Concentration In Aqueous Phase Research Articles

Determination and correlation of liquid–liquid equilibrium data for the dichloromethane + water + N,N-dimethylacetamide + NaCl system

The (liquid+liquid) equilibrium (LLE) data for the quaternary system dichloromethane (DCM)+water+N,N-dimethylacetamide (DMAC)+NaCl have been determined at (298.15 and 308.15)K and atmospheric pressure. The experimental data were correlated by using Othmer–Tobias equation, and all the linear correlation coefficients were approximate to 1. Both NRTL and UNIQUAC models were adopted to correlate the LLE data, the model parameters were regressed by nonlinear least-squares method, then the LLE data of the quaternary system were calculated. The comparison between calculated and experimental data shows good agreement. The results show that the enlargement of two-phase region occurred with an increase of salt concentration in initial aqueous phase, and adding salt to the system is beneficial to increase the selectivity of solvent.

Development of novel composite antioxidant multiple lipid particles from combination of W/O/W multiple emulsions and solid lipid nanoparticles

A novel drug delivery system, multiple solid particles (MLPs), combining the advantages of water‐in‐oil‐in‐water (W/O/W) multiple emulsions and solid lipid nanoparticles (SLN) was proposed. The MLPs were produced by simply adding the solid lipid in liquid lipid of W/O/W multiple emulsions and removing the outer aqueous phase of W/O/W multiple emulsions. MLPs could form typical W/O/W multiple emulsion microstructure by self‐emulsifying after dispersing in water. MLPs were used to encapsulate both coenzyme Q10 and tea polyphenols (CT‐MLPs), and encapsulation efficiency measurement revealed that both coenzyme Q10 and tea polyphenols had high encapsulation efficiency (98.14% and 99.36%, respectively). The effect of the factors on viscosity, stability, and solubility of CT‐MLPs were investigated, and the results showed that increasing the concentration of solid lipid glycerin monostearate or hydrophilic emulsifier polyglyceryl‐10 laurate, or decreasing the concentration of the inner aqueous phase could increase the viscosity of CT‐MLPs. Consequently, the stability of CT‐MLPs was improved by increasing the viscosity of the oil phase. Moreover, addition of glycerin monostearate also increased the water solubility of CT‐MLPs. During a 60‐day stability study, CT‐MLPs showed terrific stability and high retention ratio (above 83.82%) at various conditions.Practical applications: MLPs could act as a drug delivery system to encapsulate both lipophilic active compounds and hydrophilic active compounds, since the active compounds in MLPs had high encapsulation efficiency. MLPs also improved the photostability and storage stability of coenzyme Q10 and tea polyphenols. Furthermore, the production procedure of MLPs is a two‐step stirring method, which is widespread and easy to handle. And the lipids for producing MLPs are physiological lipids, the choice of emulsifiers depends on the administration route. With regard to industrial production aspects, MLPs have the chance to be exploited as drug delivery system in commercial products. Hence, MLPs could be applicable delivery systems for food, cosmetic, and pharmaceutical applications.CT‐MLPs were prepared by a two‐step method and exhibited solidity at room temperature. CT‐MLPs could form typical W/O/W multiple emulsion microstructure by self‐emulsifying after dispersing in water.

Critical attributes of formulation and of elaboration process of PLGA-protein microparticles

Low drug loading, burst effect during release and drug inactivation account for the main drawbacks of protein microencapsulation in poly(d,l-lactic-co-glycolic) acid (PLGA) matrix by the water-in oil-in water (W/O/W) solvent evaporation method. Thus, the current study was set to invest the critical attributes of formulation and of elaboration process which determine protein loading into microparticles as well as its further release, using albumin as protein model.NaCl concentration in the external aqueous phase, poly(vinyl alcohol) (PVA) concentration and mostly viscosity of both the internal aqueous phase and the organic phase were critical attributes for improving drug loading, with polymer molecular weight and hydrophobicity likewise directly related to albumin loading. In such a way, when using 0.5% PVA as internal aqueous phase the highest albumin loading was achieved. Optimized microparticles exhibited a sustained in vitro release of albumin over 130 days. The influence of the microencapsulation process on albumin stability and biological activity was evaluated by carrying out cell proliferation assays on PC12 cells with albumin released from microparticles. Such assay demonstrated that the microencapsulation procedure optimized in this study did not affect the biological stability of the microencapsulated protein.

Caffeic Acid Phenethyl Ester Loaded PLGA Nanoparticles: Effect of Various Process Parameters on Reaction Yield, Encapsulation Efficiency, and Particle Size

CAPE loaded PLGA nanoparticles were prepared using the oil in water (o/w) single emulsion solvent evaporation methods. Five different processing parameters including initial CAPE amount, initial PLGA amount, PVA concentration in aqueous phase, PVA volume, and solvent type were screened systematically to improve encapsulation of hydrophobic CAPE molecule, simultaneously minimize particle size, and raise the reaction yield. Obtained results showed that the encapsulation efficiency of the nanoparticles significantly increased with the increase of the initial CAPE amount (p < 0.05) and particle size (p < 0.05). Furthermore, the particle size is significantly influenced by initial polymer amount (p < 0.05) and surfactant concentration (p < 0.05). By the optimization of process parameters, the nanoparticles produced 70 ± 6% reaction yield, 89 ± 3% encapsulation efficiency, −34.4 ± 2.5 mV zeta potential, and 163 ± 2 nm particle size with low polydispersity index 0.119 ± 0.002. The particle size and surface morphology of optimized nanoparticles were studied and analyses showed that the nanoparticles have uniform size distribution, smooth surface, and spherical shape. Lyophilized nanoparticles with different CAPE and PLGA concentration in formulation were examined for in vitro release at physiological pH. Interestingly, the optimized nanoparticles showed a high (83.08%) and sustained CAPE release (lasting for 16 days) compared to nonoptimized nanoparticle.

泡沫萃取法处理含铊工业废水的研究

本研究利用泡沫萃取法处理含铊工业废水，分离泡沫相和水相，通过火焰原子吸收分光光度法测定水相中铊浓度。采用泡沫萃取法能够有效的去除含铊重金属废水，尤其对基质较复杂，盐基度高废水有良好的去除效果。实验结果表明：当废水与萃取剂体积比125:1和50:1，铊去除率达80%和95%。该方法污染小、效果稳定、操作简便。 This study used Flota-extraction to treat Tl-bearing industrial wastewater, separation aqueous phase and foam layer, through flame atomic absorption spectrophotometric method to detect thallium concentration in aqueous phase. Using Foam-Extraction method can effectively remove heavy metal waste water containing thallium, especially for waste water with complex contaminant and a high salinity has good removal effect. By experimental verification, the ratio of wastewater to extractant is 125:1 and 50:1, the removal rate of Tl could reach 80% and 95%. This method has got the characteristics of lower pollution, steady effect and user-friendly control.

Development of enoxaparin sodium polymeric microparticles for colon-specific delivery.

Background and aimsRecent studies have shown that low molecular weight heparins are effective in the treatment of inflammatory bowel disease. Therefore, there is considerable interest in the development of an oral colonic delivery pharmaceutical system allowing targeted release of heparin in the inflamed tissue. The objective of this study was to prepare microparticles for the oral administration and colonic release of enoxaparin and to evaluate the influence of certain formulation factors on their characteristics.MethodsMicroparticles were prepared by water/oil/water double emulsion technique followed by solvent evaporation. The influence of several formulation factors on the characteristics of microparticles were evaluated. The formulation factors were alginate concentration in the inner aqueous phase, polymer (Eudragit® FS 30D and Eudragit® RS PO) concentration in the organic phase and ratios between the two polymers. The microparticles were characterized in terms of morphology, size, entrapment efficiency and enoxaparin release.ResultsThe results showed that increasing sodium alginate percentage reduced the encapsulation efficiency of enoxaparin and accelerated enoxaparin release. Regarding the influence of the two polymers, reducing polymer concentration in the organic phase led to a smaller size of microparticles, a lower entrapment efficiency and an important retardation of enoxaparin release. The formulation prepared with Eudragit® FS 30D limited the release to a maximum of 3% in gastric simulated environment, a specific characteristic of oral systems for colonic delivery, and fulfilled our objective to delay the release.ConclusionsMicroparticles prepared with Eudragit® FS 30D represent a suitable and potential oral system for the colonic delivery of enoxaparin.

In situ measurement and simulation of nano-magnetite mobility in porous media subject to transient salinity.

Nanotechnologies have been proposed for a variety of environmental applications, including subsurface characterization, enhanced oil recovery, and in situ contaminant remediation. For such applications, quantitative predictive models will be of great utility for system design and implementation. Electrolyte chemistry, which can vary substantially within subsurface pore waters, has been shown to strongly influence nanoparticle aggregation and deposition in porous media. Thus, it is essential that mathematical models be capable of tracking changes in electrolyte chemistry and predicting its influence on nanoparticle mobility. In this work, a modified version of a multi-dimensional multispecies transport simulator (SEAWAT) was employed to model nanoparticle transport under transient electrolyte conditions. The modeling effort was supported by experimental measurements of paramagnetic magnetite (Fe3O4) nanoparticle, coated with polyacrylamide-methylpropane sulfonic acid - lauryl acrylate (nMag-PAMPS), mobility in columns packed with 40-50 mesh Ottawa sand. Column effluent analyses and magnetic resonance imaging (MRI) were used to quantify nanoparticle breakthrough and in situ aqueous phase concentrations, respectively. Experimental observations revealed that introduction of de-ionized water into the brine saturated column (80 g L(-1) NaCl + 20 g L(-1) CaCl2) promoted release and remobilization of deposited nanoparticles along a diagonal front, coincident with the variable density flow field. This behavior was accurately captured by the simulation results, which indicated that a two-site deposition-release model provided the best fit to experimental observations, suggesting that heterogeneous nanoparticle-surface interactions governed nanoparticle attachment. These findings illustrate the importance of accounting for both physical and chemical processes associated with changes in electrolyte chemistry when predicting nanoparticle transport behavior in subsurface formations.

Study of Pickering emulsion stabilized by sulfonated cellulose nanowhiskers extracted from sisal fiber

Sulfonated cellulose nanowhiskers (sulfonated CNWs), a kind of needle-like colloidal particles, could be obtained through sulfuric acid hydrolysis of microcrystal cellulose extracted from sisal fibers. Here, stable Pickering emulsions were prepared using the sulfonated CNWs as a stabilizer. The effects of the sulfonated CNW concentration in aqueous phase, volume ratio of water to oil, oil type, and the pH value on the stability, type, and morphology of these emulsions were investigated. The average droplet size decreases with increasing sulfonated CNW concentration and volume ratio of water to oil. Many types of oil phase were stabilized by sulfonated CNWs to form stable oil-in-water (o/w) Pickering emulsion only by adjusting the pH value of water phase. In addition, poly(methyl methacrylate)PMMA/sulfnated CNW composite microspheres were fabricated by solvent volatilization of the as-prepared Pickering emulsion. Confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) studies confirmed that sulfonated CNWs adsorbed on the surface of the PMMA microparticles. With the interesting renewability and biodegradability of the sulfonated cellulose nanowhisker, these PMMA@sulfonated CNW composite microsphere could find great potential application in food, cosmetics, drug delivery, and biological tissue engineering, etc.

Highly Selective Solvent Extraction of Zn(II) and Cu(II) from Acidic Aqueous Chloride Solutions with Mixture of Cyanex 272 and Aliquat 336

Selective solvent extraction of zinc(II) and copper(II) from aqueous acidic chloride solutions by mixture of bis(2,2,4-trimethylpentyl)phosphinic acid (Cyanex 272) and trioctymethylammonium chloride (Aliquat 336) in kerosene has been investigated. Detailed studies have been conducted by varying pH, hydrochloric acid, and chloride concentrations in aqueous phase as well as extractants concentration in organic phase. A full and high selective solvent extraction of zinc(II) over copper(II) from acidic chloride solutions has been achieved by 0.1 M Cyanex 272 and 0.06 M Aliquat 336 in kerosene while efficient Zn(II) stripping has been performed by using 1 M sulphuric acid. The following selectivity coefficients of zinc(II) over Cu(II) (SZn/Cu) during their solvent extraction from 1 M NaCl at pH 0.5 by Cyanex 272, Aliquat 336, and their mixture were found to be equal to: 1.7, 62, and 3162, respectively.

Effect of nanosize micelles of ionic and neutral surfactants on the photophysics of protonated 6-methoxyquinoline: Time-resolved fluorescence study

The excited state dynamic studies have been carried out to investigate the effects of micellar surface charge on the photophysics of protonated 6-methoxyquinoline (6MQ+) in anionic, sodium dodecylsulphate (SDS), cationic, cetyltrimethylammonium bromide (CTAB) and neutral, triton X-100 (TX100) surfactant at premicellar, micellar and postmicellar concentrations in aqueous phase at room temperature. At premicellar concentrations of SDS, there is a slight decrease in emission intensity and at micellar and postmicellar concentrations, increase in emission intensity and blue shift of spectrum has been observed. The blue shift in fluorescence spectrum and slight increase in quantum yield are attributed to incorporation of solute molecule to the micelles. Edge excitation red shift (EERS) in fluorescence maximum of 6MQ+ has been observed in all the surfactant solutions studied. The EERS has been ascribed in terms of solvent relaxation process. In SDS surfactant system, due to heterogeneous restricted motion of solvent molecules, the solvent viscosity increases which results in an increase in net magnitude of EERS. The fluorescence decay components of 6MQ+ fit with multi exponential functions in all the micellar systems studied. The location of the probe molecule in micellar systems is justified by a variety of spectral parameters such as refractive index, dielectric constant, ET (30), EERS, average fluorescence decay time, radiative and non radiative rate constants, and rotational relaxation time.

Prediction of methanol loss in liquid hydrocarbon phase during natural gas hydrate inhibition using rigorous models

Methanol is the most widely used natural gas hydrate inhibitor and it is only effective as a hydrate inhibitor in the aqueous phase. Methanol is not regenerated in natural gas inhibition process due to its intermittent application in most cases. However, a significant cost is associated with the process because of methanol loss while utilizing this inhibitor. In this work, several intelligent models along with a new mathematical correlation are presented in terms of methanol concentration in aqueous phase and temperature to precisely forecast the methanol loss in the saturated hydrocarbons phase. An excellent match was noticed between the calculated results and literature data.

High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling

Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently dipping mudstones. Despite more than 18years of pump and treat (P&T) remediation, and natural attenuation processes, CVOC concentrations in aqueous samples pumped from these deeper strata remain elevated in isolated intervals. DNAPL was detected in one borehole during coring at a depth of 27m. In contrast to core samples from the weathered zone, concentrations in core samples from deeper unweathered and unfractured strata are typically below detection. However, high CVOC concentrations were found in isolated samples from fissile black carbon-rich strata and fractured gray laminated strata. Aqueous-phase concentrations were correspondingly high in samples pumped from these strata via short-interval wells or packer-isolated zones in long boreholes. A refined conceptual site model considers that prior to P&T remediation groundwater flow was primarily subhorizontal in the higher-permeability near surface strata, and the bulk of contaminant mass was shallow. CVOCs diffused into these fractured and weathered mudstones. DNAPL and high concentrations of CVOCs migrated slowly down in deeper unweathered strata, primarily along isolated dipping bedding-plane fractures. After P&T began in 1995, using wells open to both shallow and deep strata, downward transport of dissolved CVOCs accelerated. Diffusion of TCE and other CVOCs from deeper fractures penetrated only a few centimeters into the unweathered rock matrix, likely due to sorption of CVOCs on rock organic carbon. Remediation in the deep, unweathered strata may benefit from the relatively limited migration of CVOCs into the rock matrix. Synthesis of rock core sampling from closely spaced boreholes with geophysical logging and hydraulic testing improves understanding of the controls on CVOC delineation and informs remediation design and monitoring.

Bacterial exudate effects on Cu2+ sorption by cells: Quantifying significant ternary interactions

Bacteria exude a range of ligands which have diverse effects on trace metal geochemistry. This study evaluated the effect of ligands exuded by the bacterium Anoxybacillus flavithermus on the aqueous geochemistry of Cu2+. Proton and Cu2+ binding by the exudate ligands were investigated via potentiometric titrations and polarographic studies, respectively. Despite the apparent complexity of the system the Cu2+–exudate interaction was well described by a single model reaction H2L+Cu2+⇔LCu+2H+. In a bacterial cell suspension the aqueous phase concentration of exudate ligands increased almost linearly with the age of the suspension. After 48h the exuded ligands had roughly the same total binding capacity for Cu2+ as the cells from which they were derived. To investigate the significance of the exudate on Cu2+ uptake by the bacterial cells sorption experiments were conducted in ternary systems with bacterial cells and a range of concentrations of a well characterized exudate. The systems were modeled with the parameters derived from the binary Cu2+–cells and Cu2+–exudate experiments. Under conditions where the binary model parameters predicted that the exudate ligand would hold all of the Cu2+ in solution there was unexpectedly appreciable Cu2+ sorption by the cells. This indicated the presence of significant ternary interactions involving the Cu2+, the cell surface sites and the exudate. The observations could be reasonably well described by adding to the binary model reactions a single reaction for a ternary complex with stoichiometry R2CuLH0 where R2 represents a cell wall binding site. The exudate ligands produced by bacterial cells had a significant effect on Cu2+ partitioning between the solution and solid phases under the experimental conditions employed. However, the study shows that the strong complexes that exudate ligands can form with trace metals do not necessarily inhibit trace metal uptake by cells to the extent expected from first principles.

Cucurbita pepo oil as a drug microemulsion formulation: study of phase diagram

Objective(s): Investigation of phase diagram of various drug formulations is effective to predict different phase region of drugs to detect final formula. The purpose of this research was to develop the ternary phase diagrams for a drug microemulsion system consisting of Cucurbita pepo (pumpkin) oil, surfactant (Tween 80) and deionized water. Materials and Methods: An electrical conductivity was used to study the properties of system. Particle size analysis of microemulsion system was performed by dynamic light scattering. Results: The electrical conductivity of the microemulsions increases with increasing of aqueous phase content. Structural transitions from the oil-in-water to a bi-continuous phase then inversion to water-in-oil occured in the system. Diameter of particles was calculated 70 nm (for 75 percent of particles) and 35 nm (for 25 percent of particles). Solubility results showed that microemulsion system of Cucurbita pepo oil can increase its solubility in aqueous medium due to droplet size reduction into nanometer size. Conclusion: Microemulsion technique can be used as a successful method in preparation of Cucurbita pepo oil drug formulation.

Assessing worker exposure to inhaled volatile organic compounds from Marcellus Shale flowback pits

Natural gas drilling sites employing hydraulic fracturing present a potential source of inhalation exposure to volatile organic compounds (VOCs) via the use of flowback pits. These open-air pits are used as a means of storing flowback water, a waste product of hydraulic fracturing, and represent an understudied source of VOC exposure for workers. The objective of this study was to assess this worker exposure and the resulting health risks for 12 VOCs present in flowback water stored in such an open reservoir on a drilling site. Flowback pit VOC mean, 2.5 percentile, and 97.5 percentile concentrations were used to model aqueous phase concentrations, and two models of volatilization were applied to estimate flux to the gas phase. A mass-balance approach was used to estimate gas phase concentrations that were, in turn, used to estimate worker exposure. A literature review was performed to determine VOC health effects, exposure limits, and worker protection methods. Neither model demonstrated an increased risk of adverse effects due to subchronic exposure at the 2.5 percentile and mean concentration values for the 12 VOCs as indicated by hazard quotients, hazard indices, or excess lifetime cancer risks; however, 97.5 percentile hazard indices approached 1 in one model and did demonstrate unacceptable risks in the evaluation of limitations. Either model may apply to worker health assessment depending upon industry practice; however, differing weather conditions, industry practice, and the small number of VOCs evaluated necessitate further research regarding worker risks and health effects.

Thin-film composite membranes formed by interfacial polymerization with natural material sericin and trimesoyl chloride for nanofiltration

Novel flat-sheet thin-film composite membranes for nanofiltration were fabricated through interfacial polymerization of natural polymer sericin and trimesoyl chloride (TMC) on porous polysulfone support membrane. The preparation parameters including pH of aqueous phase, reaction time, curing temperature, curing time, sericin content and TMC concentration were investigated. The properties of the resultant membrane were characterized in terms of surface chemical structure, morphological structure, surface zeta potential, pure water flux, molecular weight cut-off (MWCO), pore size and rejections to different solutes including electrolytes and organic anionic dyes. It was found that the obtained sericin–TMC composite membranes had smooth and amphoteric surfaces with an isoelectric point at pH about 4.1. The membrane with a MWCO of 880g/mol had a pure water permeability of 11.9l/m2hbar and exhibited a salt rejection order of MgCl2 (22.5%)<MgSO4 (40.5%)≈NaCl (40.8%)<Na2SO4 (95.4%) at neutral pH. The dye removal tests indicated that the obtained membrane could effectively reject the organic anionic dyes at neutral pH with good anti-fouling property, especially for the dyes with relatively higher molecular weight and/or more negative charge. Moreover, compared with the commercial nanofiltration membrane NF270, the developed sericin–TMC composite nanofiltration membrane possessed better antifouling property.

Extractive and sorption preconcentration of rhenium(VII) with the use of phosphoryl-containing podands

Interphase distribution of micro amounts of ReO 4 − between aqueous solutions of mineral acids and solutions of phosphoryl-containing mono-, di-, and tripodands, derived from 1-(methoxydiphenylphosphoryl)-2-diphenylphosphorylbenzene in dichloroethane was studied. The stoichiometry of extracted complexes was determined, the effect of HNO3, HCl, and H2SO4 concentration in aqueous phase and the nature of organic solvent on the efficiency of transition of ions into organic phase was considered. The growth of the number of phosphoryl groups in podand molecule enhances its extraction ability toward Re(VII). The possibility of selective recovery and preconcentration of Re(VII) with complexing sorbent obtained by noncovalent binding of phosphoryl-containing podand on the surface of macroporous polymer Amberlite XAD7HP was shown.

Development of performance matrix for generic product equivalence of acyclovir topical creams

The effect of process variability on physicochemical characteristics and in vitro performance of qualitatively (Q1) and quantitatively (Q2) equivalent generic acyclovir topical dermatological creams was investigated to develop a matrix of standards for determining their in vitro bioequivalence with reference listed drug (RLD) product (Zovirax®). A fractional factorial design of experiment (DOE) with triplicate center point was used to create 11 acyclovir cream formulations with manufacturing variables such as pH of aqueous phase, emulsification time, homogenization speed, and emulsification temperature. Three more formulations (F-12–F-14) with drug particle size representing RLD were also prepared where the pH of the final product was adjusted. The formulations were subjected to physicochemical characterization (drug particle size, spreadability, viscosity, pH, and drug concentration in aqueous phase) and in vitro drug release studies against RLD. The results demonstrated that DOE formulations were structurally and functionally (e.g., drug release) similar (Q3) to RLD. Moreover, in vitro drug permeation studies showed that extent of drug bioavailability/retention in human epidermis from F-12–F-14 were similar to RLD, although differed in rate of permeation. The results suggested generic acyclovir creams can be manufactured to obtain identical performance as that of RLD with Q1/Q2/Q3.

Synergistic Solvent Extraction and Transport of Zn(II) and Cu(II) across Polymer Inclusion Membranes with a Mixture of TOPO and Aliquat 336

Separation of zinc(II) and copper(II) ions from aqueous solutions by synergistic extraction and transport through polymer inclusion membranes (PIMs) has been investigated. A mixture of trioctylphosphine oxide (TOPO) and trioctymethylammonium chloride (Aliquat 336) was used as a selective extractant as well as an ion carrier in polymer membranes. The effects of hydrochloric acid concentration in the aqueous phase and extractants concentration in the organic phase on the separation process of zinc(II) and copper(II) ions have been studied. Zn(II) ions were successfully separated from Cu(II) ions in solvent extraction process using 0.025 M TOPO and 0.06 M Aliquat 336 in kerosene. Polymer inclusion membranes (PIMs) containing a mixture of TOPO and Aliquat 336 as the ion carrier have been prepared and the facilitated transport of Zn(II) and Cu(II) ions has been studied. The influence of membrane composition on the transport kinetic of Zn(II) and Cu(II) has been evaluated. Zn(II) ions were preferably transported from the aqueous solutions containing Cu(II) and above 87% of Zn(II) ions were effectively recovered from the 0.5 M HCl solution as the source phase through PIM into 0.5 M H2SO4 as the stripping phase.

Factors controlling radiocesium distribution in river sediments: Field and laboratory studies after the Fukushima Dai-ichi Nuclear Power Plant accident

This study used laboratorial estimations and determined the distribution coefficient (Kd) of 137Cs in river sediments sampled from the Abukuma River and the Kuchibuto River to investigate the particle size dependence of RCs distribution. Results show that the Kd patterns of 137Cs (particle size-dependence of Kd) were not only related to the particle size of large particles (low clay mineral content) but also to the clay mineral content of small particles (high clay mineral content) and particularly cation concentration in aqueous phase. By contrast, the Kd patterns of stable Cs (133Cs) exhibited no obvious particle size dependence. Adsorption species of Cs that was added to the river sediments at various particle sizes was almost the same at the molecular scale as determined by the extended X-ray absorption fine structure.Our findings indicate that river sediments have high fixation ability to 137Cs. Nevertheless, adsorbed 137Cs can be extracted from sediments in the water phase when salinity becomes high, such as that in seawater. The distribution patterns of 137Cs at various particle sizes can slowly down the equilibrium of the adsorption of 137Cs during the transportation of river sediments, and then the behavior of 137Cs should eventually be similar to that of stable Cs in the river system. Therefore, the particle size of sediments is an important factor in the distribution of RCs at the early stage of its deposition. In the end, RCs adsorbed on the sediments will be equilibrated with the stable Cs during its transportation in the river system. Controlling factors such as the mineralogy of sediments could possibly make the distribution patterns of RCs similar to that of stable Cs in the long run.