Synthesis, Characterization and Properties of New Lauryl Amidopropyl Trimethyl Ammoniums

A new lauryl amidopropyl trimethyl ammonium methyl carbonate with the formula CH₃(CH₂)₁₀CONH(CH₂)₃N⁺(CH₃)₃CH₃CO₃ ^? was synthesized via a high pressure process with tertiary amines and dimethyl carbonate, and its chemical structure was confirmed using ¹H-NMR spectra, mass spectral fragmentation, and FTIR spectroscopic analysis. In addition, several quaternary ammonium salts with new counterions X^? (X^?=HCO₃ ^?, HCOO^?, CH₃COO^?, CH₃CH(OH)COO^?) were also synthesized by the ion exchange reaction of methyl carbonate quaternary ammoniums with corresponding acids. The surface activities of these compounds were measured, including surface tension (??), critical micelle concentration and minimum surface area (A _min) at 25?°C. Adsorption and micellization free energies of these quaternary ammonium salts in their solutions showed a good tendency towards adsorption at interfaces. The antimicrobial activities are reported for the first time against representative bacteria and fungi for lauryl amidopropyl trimethyl ammoniums. It was found that the antimicrobial potency was Gram-positive bacteria?>?fungi?>?Gram-negative bacteria.     

Versuche zur trennung der anionen nitrat,nitrit, hyponitrit und nitrohydroxylaminat am anionenaustauscher wofatit SBW

The separation of NO₃^?, NO₂^?, N₂O₂^2? and N₂O₃^2? has been studied by elutionchromatography on the strong basic anion-exchange resin Wofatit SBW. The solutions proper for elution-chromatography have been chosen on basis of measured anion-affinities. Quantitative separations were obtained with the mixtures of N₂O₂^2?, NO₂^? and NO₃^? as well as of N₂O₃^2?, NO₂^? and NO₃^? with a solution of Na₂SO₄. Both separation methods can be applied to prepare solutions of hyponitrite and nitrohydroxylaminate which are free of nitrate and nitrite.     

Improved Synthesis and X‐Ray Structure of 5‐Aminotetrazolium Nitrate

5‐Aminotetrazolium nitrate was synthesized in high yield and characterized using Raman and multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁵N). The molecular structure of 5‐aminotetrazolium nitrate in the crystalline state was determined by X‐ray crystallography: monoclinic, P 2₁/c, a=1.05493(8) nm, b=0.34556(4) nm, c=1.4606(1) nm, β=90.548(9)°, V=0.53244(8) nm³, Z=4, ϱ=1.847 g cm⁻³, R₁=0.034, wR₂ (all data)=0.090. The thermal stability of 5‐aminotetrazolium nitrate was determined using differential scanning calorimetry; the compound decomposes at 167 °C. The enthalpy of combustion (Δ_combH) of 5‐aminotetrazolium nitrate ([CH₄N₅]⁺[NO₃]⁻) was determined experimentally using oxygen bomb calorimetry: Δ_combH([CH₄N₅]⁺[NO₃]⁻)=−6020±200 kJ kg⁻¹. The standard enthalpy of formation (Δ_fH°) of [CH₄N₅]⁺[NO₃]⁻ was obtained on the basis of quantum chemical computations at the electron‐correlated ab initio MP2 (second order Møller‐Plesset perturbation theory) level of theory using a correlation consistent double‐zeta basis set (cc‐pVTZ): Δ_fH°([CH₄N₅]⁺[NO₃]⁻(s))=+87 kJ mol⁻¹=+586 kJ kg⁻¹. The detonation velocity (D) and the detonation pressure (P) of 5‐aminotetrazolium nitrate were calculated using the empirical equations by Kamlet and Jacobs: D([CH₄N₅]⁺[NO₃]⁻)=8.90 mm μs⁻¹ and P([CH₄N₅]⁺[NO₃]⁻)=35.7 GPa.     

Heazlewoodite,Ni3S2: An electroactive material for supercapacitor application

Engineering of nanostructured materials with a unique and uniform morphological design is considered to be a competent candidate for a diverse range of electrochemical energy applications. However, the construction of ball-in-ball transition metal sulfide via the vaporization process remains a big challenge of today's research community. In this work, carbon encapsulated nickel sulfide (Ni₃S₂@C) with a complex hollow interior was synthesized and further studied with nitrogen-doped carbon encapsulated nickel sulfide (Ni₃S₂@NC) for comparison basis. We used metal salt (nickel nitrate) and organic linker (trimesic acid, TMA) as a precursor to synthesize Ni-TMA via a solvothermal method. Next, the sulfidation process was done under 5% H₂ balanced argon gas in a tubular furnace to convert into Ni₃S₂ with encapsulation of carbon. The prepared hybrid material showed ball-in-ball morphology and heazlewoodite mineral phase structure. Furthermore, the prepared materials were examined for electrochemical energy storage properties owing to their well-known faradaic dominant (battery-type) charge storage features and key positive electroactive material for today's growing hybrid electrochemical capacitor. The nitrogen-doped carbon encapsulated nickel sulfide has demonstrated good electrochemical features like a specific capacity of 442.45 F g^?1 at 5 mV s^?1 of scan rate and 373.52 F g^?1 at 2 A g^?1 of current density. Moreover, the material showed excellent capacitance retention of 81% and 70% after 5000 and 10,000 cycles run with 100% of coulombic efficiency at 8 A g^?1.     

The influence of chain‐ends on the thermal and rheological properties of some 40/60 PES/PEES copolymers

Four random, differently ended (? Cl, ? NH₂, ? OH, and ? COO^?), polyethersulfone/polyetherethersulfone (PES/PEES) copolymers were studied to investigate the influence of chain ends on thermal and rheological behaviors. The number average molar mass (M_n ≈ 9500 g·mol^?1) and the PES/PEES ratio (40/60) of all copolymers investigated were checked by ¹H NMR spectra. Thermal degradations were carried out in the scanning mode and initial decomposition temperatures (T_i) and activation energy values of degradation (E_a) were obtained. Glass transition temperature (T_g) was determined by differential scanning calorimetry and complex viscosity (η*) by rheological measurements in isothermal heating conditions (T = 270°C). All parameters determined were largely affected by copolymer chain ends and decreased according to the same order, ? OH > ? NH₂ > ? Cl > ? COO^?. The results were discussed and interpreted. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Antecedent effect of lime on nitrous oxide and dinitrogen emissions from grassland soils

The antecedent effect of lime on the gaseous products of denitrification (N₂O and N₂) was examined in a laboratory study using a clay loam soil (Soil 1) with a starting pH of 5.4, and a sandy loam soil (Soil 2) with a starting pH of 5.3. The soils were amended with 0, 2.3, 5.7 and 18.9 g CaCO₃ kg^?1, and were incubated for a period of 3 years at 4 °C during which time the soil equilibrated at pH values of 4.7, 5.8, 7.3 and 7.7 (Soil 1) and pH 4.7, 5.2, 6.6 and 7.6 (Soil 2). Ammonium nitrate, labelled with ¹⁵N (¹⁵NH₄NO₃, NH₄ ¹⁵NO₃ and ¹⁵NH₄ ¹⁵NO₃) was added to each incubation jar at a rate of 7.14 μmol N g^?1 oven dried (OD) soil. Headspace gas samples were extracted daily over a 5 days incubation period at 20 °C. The amount of N₂O and N₂, and ¹⁵N enrichment of N₂O-N in the headspace, was determined using continuous-flow isotope-ratio mass spectrometry. As pH increased, the quantity of N₂ and N₂O emitted significantly increased in both soils (P < 0.001), with a peak N₂ flux of 0.179 μmol N g^?1 OD soil h^?1, and a peak N₂O flux of 0.002 μmol N g^?1 OD soil h^?1 occurring at pH 7.6, 2 days after the addition of NH₄NO₃. The loss as N₂ far exceeded the loss of N₂O, which remained at less than 1 % of the total mineral N content of the soil. Lime generally lowered the N₂O:N₂ ratio, however the results from this study suggest that it is not a mitigation strategy for GHG emissions.     

Nitrous oxide production from soil experiments: denitrification prevails over nitrification

Nitrous oxide is produced in soils and sediments essentially through the processes of nitrification and denitrification, although several rival processes could be competing. This study was undertaken in order to better understand the controlling factors of nitrification, denitrification and associated N₂O production as well as the contribution of these two processes to the average N₂O production by soils and sediments. With this aim, soil and sediment samples were taken in contrasting periods and different land use types, each time at different depths (upper and lower soil horizons). They were incubated in separate batches in specific conditions to promote denitrification and nitrification: (1) a complete anaerobic environment adding KNO₃ for the denitrification assay and (2) an aerobic environment (21 % O₂) with addition of NH₄Cl for the nitrification assay. Potentials of nitrification and denitrification were determined by the rates of nitrate either reduced (for denitrification) or produced (for nitrification). Overall, denitrification potential varied from 70 to 2,540 ng NO ₃ ^— -N g^?1 dry soil h^?1 and nitrification potential from 30 to 1,150 ng NO₃ ^?-N g^?1 dry soil h^?1. Nitrous oxide production by denitrification was significantly (P < 0.05) greater in topsoils (10–30 cm) than in subsoils (90–110 cm), ranging, respectively, from 26 to 250 ng N₂O-N g^?1 dry soil h^?1 versus 1.5 to 31 ng N₂O-N g^?1 dry soil h^?1, i.e., a mean 19.5 versus. 6.0 % of the NO₃ ^? denitrified for the upper and lower horizons, respectively. Considering the N₂O production in relation with the nitrate production (e.g., nitrification), no significant difference (P < 0.05) was found in the soil profile, which ranged from 0.03 to 6 ng N₂O-N g^?1 dry soil h^?1. This production accounts for 0.21 and 0.16 % of the mean of the NO₃ ^? produced for the top and subsoils, respectively. On the basis of the average production by both top- and subsoils, N₂O production by denitrification is clearly greater than by nitrification under the measurement conditions used in this study, from 30- to 100-fold higher. Such a high potential of N₂O emission must be taken into account when reducing nitrate contamination by increasing denitrification is planned as a curative measure, e.g. in rehabilitation/construction of wetlands.     

A chromotropic acid modified SBA-15 as a highly sensitive fluorescent probe for determination of Fe<Superscript>3+</Superscript> and I<Superscript>−</Superscript> ions in water

A novel organic–inorganic hybrid nanomaterial (SBA-15-CA) was prepared by covalent immobilization of chromotropic acid onto the surface of mesoporous silica material SBA-15. Different techniques such as XRD, TEM, FT-IR, N₂ adsorption–desorption and TGA analyses were employed to characterize the grafting process. The data showed that the organic moiety (0.41 mmol g^?1) was successfully grafted to the SBA-15 and the primary hexagonally ordered mesoporous structure of SBA-15 was preserved after the grafting procedure. SBA-15-CA has been realized as a highly sensitive and selective fluorescent probe towards Fe³⁺ and I^? ions in aqueous media. SBA-15-CA exhibited a remarkable fluorescent quenching in the presence of Fe³⁺ ion over other competitive cations including Na⁺, Mg²⁺, Al³⁺, K⁺, Ca²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺ as well as I^? ion among a series of anions including F^?, Cl^?, Br^?, CO₃^2?, HCO₃^?, CN^?, NO₃^?, NO₂^?, SCN^?, SO₄^2?, H₂PO₄^?, HPO₄^2?, and CH₃COO^?. A good linear response was observed between the concentration of the quenchers (Fe³⁺ and I^? ions) and fluorescence intensity of SBA-15-CA with detection limits of 1.5?×?10^?7 M for Fe³⁺ and 0.2?×?10^?7 M for I^?. Moreover, the effects of various pH values on the sensing ability of SBA-15-CA were investigated. Finally, the proposed method was successfully utilized for the determination of Fe³⁺ and I^? ions in river water, well water and tap water samples.     

Ionic polymers with expanded π‐conjugation systems derived from through‐space interaction in piperazinium and homopiperazinium rings

Reactions of N‐(2,4‐dinitrophenyl)‐4‐arylpyridinium chlorides (aryl (Ar) = phenyl and 4‐biphenyl) with piperazine or homopiperazine caused opening of the pyridinium ring and yielded polymers that consisted of 5‐piperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂)₂N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) or 5‐homopiperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂CH₂)(CH₂CH₂)N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) units. ¹H NMR spectral analysis suggested that the π‐electrons of the penta‐2,4‐dienylideneammonium group of the polymers were delocalized. UV‐visible spectral measurements revealed that the π‐conjugation system expanded along the polymer chains because of the orbital interaction between electrons of the two nitrogen atoms of the piperazinium and homopiperazinium rings. However, the π‐conjugation length depended on the distance between the two nitrogen atoms; that is, the polymers containing the piperazinium ring had a longer π‐conjugation length than those containing the homopiperazinium ring. Conversion of the piperazinium and homopiperazinium rings from the boat to the chair form led to a decrease in the π‐conjugation length. The surface of pellets that were molded from the polymers exhibited metallic luster, and these polymers underwent electrochemical oxidation in solution. Copyright © 2010 Society of Chemical Industry     

Study on macromolecular metal complexes: Synthesis,characterization, and fluorescence properties of stoichiometric complexes for rare earth coordinated with poly(acrylic acid)

Poly acrylic acid (PAA) and its stoichiometric complexes with trivalent rare earth (RE) have been synthesized and well characterized by means of elemental analysis, IR, TG‐DTA, fluorescence spectra, etc. Chemical analysis indicated that the molar ratio of ? COO^? and RE³⁺in the complex was closely dependent on the pH and the molar ratio of PAA and RE in the feed. The stoichiometric complexes in which the molar ratio of ? COO^? and RE³⁺ is 3:1 can be formed under the conditions of pH 6.0 and PAA:RE = 3:1 (molar ratio in the feed). Spectroscopic studies suggested that the carboxylate bonded to the central metal ions was in the form of bidentate and these stoichiometric complexes possessed high‐temperature resistance. Due to efficient energy transfer from polymer to central metal ions, the emission intensity of Eu³⁺ and Tb³⁺complexes was stronger than that of simple compounds. Therefore, these complexes can be promising as potential fluorescent probes and photoluminous materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 351–357, 2007     

Stability constants of adipate complexes of copper(II), nickel(II), zinc(II), cobalt(II), uranyl(II) and thorium(IV) determined by electrophoresis

Stability constants of Copper(II), Nickel(II), Cobalt(II), Zinc(II), Uranyl(II) and Thorium(IV) adipates have been determined by paper electrophoresis. Adipic acid (0.005 mol dm^?3) was added to the background electrolyte: 0.1 mol dm^?3 HClO₄. The proportions of (CH₂)₄COOH COO^? and (CH₂)₄C₂O⁼₂ were varied by changing the pH of the electrolyte. These anions yielded the complexes Zn(CH₂)₄COOH COO⁺, Co(CH₂)₄COOH COO⁺, Ni(CH₂)₄COOH COO⁺, Th(CH₂)₄COOH COO³⁺, Th[(CH₂)₄COOH COO]₄, Cu(CH₂)₄ C₂O₄ and UO₂[(CH₂)₄(C₂O₄)]^2?₂, whose stability constants are found to be 10^2.8, 10^2.8, 10^3.2, 10^5.2, 10^15.3, 10^2.7 and 10^11.8 respectively (μ = 0.1, temp. 40°C).     

A Study of the Interaction of NO2 with Carbon Particles

The interaction NO₂ in air (0.5–35 ppm) with carbon particles led to three products: NO gas, and NO₂ ^? and NO₃ ^?, removed from the particles by water extraction. At 4 ppm or below, in dry or humid air, the product distribution, in relative molar amounts, was NO₃ ^? = 2NO₂ ^? = 2NO. At 20 ppm and above, the relative amounts of products depended on the presence of water vapor: in dry air NO = 3NO₃ ^? = 6NO₂ ^?; in humid air NO = NO₂ ^? = 2NO₃ ^?. For carbon slurries in water, [NO₂ ^?] = 6[NO₃ ^?] at an input concentration of NO₂ of 4 ppm. In comparison to carbon, alumina particles and glass beads removed NO₂ ineffectively. These results indicate that NO₂ oxidized the carbon particles while it was reduced to NO. NO₂ adsorbed at oxidized sites on the particles formed a surface species that was analyzed as nitrate. At high enough concentration of NO₂ (20 ppm and above), the interaction of NO and water vapor with the surface nitrate produced NO₂ ^?. In slurries NO, generated from interaction of NO₂ with carbon, reacted with surface nitrate or nitric acid in solution to form the relatively large quantities of nitrite. This work suggests that NO_x reactions with carbon in droplets or on wet surfaces could be important sources for the production of nitrous acid in the environment.     

Adsorption of CO2, CH4, CO2/N2 and CO2/CH4 in novel activated carbon beads: Preparation,measurements and simulation

A series of high performance carbonaceous mesoporous materials: activated carbon beads (ACBs), have been prepared in this work. Among the samples, ACB‐5 possesses the BET specific surface area of 3537 m² g^?1 and ACB‐2 has the pore volume of 3.18 cm³ g^?1. Experimental measurements were carried out on the intelligent gravimetric analyzer (IGA‐003, Hiden). Carbon dioxide adsorption capacity of 909 mg g^?1 has been achieved in ACB‐5 at 298 K and 18 bar, which is superior to the existing carbonaceous porous materials and comparable to metal‐organic framework (MOF)‐177 (1232 mg g^?1, at 298 K and 20 bar) and covalent‐organic framework (COF)‐102 (1050 mg g^?1 at 298 K and 20 bar) reported in the literature. Moreover, methane uptake reaches 15.23 wt % in ACB‐5 at 298 K and 18 bar, which is better than MOF‐5. To predict the performances of the samples ACB‐2 and ACB‐5 at high pressures, modeling of the samples and grand canonical Monte Carlo simulation have been conducted, as is presented in our previous work. The adsorption isotherms of CO₂/N₂ and CO₂/CH₄ in our samples ACB‐2 and 5 have been measured at 298 and 348 K and different compositions, corresponding to the pre‐ and postcombustion conditions for CO₂ capture. The Dual‐Site Langmuir‐Freundlich (DSLF) model‐based ideal‐adsorbed solution theory (IAST) was also used to solve the selectivity of CO₂ over N₂ and CH₄. The selectivities of ACBs for CO₂/CH₄ are in the range of 2–2.5, while they remain in the range of 6.0–8.0 for CO₂/N₂ at T = 298 K. In summary, this work presents a new type of adsorbent‐ACBs, which are not only good candidates for CO₂ and CH₄ storage but also for the capture of carbon dioxide in pre‐ and postcombustion processes. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Removal of Dichromate Anions with Nanofiltration‐Complexation by using Amino Calix[4]arene Derivative

Abstract

Herein the removal and recovery of chromium anions from aqueous solutions by using nanofiltration pilot‐scale equipment (Osmonics Sepa CF Membrane Cell) with a water‐soluble amino calix[4]arene derivative was studied. To understand the selectivity, the authors also examined the retention of chromium anions in the presence of Cl^?, NO₃ ^?, SO₄ ^2?, HSO₄ ^?, CO₃ ^2?, PO₄ ^3?, H₂PO₄ ^? anions in nanofiltration‐complexation. From the results water‐soluble amino calix[4]arene was effective and selective ligand for dichromate anions over nitrate anions, in a nanofiltration‐complexation system at pH 2.5. Moreover, the recovery and reusability studies of dichromate and nitrate anions and also ligand were performed.     

Gas/Aerosol Distribution of Formic and Acetic Acids

Data and correlations for evaluating the gas/aerosol equilibrium of formic and acetic acids are developed. The species considered include HCOOH(g), CH₃COOH(g), HCOOH(aq), CH₃COOH(aq), HCOO^?, CH₃COO^?, HCOONa(s), CH₃COONa(s), HCOOK(s), (HCOO)₂Ca(s), and (CH₃COO)₂Ca(s). Based on available thermodynamic data, we show that the gas /aerosol distribution of formic and acetic acids is strongly on the gas-phase side for typical sulfate/ nitrate / ammonium / sodium / chloride / water aerosols and that dissolved formate and acetate have negligible effect on the gas/aerosol equilibrium of the other components.     

Superabsorbent composite. X. Effects of saponification on properties of polyacrylamide/attapulgite

A novel superabsorbent composite from acrylamide (AM) and attapulgite (APT), polyacrylamide/attapulgite (PAM/APT), was prepared by polymerizing AM with the existence of APT in aqueous solution, and then saponified with NaOH solution. Considering the impacts of hydrophilic groups (? COONa, ? COOH, and ? CONH₂) on properties of the PAM/APT composite, the effects of saponification mode, molar ratio of NaOH to AM and saponification time on water absorbency, hydrophilic group content, and surface morphology were investigated systematically. The results indicate that the two‐step adding NaOH mode is superior to that of the one‐step mode. Among the superabsorbent composite incorporated with 30 wt% APT, the composite saponified at 95°C for 2 h with the molar ratio of 0.6 for NaOH to AM acquired the highest water absorbencies of 1715g g^?1 and 87.8g g^?1 in distilled water and in 0.9 wt% NaCl solution, respectively. The molar ratio of various hydrophilic groups at this time was 10:3:11 for ? COONa, ? COOH, and ? CONH₂ determined using linear potentiometric titration method. POLYM. ENG. SCI. 46:1762–1767, 2006. © 2006 Society of Plastics Engineers.     

RAFT polymerization of N‐vinyl pyrrolidone using prop‐2‐ynyl morpholine‐4‐carbodithioate as a new chain transfer agent

RAFT polymerization of N‐vinyl pyrrolidone (NVP) has been investigated in the presence of chain transfer agent (CTA), i.e., prop‐2‐ynyl morpholine‐4‐carbodithioate (PMDC). The influence of reaction parameters such as monomer concentration [NVP], molar ratio of [CTA]/[AIBN, i.e., 2,2′‐azobis (2‐methylpropionitrile)] and [NVP]/[CTA], and temperature have been studied with regard to time and conversion limit. This study evidences the parameters leading to an excellent control of molecular weight and molar mass dispersity. NVP has been polymerized by maintaining molar ratio [NVP]: [PMDC]: [AIBN] = 100 : 1 : 0.2. Kinetics of the reaction was strongly influenced by both temperature and [CTA]/[AIBN] ratio and to a lesser extent by monomer concentration. The activation energy (E_a = 31.02 kJ mol^?1) and enthalpy of activation (ΔH^?= 28.29 kJ mol^?1) was in a good agreement to each other. The negative entropy of activation (ΔS^? = ?210.16 J mol^‐1K^‐1) shows that the movement of reactants are highly restricted at transition state during polymerization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Bio‐electrochemical denitrification by a novel proton‐exchange membrane electrodialysis system—a batch mode study

BACKGROUND: Contamination of nitrate in ground and surface water has become an ever‐increasing and serious environmental problem. Biological methods hold the promise of converting nitrate into harmless nitrogen. A novel denitrification system which combines proton‐exchange membrane electrodialysis with simultaneous bio‐electrochemical autotrophic denitrification has been developed. The proton‐exchange membrane was used to transfer current and to exclude oxygen or other oxidative chemicals generated in the anode reaction. The H₂ generated by the cathode was utilized by autotrophic denitrifying microorganisms in the cathode cell to reduce nitrate. In this study, the transport of H⁺, a denitrification kinetics model and factors influencing the denitrification rate were explored in batch mode. RESULTS: The addition of 0.03 mol L^?1 H₂SO₄ into the anode cell enhanced proton transport and maintained the pH of the cathode cell in an appropriate range for biological denitrification. The denitrification rate was affected by applied current and biomass. Under adequate current conditions, the kinetics of the denitrification process followed a zero‐order kinetics model; the average denitrification rate for unit biomass was calculated to be 9.36 mg NO₃^?‐N VSS g^?1 h^?1. CONCLUSIONS: Results indicate that the system is suitable for denitrification. Owing to its simple structure and operation, it has the potential for use as a system to reduce nitrate in water. Copyright © 2010 Society of Chemical Industry     

Synergistic extraction and separation study of rare earth elements from nitrate medium by mixtures of sec‐nonylphenoxy acetic acid and 2,2′‐bipyridyl

BACKGROUND: Synergistic extraction has been proven to enhance extractability and selectivity. Numerous types of synergistic extraction systems have been applied to rare earth elements, among which sec‐nonylphenoxyacetic acid (CA100) has proved to be an excellent synergistic extractant. In this study, the synergistic enhancement of the extraction of holmium(III) from nitrate medium by mixtures of CA100 (H₂A₂) with 2,2′‐bipyridyl (bipy, B) in n‐heptane has been investigated. The extraction of all other lanthanides (except polonium) and yttrium by the mixtures in n‐heptane has also been studied. RESULTS: Mixtures of CA100 and bipy have significant synergistic effects on all rare earth elements, for example holmium(III) is extracted as Ho(NO₃)₂HA₂B with the mixture instead of HoH₂A₅, which is extracted by CA100 alone. The thermodynamic functions, ΔH^o, ΔG^o, and ΔS^o have been calculated as 2.96 kJ mol^?1, ? 6.23 kJ mol^?1, and 31.34 J mol^?1 K^?1, respectively. CONCLUSION: Methods of slope analysis and constant molar ratio have been successfully applied to study the synergistic extraction stoichiometries of holmium(III) by mixtures of CA100 and bipy. Mixtures of these extractants have also shown various synergistic effects with other rare earth elements, making it possible to separate them. Thus CA100 + bipy may be used to separate yttrium from other lanthanides at appropriate ratios of the extractants. Copyright © 2011 Society of Chemical Industry     

Aluminium-Based Surfactant Mesophases Structurally and Morphologically Controlled by Anions

Aluminium-based dodecyl sulfate mesophases were synthesized by the homogeneous precipitation from a mixture of aluminium nitrate, sodium dodecyl sulfate, urea and water with or without five kinds of additional anions. The addition of monovalent Cl^-, CH₃COO^- and HCOO^- anions yielded a hexagonal mesophase, whereas F^- anions induced a different mesophase. The crystallinities of these mesophases increased in the following order: NO₃ ^- and Cl^->CH₃ COO^->HCOO^->F^-, corresponding to the reverse order of affinity for Al³⁺. The resulting mesophases were also largely affected in morphology by the anion species added to form worm-like shaped particles for NO₃ ^- and/or Cl^- anions, and widely varying shapes of particles for the others. On calcination, these mesophases were transformed into -alumina particles with macro pores having the specific surface area of ca. 20 m²g^-1. On the other hand, the addition of divalent SO₄ ^2- anions or the single use of aluminium sulfate led to a mesophase with a structural period as long as 6 nm, which was deorganized into a layered phase with an interlayer spacing of 1.4 nm.