Metal Salt Solutions Research Articles

Simple and cost-effective mass production of nitrate type MgAl layered double hydroxide: Titration from concentrated solution

A mass production of nitrate type Mg/Al layered double hydroxide was examined by co-precipitation from solution by the titration of concentrated solution of metal salts with ammonium hydroxide under ambient atmosphere. The influence of the suspension pH and post precipitation aging on the products was studied. Over five grams of single-phase nitrate type Mg/Al layered double hydroxide was obtained from a hundred-milliliter suspension (initial concentration of metal salt solution of 1.6 M), which corresponded to 97% yield from the metal ion consumption. Well-defined platy particles of nitrate type Mg/Al layered double hydroxide nanoparticles were obtained by applying post precipitation aging at 80 °C under ambient atmosphere. The sample preparation has been carried out without any caution to remove carbonate contamination to obtain nitrate type Mg/Al layered double hydroxide.

Efficient reduction of organic pollutants and H2 generation using bimetallic nanoparticles coated alginate hydrogel beads

Here, a simple method is used for the preparation of calcium alginate-activated carbon composite beads (Alg-ACBDs). These beads were introduced into different metal salt solutions for decoration with single metal nanoparticle (M0) and double metal nanoparticles (M0-M0). The prepared M0/Alg-ACBDs catalysts, such as, Cu0/Alg-ACBDs, Ag0/Alg-ACBDs, Fe0/Alg-ACBDs, Cu0–Ag0/Alg-ACBDs, and Fe0–Cu0/Alg-ACBDs were evaluated against NaBH4 methanolysis. In addition, different surfactants, such as, brij-56, pluronic F-127, and urea (Co(NH2)2), different amount of NaBH4, catalyst, and temperature effect was also investigated for higher H2 generation from NaBH4 methanolysis. Similarly, the synthesized catalysts were used for the reduction of different nitrophenols (NPs) and dyes. The Fe0–Cu0/Alg-ACBDs catalyst efficiently catalyzed the reduction reaction of 4-NP and methyl orange (MO) and both were studied in detail. The corresponding reduction rate of 4-NP and MO was observed as 1.829 and 1.163 min−1, respectively. Moreover, the recyclability of the catalyst was investigated for 4-NP and H2 generation, where no decrease in the reduction percentage of 4-NP was recorded, while reduction in their catalytic rates was observed.

Development of a Controlled Injection Method Using Support Templates for the Production of Chemobrionic Materials.

Chemobrionics is a research field about the well-known self-organized inorganic structures. Numerous research works have focused on controlling their growth pattern and characteristic features. In the present study, a controlled injection method is proposed to produce more regular self-assembled chemobrionics compared to the standard direct injection technique. This method involves the injection of a metal salt solution into an agarose support template filled with an anionic solution. The obtained structures were studied by scanning electron microscopy, X-ray microtomography, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier-transform IR spectroscopy, and thermogravimetric analysis. Despite the complex mechanism and chemistry underlying the self-organization phenomena, the controlled injection method enabled the generation of regular standard chemobrionic structures with high experimental reproducibility. It provided the extraction of tubular structures from the reaction vessel without breakage, thus allowing comprehensive characterization. Furthermore, the morphological, chemical, and thermal features of these structures were highly correlated with the standard chemobrionics obtained in the direct injection method. The proposed controlled injection method holds great promise for understanding and controlling the properties of chemobrionics and related structures.

Direct Laser Writing of Microscale Metal Oxide Gas Sensors from Liquid Precursors.

Fabrication and processing approaches that facilitate the ease of patterning and the integration of nanomaterials into sensor platforms are of significant utility and interest. In this work, we report the use of laser-induced thermal voxels (LITV) to fabricate microscale, planar gas sensors directly from solutions of metal salts. LITV offers a facile platform to directly integrate nanocrystalline metal oxide and mixed metal oxide materials onto heating platforms, with access to a wide variety of compositions and morphologies including many transition metals and noble metals. The unique patterning and synthesis flexibility of LITV enable the fabrication of chemically and spatially tailorable microscale sensing devices. We investigate the sensing performance of a representative set of n-type and p-type LITV-deposited metal oxides and their mixtures (CuO, NiO, CuO/ZnO, and Fe2O3/Pt) in response to reducing and oxidizing gases (H2S, NO2, NH3, ethanol, and acetone). These materials show a broad range of sensitivities and notably a strong response of NiO to ethanol and acetone (407 and 301% R/R0 at 250 °C, respectively), along with a 5- to 20-fold sensitivity enhancement for CuO/ZnO to all gases measured over pure CuO, highlighting the opportunities of LITV for the creation of mixed-material microscale sensors.

Review on Green Synthesis of Nanoparticles using Various Strong Electrolytic Metal Solutions Mediated by Various Plant Parts

The present review targets the comparative biogenic synthesis and mechanisms of nanoparticles using various plant-parts extracts and various solutions of strong electrolytic metal salts. The metal salts are AgNO3, Zn(OAc)2, Zn(NO3)2, ZnSO4, CuSO4.5H2O, Cu(NO3)2, Cu(OAc)2, CuCl2, HAuCl4.3H2O, Mg(NO3)2, Mg(OAc)2, TiO(OH)2, Fe(NO3)2.6H2O, FeCl3.6H2O, FeCl2.4H2O, Al(NO3)2, BaCl2·2H2O, Bi(NO3)2, PdCl2, H2PtCl6.6H2O, NaHSeO3, Na2SeO3, Ca(NO3)2.4H2O, ZrOCl2.4H2O, Zr(OAc)4, NiCl2, NiSO4.6H2O, Ni(NO3)2, VCl2, Co(NO3)2 6H2O, CoCl2, Hg(OAc)2, Mn(OAc)2, (NH4)6Mo7O24, Sr(NO3)2, SnCl2.2H2O, Na2S2O3.5H2O, K2Cr2O7, Cr(NO)3.9H2O and Pb(NO3)2. These salts are soluble to produce to highly active positive metal ions in deionised water. These ions are effectively nucleated in the plant constituents. The plant acts akin to a huge ‘‘bio-laboratory” comprising of leaves, seeds, steam, root, sprout, fruits, latex, parks, fruits peel, fruits, juices. etc… which are composed of biomolecules and phytoconstituents. These naturally happening biomolecules and phytoconstituents have been recognized to play an energetic role in the formation of nanoparticles with discrete shapes and sizes thus acting as a pouring force for the manipulative of greener, safe and environmentally benign protocols for the synthesis of nanoparticles.

Sr2+ and Ba2+ salts induced conformational structure of sodium polyacrylate PAA investigated by molecular dynamics simulations

The shrinkage of sodium-poly(acrylate) PAA in divalent salt (strontium chloride (SrCl2) and barium chloride (BaCl2) solutions is investigated by atomistic molecular dynamics (MD) simulations to study the salt effect on PAA structure. The salt concentration (Cs) was varied in the range of 0 < Cs < 1 M for fully charged PAA. The PAA radius-of-gyration (Rg) decreases with Cs in the presence of both the divalent salts in qualitative agreement with experiments. The PAA chain stiffness calculated in persistence length (Lp) decreases over the entire range of Cs. At lower Cs, the PAA chains don't form aggregate, while at higher salt concentrations, PAA chains undergo self-association in both the divalent salts. The PAA-Water H-bonds decreases with Cs significantly in the presence of BaCl2 as compared to SrCl2. The PAA-Na+ radial distribution function (RDF) shows a decrease in its coordination number with Cs. The distribution of salt-ions around PAA shows that the Ba2+ condensation onto PAA is more significant than Sr2+ because of a greater coordination number for the former than the latter. Overall, the present study significantly advanced the molecular-level understanding of PAA microstructure in the dilute divalent metal salt solution.

Carbon-supported X-manganate (X[dbnd]Ni, Zn, and Cu) nanocomposites for sensitive electrochemical detection of trace heavy metal ions

Heavy metal ion pollution has always been a stringent problem facing the global environment. Therefore, the detection of heavy metal ions has been extremely important and challenging. An efficient and simple method for the preparation of carbon-supported X-manganate (XNi, Zn, and Cu) nanocomposites was explored for the individual and simultaneous electrochemical detection of Pb(II) and Hg(II). The metallic salt solutions were mixed with graphene to form the precursors through a hydrothermal reaction, and calcined in the air to obtain the final products. The structure and morphology of the synthesized NiMn2O4-graphene (NMO-GR), ZnMn2O4-graphene (ZMO-GR), and CuMn2O4-graphene (CMO-GR) nanocomposites were characterized by various methods, and NMO-GR showed more excellent electrochemical performances by square wave anodic stripping voltammetry (SWASV) than ZMO-GR and CMO-GR. NMO-GR provided a large specific surface area, abundant reaction sites, and good electrical conductivity, thereby enhancing its electrochemical performance. The electrochemical sensor based on NMO-GR displayed the widest linear ranges (1.4–7.7 μM for Pb(II) and 0.7–6.7 μM for Hg(II)) and with the lowest detection limits (0.050 μM for Pb(II) and 0.027 μM for Hg(II)) than ZMO-GR and CMO-GR. This study offered a new way to simultaneously detect Pb(II) and Hg(II), and greatly expanded its application in the field of electrochemistry.

A Sustainable Self‐Induced Solution Seeding Approach for Multipurpose BiFeO3 Active Layers in Flexible Electronic Devices

AbstractThe direct integration of crystalline oxide layers into flexible electronic systems requires the development of relatively simple, low‐temperature processing routes. Seeding represents a powerful strategy to reach this objective by the generation of preferential sites for the nucleation of crystalline phases with a reduced energy barrier. Here, a novel approach is reported where nanoseeds are generated in situ from a precursor solution using a solvent‐engineering strategy (solvent‐antisolvent). The controlled addition of an antisolvent (1,3‐propanediol) to a solution of metal salts (Bi/Fe) dissolved in acetic acid results in the formation of nanocrystals (seeds) by supersaturation. The presence of such nanoseeds is also confirmed in the deposited layers, improving significantly the crystallinity of the respective BiFeO3 thin films as complementary, deduced by piezoresponse force microscopy. Using this low‐temperature strategy, crystalline films are directly grown on flexible polymeric substrates at only 350 °C showing a remanent polarization of 10.5 µC cm−2 and a clear photovoltaic effect (11.7 µW cm−2) of interest in computer memories and energy harvesters. The flexibility of the BiFeO3 thin films may enlarge the number of applications of this multifunctional, lead‐free material in next‐generation digital and sustainable electronic devices based on a facile, low‐cost fabrication method with reduced energy consumption.

One-Step Synthesis of Sustainable Montmorillonite-Supported, Copper-Doped Magnetic Nanoparticles for Highly Specific Separation of His-Rich Proteins

Immobilized metal affinity (IMA) magnetic adsorbents exhibit an exciting preference for histidine (His)-rich proteins, whereas their application was limited due to the leaching of copper ions and poor dispersibility, greatly influencing their sustainability and adsorption performance. Herein, we propose a novel IMA adsorbent based on montmorillonite (MMT)-supported, copper-doped magnetic nanoparticles (Fe3O4−Cu/MMT) for highly specific recognition and separation of His-rich proteins. In the process, Fe3O4−Cu/MMT nanomaterials were synthesized by a one-step solvothermal method. The obtained adsorbents exhibit enhanced adsorption capacity (758.7 mg g–1) and selectivity (SF < 0.2) toward bovine hemoglobin (BHb) as a model derived from good dispersity, making more anchor sites exposed. Also, the adsorbent can be facilely regenerated with negligible leakage of copper ions and no need for re-incubation in a metal salt solution, maintaining high performance for six cycles. Furthermore, bovine blood was opted as a realistic specimen for evaluating the adsorption capability of the proposed adsorbent, emphasizing its good practicality for His-rich protein separation.

Last developments in polymers for wearable energy storage devices

Last developments in polymers for wearable energy storage devices

In-situ enhanced laser absorption in aqueous transition metal salt solution enables high-quality backside wet etching of optical glass by near-infrared lasers

A laser-induced backside wet etching technique using near-infrared laser sources (N-LIBWE) has been proposed for high-quality micromachining of optical glass. Compared with conventional LIBWE using organic dye solutions with high absorption coefficients (∼104–105 cm−1) as the liquid absorbent, the transition metal salt solution used in N-LIBWE shows the absorption coefficient of only 10-1-101 cm−1. Moreover, as we proved in this study, the etching rate of N-LIBWE is independent of the absorptivity of the liquid absorbent. How the etching occurs during N-LIBWE is still controversial. Herein, interface images with a temporal resolution of 4 ns after the start of laser irradiation are captured by a stroboscopic shadowgraphy system. Afterward, the density, pressure, and temperature distribution in the solution are calculated by a physics-based two-dimensional hydrodynamic model to explain the observed interface images. We prove that the localized laser absorption is enhanced with laser irradiation because of the in-situ formation of solid substances. It is the properties of the formed solid products instead of the normal absorption coefficient of the solution that determines the final interface status. We further prove that the formed solid substances in aqueous CuSO4 solutions are primarily amorphous nanoclusters, which benefit the enhancement of laser absorption and tend to attach to the transparent substrates, resulting in the incubation effect in N-LIBWE. Our results provide systematic mechanisms explaining the N-LIBWE process, which also benefit the deep understanding of other liquid-assisted laser materials processing technologies.

Relationship between Surface Hydroxyl Complexation and Equi-Acidity Point pH of MnO2 and Its Adsorption for Co2+ and Ni2.

MnO2 has shown great potential in the field of adsorption and has a good adsorption effect on heavy metal ions in aqueous solution, but there have been problems in the adsorption of heavy metal ions in high-concentration metal salt solutions. In this paper, different crystal forms of MnO2 (α-MnO2, β-MnO2, γ-MnO2, δ1-MnO2, δ2-MnO2, and ε-MnO2) were prepared and characterized by XRD, SEM, EDS, XPS, ZETA, and FT-IR. The reasons for the equi-acidity point pH change of MnO2 and the complex mechanism of surface hydroxylation on metal ions were discussed. The results showed that the equi-acidity point pHs of different crystalline MnO2 were different. The equi-acidity point pH decreased with the increase of reaction temperature and electrolyte concentration, but the reaction time had no effect on it. The equi-acidity point pHs of MnO2 were essentially equal to the equilibrium pH values of adsorption and desorption between surface hydroxyl and metal ions on them. The change of equi-acidity points was mainly due to the complexation of surface hydroxyl, and the equi-acidity point pHs depended on the content of surface hydroxyl and the size of the complexation ability. According to the equi-acidity point pH characteristics of MnO2, more hydroxyl groups could participate in the complexation reaction by repeatedly controlling the pH, so that MnO2 could adsorb heavy metals Co2+ and Ni2+ in high-concentration MnSO4 solution, and the adsorption rates of Co2+ and Ni2+ could reach 96.55 and 79.73%, respectively. The effects of MnO2 dosage and Mn2+ concentration on the adsorption performance were further investigated, and the products after MnO2 adsorption were analyzed by EDS and FT-IR. A new process for MnO2 to adsorb heavy metals Co2+ and Ni2+ in high-concentration MnSO4 solution was explored, which provided a reference for the deep purification of manganese sulfate solutions.

A Comparative Study of Thermal, Luminous, and Infrared Radiation Characteristics of Natural gas Flame in the Presence of Alkali, Alkali-Earth, and Transition Metallic Solution Additives

Abstract Experiments were performed to find out the effect of alkali, alkali-earth, and transition metallic additives on thermal, luminous, IR, and total radiative properties of natural gas flame. A total of 25 mL of 0.5 M alkali salts of NaNO3 and KNO3, alkali-earth salts of Ca(NO3)2, Ba(NO3)2, and Sr(NO3)2 and transition nitrate salts of Cu(NO3)2 and Mn(NO3)2 (Merck company) were prepared, and flame tests were done on each solution by using a Bunsen burner with the equivalence ratio of 1.05, which is close to the condition of stoichiometric air–fuel mixing. The optical characteristics of flame were measured in visible and infrared radiation (IR) spectrums by a TES-1332A luminance meter, BOMEM FTIR, and IR flame photography technique. Also, the total radiation was gauged by a HFP01 sensor. The results indicated that, in general, due to the increased rate of nucleation of intermediate soot particles, the flame in the presence of alkali metal additives has higher total, luminous, and IR radiation than in the presence of other metal additives. Also, the metallic additives do not significantly change the flame temperature. The results also revealed that although all metallic additives enhance the luminous radiation of flame, which is due to chemiluminescence phenomenon or atomic emission, luminous radiation of metal additives is negligible in comparison with their radiation in IR wavelengths. Furthermore, the results show that the boiling temperature of metallic salt solutions has a greater impact on flame luminosity than their ionization energy does.

Deposition of Lead Phosphate by Lead-Tolerant Bacteria Isolated from Fresh Water near an Abandoned Mine.

Specialist bacteria can synthesize nanoparticles from various metal ions in solution. Metal recovery with high efficiency can be achieved by metal-tolerant microorganisms that proliferate in a concentrated metal solution. In this study, we isolated bacteria (Pseudomonas sp. strain KKY-29) from a bacterial library collected from water near an abandoned mine in Komatsu City, Ishikawa Prefecture, Japan. KKY-29 was maintained in nutrient medium with lead acetate and synthesized hydrocerussite and pyromorphite nanoparticles inside the cell; KKY-29 also survived nanoparticle synthesis. Quantitative PCR analysis of genes related to phosphate metabolism showed that KKY-29 decomposed organic phosphorus to synthesize lead phosphate. KKY-29 also deposited various metal ions and synthesized metal nanoparticles when incubated in various metal salt solutions other than lead. The present study considers the development of biotechnology to recover lead as an economically valuable material.

Backside wet etching of sapphire substrate by laser-induced carbothermal reduction

Laser-induced backside wet etching is a promising technology to process sapphire substrate. However, the conventional working media including toxic organic and heavy metal salt solutions is not environmentally friendly. In this paper, the backside wet etching of sapphire substrate with ink as a working solution by laser-induced carbothermal reduction is achieved. Raman and XRD analyses demonstrate that ink can provide a stable carbon source and the carbothermal reduction of sapphire occurs during the etching. Numerical calculation reveals that the deposition of the carbon layer plays a crucial role in heating the sapphire to the temperature triggering the carbothermal reduction. The grooves etched by the laser-induced carbothermal reduction have smooth walls and good shape reproducibility. The linearly increase in etching depth with pulse number at the same laser fluence. The high-quality etching based on the carbothermal reduction as the etching mechanism is beneficial for fabricating microstructures on sapphire.

Combinatorial Screening of Cu-W Oxide-Based Photoanodes for Photoelectrochemical Water Splitting.

Metal oxide libraries for photoanodes for the oxygen evolution reaction (OER) were generated by printing a metal salt solution in an array layout, followed by calcination to yield 22 ternary metal oxide systems. The libraries included a ternary metal cation system based on CuWO4 with one out of eight transition or posttransition metal ions Cr, Mn, Fe, Co, Ni, Zn, Bi, and Ga in different overall atomic ratios. The photocatalyst libraries were screened by scanning photoelectrochemical microscopy for the highest anodic photocurrents. Array elements that showed promising performance were printed in another set of eight libraries with smaller increments of overall composition. Improved performance with respect to CuWO4 was found for Ga, Co, and Ni as the third element. A comparison of the most active composition of those arrays within one library showed the highest activity for Cu48Ga3W49Ox. Printing spots of identical composition (Cu48Ga3W49Ox, Cu44Ni9W47Ox, and Cu44Co9W47Ox) over a larger area facilitated further characterization by X-ray photoelectron spectroscopy ultraviolet photoelectron spectroscopy (UPS), X-ray diffraction, scanning electron microscopy, chopped light voltammetry, and scanning electrochemical microscopy for the OER. High and stable steady-state photocurrents were generated in a photoelectrochemical cell for all three electrodes even at a low constant bias voltage. The best overall photoanode composition Cu48Ga3W49Ox showed currents that were 36 times higher than the currents of the binary Cu50W50Ox system. Significant n-doping was found by UPS valence band spectra for Ga-containing materials.

OXIDE-CONTAINING MINERAL FIBERS: TYPES, METHODS OF PRODUCTION, APPLICATION AND MANUFACTURERS (REVIEW)

The article provides an overview of mineral oxide fibers of various chemical composition: aluminosilicate, alumina, silica, bio-soluble, zirconium oxide fibers and others. Methods for producing discrete and continuous fibers, such as spinning fibers from melts, sol-gel technology, spinning from solutions of metal salts, etc., are described. filtration for alumino-silicate and bio-soluble fibers; thermal insulation up to 1600 or 2000 C and reinforcement of composites used in the aerospace and defense industries for alumina fibers and fibers based on zirconium dioxide, etc. Producers of mineral oxide-containing fibers and products based on them abroad and in Russia are represented.

Design and fabrication of bimetallic plasmonic colloids through cold nanowelding.

The integration of Au and Ag into nanoalloys has emerged as an intriguing strategy to further tailor and boost the plasmonic properties of optical substrates. Conventional approaches for fabricating these materials via chemical reductions of metal salts in solution suffer from some limitations, such as the possibility of retaining the original morphology of the monometallic substrate. Spontaneous nanowelding at room temperature has emerged as an alternative route to tailor Au/Ag nanomaterials. Herein, we perform a thorough study on the cold-welding process of silver nanoparticles onto gold substrates to gain a better understanding of the role of different variables in enabling the formation of well-defined bimetallic structures that retain the original gold substrate morphology. To this end, we systematically varied the size of silver nanoparticles, dimensions and geometries of gold substrates, solvent polarity and structural nature of the polymeric coating. A wide range of optical and microscopy techniques have been used to provide a complementary and detailed description of the nanowelding process. We believe this extensive study will provide valuable insights into the optimal design and engineering of bimetallic plasmonic Ag/Au structures for application in nanodevices.

Facile synthesis of nanostructured perovskites by precursor accumulation on nanocarbons.

Perovskite-type oxides have impacted various research fields, including materials and energy science. Despite their vast potential in various applications, general and simple synthesis methods for nano-perovskites remain limited. Herein, various nano-perovskites were synthesized by a facile approach involving the use of nanocarbons. The calcination of the nanocarbon deposited with metal salts yielded nano-perovskites, emulating the morphology of nanocarbons. The accumulation of precursors (i.e., metal salts) on the surface of the nanocarbon during the evaporation of the solvent is the key step in which the precursors are homogeneously mixed prior to calcination. The homogeneity of the precursors facilitated low-temperature calcination that resulted in the formation of nano-perovskites. Various nano-perovskites, including LaMnO3, LaCoO3, LaFeO3, LaNiO3, LaAlO3, LaGaO3, CaMnO3, BaMnO3, SrMnO3, La0.7Sr0.3FeO3, La2CuO4, and Ca2Fe2O5, were successfully synthesized, demonstrating the simplicity and novelty of the method for the general synthesis of nano-perovskites.

Study on the mechanism of laccase-catalyzed polydopamine rapid dyeing and modification of silk.

Research on the polymerization of dopamine and its modification on the surface of materials has received extensive attention. In this work, the process of laccase catalyzing the rapid polymerization of dopamine and in situ dyeing of silk fabric were studied. The results showed that laccase catalyzed dyeing for 3 h under acidic conditions could achieve the dyeing effect of 24 h under an alkaline environment, and the enzyme catalyzed polydopamine showed better deposition uniformity on the substrate surface. According to molecular simulation analysis, dopamine oligomers were easily combined with the amorphous regions of silk fibroin, and dopamine oligomers and amino acids of silk fibroin could form hydrogen bonds and π–π stacking interactions. Dopamine oligomers could form intermolecular and intramolecular hydrogen bonds through amino groups and hydroxyl groups. In addition, dopamine oligomers would aggregate in the process of binding to silk fibroin and adsorbed to the surface of silk fibroin in the form of aggregates, and Michael addition reaction would also occur between dopamine oligomers and silk fibroin. Finally, the silk fabrics loaded with polydopamine were reacted with different kinds of metal salt solutions to form particles with different morphologies and crystal structures on the surface of the silk fibers, and the modified silk fabrics showed good hydrophobicity.