Trioctylphosphine Oxide Research Articles

Solvent extraction in non-ideal eutectic solvents – Application towards lanthanide separation

Hydrophobic eutectic solvents (HES) emerged as promising substitutes to the conventional organic phase used in the solvent extraction (SX) of metal ions due to the avoidance of diluents and the suppression of third-phase manifestation. However, HES present a highly structured liquid phase defined by hydrogen-bonded interactions such that intercomponent interactions are expected to play a greater role in SX using HES compared to a diluted extractant solution. In this work, the extraction of lanthanides from nitrate media by the non-ideal solvent composed of decanoic acid (C10OOH) and trioctylphosphine oxide (TOPO) was determined as a function of the lanthanide cation selection, HES molar fraction, HNO3 concentration, and temperature. Through the systematic variation of these parameters, the delicate balance between complexation and solvent reorganisation and its influence on the extraction and metal selectivity is determined by metal partition experiments, time resolved fluorescence and Raman spectroscopy, and small-angle X-ray scattering (SAXS). A compromise between maximum Ln3+ loading and selectivity was observed, driven by the variation in the quantity of weakly H-bonded TOPO and the change in the configurational entropy of the mixture. All results point towards the need to explicitly consider the HES phase structuration and its compositional changes with solute co-extraction on the Ln3+ extraction as no change in the extracted complex speciation was observed across all tested conditions. The C10OOH + TOPO was used as a model system due as lanthanide extraction using TOPO and carboxylic extractants is well described whilst the phase diagram and properties of the eutectic are reported. Nevertheless, the derived conclusions are translatable to other systems and can help guide the design and application of possible HES combinations for SX.

A leaching, solvent extraction, stripping, precipitation and calcination process for the recovery of MoO3 and NiO from spent hydrofining catalysts

Effective recovery of elements from spent catalysts can not only avoid environmental hazards, but also alleviate the pressure of resource scarcity. This study proposes a hydrometallurgical process for the selective recovery of MoO3 and NiO from the spent hydrofining catalysts. First, valuable metals were leached with 0.5 mol/L H2SO4 and 4 wt% H2O2 at 25 °C for 20 min, resulting in the dissolution efficiencies of Mo, Ni and Al were 95.6%, 96.5% and 13.8%, respectively. Then, bis-(2-ethylhexy)phosphinic acid (P227) was chosen as the Mo extractant due to its higher separation factors of βMo/Al and βMo/Fe compared to di-2-ethylhexylphosphoric acid (P204) and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507). Extraction efficiency of 99.9% Mo was achieved at pH of 0.5 with 0.3 mol/L P227, whereas only 0.061 g/L Fe and <1 mg/L of other impurity elements were co-extracted. The complete stripping of Mo was realized with 0.4 mol/L (NH4)2CO3. Subsequently, a synergistic extraction system bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) and trioctylphosphine oxide (TOPO) was employed to extract Ni, where the extraction efficiency was more than 99.9%. Around 99.9% of Ni was stripped with 9 mol/L HCl. With the addition of TOPO, not only the extraction ability of Ni was improved, but also realized the complete stripping of Ni. The two oxides MoO3 and NiO were prepared from the stripping solution. In addition, the extraction mechanism of Mo and Ni was studied. The total recovery efficiencies of Mo and Ni were 94.1% and 93.1%, with the purity of 99.9% and 99.0%, indicating that this innovative process can be utilized to recover MoO3 and NiO from the spent hydrofining catalysts.

Influence of surface modification by organic molecules on optical properties of Eu3+-doped ZnO nanocrystals

We have fabricated Eu3+-doped ZnO (ZnO:Eu) nanocrystals (NCs) surface-modified with organic molecules such as dodecylamine (DDA) and tri-n-octylphosphine oxide (TOPO) and have studied their optical properties. In the ZnO:Eu NCs without surface modification, strong broad photoluminescence (PL) band due to surface defects is observed, so the Eu3+ PL peaks are not observed because they are covered by the strong surface-defect PL band. In the DDA-capped ZnO:Eu NCs, the Eu3+ PL and the exciton PL are observed because of suppression of the surface-defect PL caused by the inactivation of the surface defects. Contrary to expectations, the surface modification with TOPO suppressed not only the surface-defect PL but also the exciton PL. As a result, the ZnO:Eu NCs with red PL due to the Eu3+ ions have been successfully prepared. We discuss the influence of surface modification by DDA and TOPO on optical properties.

β-Diketone-Driven Deep Eutectic Solvent for Ultra-Efficient Natural Stable Lithium-7 Isotope Separation

6Li and 7Li are strategic resources. Because Li+ ions have no outermost electrons and the radii of 6Li and 7Li differ by only one neutron, the separation of the naturally stable isotopes of Li, especially by solvent extraction, is recognized as a difficult problem worldwide. Therefore, in this paper, an advanced β-diketone-driven deep eutectic solvent (DES) extraction system containing 2-thenoyltrifluoroacetone (HTTA) and tri-n-octyl phosphine oxide (TOPO) is introduced to the extraction and separation of 6Li+ and 7Li+ ions. Compared with those of reported HTTA extraction systems and crown ether extraction systems, the separation coefficient (β7Li/6Li) of the β-diketone-driven DES extraction system can reach the best value of 1.068, which is now the highest known β-value reported in the extraction system. From the intramolecular hydrogen bond of HTTA to the intermolecular hydrogen bond of DES, the bond energy increases by 47.8%. Because the active site of the proton in DES provides a higher energy barrier for the separation of 7Li, the β7Li/6Li is significantly increased. The extractions were characterized by spectrum, using 1H nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The mechanism was determined on the basis of the reaction kinetics and density functional theory (DFT). The DES extractant shows excellent cycle performance with regard to stripping and reusability. In conclusion, the highly efficient, economical, and stable β-diketone-driven DES extraction system can be used for the separation of naturally stable Li isotopes, which provides good industrial application prospects.

The application of Box–Behnken design for the optimization of protocatechuic acid separation by a reactive extractant trioctylphosphine oxide

The application of Box–Behnken design for the optimization of protocatechuic acid separation by a reactive extractant trioctylphosphine oxide

Intensified Nd extraction in small channels for NdFeB magnet recycling

Neodymium (Nd) was continuously extracted from aqueous solutions by trioctylphosphine oxide (TOPO) dissolved in the ionic liquid 1-Butyl-3-methylimidazolium Bis (trifluoromethanesulfonyl)imide [C4mim][Tf2N] in small channel contactors. Kinetic studies confirmed a 1:6 Nd:TOPO extraction mechanism at high initial Nd concentrations of 0.005 and 0.01 M in a 0.001 M nitric acid aqueous phase. The continuous flow extractions were carried out in channels with 0.5 and 1 mm diameter and the effects of mixture velocity and residence time on the extraction efficiency and the mass transfer coefficient were investigated. At equal phase mixture velocities, the flow pattern studies highlighted a plug flow regime at mixture velocities of 0.01 to 0.05 m/s for both channels, resulting in interfacial areas of up to 4900 m2/m3 in the 0.5 mm channel and 2500 m2/m3 in the 1 mm channel. After 37.5 s residence time, extraction efficiencies of 80 % were found in the 0.5 mm channel at a KLα of 0.09 s−1 and 70 % at 0.04 s−1 in the 1 mm channel. The same extraction efficiencies were achieved in 1–2 h in the batch systems.

Reactive extraction of gallic acid by trioctylphosphine oxide in different kinds of solvents: equilibrium modeling and thermodynamic study

Reactive extraction of gallic acid by trioctylphosphine oxide in different kinds of solvents: equilibrium modeling and thermodynamic study

Contaminations impairing an acetic acid biorefinery: Liquid-liquid extraction of lipophilic wood extractives with fully recyclable extractants

Reactive extraction using organic solvents is regarded as an efficient method for carboxylic acid separation from dilute aqueous solutions. However, when biomass hydrolysates are used as feedstock, the contamination of extraction solvents with undesirable biomass constituents may cause problems at the industrial scale.To identify such impurities and quantify the extent of their negative influence on the extraction efficiency, a solvent of an existing acetic acid biorefinery was analyzed. High amounts of lipophilic wood extractives and minor amounts of solid humin particles were identified in the trioctylphosphine oxide-based solvent. Batch and single-drop extractions with model solutions revealed that wood extractives form complexes with trioctylphosphine oxide, thus reducing the distribution ratio and the mass transfer rate for acetic acid.Therefore, an additional purification process is required that removes the wood extractives from the solvent via liquid-liquid extraction. Five ethanolamine derivatives were screened as aqueous back-extraction solvents and the influence of the extraction parameters (amine concentration and temperature) and of multiple extraction stages was investigated.N,N-dimethylethanolamine was shown to remove 99% of fatty acids under optimized conditions. Residual amine was eliminated from the purified organic phase through washing with water or diluted acid. The aqueous back-extraction solvent could be recycled from the removed impurities via distillation.We showed that lipophilic wood extractives can contaminate organic solvents and severely impair their acetic acid extraction efficiency. We propose a novel method to remove these impurities using fully recyclable ethanolamines to restore the extraction capacity of the solvent. Adding this process to existing plants helps to increase process efficiency, maximize plant availability, and represents an important step towards valorization of previously untapped feedstocks for acetic acid production.

Controlled CO labilization of tungsten carbonyl precursors for the low-temperature synthesis of tungsten diselenide nanocrystals

We report a low-temperature colloidal synthesis of WSe2 nanocrystals from tungsten hexacarbonyl and diphenyl diselenide in trioctylphosphine oxide (TOPO). We identify TOPO-substituted intermediates, W(CO)5TOPO and cis-W(CO)4(TOPO)2 by infrared spectroscopy. To confirm these assignments, we synthesize aryl analogues of phosphine-oxide-substituted intermediates, W(CO)5TPPO (synthesized previously, TPPO = triphenylphosphine oxide) and cis-W(CO)4(TPPO)2 and fac-W(CO)3(TPPO)3 (new structures reported herein). Ligation of the tungsten carbonyl by either the alkyl or aryl phosphine oxides results in facile labilization of the remaining CO, enabling low-temperature decomposition to nucleate WSe2 nanocrystals. The reactivity in phosphine oxides is contrasted with syntheses containing phosphine ligands, where substitution results in decreased CO labilization and higher temperatures are required to induce nanocrystal nucleation.

FeS/FeS2 nanoscale structures synthesized in one step from Fe(ll) dithiocarbamate complexes as a single source precursor.

Nanoscale FeS and FeS2 mixed phases were synthesized by one-pot decomposition of (N-anil-N-piperldtc)Fe1 as FeS#1), (N-piperldtc)Fe2 as FeS#2) and (N-anildtc)Fe3 as FeS#3) complexes as precursors, with the help of tri-n-octylphosphine oxide (TOPO) coordinating solvent. Their morphology, stability, size, optical and structural characteristics were observed using various material characterization instruments. In comparison to the FeS#2 nano-flower shape, FeS#1 and FeS#3 have a uniform nano-rod shape. A one-step decomposition pattern was obtained from the thermal gravimetric analysis (TGA) results with 3% final mass residual. The high-resolution transmission electron microscopy (HRTEM) image reveals an aggregation and size diameter of around 14.47-30.25nm for the three samples. The optical response between 3.8 and 4.2eV from the three samples shows that they are inconsiderable materials for solar cells application. The diffraction peaks for the three samples matched well with the FeS/FeS2. These nanoscale materials can be used in a variety of applications, including lithium-ion batteries, biosensors, hydrogen evolution, and multifunctional nanocomposite materials.

Unraveling the effects of surface functionalization on the catalytic activity of ReSe2 nanostructures towards the hydrogen evolution reaction

Herein, the surface functionalization of ReSe2 nanostructures by surfactants was investigated. This was done to understand how the use of various surfactants affects the catalytic activity of ReSe2 nanostructures towards the hydrogen evolution reaction (HER), and to determine which surfactant would result in maximal exposure of the active edge sites without impeding the catalytic processes of the HER. Oleylamine (OLA), oleic acid (OA), and trioctylphosphine oxide (TOPO) were used as the surfactants. Powder X-ray diffraction confirmed the formation of ReSe2 nanostructures that crystallized in a distorted 1 T phase triclinic system with a P-1 space group. The FTIR, XPS, NMR, and computational studies revealed that the surfactants bind to the surface of the ReSe2 nanostructures through their respective head groups. The ReSe2 nanostructures synthesized using TOPO (ReSe2-TOPO) had the lowest on-set potential, Tafel slope, and overpotential at 10 mA/cm2 at 73 mV, 58 mV/dec, and 171 mV, respectively. The catalytic performance of the nanostructures was significantly affected by their interaction with the surfactants. A high degree of passivation by the surfactant resulted in poor catalytic activity, and a lower degree of passivation resulted in excellent catalytic activity towards the HER.

Separation and Recovery of Cu from Industrial Dust via a Solvometallurgical Process

In this study, a solvometallurgical process for the recovery of Cu from industrial dust by leaching with a lixiviant comprising hydrochloric acid (HCl) and ethylene glycol followed by extraction with trioctylphosphine oxide (TOPO) was developed. Copper, Ni, Mg, and Al contained in the dust were efficiently dissolved by using HCl in ethylene glycol, leaving most of the Ag in the residue. The parameters (concentration of the lixivant, reaction temperature, pulp density) that affect leaching efficiency were extensively investigated and optimized. TOPO was used to selectively extract Cu over other metal ions (Ni, Mg, Al, and Ag) from the obtained leachate. The Cu extraction mechanism was investigated by using the slope method, and 0.1 mol/L sulfuric acid was used to strip Cu from the Cu-loaded TOPO. McCabe–Thiele plots for Cu extraction and stripping were constructed to determine the number of counter-current stages along with the volumetric flow ratio of the two phases. Counter-current Cu extraction and stripping simulation tests were carried out to confirm its feasibility. Finally, a flow diagram of the proposed process for separation and recovery of Cu from industrial dust is provided.

Pushing the Emission Envelope for Full-Color Realization of Colloidal Semiconductor Core/Shell Nanoplatelets

Colloidal semiconductor nanoplatelets (NPLs) have been known to exhibit favorable optical characteristics, such as a narrow emission bandwidth, giant oscillator strength, suppressed Auger recombination, and polarized emission, which can merit their use in light-emitting diodes and lasing devices. However, to date, NPLs have shown a relatively limited range of emission energy because of their thickness-dependent discrete band gap and restricted choice of chemical composition (mostly CdSe-based), impeding the realization of R, G, and B full-color display based on NPLs. CdSe-based core/shell NPLs can only cover the emission range from yellowish green (∼550 nm) to red (∼620 nm). In this study, we synthesize CdZnSe/ZnS core/shell NPLs with significantly enhanced spectral tunability over a broad spectral range (425–570 nm). Particularly, to overcome the difficulty in the synthesis of composition-controlled CdZnSe NPLs, we carried out a Cd-to-Zn direct cation exchange reaction on CdSe/ZnS core/shell NPLs using ZnI2 and an oleylamine (or trioctylphosphine oxide) ligand, which allows for the composition change in NPL emitting core while maintaining the original shape of NPLs. With the control of the reaction temperature and time as well as the ligands, the exchange reaction enables us to demonstrate an unprecedentedly wide emission range and spectral tunability of NPLs with the emission wavelength reaching 425 nm. Furthermore, as the core alloying proceeds, NPLs maintain excellent color purity and exhibit linearly polarized emission. Our light-emitting devices using the cation-exchanged CdZnSe/ZnS NPLs hinted at the possibility of using the NPLs in full-color display applications. Based on the elemental mapping analysis and experimental results, we proposed the temperature-dependent cation exchange reaction process in core/shell NPLs.

Recovery of nicotinic acid (Niacin) using hydrophobic deep eutectic solvent: Ultrasonication facilitated extraction

Hydrophobic deep eutectic solvents (DES) have emerged as alternative environment friendly solvents. Here, DES was prepared using menthol (M) and trioctylphosphine-oxide (TOPO) in the molar ratio of 1:1 and 2:1 to extract nicotinic acid from its aqueous solution ultrasonically. At a molar ratio of 1:1, DES solidified whereas 2:1 remained in the liquid form at room temperature. Physical properties of DES (density, refractive index, and surface tension) were determined. TGA and FTIR analysis were also performed. The highest extraction efficiency (88.33%) and distribution coefficient (7.8) were observed with 0.01 M acid concentration. The used DES was used for 5 successive cycles without regeneration and was further regenerated using 1 N NaOH. The parameters of the extraction column like number of theoretical stages, minimum solvent to feed ratio, diameter and height were proposed for the extraction of nicotinic acid.

Roles of TOPO Coordinating Solvent on Prepared Nano-Flower/Star and Nano-Rods Nickel Sulphides for Solar Cells Applications.

The present study describes a cheap, safe, and stable chemical process for the formation of nickel sulphide (NiS) with the use of mixed and single molecular precursors. The production pathway is uncomplicated, energy-efficient, quick, and toxic-free, with large-scale commercialization potential. The obtained results show the effect of tri-N-octylphosphine oxide (TOPO) as a coordinating solvent on the reaction chemistry, size distributions, morphology, and optical properties of both precursors. Ni[N,N-benz-N-p-anisldtc] as NiSa, Ni[N,N-benzldtc] as NiSb, and Ni[N-p-anisldtc] as NiSc thermally decompose in a single step at 333–334 °C. The X-ray diffraction peaks for NiSa, NiSb, and NiSc matched well with the cubic NiS nanoparticles and corresponded to planes of (111), (220), and (311). The extrapolated linear part from the Tauc plots reveals band gap values of 3.12 eV, 2.95 eV, and 2.5 eV, which confirms the three samples as potential materials for solar cell applications. The transmission electron microscopy (TEM) technique affirmed the quantum dot size distribution at 19.69–28.19 nm for NISa, 9.08–16.63 nm for NISb, and 9.37–10.49 nm for NISc, respectively. NiSa and NiSc show a clearly distinguishable flower/star like morphology, while NiSb displays a compact nano-rod shape. To the best of the authors’ knowledge, very few studies have been reported on the flower/star like and nano-rod shapes, but none with the dithiocarbamate molecular precursor for NiS nanoparticles.

A solution-route processed multicomponent Cu2ZnSn (S1-x Sex)4 nanocrystals: A potential low-cost photocatalyst

An exemplary perspective to comprehend the underlying role of multicomponent nanocrystals such as CZTS/SSe/Se (Cu2ZnSnS4/(SSe)4/Se4) revives the thrust for pioneering the non-vacuum approach for the development of multi-component-based chalcogenides utilizing organic solvents for the formation of nanocrystals, ideal for photo-voltaic/catalysts. This article envisages the employment of Trioctylphosphine (TOP) and Trioctylphosphine Oxide (TOPO) as capping agents cum solvent for CZTS/SSe/Se; the work proceeds with the anionic ratio variations in pristine counterparts of CZTSSe, i.e., to speculate the potential of quaternary chalcogenides where the properties of different materials coalesce and able to improve the characteristics efficiently. Gradually changing the ratio during nanocrystal synthesis via a high-temperature colloidal route imposes precise control over the properties. The synthesized nanocrystals are ingrained in Se-rich and highly crystalline, inhibiting the exigency of selenization and high-temperature annealing. Electrochemical, optical, and structural analysis was intensively studied and the best aliquot Se-ratio was considered to proceed as a photocatalyst. Photocatalysis is an enunciating approach for first aiding wastewater consisting of toxic materials, especially dyes and textile effluents, under sunlight. While, the converging lens deployment uplifts the efficiency and rate of reaction by many folds, it pioneers a new route of energy applications commercially.

Analysis of persistent contaminants and personal care products by dispersive liquid-liquid microextraction using hydrophobic magnetic deep eutectic solvents

In this work, hydrophobic magnetic deep eutectic solvents (HMDESs) were used in the development of a simple and rapid dispersive liquid-liquid microextraction (DLLME) approach coupled to high performance liquid chromatography with UV detection (HPLC-UV) for the determination of ten organic contaminants including five polycyclic aromatic hydrocarbons, four UV filters, and a pesticide from water at trace levels. The HMDESs were prepared by mixing a hydrogen bond acceptor, metal halide salt, and hydrogen bond donor in suitable molar ratios. Two HMDESs, 2 tetraoctylammonium bromide ([N8888+][Br−]): cobalt chloride (CoCl2): 4 octanoic acid (OA) and 3 trioctylphosphine oxide (TOPO): neodymium chloride (NdCl3): 3 OA, offered the highest analyte extraction efficiency overall and were chosen as suitable solvents for validation of the microextraction method. Under optimized extraction conditions, the method required 30 µL of HMDES as extraction solvent, acetone (87.5 µL) as disperser solvent, a NaCl concentration of 30% (w/v), and an extraction time of 120 s at 20°C. Enrichment factors of the analytes ranged from 44.6 for 3-(4-methylbenzylindene) camphor to 66.0 for 2-ethylhexyl-4-(dimethyl)aminobenzoate. The method provided low limits of detection (LODs) ranging from 0.5 to 4.5 µg L−1, and acceptable precision, with RSD values lower than 9.6%. Furthermore, the validated method was successfully applied for tap and lake water analysis, resulting in relative recoveries of spiked samples ranging between 94.7 and 119.2%.

Removal of Co(II) from Water Using Graphene Oxide Functionalized with TOPO

One of the most immensely adsorbents for removing radioactive waste from water is graphene oxide nanosheet (GO). It has a large specific surface area and a variety functional groups, including epoxide, carbonyl, carboxyl, and hydroxyl. This work has prepared GO and functionalized with TOPO (Tri-octyl phosphine oxide). Raman spectroscopy, XRD, High-Resolution Transmission Electron Microscopy (HRTEM), and Fourier transform infrared spectroscopy utilized the unfunctionalized and functionalized GO samples. The results indicate that the produced GO-TOPO adsorbents are very effective Co (II) adsorbents in the acidic medium. The maximum adsorption of Co (II) adsorbed on GO-TOPO was approximately 134 mg/g. The ideal conditions for eliminating Co (II) from water are pH of 6 and temperature 40 °C. Langmuir and Freundlich equations have been used to describe the isothermal data. According to R square, the Langmuir model was better than the Freundlich model.

Surface-Passivated Single-Crystal Micro-Plates for Efficient Perovskite Solar Cells

Perovskite solar cells (PeSCs) prepared with single crystals (SCs) ideally exhibit higher power conversion efficiencies (PCEs) because they possess a lower density of structural imperfection and superior charge transport. However, the density of the surface defects on the SCs is still very high, thereby inevitably affecting the device performance. Herein, perovskite single-crystal micro-plates were grown on a hole-transporting material, poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine], through a space-limited inverse temperature crystallization method. The surfaces of the as-prepared SCs were passivated using trioctylphosphine oxide (TOPO) during the device fabrication to alleviate the impact of surface defects. The PCE values are averagely improved from 11.90 ± 0.30% to 14.76 ± 0.65% after the surface passivation; the champion device even exhibits a PCE of 15.65%. The results from photoluminescence and hole-only devices reveal that TOPO treatments effectively reduce the number of surface defects on the single crystals, thereby improving the photovoltaic performance. The surface passivation also inhibits the hysteresis behavior due to the lower defect density. Finally, the TOPO treatment also improves the stability of the single-crystal PeSCs, presumably due to the hydrophobic long alkyl chains. Thus, this work provides an effective approach to achieving high efficiencies of single-crystal PeSCs.

The optimum conditions of Titanium Recovery process from the Iraqi Bauxite Ore

The present work is especially concerned with the Iraqi bauxite ore that includes 4.1% of titanium element (Ti). The goal of this study is to investigate the effect of various parameters (concentration of acid, ratio of solid: liquid, stirring speed, contact time, and temperature) in order to determine the best conditions for the leaching and extraction of titanium element. All tests of leaching were conducted with different acids (HNO3, H2SO4, and H3PO4) with a ratio of solid: liquid from (1: 100) to (1: 8), the temperature of reaction from (25°C) to (50°C), period of time from (30 min) to (120 min), and speed of stirring from (400 rpm) to (1200 rpm). The best conditions were determined at (1: 100) solid: liquid ratio, (50°C) temperature, (4 M) HNO3 concentration, and (900 rpm) stirring speed. While, the titanium extraction was from leached solution by (trioctylphosphine oxide) (TOPO), tri-n-butyl phosphate (TBP), and di-2- ethylhexyl phosphoric acid (D2EHPA) dissolved in kerosene) with an organic/aqueous ratio of (1/1, 1/2, 1/3, 2/1, and 3/1); temperature of reaction and period of time are correspondingly from (25°C) to (55°C) and from (8 min) to (15 min), and speed of stirring (400 rpm). The best conditions were obtained when using (55°C) temperature, (50%) TOPO concentration, (15 min) contact time, (400 rpm) speed of stirring and (1/3) O/A ratio.