Agent In Aqueous Phase Research Articles

Cyphos Nitrate Selectively Separates Y(III) from Sr(II) Present in Acidic Feed Solution: An Efficient Ionic Liquid based Extraction Process

AbstractMutual separation of Y(III) and Sr(II) from their waste solution has been an emerging research domain due to their various industrial applications. In this investigation, we emphasize the feasibility of selective separation of Y(III) from Sr(II) present in nitric acid medium using undiluted cyphos nitrate ionic liquid (IL): trihexyl(tetradecyl)phosphonium nitrate ([P66614][NO3]) as the ligating phase. The set experimental parameters were the feed phase acidity, initial nitrate ion concentration, initial feed metal ion concentration, equilibration time and temperature to unveil the efficacy of the proposed system. Efficient extraction of Y(III) selectively in presence of Sr(II) using only a salting agent in aqueous phase without additional extractant in IL phase was highlighted. A remarkable separation factor (SF) obtained for Y(III) over Sr(II) explored the efficacy of the proposed IL system. Y(III) loading in IL phase both in unirradiated and irradiated conditions was compared to evaluate the coordination behavior of irradiated moieties. In addition, a most important advantage of the proposed system is that it employs Milli‐Q water for the back extraction (stripping) of the loaded Y(III) from IL phase and does not demand any complexing agent (water soluble). This undoubtedly corroborates the economic and environmental benefits of the proposed IL system.

Green separation and recovery of cobalt and nickel from sulphuric acid achieved by complexation-assisted solvent extraction

Ternary cathodes account for more than half of the Lithium-Ion Batteries (LIBs) cathode market share and their recycling draws the most attention. Solvent extraction is the most efficient and common method to separate and recover Co and Ni from spent ternary cathode leachates. However, the traditional extraction process produces a large amount of saline wastewater, thus will seriously pollute the environment. In this work, an environmental approach is proposed by adding a water-soluble complexing agent into the aqueous phase, the separation factor is 2 times higher and the consumption of NaOH is 90% reduced compared to the Na-saponified counterpart, which was attributed to the differences of the complexation between metal ions and complexing agent in aqueous phase. The differences in the complexing ability are enhanced with an increased local nucleophilicity index of the active sites along with a reduced molecular volume in complexing agent, thus leading to superior cobalt extraction efficiency (∼98.9%) and separation factor (∼345). In addition, because of the fact that the whole-process pollution control is needed for cleaner chemical production, a green process is developed by recovering additives through Tri-n-butyphosphate. This excellent separation performance suggests that adding complexing agent in solvometallurgical recovery process may aid in the future development of high-purity raw metals for advanced fields.

Normal and reverse AOT micelles assisted interfacial polymerization for polyaniline nanostructures

We report here the synthesis of polyaniline (PANI) nanomaterials using sodium bis (2-ethylhexyl) sulfosuccinate (AOT) micelles assisted chemical oxidative interfacial polymerization. We have employed two interfaces (chloroform-water and hexane-water) and two oxidizing agents (ammonium persulfate and ferric chloride). The anionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT) forms normal micelles in aqueous solution and reverse micelles in hydrophobic solvents like hexane or chloroform. The factors influencing the properties and morphologies of polyaniline nanomaterials such as monomer: surfactant ratio, monomer: oxidant ratio, types of interfaces and oxidants used have been studied. Powder X-ray diffraction of the polyaniline nanomaterials have revealed that polyaniline samples were semi-crystalline in nature. Morphology of polyaniline samples studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have revealed that most of the polyaniline nanomaterials synthesized using ferric chloride possess spherical nature, whereas polyaniline samples synthesized using ammonium persulfate (APS) possess short nanofibers especially at lower aniline/AOT mole ratio in feed (12.5–6.5). The four probe electrical conductivity of the samples were found to be of the order of 1.8 × 10−1 to 8.6 × 10−1 S/cm. Thermal stability of the polyaniline samples recorded by thermogravimetric analysis (TGA) have revealed that polyaniline samples were thermally stable up to 275 °C for 10% weight loss. Interfacial polymerization of aniline monomer using reverse micelles of AOT in hexane phase and ammonium persulfate as oxidizing agent in aqueous phase have been proved to be efficient method for the synthesis of short polyaniline nanofibers.

Preparation of hollow Ag/Pt heterostructures on TiO2 nanowires and their catalytic properties

A novel titanate (TiO2) nanowire (NW)@hollow silver (Ag)/platinum (Pt) heterostructure was fabricated by means of a simple wet chemical method. Briefly, Ag nanoparticles with ∼20nm in diameter were grown onto TiO2 nanowires, subsequently PtO shells with ∼1 to 4nm in thickness were deposited upon the Ag nanoparticles to form TiO2–NW@Ag–NP@PtO nanostructures. The hollow Ag-/PtOx nanostructures were achieved from Ag–NP@PtO nanostructures by outward diffusion of Ag elements from Ag–NP core to PtO shell via H2O2 treatment. Finally, hollow Ag/Pt heterostructures with diameter of approximately 20nm were synthesized by reduction of the hollow Ag-/PtOx nanostructures. Given the accessible interfaces of bimetallic Ag/Pt shell, the catalytic efficiency of the TiO2 NW@hollow Ag/Pt heterostructures was significantly enhanced, which was confirmed by the hydrogenation of p-nitrophenol into p-aminophenol with NaBH4 as reducing agent in aqueous phase. The conversion rate of p-nitrophenol was yielded as high as ∼95% for 9min under ambient atmosphere and room temperature.

Dependence of Crystal Growth of Gold Nanoparticles on the Capping Behavior of Surfactant at Ambient Conditions

A seed-mediated approach was applied to synthesize gold (Au) nanoparticles (NP) by using twin tail alkylammonium cationic surfactants such as 12-6-12 and 12-0-12 as capping agents in aqueous phase at ambient conditions. The growth of Au NP was monitored by changing the amount of seed. Spherical NP (10–50nm) and nanorods (aspect ratio = 2–3) were obtained in the presence of 12-6-12 as capping agent; their shape and size systematically deformed because of anisotropic growth with a decrease in the amount of seed. In contrast, when 12-0-12 was used as a capping agent, no anisotropic growth was observed. An effective liquid/solid interfacial adsorption of 12-0-12 prevented anisotropic growth which led to precise morphologies. This was not observed in the case of 12-6-12 because of the presence of a spacer which restricted an effective interfacial adsorption because of the steric factors. XPS and FTIR studies clearly indicated the presence of a surfactant film on the surface of Au NP, while XRD analysis demonstrated a difference in the preferential adsorption of 12-6-12 and 12-0-12 at different crystal planes of fcc geometry which resulted in a difference in their capping behaviors.

Design Bases for Modulated Complexation by Electrochemistry

The treatment of liquid organic phases to remove undesirable compounds is currently a priority in different industries. In oil refinery, it is necessary to reduce sulphur compounds, in gasolines, to below 50 ppm.The traditional form is catalytic hydrodesulphuration; however, this system is not effective for some compounds, e.g., alkyl substituted dibenzothiophenes. The processes for modulated complexation by electrochemistry are based on the capacity of a complexing agent, in a certain oxidation state, to form a bond with the molecule to be removed from a liquid phase. If the contaminant, the solute, is in an organic phase, the complexant must be soluble in aqueous phase. When the complexant is formed and in contact with both phases the contaminant is extracted. In a second stage, the complexing agent is oxidized (or reduced) to a state of less affinity to the contaminant, and the aqueous phase is placed in contact with a new organic phase where the contaminant will be discharged and concentrated. The complexant agent in aqueous phase is reduced (or oxidized) to its state of higher affinity for the contaminant and recirculated to the extraction stage. In this work, we present the conditions necessary for this process to be feasible, the criteria for the selection of the complexes, the methodology for matter balances, determination of energy consumption and thermodynamic calculations, and also three examples of an organic phase: dibenzotiophene, pyridine, and methyl thioether, using as complexing agent iron tetrakis-(p-sulphonatophenyl) porphyrin.

Corrosion mechanisms of steel concrete moulds in the presence of a demoulding agent

The behaviour of E24 mild steel, the constituent steel of most moulds for concrete, was studied by voltamperometry and electrochemical impedance spectroscopy in two electrolytes: (i) a filtered cement solution and (ii) a homogeneous mortar without large air cavities. Experiments were carried out with and without Aquadem®, a demoulding agent in aqueous phase. In the filtered cement solution, the E24 steel is passivated and the passivation mechanism is totally controlled by the anodic process, not by oxygen reduction. Whatever the experimental conditions (O2 concentration, rotation speed, immersion time), the corrosion current, i cor, is equal to the anodic plateau current and is of the order of 0.8 μA cm−2. Therefore i cor can be directly assessed from the steady state current–potential curves. The E24 steel in contact with a homogeneous mortar without large air cavities is passivated as well as in the filtered cement solution. For both electrolytes, the results are independent of the presence or absence of Aquadem®. Therefore the pitting corrosion observed in service conditions does not arise from the presence of a solid phase in the electrolyte but may result from the heterogeneity of concrete created by air cavities.

The influence of different salting-out agents on the extraction of Ce, Eu, Gd, Tb using tri-n-butyl phosphate

The extraction enthalpies ΔHo of Ce, Eu, Gd, Tb nitrates usingTBP in the presence of different salting-out agents in aqueous phase were determined. It was established that the extraction process is the most exothermic in the case of LiNO3.

Preparation of a water-soluble acylating agent: benzoylation of acids, amines, and phenols with 2-benzoylthio-1-methylpyridinium chloride in aqueous phase

2-Benzoylthio-1-methylpyridinium chloride, prepared from benzoyl chloride and 1-methyl-2(1H)-pyridothione, is found to act as an acylating agent in aqueous phase.