Oxalic Acid Solution Research Articles

Formation behavior of anodizing films on various aluminum alloys in oxalic acid solution

The formation behavior of anodic aluminum oxide (AAO) films on various aluminum alloys, was studied in 6 wt% oxalic acid solution. There were observed two different voltage-time behaviors with a sharp peak in the initial stage of galvanostatic anodizing for pure Al, AA1050 and AA5052 (group 1), and with voltage plateaus instead of a peak for AA7075, AA6061 and AA2024 (group 2). AAO film growth rate was found to be higher for the group 1 specimens than the group 2 alloys. Two different anodizing films appeared, with regularly ordered cylindrical nano-pores for the group 1 specimens and irregularly distorted nano-pores along with numerous nano-cavities for the group 2 alloys. As the anodizing time increased, the AAO films on the group 1 specimens became darkened, while those on the group 2 alloys were not darkened but only changed in color. In addition, the surface hardness of the AAO films was much higher on the group 1 specimens than the group 2 alloys.

INFLUENCE OF ACID-BASE ACTIVATION ON CHANGES IN THE SURFACE PROPERTIES OF ALUMINOSILICATES

The effect of activation with weak acids and weakly alkaline solutions on the change in the surface properties of natural materials, which are aluminosilicates, has been investigated. The use of natural sorbents has a wide range of practical applications, which actualizes the study of their physicochemical and adsorption properties. A comparative study of the native material - the flask of the Astrakhan region, as well as the material activated with a 6% solution of oxalic acid, and then activated with a solution of sodium bicarbonate of the same concentration was carried out. The study of the morphology of the obtained samples indicates a more developed surface of the native material. The presence of isometric open pores in the native material confirms the clay component. Moreover, activation with a weak acid leads to a decrease in the pore size and specific surface area by a factor of 1.3, and further exposure to a weakly alkaline solution causes the surface to become uniform (it decreases by a factor of 1.5 from the initial value). The results obtained are confirmed by the BET method. The specific surface of the material and porosity decrease by 23% upon activation with a weak acid and by 31% upon further activation with a weak alkaline solution, which also confirms the destruction of the structure. The data obtained on the change in the chemical composition during the activation process make it possible to classify the natural material as belonging to the class of montmorillonite (SiO2: 30 – 33%), and the presence of a clay component (Al2O3: 2 – 3%) indicates the destruction of the material upon activation not only with strong acids, but also with weak ones. A change in the Si/Al ratio, extraction of metal ions in the exchange region does not lead to the expected increase in the specific surface area and pore volume, which can be explained by surface recrystallization. The study of the acid-base characteristics of the surface by the pKa method indicates a wide variety of active centers on the surface and is inhomogeneous in nature, with the advantage of the cationic function. Upon activation, an increase in the anionic function of the surface is observed.

Efficient and long-lasting corrosion inhibition mechanism of an anionic surfactant on AZ91D Mg alloy in oxalic acid solution

The efficient and long-lasting corrosion inhibition mechanism of bis(2-ethylhexyl) sulfosuccinate sodium (AOT) on AZ91D Mg alloy in oxalic acid solution were studied by electrochemical methods, surface techniques, theoretical calculations and simulations. The findings demonstrated that AOT was an effective and long-lasting corrosion inhibitor, the corrosion inhibition rate of 6.75 mM AOT was 89.84 % and raised in corrosion inhibition effectiveness with increasing soaking duration. The adsorption of AOT followed Langmuir adsorption isotherm and belonged to physical and chemical mixed adsorption. The polar sulfonyl group of AOT gradually almost vertically adsorbed on its surface to produce a uniform, dense, and thick protective layer to inhibit its corrosion, and the hydrophobicity of the alkyl chain of AOT repelled corrosive medium.

Polysaccharide content and composition analysis in the herb <i>Astragalus albicaulis</i> DC

Aim – to isolate and analyze the polysaccharides content in the herb Astragalus albicaulis.
 Material and methods. The object of the study was the herb Astragalus albicaulis harvested in the Kursk region in 2022 during the period of mass flowering. To isolate the polysaccharide complex, polyphenolic compounds were previously removed from the raw material. After drying, a water-soluble polysaccharide complex, pectin substances, hemicellulose A and hemicellulose B were sequentially isolated from the extraction cake. As extractants, purified water was used to isolate the water-soluble polysaccharide complex, a mixture of 0.5% solutions of oxalic acid and ammonium oxalate (1:1) was used for pectin substances extraction, to obtain hemicelluloses – a 10% aqueous solution of alkali followed by neutralization with acetic acid. The composition of the obtained substances was analyzed after acid hydrolysis using paper chromatography.
 Results. It was found that the yield of water-soluble polysaccharides from the herb Astragalus albicaulis was 9.41% ± 0.46%, pectin substances – 17.49% ± 0.62%, hemicellulose A – 0.86% ± 0.04%, hemicellulose B – 5.36% ± 0.25%. After acid hydrolysis, 5 monosaccharides were found in the complex of water-soluble polysaccharides: rhamnose, xylose, arabinose, galactose, and glucuronic acid, of which arabinose and galactose were predominant. The monosaccharide composition of pectin substances was represented by xylose, arabinose, glucose, galactose and galacturonic acid, galacturonic acid predominated. As a result of the identification of hydrolysis products of hemicellulose A and B, rhamnose, xylose and glucose were found, the predominant monosaccharide was xylose.
 Conclusion. For the first time, complexes of polysaccharides – water-soluble polysaccharides, pectin substances, hemicellulose A and B – were isolated and studied by fractions from the herb Astragalus albicaulis, their qualitative composition was registered. The data obtained indicates that the herb Astragalus albicaulis can be used as a source of natural polysaccharides.

Effect of oxalic acid on postharvest life of tomato modified with the TomLoxB gene in anti-sense

Oxalic acid is an organic compound found in green leafy vegetables, which has proven to be effective in delaying ripening by inhibiting ethylene synthesis in fruits such as banana, mango, peach, tomato, plum, and others. In this study, the response of oxalic acid application on postharvest physiology was evaluated in transgenic tomatoes (Solanum lycopersicum) variety TA234 with the TomLoxB gene insertion in antisense, at two concentrations of oxalic acid: 3 and 10 mM, during 30 d of storage at 25 ± 1 ºC and a relative humidity of 65 - 70 %. The fruits were harvested at break stage and immersed for 10 minutes in the oxalic acid solution, which was maintained at 25 ºC. Upon treatment, less weight loss, better retention of lightness, delay in the decrease of firmness and hue angle, decrease in lipoxygenase activity, low electrolyte leakage and increase in total phenolics content were observed. The most effective oxalic acid concentration was 3 mM, that extended postharvest life by up to 30 d and reduced deterioration of the genetically modified (GM) tomatoes. In turn, the untreated GM tomatoes showed an acceptable appearance up to day 24 of storage, while the wild type fruits were kept satisfactorily for 15 d.

Extraction and Characterization of Chitosan from Eco-Green <i>Hermetia Illucens</i> for Application in Dentistry

Chitosan can be extracted from the hermetia illucens chitin. It has excellent biocompatibility, non-toxic, bioresorbable, anti-inflammatory and wound healing properties. It can be formed into a gel, granules, sheet/film, porous structure, or scaffold in dental medications. Hermetia illucens cocoons were collected and extracted from the by-product of organic waste management in Bandung City. The samples were dried in the oven at 105°C for 48h and grounded in the powder grinder and sieved. Demineralization proces were done by immersed samples in 1 M HCl for 6h. The powder then deproteinized using 1 M NaOH solution for 8h at 80 oC, filtrated, and washed with distilled water. Then, the samples were immersed in 1% KMnO4 solution for 1h, and cleaned the residue with an oxalic acid solution. Samples obtained were dried in the oven at 60 oC for 48h before deacetylated with deionized water. Characterization were done by Fourier Transform Infrared spectroscopy (FTIR), and Scanning Electron Microscope (SEM). IR spectra showed disctinctive OH bond at 3253.62 cm-1 and amide I band at 1616.98 cm-1. Degree of deacylated were calculated using infrared spectra data and resulting 77.372% indicating good character of chitosan. The result SEM were inducated typical pattern of chitosan. Further study is to fabricate the medical-grade chitosan for dental material. The chitosan from the hermetia illucens is a promising natural biopolymer for dental applications and organic waste management solutions.

Dual functional behaviour of dicationic ionic liquid as extractant and hydrophobic biphasic solvent for extraction of Pb(II) in water

Herein, it was aimed to investigate the extraction ability of hydrophobic di-cationic imidazolium-based ionic liquid with inbuilt carboxylic acid functionalities for one of the heavy metals, Pb(II) from aqueous solution. Two dicationic ionic liquids, IL-1 named 1,1′(butane-1,4-diyl)bis(3-(4carboxyphenyl)-2-methyl-1H-imidazol-3-ium) chloride and IL-2 named 1,1′(dodecane-1,12-diyl)bis(3-(4carboxyphenyl)-2-methyl-1H-imidazol-3-ium)chloride tailored with (CH2)n bridging spacer chains, n = 4 and n = 12 respectively were synthesized. The Pb(II) displayed extraction percentages greater than 90% with both the aqueous biphasic system of IL-1 and IL-2. An efficient back-stripping of the Pb(II) metal ion was done using with aqueous solution of oxalic acid. Calcination of lead oxalate salt obtained showed highest purity of PbO confirmed by PXRD and EDX data. The established experimental condition with the synthesized ionic liquids is a distinguished one as no salting out agent, no extra extracting agents other than the synthesized ionic liquids were used. Moreover, the regeneration of the ionic liquid (IL-2), and back stripping of Pb(II) as oxalate salt makes this system an efficient one with negligible loss of the ionic liquid (IL-2) into the aqueous medium thus obliging the standards of environment-friendly sustainable development.

Electrochemical anodization of cast titanium alloys in oxalic acid for biomedical applications

Titanium and its alloys have numerous biomedical applications thanks to the composition and morphology of their oxide film. In this study, the colorful oxide films were formed by anodizing cast Ti-6Al-4V and Ti-6Al-7Nb alloys in a 10% oxalic acid solution for 30 s at different voltages (20–80 V) of a direct current power supply. Atomic force microscopy was used as an accurate tool to measure the surface roughness of thin films on the nanometer scale. Scanning electron microscopy and X-ray diffraction were performed to analyze surface morphology and phase structure. According to the results, the produced titanium oxide layer showed high surface roughness, which increased with increasing anodizing voltage. The impact of anodizing voltages on the color and roughness of anodized layers was surveyed. The corrosion resistance of the anodized samples was studied in simulated body fluid at pH 7.4 and a temperature of 37 °C utilizing electrochemical impedance spectroscopy and the potentiodynamic polarization method. The anodized samples for both alloys at 40 V were at the optimal voltage, leading to a TiO2 layer formation with the best compromise between oxide thickness and corrosion resistance. Also, findings showed that TiO2 films produced on Ti-6Al-7Nb alloys had superior surface roughness properties compared to those of Ti-6Al-4V alloys, making them more appropriate for orthopedic applications. From the obtained data and the fruitful discussion, it was found that the utilized procedure is simple, low-cost, and repeatable. Therefore, anodization in 10% oxalic acid proved a viable alternative for the surface finishing of titanium alloys for biomedical applications.

Oxalic acid application method and treatment intervals for reduction of Varroa destructor (Mesostigmata: Varroidae) populations in Apis mellifera (Hymenoptera: Apidae) colonies.

Oxalic acid (OA) is a popular miticide used to control Varroa destructor (Mesostigmata: Varroidae) in western honey bee (Apis mellifera L.) (Hymenoptera: Apidae) colonies. Our aim was to investigate which method of OA application (dribbling, fogging, or vaporizing) was the most effective at reducing V. destructor infestations (Experiment 1) and to improve upon this method by determining the treatment interval that resulted in the greatest V. destructor control (Experiment 2). We used the product Api-Bioxal (97% OA) and maintained 40 honey bee colonies (10/treatment) in both experiments. In Experiment 1, the treatments included (i) dribbling 50 ml of 3% OA solution, (ii) vaporizing 4 g of solid OA, (iii) using an insect fogger supplied with 2.5% OA dissolved in ethyl alcohol, and (iv) an untreated control. After 3 weeks, only the vaporization method reduced V. destructor infestations (from 9.24 mites/100 bees pretreatment to 3.25 mites/100 bees posttreatment) and resulted in significantly increased brood amounts and numbers of adult bees over those of the controls. In Experiment 2, all colonies were treated with 4 applications of OA via vaporization at a constant concentration of 4 g OA/colony. In this experiment, the groups were separated by treatment intervals at either 3-, 5-, or 7-day intervals. We observed that 5- and 7-day treatment intervals significantly reduced V. destructor populations from pretreatment levels over that of the controls and 3-day intervals. Our data demonstrate the efficacy of OA in reducing V. destructor infestation, particularly vaporizing 4 g every 5-7 days as the most effective method of application.

Effect of water environment on mechanical behavior of coral aggregate concrete

The complex marine environment often exposes concrete to seawater and acidic conditions during its service life. To investigate the effect and mechanism of special water environments on coral sand concrete, forty-five Φ50 mm × 100 mm cylindrical coral concrete specimens were prepared and cured in freshwater, seawater and oxalic acid in this study. The specimens were cured for 7, 14, 28, 60 and 90 days, respectively. The physical and mechanical properties of the specimens under the lossless state and static failure state were tested through piezoelectric transducer (PZT) test and uniaxial compression test. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed for analyzing the mineral composition and microstructure of the specimens. The results show that the compressive strength of the specimens in seawater and freshwater initially increased and then stabilized with the curing age, whereas in oxalic acid it initially increased and then decreased. The compressive strength of the specimens at 90 days in freshwater, seawater and oxalic acid solution have increased by 54%, 18% and 21%, respectively, compared to that at 7 days. A combination analysis using microscopic and macroscopic test indicated that the completion time required for hydration in freshwater, seawater and oxalic acid solution was 28, 28 and 60 days, respectively. This study suggests that Cl− in seawater accelerates the cement hydration process, improving the early mechanical properties of specimens. During the later hydration process, the soluble CaCl2 and expansile Mg(OH)2 generated during the later hydration process which reduces the strength. In oxalic acid solution, a dense calcium oxalate coating produced through the reaction between oxalic acid and CaCO3 would reduce the degree of hydration. The formation of CO2 would increase the porosity of specimens, thereby weakening the mechanical strength of the concrete.

Сравнително изпитване устойчивостта на образци фасул към склеротинийно гниене (Sclerotinia sclerotiorum) чрез директен и индиректен метод

White mold, caused by Sclerotinia sclerotiorum, is a key disease of common beans in temperate and subtropical climates. For the climatic conditions of Bulgaria, the infection occurs mainly as a result of mycelogenic development of the sclerotia, which is why the disease is observed mostly in varieties with a prostrate type of the habitus. Due to the wide range of hosts of the pathogen and long-term preservation of sclerotia in the soil, agrotechnical measures have little effect in controlling the fungus. Therefore, breeding resistant varieties are the most effective measure to prevent the disease. The selection of appropriate and verified methods for testing the source and breeding materials is of primary importance for the success of breeding programs to increase resistance to the pathogen. The present study aimed to compare the response of bean accessions to S. sclerotiorum, by applying a direct and indirect evaluation method with a view to their parallel use in the breeding process. The studies were conducted under greenhouse conditions, and 29 bean accessions were included in them. The accessions were grown in pots (45x30x10 cm) with a soil-sand mixture. In the first trifoliate leaf, the stem was cut at 3 cm from the node of the primary leaves (STAW test). A single-sided closed plastic straw containing an agar disc from the periphery of 3-day-old cultures of four isolates cultivated on PDA medium (five plants per isolate), was placed on the cut. The reaction of the accessions was recorded 7 days after inoculation on a 9-point scale. The cut plant parts (stem and trifoliate leaf) were immersed in oxalic acid solution (20 mM brought to pH=4.0 with 1N NaOH), five plants per sample. The cut plant parts immersed in sterile water adjusted to pH=4.0 with 1N HCl were used for the control. The reaction of the accessions was recorded after 19h on a 9-point scale. The data were processed with the SPSS stat. ver. 19 software. Significant differences were observed in the response of the accessions concerning the isolates used. Weak positive or negative correlations were found between the oxalate test and the STRAW test, and the direction was related to the aggressiveness of the isolates. It was established that for accessions A195, ‘GTB Scythia’, ‘Izabel’, ‘Rhodopeia’ and ‘Pirina’ the results of the oxalic test are comparable to those of the STRW-test. The obtained results give us reason to recommend the application of the oxalate test in the initial generations of the breeding materials, after a preliminary comparative analysis of the parental forms by both methods.

Honey vs. Mite-A Trade-Off Strategy by Applying Summer Brood Interruption for Varroa destructor Control in the Mediterranean Region.

In this study, we investigated the effect of queen caging on honey bee colonies' post-treatment development and the optimal timing of method application on honey production during the main summer nectar flow. We conducted the study in nine apiaries (N = 9) across six Mediterranean countries, with a total of 178 colonies. The colonies were divided into three test groups: QC1, QC2, and C. The QC1 group involved queens caged for a total of 28 days before the expected harvesting day. In the QC2 group, queens were caged for 28 days, but only 14 days before the expected harvesting day. The C group consisted of queens that were not caged, and the colonies received common local treatments. In both the QC1 and QC2 groups, the colonies were treated with a 4.2% oxalic acid (OA) solution by trickling after the queen release. Our findings revealed no significant adverse effects (p > 0.05) on colony strength at the end of the study resulting from queen caging. However, significantly lower amounts of honey were extracted from the QC1 group compared to both the QC2 group (p = 0.001) and the C group (p = 0.009). Although there were no initial differences in Varroa destructor infestation between the groups, ten weeks later, a significantly higher infestation was detected in the C group compared to both the QC1 group (p < 0.01) and the QC2 group (p = 0.003). Overall, our study demonstrates that queen caging, in combination with the use of OA, is an effective treatment for controlling V. destructor. However, the timing of caging plays a crucial role in honey production outcomes.

The Effects of the Pre-Anodized Film Thickness on Growth Mechanism of Plasma Electrolytic Oxidation Coatings on the 1060 Al Substrate.

To increase the density of the micro-arc oxide coating, AA 1060 samples were pretreated with an anodic oxide film in an oxalic acid solution. Plasma electrolytic oxidation (PEO) was performed to investigate the effect of the thickness of the pre-anodic oxide film on the soft-sparking mechanism. The experimental results revealed that the PEO coating phases with different thicknesses of the pre-anodized films contained both Al and gamma-alumina (γ-Al2O3). The pre-anodized film changes the final morphology of the coating, accelerating the soft sparking transition and retaining the soft sparking. At a pre-anodized film thickness of ≤7.7 μm, the anodized films thickened before being broken through. When the pre-anodized film thickness was ≥13.1 μm, partial dissolution of the anodized films occurred before they were struck through. Two growth mechanisms for PEO coatings with different pre-anodized film thicknesses were proposed.

Anion Exchange Membrane Electrolyser Performance with Ni Ferrite Anodes Calcined at Different Temperatures

Hydrogen has a critical role in enabling European countries to achieve net-zero carbon targets. Hydrogen production via water splitting, using an electrolyser, is considered the "greenest" way because it does not produce any direct carbon emissions when powered by renewable sources. Among the different technologies of electrolysers (liquid alkaline, proton exchange membrane, etc.), there has been a recent surge in interest in that one based on anion-exchange membranes (AEMs). With respect to the state-of-the-art electrolysers that employ conventional acid polymer electrolyte separators (e.g., perfluorinated systems such as Nafion®), electrocatalysis with AEMs is much more promising. Accordingly, inexpensive catalysts can be used.In this work, NiFe2O4 catalysts are prepared by an "oxalate route". Nickel and iron nitrates in suitable stoichiometric ratios are added in successive steps to the oxalic acid solution. An oxidizing solution of hydrogen peroxide is then added. The obtained precipitate is first filtered and then dried. Different calcination temperatures (350, 450 and 550°C) are applied to obtain the Ni Ferrite with different surface and bulk characteristics. The catalysts are then deposited by a spray technique onto a commercial FAA3-50 (from FuMa-Tech) anion-exchange membrane, combined with a Pt-based cathode electrode, and investigated for the water electrolysis process in a single cell of 5 cm2 geometrical area. A comparison between the performance recorded with the different anode catalysts is reported and discussed. Acknowledgments The authors thank the Italian Ministry for University and Research (MUR) for funding through the FISR 2019 project AMPERE (FISR2019_01294).

Simple and environmentally friendly metal recovery from waste printed circuit boards by using deep eutectic solvents

Increased environmental awareness has necessitated the development of a simple and environmentally friendly method for metal recovery from waste printed circuit boards (WPCBs). Deep eutectic solvents (DESs) are environmentally friendly and non-aqueous lixiviants that can leach metal oxides to replace mineral acids. In this study, three choline chloride (ChCl)-based DESs were synthesized, using ethylene glycol, oxalic acid (OA), and glycolic acid (GA) as the hydrogen bond donors in the eutectic mixtures. The time-dependent leaching yields and saturated loading capacities of the DESs to typical metal oxides and Ag were evaluated. Considering the leaching performances, a simple and environmentally friendly method for metal recovery from WPCBs was established, based on two-stage DES leaching processes. The research object was the mixed metal powder collected from the mechanical processing of WPCBs. The results indicated that 90.35% of Zn, 87.47% of Pb, and 16.77% of Cu were removed from the mixed metal powder after calcination by leaching of the ChCl-GA DES and precipitation of the oxalic acid solution. When the residue was subjected to ChCl-OA DES leaching, Cu was recovered by diluting ChCl-OA DES with water. Specifically, 74.93% of Cu was separated in the form of CuC2O4·2H2O with a purity of >98 wt%. The Sn remaining in the aqueous solution was efficiently recovered by the addition of reduced Fe powder, and the recovery yield of Sn in the recovery product was 51.29%. Finally, the advantages of a simplified and environmentally friendly process framework, are highlighted by a comparison of the recovery strategy for WPCB proposed in this study with conventional pyro- and hydro-metallurgical approaches.

Quantifying the effect of grain size on weathering of basaltic powders: Implications for negative emission technologies via soil carbon sequestration

Weathering of basaltic powders was studied experimentally at 35 °C in dilute solutions of oxalic acid and carbonic acid to assess the effect of grain size and reactive surface area for materials under consideration for carbon dioxide reduction (CDR) by enhanced rock weathering (ERW). The basalts chosen for this study (with their mineralogical compositions) are the Blue Ridge (BR) meta-basalt (chlorite > epidote > plagioclase > actinolite) and Pioneer Valley (PV) basalt (plagioclase > augite > quartz > chlorite). Powders of BR and PV basalts were sieved into <45 μ m, 45–150 μ m, and >150 μm fractions, and experiments were performed in open-system reactors designed to simulate a 1 mm thick layer of basalt added to agricultural soil in the humid tropics. Weathering rate was assessed by measuring the flux of base cations leached from silicate minerals and results indicate that silt-dominated basaltic powder (<45 μ m) weathers at approximately double the rate of sand dominated (150–500 μ m) basaltic powder, both for the BR and PV basalts. This study estimates CDR rates between 2.8 and 6.8 t CO2/ha/yr across the range of grain size fractions analyzed. Etched primary mineral grains (e.g. plagioclase, augite, actinolite) with depleted base cations observed by SEM-EDS provide morphological and stoichiometric evidence of dissolution, as do the presence of frayed chlorite grains that contain adsorbed Ca and are compositionally intermediate to end-member chlorite and smectite. Small amounts of micron-scale calcite were also observed as a precipitate on mineral surfaces, likely a consequence of localized saturation of Ca and HCO3 in the matrix of the weathering powders. The results of this study help to constrain differences in weathering flux as a function of grain size, with important implications for effectiveness of CDR via ERW.

Influence of oxalic acid on the corrosion behavior of AZ91D magnesium alloy in deionized water

Due to its light weight, Mg alloy can be applied to automotive engines and cooling systems to reduce vehicle weight, energy consumption and exhaust pollution. However, ethylene glycol-type coolants can be oxidized into oxalic acid, glyoxylic acid and other substances at high temperature, which can cause the damage of Mg alloy. In this paper, electrochemical methods, hydrogen evolution and surface analysis methods were used to study the influence of oxalic acid on the corrosion behavior of AZ91D magnesium alloy in deionized water. The results indicated that the oxalic acid accelerated the corrosion of Mg alloy, and its corrosion rate increased with the concentration of oxalic acid. However, interestingly, the corrosion rate of Mg alloy in oxalic acid solution slowed as the immersed time lengthened, which could be related to the accumulation of corrosion products and the consumption of hydrogen ions. The main corrosion product of the corrosion of Mg alloy in oxalic acid solution was composed of magnesium oxalate.

Chromatography separation of minor actinides from Ln3+ rich high-level radioactive liquid waste (HLW) using bis-triazinyl-pyridine (BTP) resin

ABSTRACT Separation of Minor Actinide (MA) from High-level Radioactive Liquid Waste (HLW), especially from Ln3+, is greatly needed in the nuclear fuel cycle to reduce the long-term radiotoxicity associated with the waste and for transmutation use. Devising a simple process and designing an extractant is challenging due to the chemical similarity of An3+ and Ln3+ in aqueous solutions. Hence, a tailor-made extractant was prepared, and the partitioning of MA (An3+: 241Am and 244Cm) from Ln3+ rich HLW has been demonstrated using indigenously developed Camphor-based Bis-Triazinyl-Pyridine (CA-BTP) impregnated XAD−7 (BTP Resin). The BTP resin exhibited good adsorption selectivity toward An3+ over Ln3+, acceptable adsorption kinetic, and adequate stability against HNO3 (<2.5 mol/L) and γ-irradiation. The % decontamination factor (DF) achieved was > 99.99 for 137Cs and 154Eu, and 99.7 for Nd. Separated 241Am was precipitated with a saturated solution of oxalic acid. The performance of BTP resin reveals that it has an excellent potential to separate 241Am from Ln3+-rich HLW solution in pure form.

Iron removal from kaolin by oxalic acid using a novel pre-agitating and high-pressure washing technique

AbstractThis study reports a leaching process along with a novel physical pretreatment technique to remove iron impurities from kaolin using oxalic acid. A detailed examination of the physical properties of the minerals confirmed that almost none of the leaching-resistant iron oxides, specifically hematite, was completely interlocked with the clay minerals. Accordingly, a pre-agitating technique followed by high-pressure washing of the sample on a 600 μm sieve were applied. In this method, by discarding up to 20% of the raw material, &gt;54% of the total iron content of the raw kaolin was removed, and the iron content was reduced from 9.75% in the initial sample to &lt;6.00% in the passing fraction. Application of this pretreatment method rendered the leaching process successful at 97°C using 0.3 M oxalic acid solutions for 1 h under atmospheric pressure. Compared to the leaching of the raw material without pretreatment, which consumed at least 0.5 M oxalic acid over a minimum period of 2 h, the method used was very cost-effective and favourable, reducing the iron content of the product to &lt;1% and producing high-quality kaolin.

A new technique for the removal of red fungal stains on traditional Chinese painting on silk

The orange-red to reddish purple fungal stains on paintings and textiles are recalcitrant to be alleviated even by using oxidative methods that are corrosive to most organic materials. A novel approach of alternate applications of sodium borohydride solution with dilute acids were tested and successfully practiced on the removal of the red fungal stains on a severely disfigured traditional Chinese painting on silk. The new approach was compared with the conventional oxidative method of potassium permanganate—oxalic acid solution in terms of their effectiveness and the safety of the silk fabrics. 1% and 0.5% of sodium borohydride ethanol solution alternated respectively with dilute acetic acid and sulfuric acid were effective for the removal of the reddish fungal stains on an authentic traditional Chinese painting on silk as well as the silk fabric samples. The loss of tensile strength of the silk fabric samples induced by the new approach was much milder than did the conventional oxidative method of potassium permanganate—oxalic acid.