance exceeding that of the industrial catalyst at per Cu basis. Both ZnSiO and MgSiO were also evaluated through a simple methylene blue adsorption test. Hence, through deliberate morphological control and chemical transformation, superficially inert Stöber silica nanospheres were functionalized into transition- and earth-alkaline metal silicates, which exhibit catalytic and adsorptive properties with a nanoflower morphology that prevents interstacking of nanosheets.

Direct conversion of CH4 and CO2 to alcohols using plasma catalysis over Cu/Al(OH)3 catalysts

The direct conversion of CH4 and CO2 into high-value alcohols is a highly desirable route for efficiently utilizing these two C1 sources while mitigating greenhouse gas emissions. However, this reaction is considered one of the most challenging research topics since it suffers from the contradiction between thermodynamics and kinetics. In this study, plasma-catalytic conversion of CH4 and CO2 for the production of high-value alcohols, with methanol being the major liquid product, was achieved using Cu-based catalysts at ∼190 °C and atmospheric pressure. Herein, the Cu-based catalysts were tuned by controlling the support material (Al(OH)3, γ-Al2O3, TiO2 and CeO2), calcination temperature (400–600 °C) and copper loading (1–20 wt%) to promote alcohol production in this reaction. The results show that the 5 wt% Cu/Al(OH)3 calcined at 540 °C exhibited the highest selectivity of alcohols (∼38%), which is the best result achieved so far in the presence of a catalyst. Catalyst characterization results reveal that the redox capacity and valence state of the copper species play a crucial role in tuning the product distribution. The Cu/Al(OH)3 catalyst with strong redox capacity and abundant Cu2+ species significantly improves the selectivity of alcohols. Interestingly, the predominant alcohol gradually shifts from methanol to ethanol with increasing copper loading, and the optimal copper loading for producing methanol and ethanol was found to be 5 wt% and 15 wt%, respectively. This work provides valuable insights for designing efficient catalysts to tune the production of alcohols through the single-step plasma-catalytic conversion of CH4 and CO2.

Copper nanoparticles encapsulated in a nanoporous carbon-based catalyst in the upgradation of γ-valerolactone to 1,4-pentanediol by selective hydrogenation

This research work introduces highly dispersed Cu nanoparticles encapsulated into a nanoporous carbon (Cu@C) structure as an efficient catalytic system in selective hydrogenation of γ-valerolactone (GVL) to 1,4-pentanediol. The nanoporous carbon support and the catalysts were synthesized by sequential novel methods and characterized extensively by using a combination of different analytical techniques to determine the phase, textural, morphology, nanoparticles size, and distribution analysis, and redox behavior. The designed Cu@C embedded catalysts show moderately high activity in GVL hydrogenation with different Cu loadings. The effect of copper loadings was found to be a significant parameter in gaining the best performance in GVL conversion. The copper nanoparticles were uniformly distributed over the nano-scaled carbon structure with active metallic Cu(111) sites with high dispersion and promote GVL hydrogenation, efficiently. Over a 5Cu@C catalyst exhibited the highest GVL conversion (∼91%) and 1,4-pentanediol selectivity (∼97%) at 200 °C for a 5 h reaction time under a 5 MPa H2 pressure. The dispersion of the active copper phase in combination with a smaller particle size and surface acidity is directly correlated with the catalytic performance activity. The effects of reaction parameters such as the reaction time, temperature, and H2 pressure were systematically investigated. Overall, Cu@C is a promising non-noble metal-based catalytic system for the upgradation of biomass-based platform molecules via selective hydrogenation.

Tailoring Oxygen Vacancies and Active Surface Oxygen Species in Copper-Doped MnO2 Catalysts for Total Catalytic Oxidation of VOCs

Catalytic oxidation has been considered an essential route to tackle volatile organic compounds (VOCs)-driven pollution. To this point, surface engineering has emerged as a robust pathway to promote the efficiency of MnO2-based materials toward VOC oxidation. However, regulating such surface properties has been a critical challenge. This investigation attempts to tailor surface oxygen vacancies and active surface oxygen for the total catalytic oxidation of various VOCs (e.g., formaldehyde, isopropanol, and toluene) via doping copper into cryptomelane and birnessite-type MnO2 catalysts. The catalysts are synthesized by a novel facile successive redox precipitation method between KMnO4 and an ethanol solution containing copper nitrate precursors, followed by annealing. It turns out that the low amount of Cu dopants, corresponding to the copper-to-manganese ratio of 0.17 (RCu/Mn = 0.17), generates a tunnel-structured cryptomelane-type MnO2 with strong bulk oxygen mobility. Such a crystalline structure exhibits the best catalytic performance for the total catalytic oxidation of toluene. The higher copper loading (RCu/Mn = 0.27–0.34) drives the formation of Cu-doped layered birnessite-type MnO2 materials containing rich oxygen vacancies and high active surface oxygen species. Those catalysts promote the oxidation of isopropanol and formaldehyde, respectively. To this end, oxygen vacancies and surface oxygen species crucially steer the molecular oxygen activation and interactions toward adsorbed oxygen species, significantly promoting the total oxidation of isopropanol and formaldehyde, respectively. The explored finding could disclose an outstanding platform toward highly selective and efficient oxidation of VOCs.

Continuous single-stage elemental sulfur reduction and copper sulfide precipitation under thermoacidophilic conditions

Metal sulfide precipitation is a viable technology for high-yield metal recovery from hydrometallurgical streams, with the potential to streamline the process design. A single-stage elemental sulfur (S0)-reducing and metal sulfide precipitating process can optimize the operational and capital costs associated with this technology, boosting the competitiveness of this technology for wider industrial application. However, limited research is available on biological sulfur reduction at high temperature and low pH, frequent conditions of hydrometallurgical process waters. Here we assessed the sulfidogenic activity of an industrial granular sludge previously shown to reduce S0 under hot (60–80 °C) and acidic conditions (pH 3.6). A 4 L gas-lift reactor was operated for 206 days and fed continuously with culture medium and copper. During the reactor operation, we explored the effect of the hydraulic retention time, copper loading rates, temperature, and H2 and CO2 flow rates on the volumetric sulfide production rates (VSPR). A maximum VSPR of 274 ± 6 mg·L−1·d−1 was reached, a 3.9-fold increase of the VSPR previously reported with this inoculum in batch operation. Interestingly, the maximum VSPR was achieved at the highest copper loading rates. At the maximum copper loading rate (509 mg·L−1·d−1), a 99.96% copper removal efficiency was observed. 16 s rRNA gene amplicon sequencing revealed an increased abundance of reads assigned to Desulfurella and Thermoanaerobacterium in periods of higher sulfidogenic activity.

Performance and mechanisms of iron/copper-doped zirconium-based catalyst containing hydroxyl radicals for enhanced removal of gaseous benzene.

In the present study, novel copper-doped zirconium-based MOF (UIO-66) and copper-doped iron-based UIO-66 catalysts were prepared by hydrothermal synthesis method to improve the removal performance of gaseous benzene. The characteristics of the catalysts were analyzed by means of XRD, SEM, XPS, BET, and EPR. The copper loading catalyst had high crystallinity and irregular globular. The three kinds of catalysts with different Cu/Fe ratios had regular cubic shape. Compared with the catalyst supported with single copper, the bimetal Cu/Fe modification had a certain adjustment effect on the morphology, which specifically reflected in the uniform size and shape of catalyst particles with better dispersibility. The factors of different metal loading, dose of H2O2, and reaction temperature on benzene removal have been studied. It has been observed that in heterogeneous advanced oxidation removal of benzene, 3-Cu@UIO-66 and Cu1.5/Fe1.5@UIO-66 achieved the highest benzene removal efficiency of 81.2% and 94.6%, respectively. EPR results showed that the increase of Cu loading and different Cu/Fe ratios promoted the yield of hydroxyl radicals, thus promoted the benzene removal efficiency. The efficiency of heterogeneous oxidation removal of benzene first increased and then decreased with the increase of temperature due to H2O2 instability. DFT calculations exhibited that the Feoct-Cu-O site was a more effective activation site than the single Feoct-O site. Dissociative adsorption occurred with the O-O bond of H2O2 cracked, and the formed hydroxyls parallel adsorbed on the benzene surface. The combination of benzene and hydroxyls was strong chemisorption with the torsion angle of benzene ring obviously turned. The work was of great importance for identifying the roles of the novel catalyst for the removal of benzene pollutant from waste gases.

Inactivation of SARS-CoV-2 variants by nitrogen-doped titanium dioxide loaded with metals as visible-light photocatalysts.

We examined the inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by a nitrogen-doped titanium dioxide (N-TiO2) visible-light photocatalyst that was activated via light irradiation in the natural environment and was safe for human use as a coating material. The photocatalytic activity of glass slides coated with three types of N-TiO2 without metal or loaded with copper or silver and copper was investigated by measuring acetaldehyde degradation. The titer levels of infectious SARS-CoV-2 were measured using cell culture after exposing photocatalytically active coated glass slides to visible light for up to 60min. N-TiO2 photoirradiation inactivated the SARS-CoV-2 Wuhan strain and this effect was enhanced by copper loading and further by the addition of silver. Hence, visible-light irradiation using silver and copper-loaded N-TiO2 inactivated the Delta, Omicron, and Wuhan strains. N-TiO2 could be used to inactivate SARS-CoV-2 variants, including emerging variants, in the environment.

Liquid–liquid separation of copper and nickel ammine complexes using phenolic oxime mixture with tributyl phosphate

ABSTRACT In the present study, a complete separation of copper over nickel has been studied from an ammoniacal leach liquor of nickel laterite ore generated via the Caron process. For this purpose, a phenolic oxime (LIX 84-IC) used as the extractant molecule was mixed with tributyl phosphate (TBP) to inhibit the co-extraction of nickel with copper loading into the organic phase. The antagonistic effect of TBP was confirmed by the distribution coefficients to be D mix << D LIX 84-IC + D TBP and negative values of ∆D. The highest separation (β Cu/Ni) of >1329 was yielded using the molar ratio of organic mixture at LIX 84-IC:TBP = 0.4:0.6 at an organic-to-aqueous phase ratio of 1. The thermodynamic properties of copper extraction exhibited an endothermic nature with ΔH° value of 5.4 kJ∙mol−1, indicating the formation of inner-sphere coordination between metal ions and the organic mixture. Further, the stripping of copper from the loaded organic phase was quantitatively achieved by contacting with 1.0 mol∙L−1 H2SO4 solution at the unit phase ratio.

Recovery of Au and Ag from the roasted calcine of a copper-rich pyritic refractory gold ore using ion exchange resins

The recovery of Au and Ag from a roasted copper-rich pyritic refractory gold ore (78 g/t Au, 6.8 g/t Ag, 1.38 % Cu and 3.09 % Fe was investigated. Cyanide leaching and adsorption tests were performed at different concentrations of cyanide (1.5 g/L and 5 g/L NaCN) and the adsorbent dosages ranged from 2 g/L to 10 g/L. In the cyanide leaching tests, those performed at a high cyanide level (i.e., 5 g/L) produced high gold and silver extractions from the roasted ore apparently due to the increased availability of cyanide for gold leaching. Adsorption tests (CIL/CIP, RIL/RIP) were performed to investigate the selective recovery of gold and silver from copper-laden pregnant leach solutions obtained from cyanide leaching of the roasted ore. Activated carbon (NORIT GAC 1240), strong base resin (Purogold A194) and weak base resin (Purogold S992) were tested as adsorbents in these tests. The practical importance of increasing cyanide concentration on the selectivity (gold/silver vs copper) of resins as well as activated carbon was demonstrated. Each adsorbent offered good selectivity for gold over copper, particularly at a high concentration of cyanide (5 g/L NaCN). Purogold S992 appeared to be the most selective adsorbent with the highest gold and the lowest copper loadings. This distinctive trait makes the resin preferable for gold recovery from cyanide solutions containing significant levels of copper. Comparative pore size distribution analysis of the adsorbents has shown that Purogold S992 has the smallest pores with uniform size distribution among the adsorbents used. This was concomitant with its superior selectivity for gold at high cyanide concentration, which is linked with the small-size and linear gold-cyanide complexes c.f. large size and non-linear copper–cyanide complexes (Cu(CN)32– and Cu(CN)43-).

Singlet oxygen generation in light-assisted peroxymonosulfate activation by carbon nitride: Role of elevated crystallinity

Carbon nitride (CN) is an emerging 2D non-metal semiconductor material that could be used in photocatalysis and advanced oxidation processes (AOPs) for pollutants degradation. The radical-induced degradation by CN in photocatalysis or photo-assisted AOPs was widely reported in previous studies. Nevertheless, how the non-radical degradation by CN materials could be achieved under irradiation is neither well understood nor controlled. In this work, crystalline carbon nitride (CCN) was synthesized via a facile molten-salt method, and used to activate peroxymonosulfate (PMS) under visible light (>420 nm) to selectively and efficiently degrade tetracycline (TC). Compared to the traditional polymeric carbon nitride (PCN), CCN was found to be a superior PMS activator with the assistance of visible light, which was ascribed to the increased crystallinity of CN tri-s-triazine units and the increased number of catalytic sites, thereby optimizing the photoelectric properties. The activation performance could be further improved by copper loading, with TC degradation rate nearly six times more than that of PCN. EPR trapping and quenching tests showed that singlet oxygen (1O2) was the dominant reactive oxygen species in the CCN/PMS/visible light system, attributing to the increased graphitic N sites and formation of electron-deficient C in C–N bonding between neighboring tri-s-triazine units upon crystallinity elevation in CCN. In contrast to the conventional radical-based photocatalysis and AOP processes, the visible light-assisted non-radical AOP degradation was highlighted for the selectivity and the remarkable resistance to the impacts of background inorganic anions or natural organic matter (up to 10 mg/L) in the actual water matrix. This work revealed the 1O2 generation mechanism by CN-based materials under the joint assistance of visible light illumination and crystallinity elevation, and its excellent removal performance demonstrates the great potential of CCN-based materials in the practical wastewater treatment.

Enhancement of NOx adsorption performance on zeolite via a facile modification strategy.

Adsorption is a promising technology for simultaneously capturing nitrogen oxides (NOx) from flue gases and recycling NO2 as a profitable chemical, for which a robust and efficient adsorbent provides the key step for success in practical applications. This work reports the enhancement of NOx adsorption performances with less cost of desorption energy on Cu-ZSM-5 zeolites prepared by a facile and rapid (690s) modification method, the incipient-wetness impregnation coupled with microwave drying (IM). In comparisons to H-ZSM-5, Na-ZSM-5 and conventionally liquid-phase ion-exchanged counterparts under sub-1000ppm NOx feed concentrations and room temperature, the IM sample renders a record NOx adsorption capacity (qt,NOx) of 0.878mmol/g from dry gas stream on zeolites, and an applicable qt,NOx of 0.1mmol/g from wet gas stream with a proper copper loading (2.1wt%). The temperature programmed desorption of NOx on the optimal IM sample saturated with NOx from wet gas stream exhibit primary peak temperature lower than reported Cu-ZSM-5 and significant NO2 proportion (72.6%) in desorbed NOx. Deeper insights into advantageous NOx oxidative adsorption over the properly-loaded Cu-ZSM-5 in terms of diverse adsorbate states and competitiveness towards H2O were gained, showing IM method a promising sorbent improvement strategy for practical use.

The study on Cu-ZK-5 catalyst of copper content regulation and anti-propylene poisoning mechanism in NH3-SCR reaction

Cu-ZK-5 catalysts have been attempted to utilize as NH3-SCR because they have small pores and eight-membered ring structures. In this work, Cu-ZK-5 catalysts with different copper contents were investigated. It was found that the Cu7.55-ZK-5 catalyst showed excellent activity and resistance to propylene poisoning for NH3-SCR. When the copper content is too low, the number of active copper species is less, and the activity is poor. When the copper content is too high, CuOx species will be generated to destroy the structure of the molecular sieve and affect the activity, which manifested that the optimal copper loading of Cu-ZK-5 catalyst possesses more Cu2+ species improving the activity for NH3-SCR. Furthermore, the presence of propylene on Cu7.55-ZK-5 catalyst had little impact on the low-temperature catalytic performance and exhibited excellent propylene resistance at medium and high temperatures. The influence on the low-temperature catalytic performance of the Cu-ZK-5 catalyst is mainly since C3H6 has competitive adsorption with NO on the surface of Cu-ZK-5, which may be the main reason for slightly reducing the NOx conversion of Cu-ZK-5 catalyst.

Tuning Copper Active Site Composition in Cu-MOR through Co-Cation Modification for Methane Activation.

The industrial implementation of a direct methane to methanol process would lead to environmental and economic benefits. Copper zeolites successfully execute this reaction at relatively low temperatures, and mordenite zeolites in particular enable high methanol production. When loaded to a Cu/Al ratio of 0.45, mordenite (Si/Al 5 to 9) has been shown to host three active sites: two [CuOCu]2+ sites labeled MOR1 and MOR2, and a mononuclear [CuOH]+ site. Also at low copper loadings (Cu/Al < 0.20), mordenite has been demonstrated to activate methane, but its active site has never been reported. Here, we investigate Na+ mordenite with varying copper loadings to better understand copper speciation in mordenite. At low copper loadings, we uncover an unidentified active site ('MOR3') with a strong overlap with the [CuOH]+ site's spectroscopic signal. By changing the co-cation, we selectively speciate more MOR3 relative to [CuOH]+, allowing its identification as a [CuOCu]2+ site. Active site identification in heterogeneous catalysts is a frequent problem due to signal overlap. By changing cation composition, we introduce an innovative method for simplifying a material to allow better analysis. This has implications for the study of Cu zeolites for methane to methanol and NOx catalysis, but also for studying and tuning heterogeneous catalysts in general.

Morphology controlled Cu nanostructures grafted over rGO as highly efficient and recyclable heterogeneous catalysts to develop 1,2,3-triazole derivatives under click conditions

We report two easily synthesizable, reusable and morphology-controlled copper nanostructures grafted over rGO (i.e., rGO-CuNRs and rGO-CuNPs). The structure, morphology and the composition of the nanocatalysts have been characterized by TEM, SEM, XPS, PXRD and TGA analyses. These nanocatalysts having ‘rod-like’ (for rGO-CuNRs) as well as spherical (for rGO-CuNPs) nanostructures promoted one-pot multicomponent click reaction between in situ generated organic azide and phenyl acetylene to afford a 1,2,3-triazole derivative (L). The nanocomposites containing ‘rod-like’ morphology exhibited remarkably higher catalytic activity as compared to spherical nanoparticle counterparts. Interestingly, rGO-CuNRs exhibited rapid synthesis (∼ 60 min) of L with excellent yield (∼ 92%) involving pure water as a clean and eco-friendly reaction medium. A low copper loading, high recyclability upto 7 times with the negligible loss of catalytic activity and easy workup process is presented. The click product (L) will find promising applications as ‘polydentate click chelator’ to generate metallo-supramolecular assemblies in biomimetic chemistry.

Leaching Stability and Redox Activity of Copper-MFI Zeolites Prepared by Solid-State Transformations: Comparison with Ion-Exchanged and Impregnated Samples.

The catalyst preparation route is well known to affect the copper loading and its electronic state, which influence the properties of the resulting catalyst. Electronic states of copper ions in copper-containing silicalites with the MFI-framework topology obtained by a solid-state transformation S (SST) were studied with using EPR, UV-Vis DR, XRD, H2-TPR and chemical differentiating dissolution. They were compared with Cu-ZSM-5 and Cu-MFI (silicalite) prepared via the ion-exchange and incipient wetness impregnation. SST route was shown to provide the formation of MFI structure and favor clustering of Cu-ions near surface and subsurface of zeolite crystals. The square-planar oxide clusters of Cu2+-ions and the finely dispersed CuO nanoparticles with the size down to 20 nm were revealed in Cu-MFI-SST samples with low (0.5-1.0 wt.%) and high (16 wt.%) Cu-content. The CuO nanoparticles were characterized by energy band gap 1-1.16 eV. The CuO-like clusters were characterized by ligand-to-metal charge transfer band (CTB L → M) at 32,000 cm-1 and contain EPR-visible surface Cu2+-ions. The low Cu-loaded SST-samples had poor redox properties and activity towards different solvents due to decoration of copper-species by silica; whereas CuO nanoparticles were easily removed from the catalyst by HCl. In the ion-exchanged samples over MFI-silicalite and ZSM-5, Cu2+-ions were mainly CuO-like clusters and isolated Cu2+ ions inside MFI channels. Their redox properties and tendency to dissolve in acidic solutions differed from the behavior of SST-series samples.

Preparation of CuZn-Doped MgAl-Layered Double Hydroxide Catalysts through the Memory Effect of Hydrotalcite for Effective Hydrogenation of CO2 to Methanol

In this work, a synthesis procedure was developed to introduce transition metal ions into a MgAl-layered double hydroxide (MgAl-LDH, or hydrotalcite) by utilizing the unique “memory effect” property of calcined LDH. This technique allows our MgAl-LDH to retain its pristine flowerlike morphology, which prevents stacking of nanosheets and is fully accessible for reactants. Briefly, calcined MgAl-LDH (or MgAl-layered double oxide, MgAl-LDO) was submerged in dilute monometal or mixed transition metal nitrate solutions, allowing ion exchange of M2+ cations and the rehydration of MgAl-LDO back into LDH through the memory effect. The product was centrifuged and dried, allowing pre-selected transition metals (e.g., Cu, Zn, Ni, and Co) to occupy some of the octahedral sites of the LDH phase in which Mg2+ ions were previously located. A CuZn-doped MgAl-LDH was then carefully reduced under a hydrogen atmosphere, precipitating tiny Cu nanoparticles out of the reformed LDH nanosheets, and was subsequently used in a series of CO2 hydrogenation experiments. The bifunctional material, which comprises a CO2-sorbent LDH support with active metal cocatalysts, has achieved high specific activity per copper loading and high methanol selectivity, while maintaining a stable performance with over 70% methanol selectivity over 40 h at 280 °C. The excellent performance of this catalyst is attributed to the easily accessible active sites (Cu0 nanoparticles) located on the surface of nanostructured petals for the gaseous reactants. The performance was found to be remarkably better than that of a well-established commercial Cu-based catalyst for methanol synthesis. Future potential development could entail the functionalization of other transition metals for the utilization of CO2.

Preparation of XCu@TiO2 adsorbent for high-efficient PH3 removal in anaerobic environment and evaluation of desulfurization activity of deactivated adsorbent

In this study, we prepared high-performance copper-modified adsorbent (XCu@TiO2) via a simple and low-cost strategy to achieve efficient removal of PH3 under anaerobic conditions. The effects of copper loading and reaction temperature on the performance of the adsorbent are first investigated, and the experimental results demonstrated that the optimal adsorbent (30Cu@TiO2) had the highest PH3 breakthrough capacity (135.73 mg(PH3)‧gadsorbent-1) among all the tested adsorbents. Further characterization analysis confirmed that CuO is the active component of the adsorbent, and the excellent dephosphorization performance is attributed to its abundant alkaline sites, sufficient active oxygen, and developed pore structure. While the consumption of CuO and the accumulation of phosphorus species (H3PO4, Cu3P) on the surface and internal pores of the adsorbent are the main reasons for the deactivation of the adsorbent. Strikingly, the deactivation of the adsorbent converts its active component CuO into the P-type semiconductor Cu3P with high added value, implying that the deactivated adsorbent (Cu3P/TiO2) is a multifunctional material, and the desulfurization experiments also confirm the reusability of the deactivated adsorbent. Overall, XCu@TiO2 is a promising and efficient PH3 adsorbent that can effectively avoid the risk of secondary pollution during the treatment and regeneration of deactivated adsorbents.

Highly porous phosphate-based glasses for controlled delivery of antibacterial Cu ions prepared via sol-gel chemistry.

Mesoporous glasses are a promising class of bioresorbable biomaterials characterized by high surface area and extended porosity in the range of 2 to 50 nm. These peculiar properties make them ideal materials for the controlled release of therapeutic ions and molecules. Whilst mesoporous silicate-based glasses (MSG) have been widely investigated, much less work has been done on mesoporous phosphate-based glasses (MPG). In the present study, MPG in the P2O5-CaO-Na2O system, undoped and doped with 1, 3, and 5 mol% of Cu ions were synthesized via a combination of the sol-gel method and supramolecular templating. The non-ionic triblock copolymer Pluronic P123 was used as a templating agent. The porous structure was studied via a combination of Scanning Electron Microscopy (SEM), Small-Angle X-ray Scattering (SAXS), and N2 adsorption-desorption analysis at 77 K. The structure of the phosphate network was investigated via solid state 31P Magic Angle Spinning Nuclear Magnetic Resonance (31P MAS-NMR) and Fourier Transform Infrared (FTIR) spectroscopy. Degradation studies, performed in water via Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), showed that phosphates, Ca2+, Na+ and Cu ions are released in a controlled manner over a 7 days period. The controlled release of Cu, proportional to the copper loading, imbues antibacterial properties to MPG. A significant statistical reduction of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterial viability was observed over a 3 days period. E. coli appeared to be more resistant than S. aureus to the antibacterial effect of copper. This study shows that copper doped MPG have great potential as bioresorbable materials for controlled delivery of antibacterial ions.

Enhanced activation of peroxymonosulfate by a floating Cu0-MoS2/C3N4 photocatalyst under visible-light assistance for tetracyclines degradation and Escherichia coli inactivation

Transition metal-based photocatalysts have recently attracted much attention in photo-induced Peroxymonosulfate (PMS) activation systems. Herein, a novel floating catalyst Cu0-MoS2/C3N4-expanded graphite (Cu-MSCN-EG) was prepared by a chemical reduction method and applied as a PMS activator to remove tetracyclines (TCs) and inactivate Escherichia coli under visible light irradiation in aqueous solution. Over 99.0 % of TCs and Escherichia coli could be removed and inactivated within 1 h in Vis/PMS/Cu-MSCN-EG system. Compared to the MoS2/C3N4-EG system, the loading of zero-valent copper in the Vis/PMS/Cu-MSCN-EG system increased the reaction rate by 278 %. Raman spectroscopy and density functional theory (DFT) calculations indicated that ·OH and 1O2 were generated via two different adsorption patterns between PMS and copper (≡Cu+-OSO3-–OH and ≡Cu+–OH-OSO3-). With the light assistance, the photo-induced electrons reduced the copper leaching and enhanced the generation of ·SO4- and ·O2–, leading to a high recyclability and mineralization rate. Overall, this study provides a new insight into the fabrication of copper-based PMS activator with high efficiency and durability for contaminants degradation and pathogen inactivation.

Mechanically Driven Atom Transfer Radical Polymerization by Piezoelectricity.

Targeting sustainable and eco-friendly polymer synthesis, we demonstrate here a synergistically catalyzed atom transfer radical polymerization (ATRP) induced and controlled by interplay between ball milling (BM) and piezoelectric nanoparticles (piezoNPs). BM-induced electron transfer can be achieved through piezoNPs deformation under impact force, serving as an external stimulus to mediate polymerization. The ppm level of copper loading is sufficient in fabrication of a polymer with well-defined molecular weight and low polydispersity. High-molecular-weight polymers ranging from 33 to 74 kDa were prepared successfully through DMSO-assisted grinding. Besides, its good performance on availability of water as liquid-assisted grinding additive, the recyclability of piezoNPs, and the formation of cross-linker-free composite resin make our ATRP approach a green and practical option alongside the existent heat-, electro-, and photo-induced methods.