Aqueous Systems

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Interaction mechanisms and kinetics of ferrous ion and hexagonal birnessite in aqueous systems

Interaction mechanisms and kinetics of ferrous ion and hexagonal birnessite in aqueous systems

Reaction rate increased with an increase in tempera- ture (Fig.  11b), suggesting a corresponding increase in oxidation activity of birnessite [20]. Another possibility might be attributed to the increase of adsorption capac- ity as reaction temperature increased. Enhancement of adsorption capacity of birnessite at higher temperatures may be ascribed to the enlargement of pore size and/ or activation of the adsorbent surface (Han et al., 2006). When air was bubbled into the aqueous system, com- pared with the reaction under anoxic condition, reaction rate was increased (Fig. 11a, c) due to the participation of oxygen. The amount of released Mn 2+ increased within

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Cellulosic substrates for removal of pollutants from aqueous systems: A review. 2. dyes

Cellulosic substrates for removal of pollutants from aqueous systems: A review. 2. dyes

The adsorption of color onto various substrates has been extensively studied. As with other technologies, all dyes are not effectively adsorbed, and loadings vary from one substrate to another. Reactive, basic, acid, and azoic dyes can be readily removed using activated carbon (Horning 1978; Foo and Hameed 2010). However, carbon systems are not widely used due to the high cost associated with carbon replacement or regeneration. Adsorption efficiency is affected by solution pH. The presence of other organic and inorganic molecules that compete for adsorption sites may reduce carbon loadings and further increase operating costs. As will be discussed in more detail in later sections, other substrates have been studied, such as chitosan fiber (Yoshida et al. 1991; Yoshida and Takemori 1997), wood chips (Poots and McKay 1976), fly ash (Ramakrishna and Viraraghavan 1997), bagasse (McKay et al. 1987), rice husks, and other biomaterials (Laszlo 1994). These materials have demonstrated adsorption affinity for various dyes but may be selective for a specific type of dye class. Problems associated with material handling, separation, and disposal of these materials have generally discouraged their use on a large scale. The economic availability of these materials is often based on their proximity to the application, which may further limit their use.

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Cellulosic substrates for removal of pollutants from aqueous systems: A review. 1. metals

Cellulosic substrates for removal of pollutants from aqueous systems: A review. 1. metals

Recent years have seen explosive growth in research concerning the use of cellulosic materials, either in their as-recieved state or as modified products, for the removal of heavy metal ions from dilute aqueous solutions. Despite highly promising reports of progress in this area, important questions remain. For instance, it has not been clearly established whether knowledge about the composition and structure of the bioadsorbent raw material is equally important to its availability at its point of use. Various physical and chemical modifications of biomass have been shown to boost the ability of the cellulose-based material to bind various metal ions. Systems of data analysis and mechanistic models are described. There is a continuing need to explain the mechanisms of these approaches and to determine the most effective treatments. Finally, the article probes areas where more research is urgently needed. For example, life cycle analysis studies are needed, comparing the use of renewable biosorbents vs. conventional means of removing toxic metal ions from water.

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Salt release from potato crisps

Salt release from potato crisps

Previous studies within the Division of Food Science at the University of Nottingham have focused both on low viscosity and semi-solid/solid systems. When considering low viscosity aqueous systems the relocation of sodium ions with differing hydrocolloid types (varying free space) in various aqueous– hydrocolloid suspensions 15,16 was shown to impact the percep- tion of free aqueous sodium, additionally changes in sodium availability in starch slurries through the application of buccal amylase 17 changed the delivery of perceived salt; the develop-

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The Effect of Single, Binary and Ternary Anions of Chloride, Carbonate and Phosphate on the Release of 2,4 Dichlorophenoxyacetate Intercalated into the Zn–Al layered Double Hydroxide Nanohybrid

The Effect of Single, Binary and Ternary Anions of Chloride, Carbonate and Phosphate on the Release of 2,4 Dichlorophenoxyacetate Intercalated into the Zn–Al layered Double Hydroxide Nanohybrid

Abstract Intercalation of beneficial anion into inorganic host has lead to an opportunity to synthesize various com- binations of new organic–inorganic nanohybrids with var- ious potential applications; especially, for the controlled release formulation and storage purposes. Investigation on the release behavior of 2,4-dichlorophenoxyacetate (2,4-D) intercalated into the interlayer of Zn–Al-layered double hydroxide (ZAN) have been carried out using single, binary and ternary aqueous systems of chloride, carbonate and phosphate. The release behavior of the active agent 2,4-D from its double-layered hydroxide nanohybrid ZANDI was found to be of controlled manner governed by pseudo- second order kinetics. It was found that carbonate medium yielded the highest accumulated release of 2,4-D, while phosphate in combination with carbonate and/or nitrate speeds up the release rate of 2,4-D. These results indicate that it is possible to design and develop new delivery system of latex stimulant compound with controlled release prop- erty based on 2,4-D that is known as a substance to increase latex production of rubber tree, Hevea brasiliensis.

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Nanostructured Systems Containing Rutin: In Vitro Antioxidant Activity and Photostability Studies

Nanostructured Systems Containing Rutin: In Vitro Antioxidant Activity and Photostability Studies

All these considerations into account, the main objective of our study was to develop aqueous rutin delivery systems and to evaluate the influence of the association of rutin to different nanostructures (nanocapsules and nanoemulsions) on its in vitro antioxidant activity and UV photostability. Nanocapsules and nanoemulsions were compared to establish the importance of the polymeric layer around the nanodroplets by means of a systematic physicochemical characterization of both formulations. The development of such formulations aimed to obtain aqueous systems con- taining rutin, as an intermediate or final pharmaceutical product. To the best of our knowledge, no report on the association of rutin to polymeric nanocapsules is currently available in the scientific literature. The administration of flavonoids by means of nanovectors may be useful for the development of advanced delivery systems for these powerful compounds, in view of their adoption in primary and secondary disease prevention, either for oral or par- enteral administration [33].

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Material Corrosion in Molten Fluoride Salts

Material Corrosion in Molten Fluoride Salts

electrochemical changes. In general, the material corrosion mechanisms in molten fluoride salts are quite similar to those in aqueous solutions. The main corrosion mechanisms in aqueous systems, such as uniform surface corrosion, pitting corrosion, intergranular corrosion and galvanic corrosion, are also common in molten fluoride salts. However, the mechanisms of corrosion attack by molten fluoride salts in MSRs have never been fully understood by researchers in this field. In this paper, it is generally agreed that most corrosion mechanisms in molten fluoride salts involve with electrochemical corrosion.

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Partitioning and Extraction into Perfluorinated-Alcohol Induced Coacervates.

Partitioning and Extraction into Perfluorinated-Alcohol Induced Coacervates.

preparation, one extraction was performed by increasing temperature to cloud point to enrich proteins in small volume detergent-rich phase[14][15]. This is also consistent with sample preparation methods for other ATPSs. Moreover, one more band shows at very top of lane7 with molecular weight higher than 250kDa which could be oligomer of the proteins. The band between 150 and 250 kDa on Lane7 may either be Myosin(205kDa) or dimer of β- Galactosidase(232kDa). ATPS such as CTAB/HFIP, SDS/CTAB/HFIP and DMMAPS/HFIP systems show almost all the proteins except Myosin (rabbit muscle, pI 5.0-5.3) at 205kDa. It seems that surfactants such as SDS, CTAB, and DMMAPS have some limitations in extraction of large proteins such as myosin comparing to nonionic surfactant triton X-114. This could possibly be related to phase viscosity which may limit mass transfer between two phases. There are also other factors such as hydrophobicity difference between two phases. Moreover, it is still unknown about the effect of HFIP in stabilizing the secondary structure that might impact the partitioning behavior in PFAIC systems. Na 2 SO 4 /HFIP draws most of

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Coupling of Plasmas and Liquids.

Coupling of Plasmas and Liquids.

This chapter addresses a couple of fundamental questions regarding plasma-liquids. A qualitative study of the momentum, heat, and mass transport in a convective plasma-liquid system has been conducted in section 2.1. Several interesting results were found. Convective flow of water vapor away from the interface leads to a sharp temperature gradient between the bulk gas and liquid phases. This sharp gradient is important for accurately determining temperature-dependent rate coefficients in both the gas and liquid phases. Additionally, convection drives water vapor away from the discharge region except immediately above the liquid surface; this could have important consequences for gas-phase generation of reactive species that depend on water as a precursor. Induced convection in the liquid phase substantially changes the spatial distribution of aqueous species and increases the volume-averaged uptake of hydrophobic species but interestingly has little effect on the volume-averaged uptake of hydrophilic species. This phenomena occurs because the majority of resistance to interfacial transfer is in the gas phase for hydrophilic species and in the liquid phase for hydrophobic species; consequently, decreasing the liquid-phase mass transfer resistance by adding liquid convection has a significant impact for hydrophobic but not for hydrophilic molecules.

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Kinetics of Cation Exchange Capacity of Homoionic Sodium Form Nay Zeolite

Kinetics of Cation Exchange Capacity of Homoionic Sodium Form Nay Zeolite

The general explanations for this form of kinetic equation involves a variation of the energetic of the exchange process with the active sites are heterogeneous in NaY zeolite/ Ca aqueous solutions system. It will be seen that applicability of the simple Elovich equation for the present kinetic data indicates that the Elovich equation was able to describe the kinetics of the ion exchange of Na Y zeolite/ Ca aqueous solutions systems.

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Identification of phenolic compounds from banana peel (Musa paradaisica L ) as antioxidant and antimicrobial agents

Identification of phenolic compounds from banana peel (Musa paradaisica L ) as antioxidant and antimicrobial agents

From Table (3) the total phenolic of banana peels with different solvent systems showed significant changes in TP, TF and TT contents and the values were also dependent on the solvent polarity. From the results obtained in Table (3) it was observed that the methanolic extract contain the most phenolic and flavonoid contents because it can release the cell wall bound polyphenol from the cells and neutralize the activity of poly phenol oxidase (PPO) which degrades the polyphenol in plants as described by [30].

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Enhanced Desorption of Lindane from an Agricultural Soil Assisted by Cyclodextrin Aqueous Solutions

Enhanced Desorption of Lindane from an Agricultural Soil Assisted by Cyclodextrin Aqueous Solutions

Lindane desorptions from soils using Batch systems are shown in fig. 8 for real soil and model soil, we can see that γ-CD had a very good performance in both cases, this is probably because it has the biggest cavity volume comparing it to α-, and β-CDs, which had similar behaviors removing lindane from contaminated soils, water had a poor performance. We observe also that CDs had better performances in model soil than in real soil; this is probably due to the lack of OM in model soil with witch contaminants can interact and form bonds.

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NMR studies into colloidal stability and magnetic order in fatty acid stabilised aqueous magnetic fluids

NMR studies into colloidal stability and magnetic order in fatty acid stabilised aqueous magnetic fluids

The aqueous alkanoic acid stabilised magnetic colloids are a group of model suspensions for which nanoparticle aggregation has been studied in detail. These suspensions are stabilised by a surface bilayer coating, 10 composed of a primary chemisorbed layer with the carboxylate groups bound to the surface, and a secondary interpenetrating physisorbed layer with the hydrophilic head-groups pointing outwards. Extensive light and neutron scattering, and cryo-TEM studies 11 have shown that in aqueous suspension densely packed nanoparticle clusters are formed, which can be described as having a fractal dimension of B 2.5. This detailed knowledge of the structures formed means that the suspensions are ideal systems for study using magnetic resonance techniques. NMR relaxation studies of fatty-acid stabilised suspension have recently been reported, 12 although that work was limited to the high frequency, clinical MRI, range.

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Partitioning of Cholesterol Oxidase Produced by Streptomyces olivaceus MTCC 6820 in Different PEG-Salt-Water Aqueous Two Phase Systems

Partitioning of Cholesterol Oxidase Produced by Streptomyces olivaceus MTCC 6820 in Different PEG-Salt-Water Aqueous Two Phase Systems

ATPS were developed using PEG-salt-water systems, the top phase is continuous and is rich in PEG while the bottom phase is rich in salt. The enzymes and proteins get easily separated on the top PEG rich phase. ATPS composed of two different molecular weights of PEG-X (X= 4000 and 6000) with four different inorganic salts (ammonium sulphate, potassium phosphate, tri-sodium citrate and sodium sulphate) were used for partitioning of Chox (Table 1 and 2). PEG 4000-ammonium sulphate-water system was found to be the most suitable ATPS for Chox partitioning.

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Characterization and Classification of Solvation Properties of Interactive Phases in Coacervates, MEKC, and RPLC.

Characterization and Classification of Solvation Properties of Interactive Phases in Coacervates, MEKC, and RPLC.

vary greatly with respect to their chemical structures. While all ligands are bound to a silica substrate, the ligands in these columns are C8, C14, C18, C30, phenyl, phenylhexyl, and perfluorinated alkyl chains. In addition, many manufacturers incorporate proprietary embedded groups in these ligands to further enhance selectivity of the bonded phases. Due to the wide range of stationary phase chemistry, it is surprising that the composition of the mobile phase appears to play such an important role in the selectivity of these systems, particularly in the THF based systems. For method development purposes, changing the mobile phase organic modifier appears to be more efficient for altering selectivity than changing the stationary phase. The systems that use THF in the mobile phase cluster in a very narrow region, and are clearly delineated from the systems that use methanol and acetonitrile in the mobile phase. From examining Figure 2-1, this is due to increased hydrogen bond basicity, and decreased hydrogen bond acidity when compared to the systems using acetonitrile (group B) and methanol (group A). An interesting note is that the range of values for all system parameters is more limited for THF based systems than for ACN and MeOH. This is most noticeable for the hydrogen bond basicity strength where the systems have a narrow range of 0.398 ≤ X a ≤

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Interfacial Assembly In Aqueous Two Phase Systems

Interfacial Assembly In Aqueous Two Phase Systems

Stabilizing bio-friendly and cyto-mimetic fluid structures has important implications for drug and gene delivery, micro bio-reactors, single cell and microniche studies, and as protocells. The majority of stabilization techniques have been developed for oil-in-water and water-in-oil emulsions, which have limitations in their application to biological systems due to the presence of the oil phase. The structures built in this thesis are therefore made within water-in-water dispersions. These all water dispersions are from aqueous mixtures of two polymers that demix to form two phases, termed aqueous two phase systems (ATPSs). ATPSs are comprised of two water-rich phases and are therefore excellent candidates for hosting or implantation within biological systems. In this thesis, challenges to stabilizing ATPSs are identified and discussed, including the ultra-low interfacial tension characteristic of these systems, and new strategies are developed to overcome such challenges. The first system studied is that of casein and xanthan (a protein and a polysaccharide) which undergoes spinodal decomposition, resulting in a transient bicontinuous structure. Colloids present in this phase-separating mixture attach at the water-water interface owing to capillarity, despite the low interfacial tension. This occurs for both living and passive colloids. The living colloids, Escherichia coli and

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<p>Characterization and Dissolution Study of Micellar Curcumin-Spray Dried Powder for Oral Delivery</p>

<p>Characterization and Dissolution Study of Micellar Curcumin-Spray Dried Powder for Oral Delivery</p>

Among the above-mentioned delivery systems, poly- meric micelles have recently attracted much attention in overcoming solubility-related problems of curcumin. 14,19 Polymeric micelles, most of them are surfactants, consist of amphiphilic block copolymers that spontaneously assembled into nano-sized structures in aqueous solution. The micellar structure consists of two parts, called the core and the corona. 20 Hydrophobic drugs can be entrapped into their hydrophobic core. In contrast, for reversed micelles, the core is the hydrophilic part. This system can last longer in blood circulation and increase the half- life in the systemic circulation. 21 Furthermore, it has been reported that the encapsulation of curcumin in micelles segregates them from the alkaline environment and prevents them from hydrolysis. 19

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Self assembly of hybrid organic inorganic polyoxovanadates: functionalised mixed valent clusters and molecular cages

Self assembly of hybrid organic inorganic polyoxovanadates: functionalised mixed valent clusters and molecular cages

The synthesis and characterisation of novel functionalised poly- oxometalate (POM) clusters is a current and vibrant research fi eld. 1 The interest in POM-based materials arises from their intrinsic physicochemical attributes which prompt applications in areas such as catalysis, electronics, medicine, environmental sciences, gas storage and energy conversion. 2 Polyoxovanadates can be considered as a prominent sub-class of POMs and a large range of vanadium oxide clusters exhibiting diverse topologies have been discovered. 3 Condensation reactions in aqueous vana- date systems result in small building units that give rise to the formation of closed-shell structures. The structures reported by Müller, Zubieta and Christou clearly demonstrate that the linkage of {VO 5 } polyhedra can be controlled by small

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A Review on Aqueous Two Phase Systems with a Special Mention on Application of Ionic Liquids

A Review on Aqueous Two Phase Systems with a Special Mention on Application of Ionic Liquids

ATPS is used in primary stages of purification of recombinant therapeutic proteins expressed in prokaryotic (E.coli) and eukaryotic (hybridoma, CHO and transgenic plant cells) expression systems and its proved to be cost effective than conventional membrane filtration[17]. A study comparing the yield of α -galactosidase from Aspergillus oryzae using ATPS and conventional ion exchange chromatography showed upto 87% increase in yield of the enzyme by using ATPS[12].

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Affinity Partitioning in Aqueous Two Phase Systems pdf

Affinity Partitioning in Aqueous Two Phase Systems pdf

A convenient way of multiextraction is countercur- rent distribution (CCD). Here a number of top phases are sequentially moved over a set of bottom phases and equilibration takes place after each transfer. The process can be seen as a step-wise chromatography. The original two-phase system, number 0, contains the sample and after that a number (n) of transfers have been carried out n # 1 systems are obtained and the various proteins in the sample are distributed along the CCD train. The CCD process is visualized in Figure 10(A).

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