Phosphoric Acid Research Articles

Insight into the chemistry of Folin’s test for uric acid

Folin developed an analytical technique for uric acid spectroscopic determination. It is based on the interaction of uric acid with sodium tungstate in phosphoric acid. This produces an intense blue colour after alkalinization, whose concentration is measured. However, the structure of the organic product obtained was not mentioned. The present communication gives the references related to each reaction step, as well as information about the reaction products obtained in uric acid oxidations carried-out in acidic or in alkaline mediums. The reaction route is as follows: addition of tungstic acid to the C-C double bond, acidolysis of the organo-metallic ester, producing tungstic subacid and an epoxide. Oxirane opening to vicinal diol after reaction with water. Two carbinolamines result, which are broken by protonation at the nitrogen; carbonyl groups are formed at C-4 and C-5 with concomitant elimination of a urea molecule. This way alloxan monohydrate is formed. The blue products obtained are described.

Asymmetric Synthesis of Axially Chiral N, N‐1,2‐Pentatomic Heterobiaryl Diamines by an Organocatalytic Arylation Reaction

The utilization of axially chiral biaryl diamines has been widely acknowledged as highly advantageous structures for the advancement of chiral catalysts and ligands. This highlights their extensive range of applications in asymmetric catalysis and synthesis. Herein, we devised a direct arylation reactions of 5‐aminopyrazoles with azonaphthalenes, utilizing chiral phosphoric acid as the catalyst. This method delivers structurally novel atroposelective N, N‐1,2‐azole heteroaryl diamines with high yields (up to >98%) and good to excellent enantiomeric ratios while exhibiting a wide range of substrate compatibility.

Synthesis of Corrosion Inhibitors Based on (Thio)Urea, Orthophosphoric Acid and Formaldehyde and Their Inhibition Efficiency

في هذا البحث، يتم تحديد الظروف المثالية لتصنيع نوعين من مثبطات التآكل قليلة القسيمات، بولي ميثيلين دياميدوفوسفات (PDAF-1) وبولي ميثيلين ثيودياميدوفوسفات (PTAF-2)، استنادًا إلى مركبات مثل الثيوريا واليوريا وحمض الأرثوفوسفوريك المحتوي على النيتروجين والفوسفور. ، وكذلك يتم تحديد صيغها. في البداية، تم تصنيع (ثيو) ثنائي أميدوفوسفات - مثبط التآكل ذو العلامة التجارية PDAF-1 باستخدام اليوريا وحمض الأرثوفوسفوريك بنسبة 2:1 مول عند درجة حرارة 135-140 درجة مئوية. تم تصنيع النوع الثاني من مثبط التآكل بولي ميثيلين ثيودياميدوفوسفات (PTAF-2) بناءً على عملية التكثيف في بيئة مائية عند درجة حرارة 60 درجة مئوية، وذلك عن طريق إضافة الفورمالديهايد إلى هذا المركب الناتج بنسبة متكافئة 1:1 مول. المادة الناتجة هي مادة صلبة بيضاء، غير متطايرة، تكوين المكون الرئيسي هو 98.7٪، والمواد الأخرى - 1.3٪. قامت أطياف الأشعة تحت الحمراء بدراسة بنية هذين النوعين من مثبطات التآكل. كما تمت دراسة كفاءة تثبيط مثبطات التآكل هذه بالطرق الوزنية والكهروكيميائية في الوسائط المسببة للتآكل مثل حمض الهيدروكلوريك، H2SO4 وكلوريد الصوديوم = 3%. بالإضافة إلى ذلك، تم أيضًا دراسة العوامل المؤثرة على كفاءة التثبيط، مثل الرقم الهيدروجيني للمحلول، والمدة الزمنية، وتركيز المثبط. ووفقا للنتائج التي تم الحصول عليها، فإن كفاءة التثبيط لهذه مثبطات التآكل تتراوح بين 95.3 و 97.8٪. كما قام المجهر الإلكتروني بدراسة وتحليل آلية حماية مثبطات التآكل على سطح الفولاذ..

Aluminum Foil Surface Etching and Anodization Processes for Polymer 3D-Printing Applications

Extrusion-based polymer three-dimensional (3D) printing, specifically fused deposition modeling (FDM), has been garnering increasing interest from industry, as well as from the research and academic communities, due to its low cost, high speed, and process simplicity. However, bed adhesion failure remains an obstacle to diversifying the materials and expanding the industrial applications of the FDM 3D-printing process. Therefore, this study focused on an investigation of the surface treatment methods for aluminum (Al) foil and their applications to 3D printer beds to enhance the bed adhesion of a 3D-printed polymer filament. Two methods of etching with sodium hydroxide and anodization with phosphoric acid were individually used for the surface treatment of the Al foil beds and then compared with an untreated foil. The etching process removed the oxide layer from the Al foil and increased its surface roughness, while the anodizing process enhanced the amount of hydroxide functional groups and contributed to the formation of nano-holes. As a result, the surface-anodized aluminum foil exhibited a higher affinity and bonding strength with the 3D-printed polymers compared with the etched and pristine foils. Through the increase in the success rate in 3D printing with various polymers, it became evident that utilizing surface-treated Al foil as a 3D printer bed presents an economical solution to addressing bed adhesion failure.

Preparation and characterization of activated carbon from medlar seed by chemical activation with phosphoric acid and its application in uranium adsorption

Preparation and characterization of activated carbon from medlar seed by chemical activation with phosphoric acid and its application in uranium adsorption

Phyto-safe in vitro regeneration and harnessing antimicrobial-resistant endophytes as bioinoculants for enhanced growth and secondary metabolites yield in Nilgirianthus ciliatus

Nilgirianthus ciliatus, extensively exploited for its pharmacological properties, is now classified as vulnerable. In vitro micropropagation offers a sustainable approach for ecological conservation and rational utilization of this biodiversity resource. This study aimed to reduce endophytes during in vitro propagation and isolating antimicrobial-resistant endophytes from N. ciliatus by employing various concentrations and exposure times of Plant Preservative Mixture (PPM). Optimal results were observed when nodal explants treated with 0.3% PPM for 8 h, followed by inoculation in Murashige and Skoog (MS) medium supplemented with 3 mg/L 6-benzylaminopurine (BAP) and 0.3% PPM. This protocol achieved 82% shoot regeneration with minimal endophytic contamination, suggesting that the duration of explant exposure to PPM significantly influences endophyte reduction. Two antimicrobial-resistant endophytes were isolated and identified as Bacillus cereus and Acinetobacter pittii through 16S rDNA sequencing. These endophytes exhibited plant growth-promoting characteristics, including amylolytic, proteolytic, lipolytic activities, indole-3-acetic acid production, phosphate solubilization, and stress tolerance. In vivo application of these endophytes as bioinoculants to N. ciliatus not only improved growth parameters but also significantly increased the levels of pharmacologically important compounds, squalene, and stigmasterol, as confirmed by High-performance thin-layer chromatography (HPTLC). This study demonstrates that PPM is a promising alternative for sustainable micropropagation of N. ciliatus. Furthermore, it highlights the potential of antimicrobial-resistant endophytes as bioinoculants to improve growth and medicinal value, offering a sustainable solution for conservation and large-scale cultivation of this species.

SAL5087 bright welding wire two acid polishing process and its effect on surface roughness

Abstract In order to obtain bright aluminum alloy wires and eliminate the environmental and human hazards of traditional chemical polishing, the H3PO4-H2SO4 system chemical polishing process was developed for SAL5087, and the surface roughness was measured by laser confocal microscopy and the surface morphology was observed by sweeping electron microscopy as the evaluation index of the polishing quality. The process optimization was carried out by orthogonal experiments and the role of each component was analyzed. The experiments showed that phosphoric acid dominates the polishing process, which can effectively enhance the polishing effect under the synergistic effect with various additives.The surface roughness of the polished wire was reduced to 0.257 μm in the optimum process, and the surface was free of defects such as burrs and scratches.

Photocatalyst‐Free Chiral Phosphoric Acid‐Catalyzed Enantioselective Minisci‐Type Alkylation of N‐Heteroarenes

In this study, we present an efficient radical approach for the enantioselective Minisci‐type alkylation of N‐heteroarenes, using chiral phosphoric acid (CPA) as a catalyst under mild conditions, without the need for metals, photocatalysts, and other additives. Prochiral α‐aminoalkyl radicals generated from RAEs were successfully introduced to N‐heteroarene derivatives, including pyridine, quinoline, and isoquinoline, resulting in a range of valuable chiral alkylated N‐heteroarenes with secondary amines in high yields and good to excellent enantioselectivities (up to 98% ee). The chiral phosphoric acid catalyst not only activates the substrate and induces asymmetry but also facilitates essential electron transfer processes.

Activated carbon from agricultural industry waste for use as an adsorbent of sulfamethazine: Fascinating and environmentally friendly process

Lignocellulosic wastes have garnered interest in activated carbon (AC) production owing to their abundance and cost-effectiveness. This research utilized coffee husk as a precursor for AC. The methodology involves impregnating the waste with varying proportions of phosphoric acid (H3PO4), 1:1 and 1:3 (masswaste:massH3PO4), and activation in a microwave oven, with different power and activation times. The N2 adsorption/desorption results demonstrated high surface areas (SBET) for the ACs. The optimized AC (C1:3-1000-10) was obtained using a time of 10 min, high impregnation ratio, and power, resulting in an SBET of 1200 m2 g−1. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra confirmed the presence of functional groups, such as hydroxyl and ester, on the AC surface. Adsorption tests with sulfamethazine (SMZ) showed a 225 mg g−1 remotion capacity, highlighting the waste potential for sustainable and economical AC production. This underscores the importance of optimizing activation parameters to enhance performance and application versatility in AC production from lignocellulosic sources.

Nitrogen-Rich Covalent Organic Frameworks Composited High-Temperature Proton Exchange Membranes with Ultralow Volume Expansion and Reduced Phosphoric Acid Leakage.

Phosphoric acid (PA) leakage and volume expansion are critical factors limiting long-term stable operation of PA-doped polybenzimidazole (PBI) for high-temperature proton exchange membrane fuel cells. Enhancing the interaction between the polymer matrix and PA provides an effective way to minimize PA loss and inhibit excessive membrane swelling. The covalent organic frameworks (COFs) are helpful in improving the performance of PA-PBI membranes due to the robust frameworks, adjustable structures, and good compatibility with polymers. Here, in this work, we synthesized porous COFs named TTA-DFP containing triazine rings and pyridine groups at room temperature for as short as 2 h without oxygen isolation. TTA-DFP was then blended with commercial poly[2,2'-(p-oxidiphenylene)-5,5'-benzimidazole] (OPBI) to prepare composite membranes. The abundant alkaline N sites in TTA-DFP exhibit strong interactions with PA and OPBI, which not only provide more proton transport pathways to promote proton conduction but also immobilize PA in acidophilic micropores to reduce PA leakage. The composite membranes exhibit a much lower volume swelling ratio than that of the OPBI membrane. The PA retention of the composite membrane after 120 h of treatment at 80 °C and 40% relative humidity can reach as high as 84.6%. Particularly, the proton conductivity of the composite membrane doped with 15 wt% TTA-DFP achieves 0.112 S cm-1 at 180 °C without humidification with a swelling ratio of 24.1%. In addition, it has an optimal peak power density of 824.4 mW cm-2 at 180 °C, which is 1.7 times that of the OPBI membrane. The stability of the composite membrane is much better than that of OPBI at a current density of 0.3 A cm-2 at 140 °C for 120 h.

Biomass to biofuel: Palm kernel shells as catalyst supports for enhanced biodiesel production

AbstractThe use of agricultural biomass fibers, specifically palm kernel shell (PKS), has significant potential to enhance biodiesel production. This approach overcomes economic barriers and contributes to sustainability by repurposing agricultural biomass. This study explores the effectiveness of PKS as a cost‐effective and sustainable catalyst support. Palm kernel shell was chosen due to its high carbon content, low ash presence, and abundance as a byproduct in the palm oil industry, making it an economically viable and environmentally friendly option. In this study, an optimized activated carbon from PKS biomass was fabricated as catalyst support to enhance biodiesel production efficiency. Using response surface methodology (RSM), the PKS was impregnated with phosphoric acid and synthesized at various acid concentrations, impregnation times, and activation times to enhance porosity for catalytic support capabilities. The experimental design included a central composite design (CCD) to vary these factors systematically and determine their optimal levels. Scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis revealed significant development of porosity, affirming the efficient activation process. Energy dispersive X‐ray (EDX) analysis confirmed phosphorus incorporation during activation, indicating the formation of an intricate pore structure. Fourier transform infrared (FTIR) spectroscopy highlighted the presence of functional groups pertinent to the biodiesel reaction process. The transesterification process employing PKS as a catalyst with different biobased feedstocks, such as waste frying oils from corn, palm, and sunflower, led to biodiesel yields of varying efficiencies. Notably, corn oil had the highest yield at 94.92%. This study highlights the potential of PKS as a biobased catalyst support and contributes to the broader biorefinery concept by integrating biomass utilization into renewable fuel production.

Stability constants of mixed-ligand cobalt(II) complexes with pyridinedicarboxylic acids and small bioligands studied by potentiometric measurements

In this work, we have studied the stability constants of ternary cobalt(II) complexes with the primary ligands: pyridine-2,3-dicarboxylic acid (H22,3-Dipic, H2L) and pyridine-3,4-dicarboxylic acid (H23,4-Dipic, H2L) and secondary ligands representing low molecular mass components of blood serum: lactic acid (HLac), oxalic acid (H2Ox), citric acid (H3Cit), and phosphoric acid (H3PO4). Potentiometric data were analyzed using the least squares computational program LETAGROP. Ionic strength and temperature were both kept constant using 1.0 mol dm−3 NaNO3 as ionic medium at 25 °C. Species distribution diagrams were generated to determine the speciation variations with respect to pH.

Recovering rare earth elements from svanbergite ores by roasting and phosphoric acid leaching

Rare earth elements (REEs) are regarded as key global strategic metals, and recovering REEs from phosphate ores might constitute an alternative method of acquiring rare earth resources. Svanbergite ores in Sichuan are particular phosphates rocks that contain abundant REEs, which are valuable resources that have not been fully developed and utilized. Consequently, the development of crucial technologies for extracting REEs from svanbergite ores hold strategic and scientific significance. This study employed roasting and phosphoric acid leaching processes to recover REEs from svanbergite ores. Response surface methodology (RSM) was applied to optimize the hydrometallurgical process parameters. This study found that the optimal conditions for REEs recovery were: a roasting temperature 600℃, a roasting time of 38.72 min, a phosphoric acid concentration of 40%, a leaching liquid/solid mass ratio of 10, a leaching temperature of 75℃ and a leaching time of 70 min, resulting in a maximum predicted REE recovery rate of 83.57%. The experimental values exhibited a high degree of proximity to the predicted values, thereby substantiating the accuracy of the model and validating the plausibility of the optimized solution. Mechanistic analysis revealed that after the roasting process, the crandallite formed new acid-soluble new phases. Following the phosphoric acid leaching process, REEs were present predominantly in the form of REE3+ in the leaching solution, consequently separating the REEs from the svanbergite ores. This study provides a valuable reference for the recovery of REEs from associated rare earth phosphate ores.

A Newly Validated HPLC-DAD Method for the Determination of Ricinoleic Acid (RA) in PLGA Nanocapsules

The assessment of ricinoleic acid (RA) incorporated into polymeric nanoparticles is a challenge that has not yet been explored. This bioactive compound, the main component of castor oil, has attracted attention in the pharmaceutical field for its valuable anti-inflammatory, antifungal, and antimicrobial properties. This work aims to develop a new and simple analytical method using high-performance liquid chromatography with diode-array detection (HPLC-DAD) for the identification and quantification of ricinoleic acid, with potential applicability in several other complex systems. The method was validated through analytical parameters, such as linearity, limit of detection and quantification, accuracy, precision, selectivity, and robustness. The physicochemical properties of the nanocapsules were characterized by dynamic light scattering (DLS) to determine their hydrodynamic mean diameter, polydispersity index (PDI), and zeta potential (ZP), via transmission electron microscopy (TEM) and quantifying the encapsulation efficiency. The proposed analytical method utilized a mobile phase consisting of a 65:35 ratio of acetonitrile to water, acidified with 1.5% phosphoric acid. It successfully depicted a symmetric peak of ricinoleic acid (retention time of 7.5 min) for both the standard and the RA present in the polymeric nanoparticles, enabling the quantification of the drug loaded into the nanocapsules. The nanocapsules containing ricinoleic acid (RA) exhibited an approximate size ranging from 309 nm to 441 nm, a PDI lower than 0.2, ζ values of approximately −30 mV, and high encapsulation efficiency (~99%). Overall, the developed HPLC-DAD procedure provides adequate confidence for the identification and quantification of ricinoleic acid in PLGA nanocapsules and other complex matrices.

Direct Composite Restorations on Permanent Teeth in the Anterior and Posterior Region - An Evidence-Based Clinical Practice Guideline - Part 2: Recommendations for Composite Processing.

Part 2 of this German S3 clinical practice guideline provides recommendations for the process of manufacturing composite restorations. It covers key aspects like caries removal, field isolation, matrix and adhesive techniques, as well as light curing and polishing. The outcomes of interest include survival rates and restoration quality. A systematic literature search was conducted by two methodologists using MEDLINE and the Cochrane Library via the OVID platform, including studies up to December 2021. Additionally, the reference lists of relevant manuscripts were manually reviewed. Six PICO questions were developed to guide the search. Consensus-based recommendations were for- mulated by a panel of dental professionals from 20 national societies and organizations based on the collected evidence and ex- pert opinion. The guideline advocates for one-stage selective caries removal near the pulp and underscores the effectiveness of various isolation techniques, adhesive systems, and the crucial role of light polymerization. The use of anatomically pre- formed sectional matrices and phosphoric acid etching is recommended to enhance restoration quality. Additionally, polish- ing composite restorations is advised to improve surface finish. This guideline provides comprehensive recommendations that inform clinicians on optimizing the composite restor- ation manufacturing processes. The adoption of these best practices can improve the quality and longevity of dental restorations.

Three-liquid-phase behavior in the quaternary systems of water + phosphoric acid + diisopropyl ether + tributyl phosphate/methyl isobutyl ketone at 298.2 K

The three-liquid-phase formation in the ternary system of water + phosphoric acid + diisopropyl ether (DIPE) makes the phosphoric acid extraction only effective for acid mass fractions above 0.69. To avoid the undesirable formation of the third phase and enhance acid extraction, particularly at low concentrations, two phase modifiers, methyl isobutyl ketone (MIBK) and tributyl phosphate (TBP), were systematically studied. In order to quantify the synergetic effect of the mixed solvents of DIPE+TBP and DIPE+MIBK, the liquid–liquid equilibria for the quaternary systems of H2O+H3PO4 + DIPE+TBP and H2O+H3PO4 + DIPE+MIBK were fully established for different DIPE/phase modifier (TBP or MIBK) mass ratios (90/10, 70/30, 50/50, and 20/80) at 298.2 K under atmospheric pressure using the cloud point and Othmer graphical method. Othmer-Tobias and Hand correlations were used to fit the tie-line data and assess its consistency. In addition, the behavior of the three-phase zone was also studied as a function of the phase modifiers content. Separation factor (S) and acid distribution (D2) were used to identify the most effective solvent with the potential to enhance phosphoric acid extraction from aqueous solutions.

High-performance porous activated carbon derived from Acacia catechu bark as nanoarchitectonics material for supercapacitor applications

BackgroundThe increasing energy demands stemming from the extensive utilization of portable electronic devices are creating a huge energy deficit between demand and supply. In this scenario, it is not only sufficient to pursue and innovate the new renewable energy sources but also requires an ideal device for energy storage and conversion. MethodsIn this work, activated carbon (AC) was prepared from matured bark of Acacia catechu through a series of steps; pre-carbonization, carbonization, and activation. The AC was synthesized at different temperatures (400–800 °C) under inert atmosphere, using orthophosphoric acid as an activator. As-prepared sample (ACBH) was characterized by well-known characterization techniques. Energy storage capability was assessed in terms of Cyclic voltammetry, Galvanostatic charge-discharge, Electrochemical impedance, and Cyclic stability by three-electrode setup. Significant findingsThe ACBH-8 sample demonstrated superior electrochemical performance compared to other samples. The sample ACBH-8, as Negatrode, exhibited a specific capacitance of 282.4 F g−1 at 0.5 A g−1 and retained 95.4 % cyclic stability under 10,000 cycles. The excellent energy storage performance by green-class negatrode materials from the bio-waste substance empowers commercial applications.

Organocatalytic Asymmetric (4 + 3) Cycloaddition toward Optically Active Cyclohepta Fused Diindoles.

A novel asymmetric (4 + 3) cycloaddition of indole-2,3-quinodimethanes in situ generated from 3-methyl-2-indolylmethanols with 3-indolylmethanols via chiral phosphoric acid catalysis has been established. The cycloaddition reaction exhibits a broad substrate scope affording the diverse enantioenriched cyclohepta fused diindoles in high yields with good enantioselectivities. Significantly, this work represents the first application of 3-methyl-2-indolylmethanols as 4C synthons instead of the commonly reported three-atom synthons in cycloaddition reactions.

Solvent extraction of titanium(IV) from orthophosphoric acid media using Aliquat-336/kerosene and stripping with nitric acid

Titanium extraction from acidic solutions was investigated using Aliquat-336, considering factors like acid type and concentration for leaching, diluent type for solvent extraction, equilibration time, extractant concentration, phase ratio, and temperature. Kerosene exhibited superior performance as an aliphatic diluent for Aliquat-336 compared to other utilized diluents. The extraction efficiency was inversely proportional to the dielectric constant of the diluents. The quantitative Ti(IV) extraction efficiency from phosphoric acid (6 M H3PO4) leach liquor of ilmenite and rutile achived 98 % at room temperature (298 K) in 10 min after mixing with 0.1 M Aliquat-336 dissolved in kerosene at a phase volume ratio of 1:1 (Aq:Org). The exothermic extraction process occurred spontaneously. The proposed extraction mechanism using Aliquat-336/kerosene involves ion-pair association of the extractant with a Ti(IV) complex, confirmed by FTIR spectroscopy. The Ti(IV) ions were effectively stripped using HNO3 (3 M) with an aqueous:organic phase volume ratio of 1:1 at 25 °C after a contact time of 10 min in each step. The Aliquat-336/kerosene efficiently tested for Ti(IV) recovery from acidic Abu-Ghalaga ilmenite and rutile leachate. The findings indicate that, the phosphate medium is highly efficient in extracting Ti(IV), even with low concentration of Aliquat-336 in kerosene, especially in comparison to the impurities such as Fe, Cr, and Al. The EDX, XRD, and wet chemical analyses of the final product after the hydrolysis of stripped Ti(IV) from samples originating from the Abu-Ghalaga area and rutile samples, confirmed the formation of high-purity TiO2 (predominantly anatase phase). The SEM results showed particles with a regularly spherical structure and uniform size.

Surface characteristics of maraging steel during electropolishing as a function of polishing time

ABSTRACT Thermal-based machining process like EDM, Laser-assisted additive manufacturing process degrades the surface integrity of the component. Therefore, a post-polishing method is required to improve the surface integrity as well as the performance of the component. A gyroscope, made of maraging steel, fabricated by EDM, is utilised in space industry and has poor surface integrity, which affects its performance. Thus, electropolishing (EP), a non-conventional polishing process, is used for the above said problem as it possesses several advantages over other polishing methods. There are very few literatures available for EP of maraging steel. The present manuscript is the preliminary analysis for the electrolyte (Ortho-phosphoric acid, sulphuric acid and hydrochloric acid) and its effect on maraging steel with respect to time. The surface characteristics such as surface roughness and surface reflectivity, along with surface elemental composition, have been evaluated. With increase in time, maximum improvement in surface roughness and surface reflectivity is 61.23% and 70%, respectively. It can be concluded that the selected electrolyte gives a promising improvement in the surface characteristics of maraging steel.