Organophosphorus Acids Research Articles

Development of thermomorphic ionic liquids derived from organophosphorus acids for homogeneous extraction processes

Development of thermomorphic ionic liquids derived from organophosphorus acids for homogeneous extraction processes

Intensified extraction of vanadium from vanadium-bearing titanomagnetite (VTM) concentrate via one-stage leaching and solvent extraction using acidic organophosphorus extractant

Vanadium-bearing titanomagnetite (VTM) is a crucial source for vanadium production. Conventional methods for recovering vanadium from VTM involving combined pyro- and hydrometallurgy (production of vanadium-rich slag, followed by leaching) or direct leaching encounter significant challenges, such as vanadium losses and complexities in metal separation stage. This study proposes an innovative approach for vanadium extraction from VTM through one-stage leaching and solvent extraction (SX), utilizing an acidic organophosphorus extractant, di(2-ethylhexyl)phosphoric acid/D2EHPA, as the lixiviant. Initial assessment demonstrated the viability of D2EHPA for treating vanadium oxide (V2O5) and iron oxides (only Fe2+-containing oxides like Fe3O4 and FeO). Notably, the addition of a small amount of water had a significant impact on iron extraction. The study investigated the effects of parameters, including the amount of added water, stirring speed, D2EHPA concentration, temperature, time, and pulp density on the vanadium and iron extraction from VTM. The optimal conditions were applied to treat roasted/oxidized VTM. The findings were corroborated through analysis of the resultant loaded D2EHPA using appropriate techniques such as FTIR and UV–Vis spectroscopy. The practicability of the proposed method for treating VTM concentrate on a larger scale was demonstrated by conducting up-scaled tests. Additionally, the separation of vanadium from iron the loaded D2EHPA was explored using selective stripping with H2SO4 solution. The recyclability of D2EHPA, a critical factor for sustainability, was investigated through five cycles of extraction-stripping.

Catalyst-Free synthesis of sulfonamide-functionalized Poly(phosphonate)s and Poly(phosphate)s using Bis(aziridine)s

We present an efficient step-growth polymerization method for synthesizing sulfonamide-functionalized poly(phosphonate)s and poly(phosphate)s. The polymerization process involves treating bis(aziridine) with organophosphorus acid in toluene, without the need for any catalyst, yielding the desired polymers in high yields. Six different types of organophosphorus acids and inorganic phosphoric acid were found to be suitable for this method. Thermal analysis of the resulting poly(phosphonate)s and poly(phosphate)s revealed a decomposition temperature (Td,5%) of up to 330 °C at 5 % weight loss, while differential scanning calorimetry (DSC) analysis showed glass transition temperatures (Tg) ranging from 54 to 98 °C. Microscale combustion calorimetry (MCC) analysis demonstrated that the cross-linked poly(phosphate) derived from inorganic phosphoric acid exhibited the lowest peak heat release rate (HRR) and total heat release (THR) compared to the linear ones. These findings are expected to provide a straightforward approach for synthesizing novel phosphorus-containing polymers.

Naturally occurring phytic acid: an advanced Brønsted acid catalyst for direct amination reactions of allylic alcohols.

Phytic acid is abundant in various plant-based foods and is considered agricultural waste. Here, we demonstrate the effectiveness of this organophosphorus acid as a sustainable catalyst for the direct amination reactions of allylic alcohols. This approach is successfully performed in air using technical grade solvents, affording allylanilines in moderate to excellent yields. Challenging electron-rich anilines react effectively, and their corresponding Friedel-Crafts side products can be minimised under the optimised reaction conditions. A variety of asymmetrically substituted allylic alcohols are tolerated, while the scope is extended to amide, and C-, O- and S-nucleophiles.

Extraction of Rare Earth Elements from Chloride Solutions Using Mixtures of P507 and Cyanex 272

In this study, the extraction of rare earth elements (REEs) from chloride solutions after leaching REE carbonate concentrate with solutions of the mixtures of P507 (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester) and Cyanex 272 (bis(2,4,4-trimethylpentyl)phosphinic acid) (1:1) at various concentrations was experimentally studied. It was shown that the distribution ratios of all REEs decrease with the increasing concentration of these metals in the initial solution, which is associated with the loading of the organic phase. The most significant improvement in the extraction is observed for the heavy group of rare earth elements. The extractability of REEs increases with the increasing atomic number of the element, as is typical for the extraction of these metals with acidic organophosphorus extractants. The data obtained show that the separation factors of adjacent rare earth elements decrease slightly with the increasing concentration of metals in the initial aqueous solution. Increasing the concentration of the extractant mixture does not have a significant effect on the values of the adjacent REE separation factors. The data obtained on the distribution ratios and separation factors made it possible to propose a flow sheet for the separation of rare earth elements with the production of Y, Ho, Tb and Dy.

Enhanced molybdenum extraction and purification from acidic lixivium using organophosphorus extractants

Solvent extraction with organophosphorus extractants has potential as a low-cost method for efficient Mo recovery for acidic leaching solutions. However, improved selectivity is required to obtain high-purity Mo products. In this study, various acidic organophosphorus extractants were compared, and 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (P507) was found to be optimal for efficient Mo extraction and Fe separation from acidic leaching solutions. Under the optimized conditions (40 vol% P507, 3:1 organic/aqueous, 20 °C, 5 min), the Mo and Fe extraction efficiencies reached 98.1 % and 35.2 %, respectively, with a separation factor of 90.1. The Mo/Fe separation efficiency was further improved using a two-stage countercurrent extraction method. The Mo extraction efficiency was attributed to coordination bonds (P = O → Mo) formed between Mo(VI) oxycations and P507 dimers, as well as covalent bonds (POMo) formed by substituting the hydrogen ions in P507. Increasing the H2SO4 concentration in the leaching solution gradually transformed MoO22+ into Mo2O52+ dimers, which formed MoO2(HA2)2 and Mo2O5(HA2)2 metal complexes during the extraction process. HCl scrubbing of the loaded organic phase effectively removed Fe. For subsequent ammonia stripping of the HCl-scrubbed organic phase, the optimal ammonia concentration was 1.25 mol/L. Further increasing the ammonia concentration promoted the saponification reaction of ammonia with P507, thereby reducing the Mo stripping efficiency. In summary, using multistage countercurrent extraction, increasing the H2SO4 concentration in the leaching solution, and scrubbing the loaded organic phase with HCl facilitate efficient Mo/Fe separation, providing a feasible approach for the preparation of high-purity ammonium molybdate with broad application prospects.

Reactions of the ˙NO3 radical with nuclear extraction ligands in alkane solution.

The reactivity of the nitrate radical (NO3˙) with organophosphorus and amidic actinide and lanthanide complexing agents of interest to nuclear solvent extraction applications was measured, resulting in the first-ever reported bimolecular rate constants for this radicals' reactions in dodecane solution. The order of reactivity for neutral organophosphorus compounds showed faster rate constants with increasing electron density on the phosphoryl phosphorus atom, indicating an increasing facility for electron abstraction reactions occurring in addition to H-atom abstraction from the ligand alkane chains. The only acidic organophosphorus compound investigated, HEH[EHP], showed low reactivity with the NO3˙ radical, attributed to its dimerization in this non-polar solvent. Amide ligand reaction rates were faster than for organophosphorus molecules, suggesting more facile H-atom abstraction from carbonyl activated methylene and amyl groups. While all rate constants were slower than the diffusion-limited rate they were still rapid enough to result in significant oxidation of solvent extraction ligands in dodecane solution.

Recombinant Organophosphorus acid anhydrolase (OPAA) enzyme-carbon quantum dot (CQDs)-immobilized thin film biosensors for the specific detection of Ethyl Paraoxon and Methyl Parathion in water resources

Organophosphates pesticide (OP) toxicity through water resources is a large concern globally among all the emerging pollutants. Detection of OPs is a challenge which needs to be addressed considering the hazardous effects on the health of human beings. In the current research thin film biosensors of recombinant, Organophosphorus acid anhydrolase (OPAA) enzyme along with carbon quantum dots (CQDs) immobilized in thin films were developed. OPAA-CQDs thin film biosensors were used for the specific detection of two OPs Ethyl Paraoxon (EP) and Methyl Parathion (MP) in river water and household water supply. Recombinant OPAA enzyme was expressed in E. Coli, purified and immobilized on the CQD containing chitosan thin films. The CQDs used for this purpose were developed by a one-pot hydrothermal method from phthalic acid and Tri ethylene diamine. The properties of CQDs, OPAA and thin films were characterized using techniques like XPS, TEM, XRD, enzyme activity and CLSM measurements. Biosensing studies of EP and MP were performed by taking fluorescence measurements using a fiber optic spectrometer. The analytical parameters of biosensing were compared against an estimation carried out using the HPLC method. The biosensing performance indicates that the OPAA-CQDs thin film-based biosensors were able to detect both EP and MP in a range of 0–100 μM having a detection limit of 0.18 ppm/0.69 ppm for EP/MP, respectively with a response time of 5 min. The accuracy of estimation of EP/MP when spiked in water resources lie in the range of ∼100–102% which clearly indicates the OPAA-CQD based thin film biosensors can function as a point-of-use method for the detection of OP pesticides in complex water resources.

A Study of the Character of the Effect of an Organophosphorus Acid on the Physicochemical Characteristics of Block Copoly(sulfone arylate)s

A Study of the Character of the Effect of an Organophosphorus Acid on the Physicochemical Characteristics of Block Copoly(sulfone arylate)s

Occurrence, multiphase partitioning, drivers, and ecological risks of current-use herbicides in a river basin dominated by rice–vegetable rotations in tropical China

Rice–vegetable rotation practices prevail in subtropical and tropical agriculture worldwide, with applications of current-use herbicides (CUHs) vital for nontarget plant control. After application, CUHs migrate to environmental compartments, where the occurrence, fate, and ecological risks have not been well characterized. To further understand the occurrence and multiphase partitioning, as well as to evaluate potential drivers and mixture risks in environmental compartments, we analyzed 11 CUHs in 576 samples from 36 rice–vegetable rotations in Nandu River basin, Hainan, China. Samples included soil, water, suspended particulate matter, and sediment collected during both rice and vegetable planting periods. The CUH concentrations varied across environmental compartments, but with high levels of glyphosate and aminomethylphosphonic acid organophosphorus herbicides (OPHs) frequently detected, accounting for 82.3 % to 99.0 % in environmental compartments. Phenoxy acid (PAA) and chloroacetanilide (ANH) herbicides were detected at lower frequencies. Spatiotemporal variation was significantly different among OPHs, ANHs, and PAAs, with geographic and crop-related patterns most evident for CUHs rather than OPHs. Structural equation model, redundancy, and boosted regression tree analyses indicated environmental compartment properties (pH, organic matter, and Fe/Al oxides), crop type, and wet/dry climate were important drivers of spatiotemporal patterns. Fugacity ratios indicated multiphase partitioning and transport of CUHs differed in rice and vegetable planting periods. A new assessment framework based on species-sensitive distributions and environmental compartment weight index indicated unacceptable risks of CUHs (risk quotient >1 in >50 % of sites), with most risks from OPHs (10.5 % to 98.0 %) and butachlor, acetochlor, and 2,4-dichlorophenoxyacetic acid. Risk hot spots were identified as the soil, the central region, and the vegetable planting period, potentially threatening nontarget organisms (e.g., Lemna minor, Glomus intraradices, and Apis mellifera). This study provides a new risk assessment framework and demonstrates the domination of OPHs in CUH contamination and risks in the tropics, thus helping guide policymakers and stakeholders on herbicide management.

Enhanced LC-ESI-MS/MS Sensitivity by Cationic Derivatization of Organophosphorus Acids.

The chemical derivatization to enhance the signal intensity and signal-to-noise (S/N) of several organophosphorus (OP) acids in liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) is illustrated. The OP class of compounds represents the environmental degradants of OP nerve agents and pesticides. N-(2-(bromomethyl)benzyl)-N,N-diethylethanaminium bromide (CAX-B) was utilized to derivatize a panel of eight acids consisting of five alkyl methylphosphonic acids (ethyl-, isopropyl-, isobutyl-, cyclohexyl-, and pinacolyl-methylphosphonic acid) along with three dialkylphosphate analogs (diethyl-, dibutyl-, and diethyl thio-phosphate). The derivatization reaction with CAX-B was conducted in acetonitrile in the presence of potassium carbonate at 70 °C for 1 h. The resulting acid derivatives were analyzed with an LC-Orbitrap-ESI-MS/MS, and their dissociation processes were investigated. It was found that the derivatization procedure increased the limits of identification (LOIs) by one to over two orders of magnitude from the range of 1 to 10 ng/mL for the intact OP-acids to the range of 0.02-0.2 ng/mL for the derivatized acids utilizing an LC-MS(QqQ) in MRM mode, regardless of the sample matrix (hair, concrete, or plant extracts). The interpretation of the corresponding ESI-MS/MS spectra for each type of derivatized sub-OP family revealed the formation of characteristic neutral losses and a characteristic ion for the organophosphorus core. This derivatization is beneficial and useful for screening and identifying target and "unknown" OP acids.

POSS-crosslinked poly(vinylphosphonic acid) for efficient adsorptive removal of uranium (VI) from nuclear wastewater

Organophosphorus acid polymers with high hydrophilicity and limited swelling capacity have great application potential in disposal of uranium (VI)-containing wastewater due to its high uranium (VI) adsorption efficiency. In this work, POSS-crosslinked poly(vinylphosphonic acid) polymer is synthesized via copolymerization of octavinyloctasilasesquioxane and vinylphosphonic acid for uranium (VI) adsorptive removal from solution. The polymer has a high hydrophilicity and limited swelling capacity. The uranium (VI) adsorptive removal is performed in batch mode and the effects of polymer dosage, pH and ionic strength are investigated. The polymer shows high removal efficiency for uranium (VI) from a 120 mg L−1 solution and can achieve the complete uranium (VI) removal at 30 °C and pH 4.0 with 0.33 g L−1 polymer. The adsorption process is analyzed by comparison with the adsorption kinetic and isotherm models. Uranium (VI) adsorption on this polymer is found to be more consistent with the pseudo-second-order and Langmuir models, and the maximum adsorption capacity attains 714 mg g−1. Competitive adsorption between uranium (VI) and other metal ions on polymer is performed to analyse the adsorption selectivity. The polymer attains a 20 L g−1 uranium (VI) distribution coefficient, higher than other metal ions (0.1–1.8 L g−1). The polymer can be easily recycled for at least five times with removal efficiency above 99% and the polymer can be well applied for dynamic adsorptive removal of uranium (VI) from uranium-containing solution (5 mg L−1) in a fixed-bed column with removal efficiency above 99%. The excellent uranium (VI) removal performances of this composite polymer highlight its great potential in the disposal of uranium-containing nuclear wastewater.

Separation of Boron Isotopes in Extraction Systems Tetrafluoroboric Acid–Organophosphorus Compounds

Separation of Boron Isotopes in Extraction Systems Tetrafluoroboric Acid–Organophosphorus Compounds

A molecular dynamics study on polybenzimidazole based proton exchange membrane with dual proton conductors

Organophosphorus acid (OPA) and phosphoric acid (PA) acting as dual proton conductors co-doped into proton exchange membrane is an effective solution to simultaneously improve the proton conductivity and inhibit the leaching of PA for high temperature proton exchange membrane fuel cells (HT-PEMFCs). However, the interactions of the dual proton conductors with polymers are still unrevealed. Here we combined density functional theory (DFT) calculation with molecular dynamic (MD) simulations to investigate the interactions between amino tris (methylene phosphonic acid) (ATMP, a kind of OPA)/PA and polybenzimidazoles with different kinds of electron withdrawing groups. The study reveals strong electron-withdrawing groups could form more abundant hydrogen bonds networks, and the interactions of ATMP and PA with polybenzimidazoles lead to more free PA molecules, which both benefit the proton conductivity. Meanwhile, the addition of ATMP could reduce self-diffusion of PA, which could improve the PA retention capacity. This work provides insights for the design of high temperature proton exchange membranes.

NEW ADVANCES IN THE SYNTHESIS OF CYCLOALKA[b]INDOLS

The review summarizes data on the synthesis of compounds whose backbone is a cycloalka[b]indole heterocycle. Approaches to the synthesis of homologous structures are considered, ranging from a carbocyclic fragment with three carbon atoms to eight-membered analogues. Examples of cyclizations are presented, including those with induction of chiral centers using appropriate catalytic systems, with different enantio- and diastereoselectivity. Attention is paid to carbocyclization reactions occurring in the presence of metal complexes, lithium alkylates, inter- or intramolecular cycloaddition of allenes, activated alkenes with 1,3-dipolarophiles or diene-like systems. In the preparation of cycloprop[b]indoles, [2+1]-cycloaddition reactions of indoles with various carbenes are most often used. In approaches to the synthesis of indoles annelated with cyclobutane, [2+2]-cycloaddition reactions are used. To obtain indoles, to which 2,3-annelated carbocycles of medium size, synthetic methods are effectively used, including the use of indole derivatives, 3-nitroindole derivatives as starting materials, intra- and intermolecular reactions of 3-ethynyl-, 3-allenyl -, 3-alkenyl- or functionalized 2-alkyl-substituted indoles in the presence of complexes of palladium, gold, rhodium, copper, silver, indium, organophosphorus acids and their amides, trifluoroethanol, hexafluoroisopropanol, organic sulfo- or trifluoroacetic acids. Methods of photochemical exposure are known, leading to cyclopenta[b]indoles. In the preparation of these heterocycles, cycloaddition reactions of 1,3-dipoles generated from (2-indolyl)diarylmethanols to dipolarophiles are successfully used. Equally effective are cycloaddition reactions of 2-vinylindole derivatives to activated alkenes or carbonyl compounds in the presence of various catalysts, leading to di- or tetrahydrocarbazoles or their seven-membered homologues. One of the frequently used approaches to obtain cycloalka[b]indoles are reactions based on catalyzed transformations of indole-substituted cyclopropanes or intermolecular interaction of cyclopropanes with indoles under various conditions.

TFC membrane with in-situ crosslinked ultrathin chitosan layer for efficient water/ethanol separation enabled by multiple supramolecular interactions

Chitosan (CS) membranes have been widely applied in water/ethanol separation via membrane-based pervaporation, but a bottleneck in the practical application always exists due to their severe swelling behavior in aqueous solution and consequently low permeation flux due to the large membrane thickness. Here, thin film composite (TFC) hollow fiber (HF) membrane with an in-situ-crosslinked ultrathin CS selective layer is developed via multiple supramolecular interaction-crosslinking strategy for efficient water/ethanol separation via pervaporation. With Fe3+-phytic acid (PhA) complex pre-deposited on the substrate, the subsequently introduced CS selective layer is in-situ crosslinked via multiple supramolecular interactions, including coordination, electrostatic, and hydrogen bonding interactions. By varying the cycle number of Fe3+/PhA assembly and the species of employed organophosphorus acid, the anti-swelling properties of the resultant TFC CS membrane is enhanced and the separation performance is maximized. The optimal TFC-CS-Fe2PhA2 membrane with two cycles of Fe3+/PhA assembly has a selective layer thickness of 60 ​nm and a corresponding ultrahigh flux of 2.87 ​kg/m2 h, coupled with a permeate water concentration of 99.5 ​wt% and good long-term stability for the dehydration of 85 ​wt% ethanol aqueous solution at 50 ​°C. The supramolecular interaction-crosslinking presented in this work provides an efficient and promising strategy for the construction of TFC CS membrane with excellent anti-swelling property and superior separation performance.

ОПРЕДЕЛЕНИЕ ПЛОТНОСТИ И ДИЭЛЕКТРИЧЕСКОЙ ПРОНИЦАЕМОСТИ РАСТВОРОВ РЕДКОЗЕМЕЛЬНЫХ ЭЛЕМЕНТОВ СРЕДНЕТЯЖЕЛОЙ ГРУППЫ В ВОДНЫХ РАСТВОРАХ И В ЭКСТРАКТАХ КИСЛЫХ ФОСФОРОРГАНИЧЕСКИХ ЭКСТРАГЕНТОВ

Co-extraction of rare-earth elements from chloride solutions containing total rare-earth elements by a mixture of extractants mono-2-ethylhexyl ester of 2-ethylhexylphosphonic acid (P507) + di(2,2,4-trimethylpentyl)phosphinic acid (Cyanex 272) + 10 about. % TBP in isopar-l with a mass concentration of P507 + Cyanex 272 - 15%. The density and permittivity of solutions of rare-earth elements of the medium-heavy group in aqueous solutions and in extracts of acidic organophosphorus extractants have been determined. Initial concentrations in REE GH solutions ranged from 0.15 to 1.7 mol/dm3. The features of complex formation in a mixture of praseodymium metal and P507 extractant were studied. The initial concentrations in praseodymium solutions ranged from 0.014 to 0.149 mol/dm3.

Impregnation of preparative high‐performance solid phase extraction chromatography columns by organophosphorus acid compounds

The flexible and reversible preparation of columns for use in high-performance solid phase extraction chromatography by physisorption of organophosphorus acid extractants has been investigated in detail. Two extractants have been evaluated, bis (2-ethyl-1-hexyl) phosphoric acid (HDEHP) and 2-ethyl-1-hexyl (2-ethyl-1-hexyl) phosphonic acid (HEHEHP), but the developed procedure should be broadly applicable to other extractants. The liquid-liquid solubility of the extractants in feed solvents consisting of aqueous ethanol solutions of varying composition has been determined. The total amount of adsorbed extractant has been quantified by complete desorption and elution with ethanol followed by acid-base titrimetry. Column impregnation with feed solutions of varying concentration in the undersaturated region has been systematically evaluated, and the influence of a subsequent water wash step has been explored. It is shown that to achieve a robust and reproducible physisorption, the adsorbed amount of extractant should be determined after the wash step, and care must be taken when using indirect methods of measurement. Equilibrium Langmuir-type adsorption isotherms as a function of the extractant concentration in the feed solution have been determined. Adsorption of HEHEHP is higher than HDEHP for equal feed compositions, but the solubility of HEHEHP is lower, resulting in approximately identical maximum coverage levels. The ability of the resulting columns to separate rare earth elements have been verified for a mixture of eight metals using a combined isocratic and gradient elution of nitric acid.

A Novel Organophosphorus Acid Anhydrolase from Deep Sea Sediment with High Degradation Efficiency for Organophosphorus Pesticides and Nerve Agent.

Organophosphorus compounds (OPCs), including highly toxic nerve agents and pesticides, have been used widely in agricultural and military applications. However, they have aroused widespread concern because they persistently pollute the environment and threaten human life. Organophosphorus acid anhydrolase (OPAA) is a promising enzyme that can detoxify OPCs. Here, a novel OPAA (OPAA114644) was isolated and characterized from deep-sea sediment (−3104 m). It exhibited excellent alkaline stability, and the loss of activity was less than 20% in the pH range 5.0–9.0, even after being incubated for 30 d at 4 °C. It also exhibited high salt tolerance, and its enzymatic activity increased by approximately fourfold in the presence of 20% NaCl (w/v). Additionally, OPAA114644 exhibited high degradation efficiency for soman, dichlorvos, paraoxon, coumaphos, and chlorpyrifos with a concentration of up to 250 mg/L, with the degradation rate being 100%, 100%, 100%, 80% and 51%, respectively, in 20 min under optimal conditions. Notably, OPAA114644 dissolved in different solutions, such as 20% NaCl, 1 mM SDS, 0.05% soap, 10% methanol, and tap water, could efficiently decontaminate the residual paraoxon on the surfaces of glasses, cotton tissues, and apples. These results indicate that OPAA114644 has excellent potential for the biodegradation and bioremediation of OPCs pollution and represents a real application of OPAA in the decontamination and detoxification of foods and clothes, and in the remediation of sites such as floors. Deep-sea sediment might also be an abundant resource for various functional microorganisms and enzymes.

Separation of Samarium, Europium, and Gadolinium by Extraction with Organophosphorus Acids

Separation of Samarium, Europium, and Gadolinium by Extraction with Organophosphorus Acids