Ag Content Research Articles

Low temperature one-step synthesis of Ag nanoparticles on BaTiO3 for synergistic piezo-photocatalytic properties

It is a major constraint that complex synthesis methods limit the application of catalysts. Herein, Ag/BaTiO3 catalyst is synthesized via a facile method, which demonstrates the outstanding catalytic properties. Investigations reveal that Ag-loading BaTiO3 could increase carrier concentration, reduce the electronic impedance and enhance carrier’s separation efficiency under ultrasonic vibration, leading to superior piezocatalytic performance. Therefore, Ag/BaTiO3 catalyst presents the high degradation efficiency of 95.4 % in 50 min for RhB dye solution at light illumination and ultrasonic vibration. Moreover, when Ag content is 0.33 %, the degradation ratio of the sample still remains 81.9 % after 5th cycles, which indicates Ag/BaTiO3 catalyst has good stability. This work provides a novel and easy implement strategy for designing high performance catalysts, and could be extended to other catalytic material.

Temperature Etching and Metallic Agent Concentration Effect on Structure, Morphology and Wettability of Silicon Nanowires

Abstract. Structural, Morphologycal and Wettability of SiliconNanowires (SiNWs) elaborated using Ag assisted electroless chemical etching are investigated. Prior the etching, Ag nanoparticles (AgNPs) were deposited at room temperature in a HF/AgNO3 solution with different concentration of AgNO3. The XRD spectra of the Ag NPs deposit show a good crystallinity. The effects of temperature etching bath and concentrations of AgNO3 on the etching process were examined. The morphological study, performed using a Scanning Electron Microscopy (SEM), shows porous silicon layer of 2µm for the lower temperature etching. For 25°C, perpendicular silicon nanowires about 15µm were formed. For the higher etching temperature (50°C), the silicon nanowire about 50 nm in diameter and 50µm in length were formed. The impact of Ag concentration on the SiNWs formation is examined in the second part of the present work. It is shown that the etching depth decreases as the Ag concentration decreases with values of 2.8 μm and 2 μm for concentrations of 0.025M and 0.0125M, respectively. The hydrophobicity of the samples was monitored by measuring the contact angle between a drop of water and the sample surface. It was established that the morphology is strongly influenced by etching conditions and their wettability changes from superhydrophilic to hydrophobic. FTIR analysis confirms the oxide-free silicon nanowires.

Surface Reaction of Electroosmotic Flow-Driven Free Antigens With Immobilized Magnetic-Microbeads-Tagged-Antibodies in Microchannels.

Immunoassays based on reactions between target pathogen (antigen; Ag) and antibody (Ab) are frequently used for Ag detection. An external magnetic field was used to immobilize magnetic microbeads-tagged-antibodies (mMB-Ab) on the surface of a microchannel in the capture zone. The mMB-Ab was subsequently used for Ag detection. The objective of this numerical study, with experimental validation, is to assess the surface reaction between mMB-Ab and Ag in the presence of electro-osmotic flow (EOF). First, immobilization of mMB-Ab complex in the wall of the capture zone was achieved. Subsequently, the Ag was transported by EOF toward the capture zone to bind with the immobilized mMB-Ab. Lastly, mMB-Ab:Ag complex was formed and immobilized in the capture zone. A finite volume solver was used to implement the above steps. The surface reaction between the mMB-Ab and Ag was investigated in the presence of electric fields (E): 150 V/cm-450 V/cm and Ag concentrations: 0.001 M-1000 M. The depletion of mMB-Ab increases with time as the E decreases. Furthermore, as the concentration of Ag decreases, the depletion of mMB-Ab increases with time. These results quantify the detection of Ag using the EOF device; thus, signifying its potential for rapid throughput screening of Ag. This platform technology can lead to the development of portable devices for the detection of target cells, pathogens, and biomolecules for testing water systems, biological fluids, and biochemicals.

Pyrite geochemical fingerprinting on skarn ore-forming processes: A case study from the Huangshaping W–Sn–Cu–Pb–Zn deposit in the Nanling Range, South China

Pyrite geochemistry has been extensively used to reveal ore-forming processes in diverse ore deposits, but its application in skarn systems is not well understood. The Huangshaping deposit in the Nanling Range (South China) uniquely develops W–Sn–Pb–Zn and Cu–Pb–Zn skarn mineralization systems, and both two systems have formed multi-types of pyrite, which provides a good window to reveal the mineralization histories of different skarn systems using pyrite trace element geochemistry. In the Cu–Pb–Zn system, texturally homogeneous Py1 mainly occurs in calcite veins within the host rock, whereas texturally homogeneous Py2 in the calcite-sulfide stage mainly occurs in skarn orebodies. Py3 in the siderite-sulfide stage replaces Py2 and commonly develops abundant pores or fractures, resembling the “bird's eye” texture. In the W–Sn–Pb–Zn system, Py4 in calcite veins can be divided into the oscillatory-zoned Py4a and irregular Py4b under BSE, and Py4b commonly replaces Py4a as veins or overgrowth. Texturally homogeneous Py5 in the calcite-sulfide stage occurs in skarn orebodies and is replaced by Py6 with a “bird's eye” texture in the siderite-sulfide stage.In the Cu–Pb–Zn system, Py1 may have formed by fluid cooling during its ascent along the hydraulic fractures indicated by its enrichment of Co, Ni, As, Sb, and Tl, whereas Py2 is likely formed under higher temperature and pH conditions caused by intense fluid-rock interactions evidenced by its depletion of Co, Ni, As, Sb, and Tl as well as its enrichment of Zn and Ag. In the W–Sn–Pb–Zn system, Py4b has higher contents of Co, Ni, As, Sb, and Tl than Py4a and similar contents of Ag, Zn, and Mo with Py4a, suggesting that decreasing temperature may have controlled the formation of Py4b. Py5 is featured by the depletion of As, Sb, Tl, and Mo as well as the enrichment of Zn and Ag, indicating that Py5 is likely formed under higher temperature and pH conditions resulting from the intense fluid-rock interactions. Marcasite replaces pyrrhotite and then is replaced by pyrite may be an important precipitation mechanism for pyrite with a “bird's eye” texture (Py3 and Py6) in both two skarn systems at Huangshaping. This study demonstrates that fluid-rock interaction is an important mechanism for sulfide precipitation at Huangshaping, which shows that pyrite geochemistry has good potential to reveal mineralization histories in skarn systems.

Magmatic evolution of the Kolumbo submarine volcano and its implication to seafloor massive sulfide formation

Seafloor massive sulfides form in various marine hydrothermal settings, particularly within volcanic arcs, where magmatic fluids may contribute to the metal budget of the hydrothermal system. In this study, we focus on the Kolumbo volcano, a submarine volcanic edifice in the central Hellenic Volcanic Arc hosting an active hydrothermal system. Diffuse sulfate-sulfide chimneys form a Zn-Pb massive sulfide mineralization with elevated As, Ag, Au, Hg, Sb, and Tl contents. These elements have similar behavior during magmatic degassing and are common in arc-related hydrothermal systems. Trace-element data of igneous magnetite, combined with whole rock geochemistry and numerical modelling, highlights the behavior of chalcophile and siderophile elements during magmatic differentiation. We report that, despite early magmatic sulfide saturation, chalcophile element contents in the magma do not decrease until water saturation and degassing has occurred. The conservation of chalcophile elements in the magma during magmatic differentiation suggests that most of the magmatic sulfides do not fractionate. By contrast, upon degassing, As, Ag, Au, Cu, Hg, Sb, Sn, Pb, and Zn become depleted in the magma, likely partitioning into the volatile phase, either from the melt or during sulfide oxidation by volatiles. After degassing, the residual chalcophile elements in the melt are incorporated into magnetite. Trace-element data of magnetite enables identifying sulfide saturation during magmatic differentiation and discrimination between pre- and post-degassing magnetite. Our study highlights how magmatic degassing contributes to the metal budget in magmatic-hydrothermal systems that form seafloor massive sulfides and shows that igneous magnetite geochemistry is a powerful tool for tracking metal-mobilizing processes during magmatic differentiation.

The role of Ag ions incorporation on the Magnetic, and Antimicrobial Properties of NiO Nanoparticles

Ni1-xAgxO nanoparticles (NPs) with x = 0.00, 0.02, 0.04, 0.06, and 0.08) were fabricated using the composite hydroxide mediated (CHM) method. The effects of Ag doping on the structural, magnetic, and antimicrobial characteristics of NiO NPs have been reported. The stretching mode of the Ni–O molecules was identified at 443 cm−1 in the Fourier transform infrared spectra. The aggregation of nanoparticles with different sizes and shapes is seen under transmission and scanning electron microscopes. The blocking temperature (TB) peak in zero-field cooled (ZFC) magnetization curves display the magnetization from the core of NPs. This peak is absent for the samples with x=0.00 and 0.02, which show instead a small net magnetization from the antiferromagnetic core of these NPs. However, a TB peak was found for the samples with x=0.04,0.06and0.08, at 22, 72, and 65 K, respectively, which indicates that the magnetization is induced from the AFM core of NiO NPs for higher Ag doping. With an increasing concentration of Ag in the NiO NPs, the net magnetization did increase and a maximum was found for x = 0.04 at 300 K. For a higher doping concentration of 8 % Ag, a sharp decrease in magnetization was observed. Furthermore, the efficacy and synergistic effect of Ag doping had been analyzed for the effective improvement of the antibacterial properties of NiO NPs. Pure and Ag-doped NiO NPs were exploited to assess their anti-microbial activity against Enterobacter sp., E. coli, P. aeruginosa, and S. pyrogens. The study revealed that anti-bacterial or anti-biofouling properties were introduced as an additional attribute to NiO NPs by incorporation of Ag ions due to its inherent nature as an antimicrobial agent and enhanced its capability to sterilize microbial pathogens.

Optimizing photovoltaic performance: Strategic enhancement of Ag-doped graded CAZTS solar cells achieving 27.3% efficiency

The Ag-doped Cu2ZnSnS4 (CAZTS) based solar cell has been explored, with varying Ag concentrations (x = 0, 0.1, 0.2, 0.3, 0.4) in the composition (Cu1−xAgx)2ZnSnS4. In order to mitigate back surface recombination in CAZTS-based solar cells, a Sn2S3 layer has been incorporated as a back surface field (BSF). Further, the efficiency enhancement employs a bandgap grading approach, elevating efficiency from 15.8 % to 24.7 % compared to devices without the graded structure. Additionally, the thickness and total defect density of the CAZTS layer are optimized. The result demonstrates that the optimized value of the CAZTS layer’s thickness is 1.1 µm, and the defects are 1 × 1012 cm−3. To further enhance the performance, the doping variation of the CAZTS layer has also been investigated. The findings indicate that the maximum efficiency of 27.32 % is attained with a doping value of 1 × 1016 cm−3.

Effects of micro-alloying Ag on microstructure, mechanical properties and corrosion behavior of extruded Mg-2Zn-0.2Ca-xAg alloys

The present work investigates effects of micro-alloying Ag on the microstructure, mechanical properties and corrosion behavior of as-extruded Mg-2Zn-0.2Ca alloys. The addition of Ag, up to 0.5 wt%, induce limited difference on microstructural characteristics such as slightly coarser microstructures due to the enhanced dynamic recrystallization process and the presence of refined precipitates. The tensile properties of the alloy were not significantly changed by Ag addition, i.e., all the alloys exhibited exceptional elongation of ∼30%, moderate tensile yield strength and ultimate strength of ∼140 MPa and ∼240 MPa, respectively. The corrosion performance of the alloys was progressively deteriorated with increasing Ag content i.e., the corrosion rate increased from 0.40 ± 0.23 mm/y for Mg-2Zn-0.2Ca alloy to 3.27 ± 0.24 mm/y for the Mg-2Zn-0.2Ca-0.5Ag alloy. The compromised corrosion performance was attributed to a large electrode potential difference between the nobler Ca2Mg6Zn3 phase and the α-Mg matrix as well as a less protective corrosion film, by increasing Ag addition.

Activated carbon impregnated with Ag(0) and Cu oxides for the removal of Escherichia coli, Giardia, and Cryptosporidium (oo)cysts from water

Granular activated carbon (GAC) impregnated with silver or copper was evaluated as a point-of-use water treatment to improve the microbiological quality of drinking water processed by low-cost, newly developed GAC filters. Experiments were carried out in a point-of-use water purifying system using packed-bed filters of GAC impregnated with various concentrations of Ag(0) or Cu oxides. The pore and surface properties were studied in terms of BET volumetric measurement with nitrogen adsorption (BET area of metal-impregnated GAC lies within the range of 602 ∼ 866 m²g−1, while the surface area of non-treated GAC is 870 m²g-1), X-ray diffraction (identifying the presence of metallic silver and copper oxide in the GAC structure) and Scanning Electron Microscopy (revealed the presence of metal compounds deposited on the GAC surface). The performance of filters with GAC (water treatment capacity of 4 L/g) was evaluated against microbiological contaminants in synthetic water so that the best loading concentration to remove microorganisms from test water could be determined. The removal efficiency against Escherichia coli was higher when the amount of metal impregnated on GAC increased. GAC impregnated with Ag(0) at 5.0 wt% had a strong antibacterial activity for the growth of Escherichia coli. Samples of GAC impregnated with Ag(0) at 1.0 wt% and Cu oxides at 0.5 wt% were more efficient in the removal of Giardia and Cryptosporidium (oo) cysts. The above evaluations showed that the proposed apparatus, based on a gravitational point-of-use filter with an adsorbent with metals has antibacterial properties and may be recommended to communities for household treatment of drinking water.

More than the barrier effect: Biodegradable Mg-Ag alloy membranes for guided bone/tissue regeneration

Magnesium (Mg) and its alloys have emerged as promising candidates for guided bone/tissue regeneration (GBR/GTR) due to their good mechanical properties, biosafety, and biodegradability. In this study, we present a pioneering application of Mg-Ag alloys featuring tunable corrosion behaviors for GBR/GTR membranes, showcasing their in vitro antibacterial effects, cell migration, and osteogenic differentiation abilities. Mg-Ag alloys with different Ag contents were engineered to facilitate the cell migration of murine fibroblasts (L929) and the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). The Mg-Ag alloy consisted of recrystallized α-Mg grains and fine Mg4Ag second phases, with an observable refinement in the average grain size to 5.6 µm with increasing Ag content. Among the alloys, Mg-9Ag exhibited optimal mechanical strength and moderate plasticity (tensile yield strength of 205.7 MPa, elongation of 20.3%, and a maximum bending load of 437.2 N). Furthermore, the alloying of Ag accelerated the cathodic reaction of pure Mg, leading to a slightly increased corrosion rate of the Mg-Ag alloys while maintaining acceptable general corrosion. Notably, compared with pure Mg, Mg-Ag alloys had superior antibacterial effects against Porphyromonas gingivalis (P. gingivalis) and Staphylococcus aureus (S. aureus). Taken together, these results provide evidence for the significant clinical potential of Mg-Ag alloys as GBR/GTR membranes.

Quartz fiber supported Ag nano-islands as flexible SERS substrate with stable distributed “hot-spot” in rapid detection of pesticide residue

Island-shaped Ag nanoparticles are prepared under the support platform of quartz fabric by a simple chemical deposition method. The prepared flexible SERS substrate in this study demonstrates highly sensitive, excellent signal reproducibility and stability. The enhancement ability can be adjusted by varying concentration of Ag+ during synthesizing process, which would lead to the variation of size and gaps of Ag nanoparticles, thus affecting the LSPR effect. Moreover, the prepared SERS substrate shows great practical potential in rapid detection of contaminated fruit with different sampling method.

Investigation of the third-order optical nonlinear enhancement properties of Ag doped chalcogenide glass films

Chalcogenide glass is widely recognized as an excellent nonlinear optical material. Enhancing its nonlinear optical properties through metal doping has emerged as a prominent research avenue in the field of chalcogenide glass. In this paper, silver (Ag) doped Ge28Sb12Se60 (GSS) chalcogenide glass films with different concentrations were prepared by co-evaporation method. The nonlinear absorption coefficients (β) of different samples were investigated by open-aperture top-hat Z-scan experiments and pump-probe experiments, and the nonlinear refractive index (γ) values were determined using the Tichy-Ticha relation. The results showed that the nonlinear absorption of GSS thin films can be improved by Ag doping. The nonlinear absorption coefficient β exhibits the maximum enhancement of about 2.5 times at 8.3% concentration, with the maximum β reaching 1.83×10−6 m/W. The nonlinear absorption mechanism observed in the thin films can be attributed to free carrier absorption, and the free carrier lifetime is positively correlated with the Ag doping concentration. Within the selected Ag concentration range, the nonlinear refractive index (γ) of Ag doped chalcogenide glass films continues to increase, reaching about 3 times at 30.7% concentration, with the maximum γ being 4.643×10−17 m2/W. Additionally, the third-order nonlinear polarizability (χ(3)) values can be increased from 1.014×10−11 esu to 3.314×10−11 esu with increasing Ag concentration. The research results in present paper are of great significance for further exploration of the optical nonlinear enhancement properties and carrier recombination dynamics in chalcogenide glass.

Enhancing Contaminant Removal in Sewage Treatment Plant Effluent with PES/Ag Membrane

In this study, a silver-infused membrane was fabricated using an ex-situ method that involved blending silver nanoparticles (AgNPs) with Polyethersulfone (PES) as the base polymer in treating sewage treatment plant (STP) effluent. Three distinct membranes denoted as S1(Ag0), S2(Ag0.5) and S3(Ag2.0) were manufactured with varying weight percentages of polymer and silver (Ag) contents. The objective was to investigate the effect of the dosage of AgNPs on membrane characterization and performance, encompassing pure water flux filtration tests, organic rejection tests, and antibacterial properties. The results showed that all PES/Ag membranes demonstrated robust performance in removing total suspended solids (TSS), chemical oxygen demand (COD), apparent colour (Hazen unit), total dissolved solids (TDS), turbidity, conductivity, total Kjeldahl nitrogen (TKN), and Escherichia coli (E. coli), complying to Class IIB (Recreational use with body contact) of the Interim National River Water Quality Standards (INWQS) for Malaysia ruled by the Department of Environment Malaysia (DOE). The results also highlighted that upon the addition of AgNPs, the E. coli removal of the membrane S3(Ag2.0) was further improved to 99.87%. The results have evidenced that the PES/Ag membranes could reject E. coli effectively, proving their value in treating bacteria-contaminated surface water. In conclusion, this study highlights the effectiveness of PES/Ag membranes as a viable solution for domestic sewage treatment, aligning with stringent water quality requirements.

Gold source and deposition in the Sanakham gold deposit, SW Laos: Constrains from textures, trace element geochemistry and in-situ sulfur isotopes of pyrite

The Luang Prabang (Laos) – Loei (Thailand) metallogenetic belt is endowed with major porphyry-skarn, and epithermal gold deposits. The Sanakham gold deposit is a newly discovered hydrothermal vein-type orogenic gold deposits (10.6 t Au @ 3.05 g/t) in the belt, and consist of a series of quartz-sulfide veins that are controlled by secondary structures of the regional NNE-trending brittle-ductile shear zone. Its mineralization can be divided into four stages: (I) quartz–pyrite–arsenopyrite, (II) quartz–pyrite–pyrrhotite–chalcopyrite, (III) quartz–pyrite–base-metal sulfide, and (IV) quartz–carbonate. Three pyrite generations were identified: py1 (stage I) as disseminated euhedral to subhedral coarse grains; py2 (stage II) as subhedral to anhedral fine grains occur around the cataclastic and corrosion textures in py1; py3 (stage III) as subhedral to anhedral fine grains occurred in sulfide veins or veinlets that overprint the existing quartz-sulfides. All three generations of pyrite have low trace-element contents including very low lattice-bound gold (py1: 0.040 ppm; py2: 0.098 ppm; py3: 0.028 ppm) and arsenic (py1: 227 ppm; py2: 133 ppm; py3: 13.3 ppm) contents. Visible gold grains are sited in textures of pyrite grains that relate to brittle cataclastic deformation. Considering the relatively low contents of pyrite in the ores of Sanakham, it is impossible to derive the high-gold grade orebodies through local remobilization of originally lattice-bound gold in pyrite. The py2 might be formed during hydrothermal overprinting and dissolution of py1 led by continuous supply of ore fluids with relatively higher contents of Au, Ag, Cu, Sb, Te, Pb, and Bi. A reduction reaction related to reduced carbon species in wallrock is an assignable cause for gold deposition, even though the fluid-rock interaction and fluid immiscibility processes might be important. The Au- and As-poor pyrites have similar δ34S values (py1: –2.58 to –0.83 ‰; py2: –2.17 ‰ to + 0.25 ‰; py3: –1.24 to –0.60 ‰ ppm) that close to 0 ‰, indicating the sulfur may have been originated from magmatic or mantle sources. Therefore, we propose that the Sankham gold deposit is a member of the orogenic deposit class, but notably characterized by the low concentrations of invisible gold in the relatively As-poor pyrite lattice.

Deciphering the improvement in (H2-)C3H6-SCR performance of Ag/Al2O3 catalysts prepared from warm-water-treated alumina: A NMR-assisted identification of the Ag anchoring sites of the alumina support

Lean exhausts aftertreatment has been the subject of numerous investigations due to ever stringent regulations on pollutants emissions such as that of NOx. Among aftertreatment technologies, the selective catalytic reduction of NOx by the hydrocarbons (HC-SCR) has been studied intensively, in particular by using Ag/Al2O3 materials. The present work highlights that pretreatment of pristine Al2O3 in warm water prior to Ag deposition allows to prepare catalysts of significantly higher (H2-)C3H6-SCR performance compared to conventional Ag/Al2O3 catalysts. In addition, NOx-TPD-C3H6-SCR structure-activity correlations indicate that optimum composition of the Ag/Al2O3 catalysts can be improved by about 50% in terms of Ag content for the first time. Unprecedented in-depth NMR investigations allow for the identification of the alumina sites of importance in the anchoring of Ag. These sites are µ1-OH groups located near the (100)/(110)l edge and then near the (110)b/(100) edge of Al2O3 crystallites and bonded to octahedrally coordinated Al species.

Element geochemical differences in lower Cambrian black shales with hydrothermal sedimentation in the Yangtze block, South China

Abstract Hydrothermal activities occurred in the Yangtze block, South China, and affected the process of black shale sedimentation in the early Cambrian. Their specific influences, such as the sources, sedimentary environment, and mineralization, have not yet been revealed. Fortunately, the influences are explained through the geochemistry comparison of different wells FY1, XJ1, HY1, and XA1 in northwestern Hunan. The outcomes of the tectonic setting, distinguishable by element indicators, are disorganized. This is caused by the variable element composition, sedimentary recirculation of material source, and hydrothermal materials. FY1, the closest well to Zhangjiajie where Ni–Mo ores were formed by hydrothermal sedimentation, has more different features on the elemental geochemistry, but many indexes still indicate that it is normal sediments. XA1, which is far from the other wells and deposited in the deep-water basin, has significantly more differences in geochemical properties and shows more about normal marine deposition. XJ1 and HY1 are intermediate between them. Based on these wells, the hydrothermal contribution to the black shale sedimentation is not significant. However, some contents of trace and rare earth elements change widely because hydrothermal materials can diffuse and deposit over long distances. The concentration of Ag, As, Ba, Mo, Ba, U, and V generally has dozens of times higher than that of Upper Continental Crust. The early Cambrian environment was primarily anoxic/euxinic with enough sulfur, which is beneficial for enriching metal elements and organic matter. The sequence FY1, XJ1, HY1, and XA1 in turn has the same performance on the distance with Zhangjiajie, different intervals of suboxic environment and element enrichment, and hydrothermal-fluid-addition Ni abundance. Therefore, hydrothermal processes indeed provide materials for element enrichment and support the reducing environment, but the impact of hydrothermal activity decreases on the plane.

Multifunctional graft-IPN hydrogels of cellulose nanofibers and poly(N-isopropyl acrylamide) via silver-promoted decarboxylative radical polymerization

Interpenetrating polymer networks (IPNs) have emerged as innovative materials for a wide range of applications. Owing to the crosslinked structure of their polymer components, IPNs exhibit superior properties relative to their single component counterparts. Here, we report a new class of multifunctional graft-interpenetrating polymer network (graft-IPN) hydrogel composites of poly(N-isopropylacrylamide) (PNIPAM) grafted onto cellulose nanofibers (CNFs) via silver(I)-promoted decarboxylative polymerization. This novel approach involves the Ag-promoted graft polymerization and the crosslinking of PNIPAM in the CNF network, forming a hybrid of semi-IPN and graft-copolymer hydrogel. Different from conventional PNIPAM-CNF IPNs, the CNFs in graft-IPN hydrogels form an interconnected network as a result of crosslinking between neighboring grafted PNIPAM. Silver nanoparticles (AgNPs) are also formed in situ in the graft-IPN hydrogel matrix, demonstrating the dual functionality of silver as both a catalyst in the polymerization and an eventual antibacterial agent in the hydrogel. The network structure of graft-IPN hydrogels can be controlled by crosslinker and Ag(I) concentration, therefore modulating their thermo-responsive, mechanical, and swelling properties. The grafting of PNIPAM from CNFs shifts the volume phase transition to 36 °C and significantly improves the mechanical strength and swelling capacity of the hydrogels. Ultimately, this work demonstrates the excellent potential of these multifunctional graft-IPN hydrogels with controllable thermosensitivity, mechanical strength and anti-microbial activity as engineered biomaterials for advanced applications in biomedicine, engineering, and industry.

Green synthesis of lichenan-decorated silver nanoparticles for catalytic hydrogenation of organic dyes and bacterial disinfection

Developing an eco-friendly and efficient homogeneous catalyst for treating complex wastewater containing toxic organic pollutants and bacteria is in significant demand. Herein, ultra-small Ag nanoparticles (NPs)-loaded random coil lichenan nanocomposite (L-AgNP) was prepared through a low-cost and green one-step in-situ reduction strategy using lichenan as the reducing agent. The random coil of lichenan acted as a micro-reactor to disperse and stabilize AgNPs via the Ag-O bonding interaction. In the participation of NaBH4, L-AgNP nanocomposite could achieve greater catalytic efficiency for catalyzing reduction of 4-nitrophenol (∼120 s, 34.34 × 10−3 s−1) with the smaller size of AgNPs or the higher content of Ag. The nanocatalyst also exhibited outstanding catalytic efficiency for congo red, rhodamine B, methylene blue, and methyl orange. The L-AgNP could be easily recycled through ethanol precipitation and continuously reused for ten cycles with a tiny loss of conversion rate. Furthermore, L-AgNP also displayed favorable antibacterial activity, inhibiting the growth of Escherichia coli and Staphylococcus aureus with more than 98 % disinfection ratio. This work provides a green strategy to develop polysaccharide-based multifunctional homogeneous catalysts focusing on wastewater purification.

Role of Oxidants in Metal Extraction from Sulfide Minerals in a Deep Eutectic Solvent.

Metallurgical applications of deep eutectic solvents (DESs), known as ionometallurgy, have received significant research attention in recent years. While many studies claim that DESs are generally green and enhance process efficiency, others believe that industrial applications of ionometallurgy are generally not viable. Here, we report on leaching experiments of a sulfide flotation concentrate using ethaline, a chloride-based DES, in the presence of common oxidants. Following a mineral-based approach, we compare results with those obtained from aqueous chloride solutions to assess the influence of the leaching medium. We aim to contribute to a basic understanding of key differences between DESs and aqueous solutions and hope that this will help to make informed decisions about the suitability of DESs for leaching applications. Experiments were performed on a feed concentrate comprising a mixture of sulfide minerals along with substantial concentrations of Au, Ag, and Te. We found similar leaching behaviors for ethaline and aqueous solutions in nonoxidative leaching. However, when oxidizing agents were introduced, ethaline exhibited higher leaching efficiencies. Notably, the oxidation rate of pyrite in ethaline was very low, while chalcopyrite exhibited high oxidation rates. Furthermore, the results highlight significant variations in leaching rates depending on the type of oxidant, with the highest rate observed for I2, followed by CuCl2, and FeCl3. H2O2 and O2 were less effective. The leaching of gold-silver tellurides was possible in ethaline. This could be of particular significance, given that Au-Ag-Te compounds pose challenges in conventional cyanide treatment.

Ag Behavior on TiN Thin Films for Decorative Coatings

TiN-Ag ceramic coatings deposited by magnetron sputtering on silicon wafers and AISI F138 stainless-steel substrates with different Ag concentrations were evaluated for their application as decorative coatings. The results obtained indicated an almost linear increase in the thickness and roughness of the film as a function of the increase in the silver content of the film. For Ag concentrations greater than (8.3 ± 0.5) at %, a matte/satin finish was observed, i.e., a dull surface, produced by the agglomeration of particulates and the increase in roughness, respectively, which was corroborated by SEM and AFM analyses. The EDS analyses indicated particles with a high concentration of silver, but the elements titanium and nitrogen were also observed, indicating the formation of the TiN-Ag coating. The L*a*b* parameters in the CIELab color space were evaluated. No major variations were observed for coatings A and B (Ag concentrations of (4.1 ± 0.4) and (6.3 ± 1.2) at %, respectively). When the Ag content increased substantially, there was a corresponding decrease in L* values, as well as a shift in red reflectance. Furthermore, unwanted changes in the visual appearance and resistance to accelerated corrosion (salt spray) were also analyzed, as these factors compromised the film’s aesthetics in decorative applications.