Pure Acid Research Articles

Azeotropic formic acid-water separation by sulfolane extractive distillation feasibility study

ABSTRACT Due to the formation of an azeotrope at 57.6 mol.% formic acid under atmospheric pressure, conventional distillation is ineffective for separating formic acid and water into pure components. This study explores the use of extractive distillation with sulfolane as a solvent to overcome this limitation. The binary interaction parameters for the formic acid-water and sulfolane-water systems were determined using the NRTL model in Aspen Plus V10 software, based on experimental data. The investigation focuses on the effect of varying solvent concentrations on the thermodynamic equilibrium and the relative volatility of water to formic acid. The proposed process design incorporates two sequential columns: an extractive distillation column and a solvent regeneration column, both operating under reduced pressure. Simulation results confirm the feasibility of this method for purifying formic acid. For water concentrations between 80% and 50%, the boiler energy consumption in the extractive distillation process decreases by 42%. The regeneration column operates at 0.254 bar to minimise corrosion and ensure complete recovery of sulfolane. This study highlights the effectiveness of extractive distillation with sulfolane, achieving a high recovery rate of nearly pure formic acid.

Carbon Flow in Acidic CO2 Electroreduction.

Electrochemical CO2 reduction in acidic media attracts extensive research attention due to its potential in increasing carbon efficiency. In most reports, alkali cations are introduced to suppress hydrogen evolution and to promote CO2 reduction. However, the mass transport of alkali cations through cation exchange membrane induces the change of electrolyte compositions. Herein, the variation of electrolyte compositions and the flow of carbon during CO2 reduction are analyzed quantitatively by simulation and experiments. If the initial amount of alkali cations in the anolyte is higher than the initial amount of H+ in the catholyte, the pH of the catholyte increases remarkably in long-term CO2 reduction electrolysis, resulting in the decrease of carbon efficiency. Bicarbonate salt precipitation on the cathode with alkali cation-containing catholyte is another origin of the decrease of CO2 reduction Faradaic efficiency and carbon efficiency. To maintain high carbon efficiency, the electrolyte should contain low concentration of alkali cations or even be free of alkali cations. Decorating the catalyst of cathode with ionomer with high density of cation sites enables CO2 reduction in pure acid solution, achieving 30-h stable carbon efficiency.

Accurate determination of purity for organic compounds using adiabatic calorimetry

Adiabatic calorimetry is a reliable method for determining the purity of organic compounds, offering significant advantages over chromatography by eliminating the need for impurity separation. Despite its longstanding application, research in this area has been limited. This study comprehensively assessed the purity of tetradecanoic acid, n-heptadecane, and phenol using adiabatic calorimetry, comparing the results with those obtained through chromatography. The results demonstrated that tetradecanoic acid purity can be accurately measured, while n-heptadecane exhibited satisfactory repeatability in purity determination without sample separation in polycrystalline forms. Furthermore, the purity of phenol was effectively assessed using adiabatic calorimetry, where chromatography faced challenges. Overall, this study validates adiabatic calorimetry as a robust technique for organic compound purity determination and suggests avenues for further research in this domain.

Photothermally-activated suspended aerogel triggers a biphasic interface reaction for high-efficiency and additive-free hydrogen generation.

The need for a sustainable hydrogen supply has sparked significant efforts to develop effective liquid hydrogen carriers with high hydrogen content that can be safely stored and undergo controlled hydrogen release. However, a major challenge lies in the ultralow hydrogen evolution rate caused by the direct dehydrogenation of liquid hydrogen carriers. Conventionally, accelerant additives are employed to improve the dehydrogenation rate, but this strategy inevitably sacrifices the hydrogen storage density. Therefore, achieving high-efficiency hydrogen release and high storage density remains a daunting task. Herein, we develop an innovative photothermally-activated suspended biphasic reaction strategy, which absorbs solar radiation and re-radiates infrared photons to induce photothermal evaporation and in situ dehydrogenation of liquid hydrogen carriers, fundamentally circumventing the employment of additives. Furthermore, by leveraging this phase transition-induced biphasic reaction design, the strategy improves the required reaction temperature and drastically lowers hydrogen transport resistance. Therefore, an impressive hydrogen evolution rate of 386 mmol g-1 h-1 is achieved from pure formic acid with an ultrahigh hydrogen storage density of 53 g L-1, representing a threefold improvement in rate compared to state-of-the-art strategies. Our approach introduces a fresh perspective for the dehydrogenation of liquid hydrogen carriers, encompassing formic acid, hydrazine hydrate, and so on, and concurrently guarantees exceptional hydrogen release capabilities and excellent hydrogen storage density.

Enantioselective Synthesis of Chiral β2-Amino Phosphorus Derivatives via Nickel-Catalyzed Asymmetric Hydrogenation.

Compared with chiral β3-amino phosphorus compounds, which can be easily derived from natural optically pure α-amino acids, obtaining chiral β2-amino phosphorus derivatives remains a challenge. These derivatives, which cannot be derived from chiral natural amino acids, possess unique biological activities or potential catalytic activities. Herein, highly enantioselective hydrogenation for the preparation of chiral β2-amino phosphorus derivatives from E-β-enamido phosphorus compounds is reported by using a green and low-cost earth-abundant metal nickel catalyst (13 examples of 99% ee). In particular, this catalytic system provides the same enantiomer product from the E- and Z-alkene substrates, and the E/Z-substrate mixtures provide good results (up to 96% ee). The products can be diversely derivatized, and the derivatives exhibit good catalytic activities as novel chiral β2-aminophosphine ligands. Density functional theory calculations reveal that the weak attractive interactions between the nickel catalyst and the substrate are crucial for achieving perfect enantioselectivities. In addition, the different coordination modes between the E- or Z-substrates and the catalyst may result in the formation of the same enantiomer product.

Liposomal and Nanostructured Lipid Nanoformulations of a Pentacyclic Triterpenoid Birch Bark Extract: Structural Characterization and In Vitro Effects on Melanoma B16-F10 and Walker 256 Tumor Cells Apoptosis.

Background/Objectives: Pentacyclic triterpenoids are increasingly studied as anticancer agents with many advantages compared to synthetic chemotherapeutics. The aim of this study was to prepare liposomal and nanostructured lipid formulations including a standardized extract of silver birch (Betula pendula) outer bark (TTs) and to evaluate their potential as anticancer agents in vitro, using Melanoma B16-F10 and Walker carcinoma cells. Methods: Appropriate solvents were selected for efficient TTs extraction, and original recipes were used to obtain Pegylated liposomes and nanolipid complexes with entrapped TTs, comparative to pure standards (betulinic acid and doxorubicin) in similar conditions. The composition, morphology, and sizes of all nanoformulations were checked by high-performance liquid chromatography/mass spectrometry, Transmission Electronic Microscopy, and Diffraction Light Scattering. The entrapment efficiency and its impact on cell viability, cell cycle arrest, and apoptosis by flow cytometry was also measured on both cancer cell lines. Conclusions: The standardized TTs, including betulin, lupeol, and betulinic acid, showed good stability and superior activity compared to pure betulinic acid. According to experimental data, TTs showed good entrapment in liposomal and NLC nanoformulations, both delivery systems including natural, biodegradable ingredients and enhanced bioavailability. The apoptosis and necrosis effects were more pronounced for TTs liposomal formulations in both types of cancer cells, with lower cytotoxicity compared to Doxorubicin, and can be correlated with their increased bioavailability.

Synthesis of enantiomerically enriched β-substituted analogs of (S)-α-alanine containing 1-phenyl-1H-1,2,3-triazole groups

A synthesis of new enantiomerically enriched derivatives of (S)-α-aminopropionic acid, containing in the β-position 1,2,3-triazole groups coupled with a o-, m- and p-substituted phenyl residue, was developed based on Cu(I) catalyzed [3 + 2] cycloaddition of azides with alkynes. As the starting materials was used the square-planar Ni(II)complex of the Schiff base of propargylglycine with the chiral auxiliary BPB (Benzylprolylbenzophenone) and 1,4-substituted phenyl azides. The assignment of the (S)-absolute configuration of the α-carbon atom of the amino acid residue of the main diastereomeric complexes of the cycloaddition products was carried out on the basis of positive Cotton effects in the region of 480–580 nm of the circular dichroism spectra. The target amino acids were isolated from acid hydrolysates of diastereomeric complexes using ion-exchange demineralization and crystallization from aqueous ethanol. Additional confirmation of the absolute configuration and determination of the enantiomeric purity of the target amino acids were carried out by chiral HPLC analysis. As a result, seven new non-proteinogenic (S)-α-amino acids, containing in the β-position a 1,2,3-triazole moiety, were synthesized.

Effect of preparations containing humic substances and pure humic acids on colony growth and spore germination of entomopathogenic fungi from the Beauveria genus

The experiment examined the effect of commercially available preparations containing humic substances in comparison with pure humic acids on the growth and germination of spores of entomopathogenic fungi (EPF) of the genus Beauveria in vitro. AmiAGRA, HumiAGRA, AlgoHUM (recommended field dose) and pure humic acids extracted from peat, brown coal and mushroom substrate were added to Sabouraud's culture substrate. Observation of the growth of colonies of the tested species of EPF was carried out every 5 days until day 20, measuring their diameter (mm). In the second stage of the experiment, the culture medium with the addition of preparations and pure humic acids was applied in a thin layer to the surface of glass slides and 0.1 ml of an aqueous solution with spores was introduced. Observation was carried out after 24 and 48 hours, and the results obtained were expressed as percentages of the control. The conducted research showed that on the 20th day of culture (on average), preparations containing humic substances had a stimulating effect, while pure acids slightly limited the growth of colonies of the tested isolates. The growth of the colony of the fungus B. basianna was most strongly stimulated by AmiAGRA, and B. brongniartii by HumiAGRA. The share of germinated spores of the tested isolates after 48 hours of contact with the substrate was higher than after 24 hours. It was found that more spores germinated on substrates with the addition of preparations containing humic substances than on pure humic acids.

A 12-month retrospective review of pressure injury plastic surgical flap techniques utilizing pure hypochlorous acid (pHA) preserved wound solution for wound bed preparation.

The presence of heavy microbial colony formation, polymicrobial infection, and local altered pH contribute to the high rate of postoperative complications following surgical reconstruction of stage IV pressure injuries (PIs). The objective of this study was to determine the rate of bacteria-related postoperative complications following surgical reconstruction of stage IV PIs in which a pure hypochlorous acid (pHA) antimicrobially preserved wound cleaning solution was used. This 1-year retrospective review evaluated the outcomes of patients who underwent surgical reconstructive treatment of chronic stage IV PI. Surgical management consisted of wide debridement, intraoperative cultures, and irrigation with 8 to 10 minutes indwelling of a pHA antimicrobially preserved wound cleaning solution prior to closure and application of incisional negative pressure wound therapy (iNPWT). Thirteen patients (18 chronic, stage IV PIs) were included in the study. Intraoperative cultures were positive for 10/18 wounds (55.6%). A bacteria-related postoperative complication occurred in 1 patient (1/13, 7.7%; postoperative dehiscence requiring reoperation). Adjunctive irrigation and indwelling of a pHA antimicrobially preserved wound cleansing solution in the surgical management of chronic, stage IV PIs in this 1-year retrospective review resulted in a 7.7% bacteria-related postoperative complication rate.

Analysis of the use of Nano-engineered Composite Energy Retention Materials in Eco-Building Layouts

Abstract This analysis is to approaching the usage of the heat retention phase transition materials in structure of building establishment energy preservation blend, in this research infusing the Nano-engineered composite energy retention substances into Eco-building layouts. Altered C (Carbon) nanotubes, manufactured by acid mixture fermentation and Attrition milling, were blended with saturated fatty acid to produce heat retention state transition materials. Analytic outcome shows that acidified Nano Carbon tubes thwart the heat capacity dispersion of stereophonic acid molecular fragments, resulting in heat conducting capacity is 1.2 times higher compared to the pure saturated fatty acid when Nano Carbon tubes are appended with a volume ratio of 1%. Eventually, Nano-engineered composites energy staking materials illustrates higher prospect for application in Eco-building layouts.

Development of faba protein-tannic acid conjugate via free radical grafting: Evaluation of interaction mechanisms and antioxidative properties.

A soluble fraction of faba bean protein was conjugated with tannic acid via the free-radical grafting method using a mixture of ascorbic acid and hydrogen peroxide. Surface plasmon resonance showed a strong bonding between them, while the free amino and thiol group measurements indicated tannic acid's bonding with the amino groups and cysteine residues on the proteins. Structural analysis using intrinsic fluorescence and surface hydrophobicity demonstrated tannic acid's interaction with the aromatic and hydrophobic amino acids of the protein. The conjugate showed about 77% DPPH, 89% ABTS, and 83% hydroxyl radical scavenging activities and superior ferric-reducing ability compared to the protein alone and the mixture of protein and tannic acid. Electron paramagnetic resonance (EPR) spectroscopy revealed 97.8% radical scavenging ability of the conjugate, comparable to the pure tannic acid. The exceptional antioxidative properties of conjugate can be utilized to delay lipid oxidation in protein-stabilized oil-in-water emulsions.

Application of vegetable oils as pharmaceutical ingredient: the impact of liquid lipid type on the characteristics of nanostructured lipid carrier

Recently, drug encapsulation using a Nanostructured Lipid Carrier (NLC) has gained attention in formulation studies due to its high loading capacity and prevent drug expulsion during storage. Drug loading capacity is mainly affected by lipid type and composition, especially liquid lipids. Therefore, this research aims to evaluate the potential of avocado oil as a liquid lipid of NLC replacing pure oleic acid. All components including oil, glyceryl monostearate, Tween 20®, and Span 60® were processed to NLC by solvent injection method. The colloidal characteristics of NLC dispersion in water and 20 mM PBS pH 7 were determined, including transmittance, particle size, size distribution, zeta potential, loading capacity (LC), and loading efficiency (LE) of capsanthin in NLC. The results showed that NLC containing oleic acid (Fola) and avocado oil (Favo) dispersion in PBS exhibited a similar transmittance and zeta potential of 69-74% and -51 to -58 mV, respectively, whereas the particle size and size distribution of Favo were significantly higher than Fola. Moreover, the 1.3-fold higher LC and LE of Favo compared to Fola was insignificant (p>0.05). Additionally, the Tween 20® and Span 60® ratio of Favo should be improved to obtain an ideal particle size and size distribution as in Fola. In conclusion, avocado oil indicated the potential to be utilized as a liquid lipid of NLC formulation regarding zeta potential and drug loading. However, the surfactant composition should be adjusted to reduce the particle size of the NLC, leading to permeability enhancement in delivery, particularly oral administration.

Optimization of RNA extraction protocol from Eucalyptus and Populus species for gene expression studies

ABSTRACT Extraction of high-quality RNA is complicated due to the presence of polysaccharides and polyphenols in woody plant species like Eucalyptus and Populus. To conduct gene expression studies, RNA must be of high quality and intact integrity. Although, RNA extraction kits make the process quick and easy but they might not consistently provide high-quality RNA from Eucalyptus and Populus. Therefore, the primary objective of this work is to optimize a repeatable and systematic CTAB method for RNA extraction of high quality from Populus and Eucalyptus leaves. According to the study results, the optimized CTAB approach is more suitable for these plant species than RNA extraction kits. The agarose gel electrophoresis demonstrated that the RNA samples retained their integrity due to the presence of distinct 28S and 18S rRNA bands. Additionally, the RNA integrity number was found to be between 7.2 and 8.0. As indicated by the A260/A280 ratios, the optimized method’s RNA extraction yielded minimal levels of polysaccharide and polyphenol contamination. For Eucalyptus, the absorbance values ranged from 1.98 to 1.99 while for Populus it was 1.97 to 1.98. Similarly, the A260/230 ratios, which represent the second indicator of nucleic acid purity, were found to be 2.01 to 2.08 and 2.02 to 2.09 for Eucalyptus and Populus, respectively. The high-quality RNA was shown to be appropriate for use in further processes, such as cDNA synthesis, gene amplification, and real-time quantitative PCR (RT-qPCR).

The Proton´s Potential: How Acidic Is Sulfuric Acid at All?

Hammett and Deyrup introduced the H 0 function to gather “acidity in terms of a basic indicator”.[1] Since then, the H 0 acidity function and those derived from it have been used to specify the acidity of various solutions or pure acids, and particularly superacids. However, over the course of time, the distinction between the H 0 acidity and the pH acidity seems to have become confused or completely obscured for a number of researchers, as if the two are to be considered the same. The activity coefficients, or more precisely, the medium effect f of an indicator base B and its protonated form BH+ are integral part of the H 0 acidity function definition: H 0 = − lg a H2O(H+, S) − lg (f B / f BH+ )S is a non-aqueous solvent or a highly concentrated acid, the activity a H2O refers to the aqueous reference state. In contrast, the pH acidity is introduced as unifying scale pHabs H2O that only accounts for the chemical potential of the proton, or, since the activity of a chemical entity is defined by its chemical potential, for the activity of the proton:[2] pHabs H2O = − lg a H2O(H+, S)This scale allows the straightforward comparison of the pH acidity of all homogeneous and isotropic media and can be regarded as continuation of the aqueous pH scale defined by Sørensen into both, the acidic and basic direction.Our investigations with potentiometric measurements on two different types of electrochemical cells, one of which is the H+ analog of the determination of Gibbs transfer energies of the Ag+- and the Cl−-ion,[3] indicate that the H 0 function, if misinterpreted as extension of the pH acidity, underestimates the proton´s chemical potential in pure sulfuric acid by at least 11 orders of magnitude. The difference of the pH and the H 0 acidity scales can be quantified by subtracting above two equations:(pHabs H2O − H 0) RT ln10 = Δtr G°(B, H2O → H2SO4) − Δtr G°(BH+, H2O → H2SO4)High level quantum chemical computations of Gibbs solvation energies of the indicator bases B and their protonated forms BH+ that were used by several investigators[4] on the one hand, and of chemical entities expected to be present in sulfuric acid – water mixtures on the other, support our experimental findings.We provide a rule of thumb to calculate pHabs H2O values into H 0 values, pHabs H2O ≈ H 0 4/3 (see Figure), it has to be noted, however, that this rule only applies to sulfuric acid.

1H and 13C NMR and FTIR Spectroscopic Analysis of Formic Acid Dissociation Dynamics in Water.

The formation and transport of ionic charges in formic acid-water (HCOOH-H2O) mixtures with initial water mole fractions ranging from XH2Oi = 0 to 1 were investigated using 13C and 1H NMR, FTIR spectroscopy, viscosity, conductivity, and pH measurements. The maximum molar concentration of ions (H3O+ and HCOO-), along with the relative differences between theoretical and experimental densities, spin-lattice relaxation times (T1), activation energies (Ea), viscosity (η), and conductivity (σ), were identified within the range of XH2Oi ≈ 0.5-0.7. These results indicate that pure formic acid (FA) solutions predominantly consist of cyclic dimers at room temperature. As the water mole fraction increases up to 0.6, a structural shift occurs from cyclic dimers to a mixture of linear and cyclic dimers, driven by the formation of strong hydrogen bonds. Beyond a water mole fraction of 0.6, the structure transitions to linear dimers, with FA molecules behaving as free entities in the water. Furthermore, the acidity was found to increase approximately 2-fold with every 0.1 increment in water mole fraction. These findings are critical for understanding the kinetics of formic acid anions in body fluids, the structure of the hydrogen bonding network, and ionization energies.

Ellagic acid/Fe nanocomposite thin film with high power conversion efficiency for photovoltaic devices

This study synthesizes and characterizes an ellagic acid/Fe nanocomposite thin film ([Ellag-A/Fe·6H2O]NCTF) to enhance photovoltaic device efficiency, achieving a notable power conversion efficiency of 14.5 %. Using FT-IR, TGA, XRD, SEM, and optical analyses, the nanocomposite's structural, thermal, and optical properties were investigated, revealing a polycrystalline structure with improved thermal stability over pure ellagic acid. Density Functional Theory (DFT) calculations show a large energy gap of 1.08 eV, indicating stability and high excitation energies. The combination of organic ellagic acid with iron nanoparticles makes ([Ellag-A/Fe·6H2O]NCTF a promising material for photovoltaic applications.

Study on the influence characteristics of multi-working condition parameters on membrane electrode type CO2 electrolyzer

The electrochemical conversion of carbon dioxide (CO2) into basic chemicals or carbon-based fuels is a promising new strategy for carbon resource utilization. Within this domain, solid-electrolyte CO2 electrolyzer demonstrate significant potential for the continuous production of pure formic acid solutions. This study, leveraging a 4 cm2 visualization electrolyzer, explores the impact of three working condition parameters on performance: working voltage, gas flow rate, and the intermediate chamber water flow rate. It compares the variations in current density, formic acid concentration, and the distribution of liquid water on the cathode side under different working conditions. The results indicate that the working voltage, current density, and formic acid yield are all positively correlated; overly low gas flow rates can lead to CO2 deficiency and diminished electrolyzer performance; concentration control of the formic acid solution is effectively achieved by adjusting the intermediate chamber water flow rate; and during the electrolyzer reaction process, almost all of the liquid water is positioned at the bends downstream of the cathode flow channel.

Toward the bioleaching of bauxite residue by Gluconobacter oxydans.

This project evaluated a biologically mediated strategy to solubilize several rare earth elements and critical raw materials, including scandium, from bauxite residue. This work seeks to expand on previous research on contact leaching with bauxite. In this study, Gluconobacter oxydans was shown to secrete mixed organic acids, including gluconic acid, which was superior to pure gluconic acid in the dissolution of bauxite residue, even at low molarities. In situ contact leaching with G. oxydans significantly promoted the dissolution yield (recovery of metal present in the ore) of yttrium, aluminum, calcium, and titanium (41.18%, 67.79%, 80.16%, and 59.41%, respectively) but allowed for only marginal dissolution yield of scandium, lanthanum, cerium, and neodymium (13.40%, 14.74%, 24.41%, and 10.67%, respectively) at relatively low pulp densities. In addition, the dissolution yields of rare earth elements were reduced further with time, presumably as the oxides of these elements fell out of solution. This work builds on previous research that seeks to extract rare earth elements and critical raw materials from bauxite residue through contact leaching with organic acids. Some elements such as yttrium, aluminum, calcium, and titanium could be effectively solubilized; however some elements showed reduced solubility, possibly due to tight association with the iron phase of the residue. However, the relative ease and speed of leaching, and improved solubilization, suggest that this could be a viable method for securing critical raw material supplies.

Deep Learning for the Study of Urinary Stone Composition from Computed Tomography Images.

Urinary stones composed of uric acid can be treated with medicine. Computed tomography (CT) can diagnose urinary stone disease, but it is difficult to predict the type of uric stones. This study aims to develop a method to distinguish pure uric acid (UA) stones from non-uric acid (non-UA) stones by describing quantitative CT parameters of single-energy slices of urinary stones related to chemical stone types. Clinical data, CT images, and stone composition analysis results of patients with urinary stones clinically diagnosed at The Department of Urology, Affiliated Hospital of Qingdao University between 1 January 2018 and 31 December 2020 were collected and retrospectively analyzed. The above data were preprocessed and fed into a convolutional neural network to perform deep learning (DL) of the model, and the dataset was validated at a ratio of 4:1. The area under the curve (AUC) value of the receiver operating characteristic (ROC) curve and the confusion matrix were utilized to evaluate the predictive effect of the model. A retrospective analysis of 918 non-enhanced thin-slice single-energy CT images of known chemical stone types (124 with UA stones and 794 with non-UA stones) was conducted using a DL model. Compared with the results of ex vivo analysis by infrared spectroscopy, the prediction model obtained an AUC of 0.83 for the dichotomous classification of UA stones and non-UA stones. The accuracy of the model was 97.01%, with an F1 score of 89.04%, sensitivity of 84.62%, and specificity of 82.28%. This DL model constructed based on convolutional neural network analysis of thin-slice single-energy CT images is highly accurate in predicting the composition of pure UA and non-UA stones, providing a simple and rapid diagnosis method.

Study on the integrated technology of arsenic removal and tungsten extraction based on the formation and decomposition of arsenotungstic acid

Arsenic is an accompanying element in sulfide minerals and distributed in dusts, solutions and slags during the metallurgical process. Particularly, arsenic removal from acidic solutions has long challenged hydrometallurgy. Herein, an integrated technology for arsenic removal and tungsten extraction based on the formation and decomposition of arsenotungstic acid is proposed. By leaching scheelite with H3AsO4-H2SO4 solution, arsenotungstic acid was formed with a tungsten leaching rate of 99.9 %. The arsenic content in the resulting gypsum was 0.003 wt%, which was lower than the initial 0.2 wt% in scheelite. Afterwards, the arsenotungstic acid can be selectively extracted by dodecanol, and the extraction rate increases with decreasing temperature and increasing acidity. It is also for this reason that the loaded organic phase can be easily stripped with hot water above 70 °C to obtain a pure arsenotungstic acid solution. When arsenotungstic acid reacted with ammonium, the resulting AAT precipitate has a particle size of less than 2 µm, which is much smaller than that of conventional ammonium paratungstate and reaches the ultrafine level. In the hydrogen reduction process of ammonium arsenotungstate, arsenic had an inhibitory effect on the growth of tungsten grains, resulting in the formation of tungsten powder with nanograins. Meanwhile, arsenic was reduced, volatilized, and finally condensed into elemental arsenic with metallic luster. The arsenic content in tungsten powder was 0.009 wt%, and the arsenic removal rate was 99.7 %. This work utilized arsenic acid and sulfuric acid as leaching agents for scheelite, and finally prepared two products of ultrafine tungsten powder and elemental arsenic, which provided a new approach for arsenic removal from highly acidic solutions and resource utilization of waste arsenic acid solution.