Trioctyl Phosphate Research Articles

Fabrication of highly flame retardancy and impact strength polylactide foams with phosphorus-containing and agricultural waste-derived multifuctional additives

Research on green polymeric foams is crucial for sustainable development. A polylactide (PLA) foam with a bio-based multifunctional flame-retardant additive derived from agricultural waste was developed and evaluated. Various PLA-based foams were prepared using melt extrusion. A PLA foam with 10 phr of trioctyl phosphate (TOP) showed enhanced crystallization ability, desirable impact strength, and excellent flame retardancy. However, TOP presents concerns for health and the environment. Therefore, bio-based flame retardants (BFRs) derived from agricultural waste were used to partially replace TOP and support the environment friendly and sustainable practices of the bio-circular-green (BCG) economic model. The study used a combination of 2.5 phr of pumpkin shell powder (PK) and 7.5 phr of TOP to produce a PLA foam that achieved a UL-94 V-0 rating, indicating excellent flame retardancy. The impact strength of this foam was about 84 % greater than that of neat PLA foam. The successful incorporation of agricultural waste-derived additives in PLA foam could not only contribute to sustainability but also add value to agricultural waste by repurposing it for a useful application.

Highly enhanced fluoride removal from aqueous systems via solvent extraction utilizing trialkyl phosphine oxide as an efficient extractant

Solvent extraction (SX) has been recognized as an efficient approach for the large-scale removal of impurities, demonstrating considerable potential for fluoride extraction in industrial applications. However, existing fluoride extraction methods typically require the incorporation of additives to form complexes with fluoride for its removal. Due to the excessive additive requirements for efficient fluoride removal, these methods inevitably result in secondary contamination of feed solution, necessitating additional purification efforts to remove them. In this study, four extractants (trioctyl amine, tributyl phosphate, trioctyl phosphate, and trialkyl phosphine oxide (TRPO)) were investigated for fluoride removal via hydrogen bonding with hydrofluoric acid (HF). Various parameters, including the concentrations of extractants and stripping agents, pH values, extraction time, and temperature were initially optimized. It was found that TRPO exhibits the highest extraction efficiency for HF, with a single-stage extraction rate exceeding 70 %. Complete fluoride removal (> 99.9 %) was achieved through a consecutive four-stage extraction process. Further experiments, including maximum loading and slope analysis, combined with FT-IR and 19F NMR characterization, and DFT calculations elucidate the mechanism of the extraction. The transfer of HF into the organic phase is accomplished by the formation of a 1:1 hydrogen-bonded complex with TRPO. The loaded fluoride in the organic phase can be easily stripped by a base to get a fluoride salt. This study paves the way for the construction of novel SX systems to remove fluoride as HF.

Mechanisms for the separation of Li+ and Mg2+ from salt lake brines using TBP and TOP systems

The tributyl phosphate (TBP)/FeCl3 system has been widely used for lithium extraction from high‑magnesium salt lakes. However, at high TBP concentrations, the Li/Mg selectivity is significantly lower. This study revealed that at high TBP concentrations, TBP alone extracted Mg2+ to form MgCl2·6TBP as the main product, thus affecting the extraction efficiency of Li+. On this basis, a neutral phosphate with long carbon chains, trioctyl phosphate (TOP), was used to replace TBP. The separation capacity and extraction mechanism of the TOP/FeCl3 system were studied, and density functional theory (DFT) calculations were employed to model the cationic complexes of the TOP and TBP systems. The results showed that in the presence of FeCl3, the extraction efficiency of Li+ (ELi) reached 91 %, and the Li/Mg separation factor (βLi/Mg) was 5688. In contrast, in the TBP/FeCl3 system with the same concentration, the ELi and βLi/Mg values were much lower at 74 % and 239, respectively. Furthermore, the TOP complex of Li+ had shorter Li − O bond lengths and a more negative binding energy, while that formed with Mg2+ had longer Mg − O bond lengths and the smallest HOMO–LUMO gap, indicating that TOP bonded more stably with Li+ and was less prone to Mg2+ extraction than TBP.

Highly efficient lithium extraction from magnesium-rich brines with ionic liquid-based collaborative extractants: Thermodynamics and molecular insights

Selective extraction of Li+ from high Mg2+/Li+ ratio brines with ionic liquid (IL) based collaborative extractants was investigated by experiments, thermodynamic analyses, and quantum chemical (QC) calculations. Effects of different IL cationic structures and organophosphorus ligands on extraction performances were studied. The results demonstrated that the system 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide + trioctyl phosphate ([HOEMIM][Tf2N] + TOP) was considered as the best extractant, with the very high extraction efficiency of Li+ (83.16 %) and separation selectivity of Li+/Mg2+ (742.11), which is higher than values reported in literature. The thermodynamic model ePC-SAFT was first extended to quantitatively predict the phase equilibria of the so-called “organic–inorganic complex strong electrolyte system” presented in this work. The molecular-level extraction mechanism was explored by QC calculation, indicating that the strong multi-site intermolecular interactions between Li+ and [HOEMIM][Tf2N] + TOP break the Li+ hydration. This work provides guidance to rationally design novel IL-based extractants for efficient extraction of Li+.

Extraction mechanism of germanium in sulfate solutions using a tertiary amine (N235)-based solvent extraction system

With the increasing demand for germanium in high-technology fields, the recovery of germanium has gained a great deal of attention. In this study, classical methods (including stoichiometry and saturation methods) were combined with spectroscopic methods (FT-IR, NMR, and ESI-MS) to investigate the mechanism of Ge(IV) extraction from a sulfuric acid solution using the tertiary amines (N235) and trioctyl phosphate (TOP) system. The results indicate that Ge(IV) was extracted as a Ge(OH)(HL)3 anion complex, and tartaric acid is coordinated to Ge(IV) via a CO bond from the carboxylate group. The extraction process followed an anion exchange mechanism. TOP participated in the formation of extraction complexes through hydrogen bonds in the form of GeOH⋯OP but did not co-extract germanium with N235. The extracted complex species were Ge(OH)(HL)2L·HN(R1)3 and Ge(OH)(HL)L2·[HN(R1)3]2 (R=C8H17). The apparent equilibrium constants of the extraction reactions Kex were 100.36 and 100.43 at tartaric acid/Ge(IV) ratios of 5 and 3, respectively. The thermodynamic constants for the extraction process were ΔH=−0.457 kJ·mol−1, ΔS=1.176 kJ·mol−1·K−1, and ΔG=−351.081 kJ·mol−1.

Extraction behavior of germanium from synthetic leaching solution of secondary zinc oxide in tertiary amine (N235)-trioctyl phosphate (TOP) system

In continuation with our previous work, in the present study, the tertiary amine-trioctyl phosphate-sulfonated kerosene system was employed to recover Ge(IV) from the synthetic leachate of secondary zinc oxide. The effects of different complexing agents (tartaric acid, citric acid, oxalic acid, gallic acid, and salicylic acid) and impurities (Zn(II), Fe(III), Cd(II), Si(IV), and As(III)) on the extraction of Ge(IV) were investigated. Under comparable conditions, the extraction of Ge(IV) with the aforementioned complexants had the following order in terms of extraction efficiency: tartaric acid > citric acid > gallic acid > oxalic acid, or salicylic acid. The reason for the low extraction efficiency of Ge(IV) with the addition of oxalic acid was revealed by an extraction comparison using pure germanium and polymetallic solutions. Furthermore, a stoichiometry analysis of the extracted complex indicated that the extracted Ge(IV)-organic species was R3NH·Ge(OH)4(HT)·0.5TOP with the addition of tartaric acid. The concentration of Ge(IV) in the loaded organic phase was less than 1 mg/L when three-stage countercurrent stripping was adopted at an O/A ratio of 1/3 and 25 °C for 10.5 min.

Recovery of Ge(IV) from synthetic leaching solution of secondary zinc oxide by solvent extraction using tertiary amine (N235) as extractant and trioctyl phosphate (TOP) as modifier

The N235–TOP–sulfonated kerosene system was applied for the recovery of Ge(IV) from a synthetic sulfuric acid leaching solution of secondary zinc oxide, containing Ge(IV), Zn(II), As(III), Fe(III), Si(IV), and Cd(II). The co-extraction of As(III) with Ge(IV) is a challenging problem in the extraction of Ge(IV) from aqueous solution by N235. However, TOP, as a modifier, suppressed the co-extraction of As(III) significantly. The effects of factors including N235 concentration, extraction time, tartaric acid to Ge(IV) molar ratio and temperature on the extractions of Ge(IV) and As(III) were studied. At an organic/aqueous (O/A) phase ratio of 1/1, aqueous phase pH of 1.2, extraction time of 10.5 min, tartaric acid-to-Ge(IV) molar ratio of 5.0, and temperature of 25 °C, the extraction efficiency of Ge(IV) reached 93.9%, whereas only 1.3% of As(III) was extracted by the 25%(v/v)N235–10%(v/v) TOP–sulfonated kerosene system in a single stage extraction. The Ge(IV) in the raffinate was less than 1.5 mg/L when employing a five-stage continuous countercurrent extraction at an O/A ratio of 1/10. In addition, aqueous NaOH solution of 0.5 mol/L was an appropriate reagent for the stripping of both Ge(IV) and As(III) at an O/A ratio of 1/1 and 25 °C for 10.0 min.

Explosion characteristics of mixtures containing hydrogen peroxide and working solution in the anthraquinone route to hydrogen peroxide

Abstract The explosive properties of mixtures of aqueous hydrogen peroxide (H2O2) and working solution (WS), and the main components of the working solution (1, 3, 5-trimethyl benzene(TMB), trioctylphosphate (TOP)) were investigated by the drop weight test. The explosion range was interpreted by thermal calculation, and the calculated results agreed well with the experimental test. The explosion mechanism of the TMB/H2O2 mixture is the partial oxidation of TMB by H2O2, which is qualitatively obtained by analyzing the gaseous and liquid products of the TMB/ H2O2 mixture after explosion. Finally, a proposed explosion mechanism was suggested.

H2 solubility and mass transfer in anthraquinone working solution: Experimental and modeling study

This work was focused on the measurement of the solubility of hydrogen (H2) in anthraquinone working solution at temperatures of 30.0–80.0°C and pressures of 0.2–3.0MPa by the method of experimental and COSMO-RS model study. The influence of various factors, i.e., including pressure, temperature and solvent volume ratio, on H2 solubility was investigated. According to the experimental results, H2 solubility in anthraquinone working solution increases with the increase of pressure. At low pressures, the temperature had little effect on H2 solubility while under high pressures H2 solubility increases with increasing temperature. Henry's constant lnH has a good linear relationship with 1/T (lnH=−1319.1/T+9.91). The effect of volume ratio of trioctyl phosphate to trimethylbenzene on the solubility of hydrogen was studied and the results showed that increasing the amount of trimethylbenzene was conducive to the dissolution of hydrogen. In addition, there is a linear relationship between ln((P0−Pe)/(Pt−Pe)) and the time t. Gas–liquid mass transfer coefficient was obtained by calculating the slope of the line.

Physicochemical characteristics and sorption capacities of heavy metal ions of activated carbons derived by activation with different alkyl phosphate triesters

Five alkyl phosphate triesters (APTEs), including trimethyl phosphate (TMP), triethyl phosphate (TEP), triisopropyl phosphate (TPP), tributyl phosphate (TBP) and trioctyl phosphate (TOP), were used as activating agents for preparing activated carbons (AC-APTEs) with high surface acidity and metal ion sorption capacity. N2 adsorption/desorption isotherms, surface morphologies, elemental compositions, results of Boehm's titration and sorption capacities of heavy metal ions of the carbons were investigated. AC-APTEs contained much more acidic groups and exhibited much less surface area (<500m2/g) in comparison with activated carbon (AC-PPA, 1145m2/g) obtained from phosphoric acid activation. For the AC-APTEs, AC-TOP had the highest surface area (488m2/g), AC-TMP showed the highest yield (41.1%), and AC-TBP possessed the highest acidic groups (2.695mmol/g), oxygen content (47.0%) and metal ion sorption capacities (40.1mg/g for Ni(II) and 53.5mg/g for Cd(II)). For the carbons, AC-APTEs showed much larger Ni(II) and Cd(II) sorption capacities than AC-PPA, except AC-TPP. The differences of the carbons in the physicochemical and sorption properties suggested surface chemistry of the carbons was the main factor influencing their sorption capacities whereas the pore structure played a secondary role.

Solubility of 2-tert-butylanthraquinone in binary solvents

The solubilities of 2-tert-butylanthraquinone (TBAQ) in three binary solvents 1,3,5-trimethylbenzene (TMB)+2,6-dimethyl-4-heptanol (diisobutylcarbinol, DIBC) with 3:1, 3:2, 1:1 and 2:3 in the volume ratio of TMB to DIBC (solvent ratio) were determined in the temperature range from 303.15 to 333.15K by the equilibrium method. As a comparison, the solubilities of TBAQ in solvent mixtures TMB+2-methylcyclohexyl acetate (MCA) and TMB+trioctylphosphate (TOP) were also determined. The solubilities of TBAQ in all the binary solvents always increased with rising temperature and solvent ratio. At the same temperature and solvent ratio, the solubilities of TBAQ in TMB+DIBC were close to those in TMB+MCA and much higher than those in TMB+TOP. Two activity coefficient models NRTL equation, Wilson equation and modified λ–h equation were applied to correlate and predict the solubilities of TBAQ in mixed solvents. The satisfactory correlation were obtained using all three equations and the NRTL equation gave relatively good prediction with the average and maximum relative deviation of 1.87% and 5.06%, respectively.

Potentiometric and semi-empirical quantum chemical studies on liquid–liquid micro-extraction of 4-tert-butylphenol with trioctyl phosphate clusters

In the present paper, the liquid–liquid micro extraction of 4-tert-butylphenol from aqueous solution to trioctyl phosphate organic phase in carbon paste electrode was studied by potentiometry and semi-empirical quantum chemistry with MOPAC2009. The extraction dynamic process was monitored by open circuit potential method, which follows an exponential association function with the apparent first extraction kinetic rate constant of 0.01685s−1. The Nernstian plot of potential difference of the open circuit potentials against logarithm of 4-tert-butylphenol concentration at 500s extraction time gives a slope of 0.01382, and indicates that 3 or 4 of 4-tert-butylphenol molecules can be extracted by one cluster of trioctyl phosphate dimer. This equation can also serve as working curve for the determination of 4-tert-butylphenol in the concentration range of 1.0×10−4–5.0×10−7M with detection limit of 5.0×10−7M (n=3, ratio of signal/noise=3). The semi-empirical quantum chemical calculation offers a thermodynamic evidence for the molecular mechanism of the liquid–liquid micro extraction of 4-tert-butylphenol from aqueous solution to trioctyl phosphate cluster.

Facile Fabrication of Novel Magnetic and Fluorescent Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;-CdSe Nanocomposites

Novel Fe3O4-CdSe nanocomposites were prepared by depositing semiconductor on monodisperse magnetic nanoparticles. First, monodisperse Fe3O4 nanoparticles were fabricated by a solvothermal process in which iron acetylacetonate (Fe(acac) 3 ) was used as precursor, phenyl ether as reaction medium, oleic acid as surfactant and oleylamine (OAm) as both surfactant and reducing agent. Novel Fe3O4 -CdSe heterostructures were prepared using 1-octadecene as high boiling solvent, cadmium oxide as Cd precursor, trioctyl phosphate (TOP)-Se as Se precursor, n-hexadecylamine (HDA) as surfactant, and stearic acid (SA) as growth promoter and nucleating agent. The structure and properties of the Fe3O4 -CdSe nanocomposite were fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), UV-Vis spectrum, and photoluminescence (PL). CdSe nanoparticles were successfully attached to the surface of Fe3O4 and grew along the c-axis to form novel jujube pit-liked and nail-liked heterostructures with a width of 3.6 nm and length of 14.5 and 32.5 nm,respectively. The novel nanocomposites were a combination of magnetite Fe3O4 and hexagonal CdSe rods, and exhibited strong fluorescent emission without obvious quenching and excellent superparamagnetic properties. Fluorescent absorption shifts to longer wavelength as the length of the CdSe rods increases. The saturation magnetization of Fe3O4 nanoparticles, jujube pit liked and nail liked Fe3O4-CdSe nanocomposites were 57.80, 40.76, and 31.10 emu·g -1 , respectively.

Gas chromatographic retention of alkyl phosphates on ionic liquid stationary phases

Retention behaviors of alkyl phosophates were studied on a series of ionic liquid gas chromatography columns. The selectivity of the IL columns for alkyl phosphates were compared with a 5% phenyl column as a route to evaluating the potential use of IL columns in the analysis of alkyl phosphates in petroleum samples in both one- and multi-dimensional GC. Most interestingly, we demonstrate for the first time the dependence of elution order on separation temperature for members of a homologous series of compounds. At low temperatures it was found that trihexyl phosphate eluted before trioctyl phosphate, while at higher temperatures this pattern was reversed.

Reactive extraction and recovery of mono-caffeoylquinic acids from tobacco wastes by trialkylphosphine oxide

The feasibility of reactive extraction of mono-caffeoylquinic acids (mono-CQAs) from aqueous extract solutions of tobacco wastes was studied. The mixed solvent system, initial pH, extractant concentration, complexation stoichiometry, equilibrium and mechanism were discussed. The results indicated that the extraction ability of extractants decreases in the order trialkylphosphine oxide (TRPO)>N235≈tributylphosphate (TBP)>trioctyl phosphate (TOP). Using a 1:1 ratio of 20% TRPO/kerosene to sample volume, one step recovered 94.9% of the mono-CQAs from an aqueous solution at pH 3. The complexation stoichiometry between TRPO and the mono-CQAs was 1:2 or 1:3, but the formation of 1:2 complexes was favored. The extraction equilibrium of the mono-CQAs was fit to a Henry isotherm, and the process was exothermic. Hydrogen-bond interactions between TRPO and mono-CQAs were confirmed by Fourier-transform infrared (FTIR) spectra, and the changes in the wavenumbers of absorbances increased with decreasing pKa values of the mono-CQAs.

Hydrogen peroxide synthesis by direct photoreduction of 2-ethylanthraquinone in aerated solutions

A new synthesis method of hydrogen peroxide was investigated by the photoreduction of 2-ethylanthraquinone (AQ) in water-insoluble organic solvents. Through optimizing the photoreduction condition including solvent, atmosphere and irradiated time, the photolysis system of 1,3,5-trimethylbenzene/trioctyl phosphate (3:1) solvent mixture under oxygen atmosphere was found to give a high yield of hydrogen peroxide. Furthermore, the formation mechanism of hydrogen peroxide was proposed, i.e. photoreduction and subsequent oxidation of AQ. The photoreduction of 2-ethylanthraquinone undergoes the hydrogen abstraction from solvent to form the anthrahydroquinone, which is subsequently oxidized by oxygen to give hydrogen peroxide.

Effects of Trioctyl Phosphate and Cresyl Diphenyl Phosphate as flame-retarding additives for Li-Ion battery electrolytes

Safety concerns related to lithium-ion batteries have been the key obstacle to their application in hybrid electric vehicles. Trioctyl Phosphate (TOP) and Cresyl Diphenyl Phosphate (CDP) were studied as potential flame-retarding additives for lithium-ion batteries. The electrochemical performance and thermal stability of the additive-containing electrolytes, in combination with a cell comprising a LiCoO2 cathode and Mesocarbon Microbeads (MCMB) anode, were tested in coin cells. Cyclic Voltammetry (CV), Differential Scanning Calorimetry (DSC), Electrochemical Impedance Spectroscopy (EIS), and Scanning Electron Microscopy (SEM) were used for the experimental analysis. The study results revealed that CDP addition at 5 wt.% improved the cell stability due to the lower rate of the charge-transfer resistance increase over 30–50 cycles. CDP was demonstrated to be a better flame-retarding additive than TOP.

Flow-through Chloroquine Sensor and Its Applications in Pharmaceutical Analysis

Poly (vinyl chloride) membrane electrodes that responded selectively towards the antimalarial drug chloroquine are described. The electrodes were based on the use of the lipophilic potassium tetrakis(4-chlorophenyl)borate as ion-exchanger and bis(2-ethylhexyl)adipate (BEHA), or trioctylphosphate (TOP) or dioctylphenylphosphonate (DOPP) as plasticizing solvent mediator. All electrodes produced good quality characteristics such as Nernstian- and rapid responses, and are minimally interfered with by the alkali and alkaline earth metal ions tested. The membranes were next applied to a flow-through device, enabling it to function as flow-injection analysis (FIA) detector. The performance of the sensor after undergoing the FIA optimization was further evaluated for its selectivity characteristics and lifetime. Results for the determination of chloroquine in synthetic samples that contained common tablet excipients such as glucose, starch, and cellulose, and other foreign species such as cations, citric acid or lactic acid were generally satisfactory. The sensor was also successfully used for the determination of the active ingredients in mock tablets, synthetic fluids and biological fluids. The sensor was applied for the determination of active ingredients and the dissolution profile of commercial tablets was also established.

Integrated Process of H2O2 Generation through Anthraquinone Hydrogenation−Oxidation Cycles and the Ammoximation of Cyclohexanone

The liquid−liquid-phase equilibrium of a five-component system of methanol−water−H2O2−trimethylbenzene−trioctyl phosphate was studied, and the data were correlated with UNIQUAC and NRTL models, respectively, and used for the simulation of the extraction of H2O2 with an aqueous methanol solution in the H2O2 production process based on anthraquinone hydrogenation−oxidation cycles. The results showed that, with an aqueous methanol solution for the extraction of H2O2, after a few cycles the concentration of methanol in an anthraquinone working solution becomes constant and would not influence the H2O2 production process. All of the impurities in the H2O2 solution obtained with an aqueous methanol solution as the extractant from the H2O2 generation process as well as the stabilizers and corrosion inhibitors that should be added in the H2O2 solution did not appreciably affect the direct ammoximation of cyclohexanone with NH3 and H2O2 catalyzed by TS-1. The results indicated that the processes of cyclohexanone oxime production through the direct ammoximation of cyclohexanone and H2O2 generation through the anthraquinone hydrogenation−oxidation cycles could be integrated.

Development of Durable Nitrate-Selective Membranes for All-Solid State ISE and ISFET Sensors Based on Photocurable Compositions

Novel nitrate-sensitive membranes have been developed using an aliphatic urethane diacrylate photocurable polymer. This polymer has been chosen due to its easy and fast deposition procedure compared with PVC membranes and its compatibility with microelectronic techniques. These membranes were obtained after UV irradiation during no more than 60 seconds. To optimize their composition and evaluate the chemical response ion selective electrodes (ISEs) with solid inner reference were used. Studies of different plasticizers for nitrate PVC membranes and compositions increasing the ratio between oligomer and diluting agent were performed. ISEs developed presented a sensitivity of −56 mV/dec and a lifetime up to one year. Membrane compositions containing dibutyl phthalate and trioctyl phosphate as plasticizers were deposited onto ISFETs. Studies to elongate ISFETs lifetime were carried out modifying the encapsulation methodology, by using the same polymer family. ISFETs showed a sensitivity between 65–69 mV/decade, depending on the plasticizer, and a linear range of 2.4×10−5−0.06 M. The long-term stability of ISFET sensors with trioctyl phosphate plasticizer was up to 10 months, being superior to that described in the literature for PVC membranes and even for other kind of polymers.