Oxalic Acid Solution Research Articles

Improvement in heat resistance of electric heating alumite carriers

Alumite carriers were prepared by using Al/Ni-Cr-Alloy/Al clad materials with different Pore widening treatment (PWT) durations of 0, 2, 4, 6 and 8 h to observe its effect on the alumina surface structures and the overall heat resistance. Aluminum clad materials were first anodized in 298 K 4 wt% oxalic acid with 50 A/m2 electric current. Subsequently, PWT was carried out in the same oxalic acid solution at 298 K. After calcination at 623 K for 1 h, samples underwent Hot water treatment (HWT) in 358 K hot water for 2 h before lastly calcinated at 773 K for 3 h. It was found that heat resistivity improved drastically when PWT was carried out for longer than 6 h. Results also showed that alumite carriers’ surface structure changed drastically after 6 h of PWT from fragment structure into a sponge-like structure. By manipulating the PWT durations, alumite carriers produced successfully withstood up to 1223 K without needing to induce diffusion layers by preheating. Therefore, alumite carriers produced with 6 h and 8 h of PWT showed promising potential for the usage in high temperature steam reforming reactions with electric heating.

Direct joining of PP-Al5052 hybrid with high bonding strength by two-step anodization treatment and polymer modification

Polymer-metal hybrid (PMH) structures with excellent physical and chemical properties are widely required in aerospace, electrical, automotive and many other fields. It is one of the key challenges for the joining operation between the metal and polymer at the interface. In this study, pretreatment on aluminum alloy (Al5052) sheet by two-step anodization and maleic anhydride-grafted polypropylene (PP-g-MAH) were applied to enhance the bonding performance of PMH structures via injection-molded direct joining process. The effects of anodization treatments on the interfacial wettability, surface morphology and tensile strength were investigated. Besides, the bonding mechanism was further analyzed by molecular dynamics (MD) simulation method. Experimental results showed that the hierarchical nanopores and branched structures were formed after the two-step anodization process, which greatly improved the surface wettability. Using oxalic acid solution as the electrolyte in the second anodization, the bonding strength of PP-Al5052 sheet was greatly improved. With PP-g-MAH resin, the bonding strength reached a maximum of 17.54 MPa, resulting in a tensile failure at the PP-g-MAH part itself. MD simulations revealed that the MAH groups contributed to enhancing the interfacial interactions, while the existence of phosphate ions decreased the chemical interactions at the interface.

THE INFLUENCE OF FORMIC ACID, OXALIC ACID AND ESSENTIAL OILS ON THE FREE ACIDITY IN HONEY

The aim of the study was to monitor the changes in the free acidity of honey after administration of three anti-varrotic treatments with the use of formic acid (FA), oxalic acid (OA) and essential oils as the active substances in commercial preparation. To the first experimental group, 60 % FA was administered by vaporization using the vaporizer Nassenheider Professional® (group F). OA was administered by the contact in the form of 26.8 % (w/w) glycerine solution of OA on special workshop towels (group O). Essential oils were administered in the form of the commercial product Bisanar® (group B). The control group received no treatment during the experiment. Although the acidity of the honey in the B group during the experiment did not show significant difference compared to the control group (p = 0.769) and only a slight difference was determined in the O group (p = 0.416), the F group showed significant increase of the values compared to the control group (p = 0.015). The average value of free acidity in honey of this experimental group did not decrease notably under the legislative limit after two weeks following removing the treatment from the hive. Free acidity in the F group reached the value of 57.50 ± 25.19 mEq/kg (milliequivalents per kg) at the end of the experiment. Treatments by OA and Bisanar® are more suitable to supress varroosis during the summer without significant increase of free acidity in honey.

Experimental Study of the Activation Effect of Oxalic Acid on the Dissolution of Rare Earth Elements in the Typical Diagenetic Minerals of Coal Seams

Rare earth elements (REEs) are considered to be one of the most important metal raw materials, and coal seams are one of the potential sources of REEs. As a low-molecular-weight organic acid, oxalic acid has a strong ability to migrate and dissolve minerals. The coal seam is formed by herbaceous plants and contains more oxalic acid, which may affect the enrichment and transport of REEs during coal formation. Based on the provenance minerals and enrichment carriers of REEs in the coal seam, granite and its weathered minerals (plagioclase, kaolinite, montmorillonite, and quartz) were selected for oxalic acid leaching experiments, to clarify the activation ability of oxalic acid for REEs in coal seams. Experimental results have shown that oxalic acid dissolves minerals and leads to the dissolution and migration of REEs. The higher the concentration of oxalic acid, the stronger the dissolution ability. Each element has a similar dissolution ability in high-concentration oxalic acid solutions, while the ionic radius and electronegativity can cause abnormal distribution of individual elements. The REE dissolution ability in different minerals is controlled by the crystal structure, and the re-adsorption of minerals inhibits the dissolution of REEs in low-concentration oxalic acid solutions. In addition, comparative analysis of REE distribution characteristics in natural water shows that the dissolution and migration of REEs are complexly affected by many factors in addition to pH and fluid environment. Therefore, the activation effect of oxalic acid on REEs in coal seams needs to be further studied.

Ore composition and native gold characteristics of an ore occurrence in Eastern Transbaikalia

The article deals with the characteristics of the ores of an ore occurrence of the Munginsky cluster located on the western flank of one of the commercial fields of Eastern Transbaikalia. The ores of this promising ore occurrence are underexplored, especially in the technological aspect, which served the basis for studying their composition and characterizing native gold as their main commercial component. The composition of ores and altered rocks was studied by the following methods: atomic emission spectral quantitative analysis, X-ray fluorescence, as well as phase atomic absorption and atomic emission analysis with inductively coupled plasma ICP-AES. The mass fraction of total and organic carbon was determined in the Central Fire Assay Laboratory of JSC Pokrovsky Rudnik, Blagoveshchensk. The proportion of carbonate carbon dioxide was determined by the method of titrimetric determination of carbon dioxide. The content of gold was given according to the data of assay melting, the content of silver – according to the data of atomic absorption analysis. Petrographic and mineragraphic studies were carried out using an optical microscope Olympus BX-51. The mineral composition of the ore sample was also estimated based on the results of X-ray diffraction analysis. The quantitative mineral composition was studied on the crushed material of the original ore with a particle size of -2 mm using the microscopic study data of transparent and polished thin sections on a microscope Nikon Eclipse LV 100 POL. The content of iron hydroxides was determined from the weight difference after the sample was treated with a 10 % oxalic acid solution in a water bath. Comparison of the results obtained on the ore occurrence with the materials on the ore composition of the closest deposit located in 30 km demonstrates that on the one hand they are similar and uniform, and on the other hand they feature some differences. Their common parameters include a rather high degree of sulfide content of ores and similar chemical and mineral composition with the predominance of arsenopyrite, an increased role of bismuth as well as the predominance of fine gold and its similar morphological characteristics. This fact allows to consider the ore occurrence under investigation as an integral part of a single ore system of the closest deposit.

Third order non-linear optical properties of cadmium magnesium oxalate crystals grown by silica gel technique

Cadmium magnesium oxalate (CdMgO) crystals were grown by silica gel technique. Crystals were optimized by parameters like specific gravity of sodium meta silicate (SMS), concentration of the oxalic acid (C2H2O4·2H2O) solution, pH of the gel, gel setting time, concentration of the cadmium chloride (CdCl2·2H2O) and Magnesium chloride (MgCl2·6H2O) solutions. Grown oxalate crystals examined under Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared (FTIR) spectrum, Raman spectrum and Z-scan instruments. Grown materials are crystallizes in the triclinic system space group P1 with lattice parameters, a = 5.9906 Å, b = 6.6215 Å, c = 8.4736 Å and α = 74.55°, β = 74.091°, γ = 80.911°. Comparison study of FTIR and Raman spectrum of grown crystals were discussed. Third order non-linear optical parameters such as nonlinear absorption coefficient (β=∼10−4cm/W), nonlinear refractive index (n2 = ∼10 −9 cm2 /W), susceptibility (χ(3) =∼10−7esu) and molecular hyperpolarizability (hγ =∼10−27esu) were determined from Z-scan experimental data analysis.

Superior sinterability of copper oxalate-coated Cu particles in a double reductant system and rapid compression sinter-bonding characteristics between Cu finishes

High-speed die attachment by compression (2 MPa) sinter-bonding at 300 °C in air was accomplished using a paste containing bimodal-sized (average sizes: 2 μm and 340 nm) copper oxalate-coated Cu particles, yielding a Cu-to-Cu bonding owing to the formation of a Cu bond line that can provide mechanical durability at high temperatures and excellent thermal conductivity. The particles were fabricated by immersing Cu particles in an oxalic acid solution, and a double reductant recipe was adopted to minimize the oxidation of the Cu particles and Cu finishes. The copper oxalate coatings inhibited the oxidation of Cu particles until decomposition at 290 °C, and the in-situ decomposition induced the generation of active Cu atoms, which significantly elevated the sinterability. Therefore, a sufficient shear strength exceeding 20 MPa and a near-full-density bond-line structure were achieved after bonding for only 1 and 3 min, respectively. Furthermore, the bond line did not contain an organic residue, differently observed in a paste directly including carboxylic acid. Therefore, the suggested paste formulation demonstrates the feasibility of a rapid solid-state sinter-bonding technique using low-cost Cu particles.

Effect of surface anodizing on the bonding properties of aluminum alloy/glass-fiber reinforced polypropylene random copolymer hybrid joints

Polymer-metal hybrid (PMH) joints of glass-fiber reinforced polypropylene random copolymer (GFRPPR) and aluminum alloy were prepared by the self-made hot pressing technology (HPT). The PPR copolymer was grafted with maleic anhydride and reinforced with 30% short glass fiber, and the aluminum alloy surface was anodized in oxalic acid and phosphoric acid solution, respectively. The PMH interfaces were mainly characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle tests. Anodized in the phosphoric acid solution, the anodized aluminum alloy surface showed needle-shaped honeycomb-like microstructures. The phosphoric acid anodized aluminum alloy surface was beneficial for polymer melt to flow into and form interlocking microstructures due to its micro porous structure, and the corresponding tensile shear strength and work of fracture reached up to 10.88 MPa and 16.15 kJ m−2, respectively.

Carbonate treated coffee powder (CTCP) for selective sorption of Pu4+ over Am3+, Np4+, NpO22+, and PuO22+ from aqueous acidic solution: Investigation on mechanism, kinetics, thermodynamics, stripping and radiolytic stability

An attempt was made for understanding the sorption behaviour of different actinide ions Pu4+, PuO22+, Am3+, Np4+, and NpO22+ on carbonate treated exhausted coffee powder (CTCP). Very efficient sorption of Pu4+ over other actinide ions from aqueous acidic medium was observed. Almost 4 h were required for achieving equilibrium. Experimental results for Pu+4 were fitted into different sorption isotherm model: Langmuir isotherm, Freundlich isotherm, D.R, isotherm and Temkin isotherm. Based on the linear regression, it was found that, Freundlich isotherm was predominantly operative. Pseudo 2nd order kinetics was found to be effective for the sorption of Pu+4. More than 80 % of loaded Pu4+ was found to desorb by 0.25 M oxalic acid solution. CTCP exhibited relatively good radiation stability. Sorption of Pu+4 on CTCP was exothermic, and spontaneous in nature. The sorption process was simple, cost effective and environmentally benign, as it did not involve any sophisticated, multi-step, sorbent synthesis.

Effect of Chemical Conversion Treatment with Oxalic Acid Solution in the Corrosion Resistance of Galvanized Steel in Soybean Biodiesel with Natural Additives

Effect of Chemical Conversion Treatment with Oxalic Acid Solution in the Corrosion Resistance of Galvanized Steel in Soybean Biodiesel with Natural Additives

Investigating cotton dyeing using exotic wood waste sawdust

Investigating cotton dyeing using exotic wood sawdust. The study investigated the possibility of using extracts from various species of exotic wood, obtained from waste sawdust, for dyeing cotton fabrics. Material from Obeche, Iroko, Merbau, Apple tree, American walnut, Tulip tree, Cumaru and Rosewood were used for the tests. Solutions of oxalic acid, tin chloride, aluminum sulfate and ferric chloride were used as mordants, along with no-mordant tests. The color was determined in the CIE L*a*b* coordinate system. Color fastness was tested using n-hexane for dry cleaning and acidic, alkaline and hydrogen peroxide bleach solutions. The results showed a strong dependence on the type of wood, the mortar used and the washing agent and covered a wide spectrum of color intensity and fastness. The best results were obtained for Rosewood, Merbau and Apple trees, while Tulip tree and American walnut turned out to be practically useless. Among the mordants used, the most intense colors were produced by metal salts, including ferric chloride, which strongly darkened fabrics. Dry cleaning proved to be the mildest of those tested, with the least effect on color fading.

Purification of Carrier-Free 47Sc of Biomedical Interest: Selective Separation Study from natCa(n,γ)

47Sc for theranostic medical applications was produced from the neutron activation of a natural calcium target. Liquid–liquid extraction for separation of the 47Sc radioisotope from 47Ca was carried out with the extractant Cyanex 272 ((2,4,4-trimethylpentyl) phosphinic acid). The effects of various extraction parameters on the extraction efficiency and separation of the two radionuclides were investigated, including the extraction time, pH, metal ion concentrations, extractant concentration, diluent type, and phase ratio. It was shown that the extraction yield of the 47Sc radioisotope with the proposed procedure is about 90%, with a fast separation time of 10 min, at pH 1.8 (0.01 M HCl), and with low E (1%) for 47Ca and high separation factors. The stripping % of the loaded 47Sc isotope was about 99.2% using 0.4 M oxalic acid solution with a purity of 99.9%.

Recovery of light rare earth elements, cerium, lanthanum, and neodymium from alluvial gold mining waste from the Bagre-Nechí mining district in Colombia using acid leaching, oxalate precipitation and calcination

This paper investigates different leaching conditions with hydrochloric acid and sulfuric acid, which perform the maximum extraction of cerium, lanthanum, and neodymium from a dephosphorized monazite concentrate obtained from alluvial gold mining waste from the Bagre-Nechí mining district in Colombia, for the subsequent recovery of oxides of these metals. Sulfuric acid as the leaching medium at all evaluated concentration, time, and temperature conditions gave highest extractions. The addition of 10% (v/v) H2O2 increased rare earth dissolution up to 93% in H2SO4 medium. Thermodynamic analysis indicates that H2SO4 solutions show a higher capacity to solubilize REEs as opposed to HCl solutions, thus supporting the experimental results. Rare earths in sulfuric acid liquor can be recovered up to ∼100% by precipitation with a 1.0 M oxalic acid solution at 25 °C for 120 min, followed by the calcination of the oxalate precipitate at 850 °C for 120 min. The final product was characterized by XRD, which indicated a composition of CeO2, La2O3, and Nd2O3. The results of the XRD analysis show the REE phase transformation throughout the process.

Precipitation of Ferrous Oxalate from Ferrous Ammonium Sulfate in Oxalic Acid Solution

A kinetic study was conducted experimentally for the precipitation of ferrous oxalate. The ferrous oxalate, in the form of dihydrate (FeC2O4·2H2O), was produced by the acidic dissolution of ferrous ammonium sulfate (Fe(NH4)2(SO4)2) in an aqueous solution of oxalic acid, and then precipitated by nucleation and particle growth from supersaturated solution. The effect of the concentration of ferrous ammonium sulfate and oxalic acid as raw materials was investigated on the kinetics of the ferrous oxalate precipitation. Temperature was kept constant at 25 °C. The surface morphology, atomic compositions, and crystal phase were characterized for the ferrous oxalate precipitate collected. As the initial concentration of ferrous ammonium sulfate increased, the initial precipitation of ferrous oxalate occurred faster. The concentration of oxalic acid did not significantly affect the rate of precipitation of ferrous oxalate. The experimental behavior of ferrous oxalate precipitation was modeled with first-order models of reaction kinetics.

Characterization of Cobalt Oxalate Dihydrate Obtained from Spent Co-Mo/Al2O3 Hydrodesulfurization Catalyst

In this study, roasted spent Co-Mo/Al2O3 hydrodesulfurization (HDS) catalyst was dissolved in oxalic acid (H2C2O4) solution and optimum conditions were determined for obtaining cobalt oxalate dihydrate (CoC2O4∙2H2O). The thermal decomposition behavior of the obtained CoC2O4∙2H2O was investigated by TG/DTG-DTA analysis. The characterization of CoC2O4∙2H2O was carried out by XRD, FT-IR and SEM-EDS analytical techniques. Optimum conditions for the production of CoC2O4∙2H2O were determined as 25 oC temperature, 0.25 M H2C2O4 concentration, 1/20 g mL-1 solid/liquid ratio and 300 rpm stirring speed. CoC2O4∙2H2O was obtained with a reaction yield of 90.9 %. TG/DTG-DTA analysis carried out in dry air atmosphere showed that CoC2O4∙2H2O decomposed in two steps. In the first step that occurs between 118-196 oC temperatures, CoC2O4∙2H2O is dehydrated. In the second step, which occurs between 248-279 oC temperatures, it was determined that metallic cobalt was formed first, and then metallic cobalt was oxidized and converted into Co3O4 compound because it was performed in the air atmosphere.

Study of Anodic Film’s Surface and Hardness on A356 Aluminum Alloys, Using Scanning Electron Microscope and In-Situ Nanoindentation

The A356 aluminum alloy is a very commonly used alloy in the automotive industry, for parts such as pistons, cylinder heads, and connecting rods, for which the mechanical properties can be effectively increased by anodizing. In this work, oxide layers were formed in oxalic acid solution with defined parameters on A356 aluminum alloy and then studied by using a novel combination of the scanning electron microscope (SEM) and in-situ nanoindentation. The purpose of this research is to understand the relationship between the substrate and the oxide layer by examining its microstructure and nanohardness. Based on the experimental results showing special composite microstructure and corresponding high hardness, this alloy seems to be a good alternative for replacing steel brake disks in an environmentally conscious manner.

Cu Deposition on AAO Substrate for Interposer Applications

In recent days, the demand for high-performance devices has increased in the semiconductor industry. These devices require integrated circuits to test out their performance. For this purpose, interposer with both vertical and horizontal copper circuits which offers advanced connections is used. Interposer consists of a substrate material and metal circuits. Common substrate materials for the interposer are silicon and glass. Whereas anodized aluminum oxide (AAO) has less current leakage than silicon substrate, which results in no need for the insulation, and has a vertically self-aligned nanopore structure though wet etching process, which enables high density holes with less cost. AAO was proposed as a substrate material for interposer.AAO substrate was fabricated using 0.3M oxalic acid solution, followed by fabricating through-hole of AAO. For the interconnection, copper layer was deposited on the surface and hole of AAO substrate by electroless and electrochemical techniques sequentially. Sol-gel catalyst was adopted followed by heat treatment, instead of Sn/Pd catalyzation, to increase the adhesion property and breakdown voltage. Fabricated AAO is a circle shape with 4.8 cm diameter and average pore size is about 98 nm. Cu electroless deposition was performed on AAO with and without through-holes. Thin Cu layer was deposited without voids. The adhesion was measured by SCRATCH TESTER PRO, J&L Tech, Korea, showing first crack around 1.5 N to 2 N. Pulse electrodeposition with surfactant was used to fill the trough-hole of AAO substrate for through-AAO interconnects. The more details will be presented. Figure 1

Yttrium doped ZnO nanofillers reinforced epoxy coating for anticorrosion application

In the present study, synthesized pure and Yttrium (0.5, 1.0, 1.5, 2.0 and 2.5 mM) doped Zinc Oxide (YZO) nanoparticles by chemical precipitation method. X-ray diffractogram asserts the hexagonal wurtzite structure of ZnO nanoparticles. The average crystallite size was found to be 22–17 nm. The hexagonal shape, surface morphology, particle size and elemental composition of the samples were analyzed by FESEM, HRTEM and EDAX. The anticorrosive property of nanoscopic size (17 nm) YZO/epoxy nanocomposite was studied by electrochemical impedance spectroscopy (EIS) technique in both neutral and acidic media. Epoxy/YZO nanocomposites were prepared using different loadings (0.05, 0.10 and 0.15 wt%) of yttrium doped ZnO nanoparticles. The results obtained confirm that 0.10 wt% is the optimum concentration to get superior anticorrosion activity Epoxy/YZO nanocomposites were applied on mild steel substrates. The acquisition of yttrium doped ZnO nanofillers into the plain epoxy coating materially increased the charge transfer resistance Rct by 3.5 times in oxalic acid solution as against epoxy/ZnO coating. This encapsulates that the YZO nanoparticles are a potential anti-corrosive filler in coat on mild steel.

Enhanced vanadium adsorption performance on aminophosphonic chelating resin with oxalic acid regeneration

Impurities adsorbed on the resin will hinder the adsorption of valuable ions and affect the reusability of the resin. In this paper, the reusability of D418 aminophosphonic chelating resin for vanadium enrichment from the acid leaching solution of black shale was studied with oxalic acid solution as regenerant. Under the regeneration conditions of oxalic acid concentration of 0.8 mol/L, and a reaction time of 30 min, the exhausted D418 aminophosphonic chelating resin was efficiently regenerated, and the vanadium adsorption efficiency increased from 83.97% to 94.87%, which was related to the formation of amide group. During the regeneration experiments, the oxalic acid can complex with Fe3+ and Al3+ to form Fe(C2O4)2-, Fe(C2O4)33-, Al (C2O4)2- and Al (C2O4)33-, and then effectively remove Fe3+ and Al3+ ions on the exhausted D418 aminophosphonic chelating resin. Meanwhile, the adsorption or desorption performance of Fe and Al on the resin was not changed significantly. Therefore, the D418 aminophosphonic chelating resin can be stably and effectively reused to adsorb vanadium from the acid leaching solution of black shale with oxalic acid regeneration.

Synthesis and application of chloroacetamides in pyridinium based ionic liquid for high temperature extraction of uranyl ion: A novel and 'green' approach for extractive mass transfer at elevated temperature

Two different chloroacetamides viz 2-chloro-N-methyl-N-phenylacetamide (MACA) and 2-chloro-N-(3-methylpyridin-2-yl)acetamide (AMPCA) have been synthesized and applied for the extraction of uranyl ions from acidic feed. 1-Ethyl-2-methylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid (IL) has been used at elevated temperature for liquid–liquid biphasic mass transfer. An effort has also been made to study the mechanism of extraction, kinetics, thermodynamics, speciation, radiolytic stability and elution behavior of UO22+. The investigation revealed the predominance of ‘cation exchange’ mechanism. The D values in 2-chloro-N-methyl-N-phenylacetamide (MACA) were found to be more than that of 2-chloro-N-(3-methylpyridin-2-yl)acetamide (AMPCA). The species were found to be[(UO2(NO3)(MACA)2]+ and [(UO2(NO3)(AMPCA)2]+. Back extraction studies using aqueous solution of oxalic acid and sodium carbonate revealed that, the stripping of uranyl ion from AMPCA in ionic liquid was better than that of MACA. However, MACA exhibited better radiolytic stability as compared to AMPCA in ionic liquid. To understand the complexation of UO22+ with MACA and AMPCA, theoretical calculations were carried out.