Phosphoric Acid Research Articles

A pore scale model study of mass transfer and electrochemical reaction in cathode catalytic layer of high-temperature polymer electrolyte membrane fuel cells

The mass transfer and related electrochemical reactions in the catalytic layer (CL) are crucial for the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), but there is a lack of understanding of the optimal phosphoric acid content and Pt/C catalyst loading in the CL. In this work, we investigate the influences of Pt/C catalyst numbers (NPt/C) and phosphoric acid film thickness (δPA) on mass transfer and electrochemical reactions of the cathode CL using a pore-scale model (300 × 300 × 300 nm3). The results reveal that larger NPt/C and δPA can impede oxygen diffusion, while lower NPt/C and δPA lead to fewer reaction active sites and lower conductivity, both of which result in lower current density. Therefore, the balance of three-phase transport is extremely important for CL. There is a 3D volcanic relationship between current density, Pt/C catalysts, and phosphoric acid film. At NPt/C = 200 (7407 per μm3) and δPA = 4 nm (the volume fractions of 37.22 % and 17.87 %), the highest current density can be achieved at a potential of 0.5 V (vs. RHE), which increased with the decrease of potential. This work is valuable for understanding the optimizing the microstructure and three-phase transport pathway of the CL to improve the performance of HT-PEMFCs.

Isolation of endophytic fungi from wild rice species for disease management and growth promotion in cultivated rice (Oryza sativa L.)

ABSTRACT The focus of plant health management is shifting from synthetic chemicals to bio-agents, and endophytes are beneficial for this purpose. In the present study, we isolated eleven endophytic fungi from seven wild rice species. Independent treatment of endophytic fungi in rice showed significant improvements in plant growth, higher tillering and percent fertility, panicle number/hill and filled grain number in endophyte-inoculated plants compared to control plants. Growth promotion activities of two endophytes Curvularia lunata (NRRI EF-11) and Hypocreals sp. (NRRI EF-8) were recorded with increased rice yield. These isolates also exhibited higher plant growth promoting chemicals namely, Indole acetic acid (IAA) and Inorganic phosphate (IP) which was realised into better growth promotion in rice. The biocontrol efficacy of endophytic fungi was highest in NRRI EF-11among all isolates as indicated by inhibition of radial growth of pathogens by 76.98–77.06% and in NRRI EF-8 by 74.81–76.61%, which is due to higher production of prussic acid. Defense induction was confirmed by analyzing the expression of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) defense enzymes, where expression of CAT, POD and SOD increased by 19.44–25.86, 2.70–3.16, 11.14–12.95 Units g−1 in treated NRRI EF-11 plants and 18.39–25.84, 2.16–2.94, 10.96–12.62 Units g−1 in treated NRRI EF-8 plants, respectively. These two endophytes have the potentiality to manage crop health in a sustainable way.

Comparative transcriptomic and physiological analyses unravel wheat source root adaptation to phosphorous deficiency

Phosphorus (P) is a crucial macronutrient for plant growth and development. Basic metabolic processes regulate growth; however, the molecular detail of these pathways under low phosphorous (LP) in wheat is still unclear. This study aims to elucidate the varied regulatory pathways responses to LP stress in wheat genotypes. Phenotypic, physiological, and transcriptome analyses were conducted on Fielder (P efficient) and Ardito (P inefficient) wheat genotypes after four days of normal phosphorous (NP) and LP stress. In response to LP, Fielder outperformed Ardito, displaying higher chlorophyll content-SPAD values (13%), plant height (45%), stem diameter (12%), shoot dry weight (42%), and root biomass (75%). Root structure analysis revealed that Fielder had greater total root length (50%), surface area (56%), volume (15%), and diameter (4%) than Ardito under LP. These findings highlight Fielder’s superior performance and adaptation to LP stress. Transcriptome analysis of wheat genotype roots identified 3029 differentially expressed genes (DEGs) in Fielder and 1430 in Ardito, highlighting LP-induced changes. Key DEGs include acid phosphatases (PAPs), phosphate transporters (PHT1 and PHO1), SPX, and transcription factors (MYB, bHLH, and WRKY). KEGG enrichment analysis revealed key pathways like plant hormones signal transduction, biosynthesis of secondary metabolites, and carbohydrate biosynthesis metabolism. This study unveils crucial genes and the intricate regulatory process in wheat’s response to LP stress, offering genetic insights for enhancing plant P utilization efficiency.

Enhancing Performance and Stability of High-Temperature Proton Exchange Membranes through Multiwalled Carbon Nanotube Incorporation into Self-Cross-Linked Fluorenone-Containing Polybenzimidazole.

Addressing critical challenges in enhancing the oxidative stability and proton conductivity of high-temperature proton exchange membranes (HT-PEMs) is pivotal for their commercial viability. This study uncovers the significant capacity of multiwalled carbon nanotubes (MWNTs) to absorb a substantial amount of phosphoric acid (PA). The investigation focuses on incorporating long-range ordered hollow MWNTs into self-cross-linked fluorenone-containing polybenzimidazole (FPBI) membranes. The absorbed PA within MWNTs and FPBI forms dense PA networks within the membrane, effectively enhancing the proton conductivity. Moreover, the exceptional inertness of MWNTs plays a vital role in reinforcing the oxidation resistance of the composite membranes. The proton conductivity of the 1.5% CNT-FPBI membrane is measured at 0.0817 S cm-1 at 160 °C. Under anhydrous conditions at the same temperature, the power density of the 1.5% CNT-FPBI membrane reaches 831.3 mW cm-2. Notably, the power density remains stable even after 200 h of oxidation testing and 250 h of operational stability in a single cell. The achieved power density and long-term stability of the 1.5% CNT-FPBI membrane surpass the recently reported results. This study introduces a straightforward approach for the systematic design of high-performance and robust composite HT-PEMs for fuel cells.

Studies on uranium sorption from Egyptian wet-process phosphoric acid using silicone rubber modified with thiourea and methyl methacrylate composite

ABSTRACT The application of silicone rubber modified by thiourea and methyl methacrylate composite SRTM aimed at the sorption of uranium from commercial phosphoric acid is the highest objective of this examination effort. The impact of various factors on sorption efficiency for example adsorbent dose (g/ml), temperature, phosphoric acid concentration, and shaking time have remained studied. XRD, XRF, EDX, SEM, Zeta potential, BET, and FTIR analyses remained carried out to determine the properties of the produced composite. The attained results showed the sorption capacity for uranium as 25.19 mg g− 1 at the mentioned conditions; commercial phosphoric acid, 30% P2O5, 120 min, and room temperature. The investigational documents have been designated fine with pseudo-second-order kinetic scientific calculations. Balance process described by isotherm model’s Langmuir. uranium sorption thermodynamic considerations showed a spontaneous procedure and exothermic nature (ΔG (kJ/mol) = −13.8:-11.3, ∆H(kJ/mol) = −34.9, ∆S (J/mol K) = −70.9). Mechanism and reusability sorption were studied and Desorption efficiencies of about 95% for U (VI) were achieved using 1.0 M sulphuric acid solution.

Enhanced adsorption capacity of antibiotics by calamus-biochar with phosphoric acid modification: Performance assessment and mechanism analysis

BackgroundAdsorption is one of the effective methods to remove antibiotics from water. Plant-based biochar can be effectively modified to enhance the adsorption capabilities of antibiotics. MethodsCalamus biochar (PBC) was modified by phosphoric acid to study its adsorption efficacy on erythromycin (ERY) and sulfamethoxazole (SMX). Significant FindingsPBC had a pore density of 0.771 m3·g−1, an average pore size of 5.14 nm, and an enormous surface area of 797 m2·g−1. PBC had been shown to incorporate a substantial quantity of functional groups containing oxygen by FTIR and XPS investigations. With these surface chemical and physical characteristics, PBC adsorbed 325 mg·g−1 of ERY and 216 mg·g−1 of SMX, which was tenfold higher compared to that of unmodified biochar and industrial-activated carbons. Quantitative analysis of adsorption mechanisms showed that the adsorption of ERY by PBC mainly included oxygen-containing functional group complexation and pore filling, whereas, the π-π interaction and pore filling were the leading mechanisms in the adsorption process of SMX. This research offers insights into the preparation of plant biochar with excellent antibiotic adsorption performance.

Establishment of chemical fingerprint and determination of main active ingredients in Centellae Herba by HPLC combined with multivariate chemometrics analysis

AbstractIn this paper, a simple and efficient high‐performance liquid chromatography method was established to analyze the chemical composition fingerprint of Centellae Herba (CHA) and determine five triterpenoid active components in CHA, namely, asiaticoside B (AB), madecassoside, asiaticoside, madecasic acid, and asiaticoic acid. The separation of the compounds was carried out on an XD‐C18 column (250 mm × 4.6 mm, 5 µm), the wavelength of the ultraviolet detector was set to 205 nm, and the mobile phase was composed of acetonitrile −0.05% phosphoric acid, 2 mmol/L β‐cyclodextrin aqueous solution, and gradient elution at the flow rate of 1.0 mL/min. A general chromatographic fingerprint consisting of 20 characteristic peaks of 18 batches of CHA samples was established, and the samples were classified and evaluated by similarity analysis, hierarchical cluster analysis, and principal component analysis combined with multivariate econometric analysis. In quantitative analysis, all calibration curves showed good linear regression in the test range (r > 0.999), the average recovery was 96.12%–104.63%, and the relative standard deviations of repeatability and stability were less than 2.00%. The results show that the method is accurate and effective and can be used for the comprehensive quality control of CHA.

Air-mediated phosphoric acid activation strategy for preparation of oxygenated functional groups rich activated carbon for capacitive deionization

Atmosphere during H3PO4 activation is vital to the texture structure and surface-interface properties of activated carbon (AC), but the researches are way out of sufficiency. In this work, it is found that the air in the H3PO4 activation process is not only conducive to the introduction of more-oxidized oxygenated functional groups on ACs, but also beneficial to the formation of micropores rather than mesopores. Besides, as the air content increases in H3PO4 activation, the ACs’ ash, phosphorous content and conductivity reduce, but their wettability, disorder degree and defect number increase. In addition, the potential of zero charge of the as-prepared ACs is positively correlated with the O-CO content, which show a pattern of first increasing and then decreasing with the increase of air content. Benefit from the improved hydrophilicity, electrolyte-affinity, additional adsorption sites for sodium ions, the optimal AC exhibits excellent salt adsorption capacity of 12.08 mg g−1 and good cycling stability at 1.0 V in single-pass capacitive deionization. This work not only establishes a novel and effective method for regulating the texture structure and surface properties of ACs, but also provides promising cathode candidates for capacitive deionization application.

[Effects of Biochar on Growth and Pollutant Accumulation of Lettuce in Soil Co-contaminated with Tetracycline and Copper].

Through lettuce potting experiments, the effects of different types of biochar (apple branch, corn straw, and modified sorghum straw biochar with phosphoric acid modification) on lettuce growth under tetracycline (TC) and copper (Cu) co-pollution were investigated. The results showed that compared with those under CK, the addition of biochar treatment significantly increased the plant height, root length, shoot fresh weight, and root fresh weight of lettuce (P < 0.05). The addition of different biochars significantly increased the nitrate nitrogen, chlorophyll, and soluble protein content in lettuce physiological indicators to varying degrees, while also significantly decreasing the levels of malondialdehyde, proline content, and catalase activity. The effects of biochar on lettuce physiological indicators were consistent during both the seedling and mature stages. Compared with those in CK, the addition of biochar resulted in varying degrees of reduction in the TC and Cu contents of both the aboveground and underground parts of lettuce. The aboveground TC and Cu levels decreased by 2.49%-92.32% and 12.79%-36.47%, respectively. The underground TC and Cu levels decreased by 12.53%-55.64% and 22.41%-42.29%, respectively. Correlation analysis showed that nitrate nitrogen, chlorophyll, and soluble protein content of lettuce were negatively correlated with TC content, whereas malondialdehyde, proline content, and catalase activity were positively correlated with TC content. The resistance genes of lettuce were positively correlated with TC content (P < 0.05). In general, modified biochar was found to be more effective in improving lettuce growth quality and reducing pollutant accumulation compared to unmodified biochar, with modified sorghum straw biochar showing the best remediation effect.

Innovative production of phosphoric acid-hydrolyzed chitin nanocrystals for Pickering emulsion stabilization

Addressing the need for sustainable emulsification methods, this study introduces a novel approach by producing chitin nanocrystals (PA-ChNCs) through solid-state hydrolysis using minimal phosphoric acid. The aim was to assess the capability of PA-ChNCs to stabilize Pickering emulsions. Our investigation revealed a pH-responsive variation in particle size and surface charge of PA-ChNCs, critical for emulsion stability. They varied from 321.5 ± 10.5 nm to 2366.7 ± 171.6 nm and from 33.7 ± 1.2 mV to −19.9 ± 1.4 mV, respectively, when pH increased from 3 to 10. Notable, emulsions with a 50% oil-to-water (O:W) ratio presented larger droplets with increased viscosity, enhancing stability over 30 days significantly. In contrast, higher PA-ChNCs concentrations (2.0 wt%) at pH 10 resulted in smaller droplets and higher viscosity, indicating superior emulsion stability. This research contributes novel insights into eco-friendly emulsifier development, utilizing seafood byproducts and underscoring the use of PA-ChNCs as effective Pickering emulsion stabilizers in food applications.

RP-HPLC METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF CURCUMIN AND RESVERATROL IN NANO-MICELLE: DUAL DRUG DUAL FORM SIMULTANEOUS ESTIMATION

Objective: To develop a reverse-phase high-performance liquid chromatography (RP-HPLC) method for simultaneous estimation of conjugated form of Curcumin (CCMN) and free form of Resveratrol (RSV) in nano-micelle. Methods: The conjugation of lipophilic CCMN and hydrophilic Chitosan (CHT) through succinyl linker produce amphipathic molecule that can self-assemble into RSV solution to form micelle. Here RSV exists in micelle core as free form and CCMN with micelle backbone as conjugated form. So it required to estimate conjugated drug and free drug simultaneously from nano-micelle. We developed a RP-HPLC method, utilized C18 column, follow flow rate of mobile phase 1.0 ml/min, which consist of acetonitrile with water (0.5% Ortho Phosphoric acid, pH 4.6) in the ratio of 1:1 for 20 min. Injection volume was 10μl and column temperature 25 ℃. Isosbestic detection of both drugs was at 254 nm. Results: The retention time of RSV and CCMN were at 8.15 min and 11.41 min respectively, completely distinguished sharp peak of CCMN and RSV developed with resolution 7.360±0.117, wide range of linearity with correlation coefficient value (R2) of CCMN and RSV were 0.99987 and 0.99992 respectively and recovery value of CCMN and RSV were 100.041±0.22 % and 100.041±0.21 % respectively. The RSD (relative standard deviation) for accuracy, precision and robustness of the method was found to be less than 2%. Conclusion: The develop method for simultaneous estimation of conjugated CCMN and free form of RSV in the nano-micelle formulation was consider to be accurate, precise, robust and sensitive.

Natural low corrosive phytic acid electrolytes enable green, ultrafast, stable and high-voltage aqueous proton battery

Proton is a promising charge carrier for aqueous rechargeable batteries due to its small ionic radius, fast diffusion kinetics and great abundance in nature. However, commonly-used proton battery electrolytes are strong acids, such as sulfuric acid, phosphoric acid, etc., which always leads to the notorious rapid corrosion of electrode and metal components, and thus the poor cyclability, the limited materials option and high maintenance cost. Here, we reported a new-type high-concentration phytic acid (PA) electrolytes, which exhibits marvellous superiorities including environmental friendliness, low corrosiveness, high ionic conductivity (133.3 mS cm−1) and wide working potential window (∼2.9 V) in contrast to conventional acid electrolytes. The experimental and calculation results indicated that the scarcity of free water in high-concentration PA electrolytes and the desolvation effect of the preferentially absorbed PA interfacial layer on the electrode surface work in synergy to inhibit the water activity and thus prevent electrode dissolution and side reactions. Benefiting from this, the assembled K0.2VO0.6[Fe(CN)6]0.8•6H2O (VHCF)//MoO3 button-type proton battery shows an average discharge voltage of 0.7 V with a pair of well-defined redox peak at about 1.4 V, great rate performance, excellent cycling stability (87.9% capacity retention after 1000 cycles at 5 A g−1) and superb coulombic efficiency at various current densities (1 A g−1–50 A g−1). Attributed to good anti-freezing properties of the electrolytes, the proton battery can also run normally at -60 °C and exhibit competent performance (a capacity retention of 45 mAh g−1 at 0.1 A g−1 after 540 cycles). Such green low corrosive electrolyte will be fully compatible with conventional battery fabrication process, and open brand new avenue for the development of aqueous proton battery.

Fast proton conductors for low humidity: hydrophilic sulfonated and phosphonated polysilsesquioxanes with Al-O-P crosslinks.

Proton-conducting polysilsesquioxane oligomers with core-shell structures consisting of hydrophilic silica-rich cores surrounded by an organic layer with sulfonic and phosphonic acid groups were synthesized. They were crosslinked by mixing with phosphoric acid and aluminum ions to form a hydrophilic Al-O-P framework. The resulting polymers were clear, uniform, flexible, and exhibited a high proton conductivity above 100 °C in non-humidified low-humidity air (∼22 mS cm-1 at 120 °C and ∼1%RH) because of their high sulfonic acid concentration and high water retention capability.

PROCESSING OF A WASHED DRY CONCENTRATE CONTAINING 26% P2O5 INTO AMMOPHOSPHATE, SULPHO- AND NITROAMMOPHOSPHATE FERTILIZERS

The process of obtaining ammophosphate by means of phosphoric acid decomposition of washed dried concentrate (WDC) with 26 % Р2О5 and 10 % СО) - raw material for the production of thermally fired concentrate, has been studied. The extraction phosphoric acid contains (mass. %): 16.46 P2O5, 0.06 CaO, 1.11 MgO, 0.27 Fe2O3, 0.41 Al2O3, 2.98 SO3 and 0.99 F. The mass ratio of WPPA: WDC ranged from 100: 10 to 100: 30. Then acidic phosphate pulps (at 65°C) after 45 minutes were ammoniated to pH = 3.8, granulated and dried at 85 - 90°C. It has been shown that the nitrogen content in the finished product ranges from 4.92 - 7.11 %, total phosphorus (P2O 5t.) 41.48 - 46.44 %, phosphorus assimilated by plants (P2O5acceptable) 34.79 - 45.11 %, water-soluble phosphorus (P2O 5w.s.) 23.49 - 37.73 %. The addition of 5 - 7.5 % H2SO4 or HNO3 in the form of a monohydrate makes it possible to intensify the process of phosphoric acid decomposition of phosphate raw materials and to obtain sulfo- and nitroammophosphate with significantly highcontents of P2O5 acceptable and P2O5 w.s.. So, with a weight fraction of WDC equals to 30 and weight fractions of H2SO4 - 5 and 7.5, there have been 37.6 and 34.47 % P2O5 total in sulfoammophosphate; 24.11 and 22.06 % CaO t. , 88.75 and 96.4 % P2O5 acceptable: P2O5t., 77.39 and 79.54 % P2O5 w.s. : P2O5t., 6.03 and 7.08 % nitrogen, respectively. In the case of using HNO3, nitroammophosphate contains the largest amount of nitrogen due to additionally introduced nitric acid, but the phosphate raw material has a relatively low decomposition coefficient. The strength of granules of all brands of fertilizers averages 3.50 MPa and are quite suitable for bulk storage and transportation. Material balances for the production of ammophosphate, sulfoammophosphate and nitroammophosphate have been calculated.

QUANTIFICATION AND QUALITY CONTROL OF TRIPLE-DRUG COMBINATION EMPLOYED FOR GASTRIC ULCER USING STABILITY-INDICATING SELECTIVE RP-HPLC TECHNIQUE

Objective: A seven-day regimen consisting of vonoprazan (VNP), amoxicillin (AXC) and clarithromycin (CRC), administered twice daily, has been permitted and reimbursed by health coverage as initial therapy. No technique has been implemented yet to determine the quantities of VNP, AXC, and CRC combination. This work effectively aimed at estimating these medications (VNP, AXC, and CRC) at the same time by developing an HPLC technique that saves money and time. Methods: The VNP, AXC, and CRC were separated in a “Waters” column (C18 nature; 250 mm sized length; 4.6 mm sized internal diameter; 5 µm sized particle; 25 °C temperature). Phosphoric acid (0.1% in water; pH 4.2) and absolute methanol (50:50, v/v) comprise the mobile phase. The drug product, Voqueznatripak, was subjected to hydrolysis, oxidation, photolysis, and thermal stressors with the intent to cause enforced degradation. The suggested "HPLC conditions" were verified in compliance with ICH guidance. Results: The measurements had a linear range of 10–20 µg/ml for VNP and 250–750 µg/ml for AXC and CRC. The AXC, CRC, and VNP had LOQ’s 5.302 µg/ml, 5.487 µg/ml and 0.523 µg/ml, respectively. Precision measurements were<0.2% RSD and accuracy ranges were 99.40% to 101.46%. The newly devised “HPLC conditions” specificity attribute and stability-indicating quality were also validated by forced degradation tests. Conclusion: The newly devised “HPLC conditions” for analysing AXC, CRC, and VNP in formulation dosage form and stability samples might be adapted by quality control laboratories. The devised “HPLC conditions” is qualified and consistent to reveal and detect any probable change in the drug product assessments throughout stability experiments.

Tetramethyl poly(aryl ether ketone) modified by DABCO cationic polymer for high temperature proton exchange membrane fuel cells

Rationally constructing proton transport channel within high temperature proton exchange membranes (HT-PEMs) plays a critical role in lowering the mass transfer resistance and thus improving the performance of HT-PEM fuel cells (HT-PEMFCs). We herein designed a microphase-separated structure to promote proton transmitting by incorporating 1,4-Diazabicyclo[2.2.2]octane (DABCO) cationic polymer into tetramethyl poly(aryl ether ketone) (TMPAEK). The flexible and cationic segments afforded a polarity difference from TMPAEK, resulting in easier phosphoric acid adsorption. High proton conductivity of 135 mS cm−1 was obtained under anhydrous conditions at 150 °C. Besides, the hydrophilic domains that containing N-heterocycle could stabilize phosphoric acid through hydrogen bonding interactions, resulting in high phosphoric acid retention of ∼80 % after 288 h test. A Peak power density of 496 mW cm−2 was achieved in non-humidified H2/O2 without back pressure at 140 °C, which was higher than that of m-PBI under the same conditions. This work not only paved a way to tailor the ion conductivity of membrane, but also provided a highly competitive membrane for HT-PEMFCs.

An exploratory metabolomic study reveals the Dipsacus asper-Achyranthes bidentate herb pair against osteoarthritis by modulating imbalance in polyunsaturated fatty acids and energy metabolism

Osteoarthritis (OA) is a degenerative joint disease primarily affecting the cartilage. The therapeutic potential of the Dipsacus asper-Achyranthes bidentate herb pair for OA has been acknowledged, yet its precise mechanism remains elusive. In this study, we conducted a comprehensive analysis of metabolomic changes and therapeutic outcomes in osteoarthritic rats, employing a gas chromatography-mass spectrometry-based metabolomics approach in conjunction with histopathological and biochemical assessments. The rats were divided into six groups: control, model, positive control, Dipsacus asper treated, Achyranthes bidentata treated, and herb pair treated groups. Compared to the model group, significant reductions in levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and iNOS were observed in the treated groups. Multivariate statistical analyses were employed to investigate metabolite profile changes in serum samples and identify potential biomarkers, revealing 45 differential biomarkers, with eighteen validated using standard substances. These analytes exhibited excellent linearity across a wide concentration range (R2>0.9990), with intra- and inter-day precision RSD values below 4.69% and 4.83%, respectively. Recoveries of the eighteen analytes ranged from 93.97% to 106.59%, with RSD values under 5.72%, underscoring the method's reliability. Treatment with the herbal pair effectively restored levels of unsaturated fatty acids such as linoleic acid and arachidonic acid, along with glucogenic amino acids. Additionally, levels of phosphoric acid and citric acid were reversed, indicating restoration of energy metabolism. Collectively, these findings highlight the utility of metabolomic analysis in evaluating therapeutic efficacy and elucidating the underlying molecular mechanisms of herb pairs in OA treatment.

Use of di-(2-ethylhexyl)-orthophosphoric acid for the extraction of lanthanum, neodymium, samarium and yttrium from nitric acid solutions

The process of separating rare-earth elements into individual components is considered the most important problem in rare-earth technology because of the similarity in their physical and chemical properties. Currently in the world dialkyl phosphate compounds are widely used as effective extractors for rare earths. However, most extraction processes have been studied from hydrochloric acid or perchlorate solutions. In Russia, tributyl phosphate has long been used to extract rare earths from nitric acid solutions, but the distribution coefficients of the elements are not high, and the process must be repeated multiple times. In this study di-(2-ethylhexyl)-orthophosphoric acid was used for the extraction of lanthanum, neodymium, samarium, and yttrium from nitric acid solutions. When the concentration of nitric acid increased, distribution coefficient of elements gradually decreased to minimum (in the range of 1 to 5M) then increased backward. However, when the concentration was too high (C > 5M), nitric acid was extracted to the organic phase due to the properties of the phosphoryl group. Moreover, the study of dependence of solvation number of neodymium on the concentrations of nitric acid shows that rare earths in the organic phase can be extracted as Re(HA2)3 (C < 1M) or Re(NO3)3«3HA (C > 5M).

Development and Validation of Fast and Sensitive RP-HPLC Stability-Indicating Method for Quantification of Piroxicam in Bulk Drug.

A simple, rapid, sensitive, and cost-effective green solvent-assisted reverse-phase high-performance liquid chromatographic technique, coupled with a photodiode array detector, was developed and validated for the estimation of piroxicam (PRXM). The chromatographic separation was achieved by using a C-18 (250 × 4.6) mm, 5-μm stationary phase and a mobile phase consisting of methanol and 0.1% ortho-phosphoric acid in water in a ratio of (80:20) v/v at a flow rate of 1ml/min. The detection was carried out at a wavelength of 254nm with a constant injection volume of 10μL throughout the analysis. The calibration curve was observed to be linear over the optimum concentration range of 50-300μgmL-1, with an R2 value of 0.9995. The developed method was validated as per the International Council for Harmonisation (ICH) Q2 (R1) guideline. Various parameters like selectivity/specificity, accuracy/recovery, linearity, precision, detection limit, quantitation limit, robustness and stability of analyte in solution were performed for the method validation. The PRXM was evaluated under stressed conditions, including acidic, basic, oxidative, thermal and photolytic, as per ICH Q1 (R2) guidelines. Significant degradation was observed in acidic and basic degradation conditions. Conversely, the drug substance showed stability when exposed to oxidative, photolytic and thermal degradation conditions.

Analysis Risk K3 Using JSA and HIRARC Methods Phosphoric Acid Factory on PT. Petrokimia Gresik

PT. Petrokimia Gresik is one of the industries that produce fertilisers, non-fertilizers, and other chemicals. PT. Petrokimia Gresik is divided into several departments, including the phosphoric acid factory. This research aims to identify and reduce potential hazards during the production process. This research uses (JSA) method to identify the hazard stage and (HIRARC) method to conduct risk analysis. Based on the risk hazard identification results, each job will be assessed based on severity and likelihood to establish the risk level. The research found that all extreme-risk jobs had 4 risks, high risks had 15 risks, medium risks had 2 risks, and no jobs with low-risk levels were found. The control plan carried out in this study is to control by elimination, engineering, administration, and personal protective equipment (PPE). Keywords: Occupational Health Safety, JSA, HIRARC.