Kinetics of Solvent Extraction of Iron(III) from Sulfate Medium by Purified Cyanex 272 using a Lewis Cell

Abstract

The kinetics of the forward and backward extraction of the title process have been investigated using a Lewis cell operated at 3 Hz and flux or (F) – method of data treatment. The dependences of (F) in the forward extraction on [Fe³⁺], [H₂A₂]_(o), pH, and [HSO₄ ^?] are 1, 0.5, 1, and ?1, respectively. The value of the forward extraction rate constant (k _f ) has been estimated to be 10^?7.37 kmol^3/2 m^?7/2 s^?1. The analysis of the experimentally found flux equation gives the following simple equation: F _f =10^0.13 [FeHSO₄ ²⁺] [A^?], on considering the monomeric model of BTMPPA and the stability constants of Fe(III)‐HSO₄ ^? complexes. This indicates the following elementary reaction occurring in the aqueous film of the interface as rate determining: [FeHSO₄]²⁺+A^?→[FeHSO₄.A]⁺. The very high activation energy of 91 kJ mol^?1 supports this chemical reaction step as rate-determining. The negative value of the entropy change of activation (?94 J mol^?1 K^?1) indicates that the slow chemical reaction step occurs via the S_N2 mechanism.

The backward extraction rate can be expressed by the equation: F _b =10^?5.13 [[FeHSO₄A₂]]_(o) [H⁺] [H₂A₂]_(o) ^?0.5. An analysis of this equation leads to the following chemical reaction step as rate-determining: [FeHSO₄A₂]_(int)→[FeHSO₄A]+A_(i) ^?. However, the activation energy of 24 kJ mol^?1 suggests that the backward extraction process is intermediate controlled with greater contribution of the diffusion of one or the other species as a slow process. The equilibrium constant obtained from the rate study matches well with that obtained from the equilibrium study.     

A bipolar electrospray source of singly charged salt clusters of precisely controlled composition

The few clusters [B^?_nA⁺_n+1]⁺ (n = 0,1) with resolvable mobilities formed in electrosprays of large salts have been used for nanoparticle instrument testing and calibration at sizes smaller than 2 nm. Extensions of this modest size range by charge reduction with uncontrolled gas phase ions has resulted in impure singly charged clusters. Here, we combine two oppositely charged electrosprays of solutions of the same salt B^?A⁺, including: (C_nH_2n+1)₄N⁺Br^? (n = 4,7,12,16), the large phosphonium cation (C₆H₁₃)₃(C₁₆H₃₃)P⁺ paired with the anions Im^? [(CF₃SO₂)₂N^?] or FAP^? [(C₂F₅)₃PF₃^?], and the asymmetric pair [1-methyl-3-pentylimidazolium⁺FAP^?]. Both polarities are simultaneously produced by this source in comparable abundances, primarily as singly charged A⁺_nB^?_n±1, with tiny contributions from higher charge states. Some but not all of these clusters produce narrow mobility peaks typical of pure ions, even beyond n = 43. Excellent independent stable control of the positive and the negative sprays brought very close to each other is achieved by isolating them electrostatically with a symmetrically interposed metallic screen. Two nanoDMAs covering the size range up to 30 nm (Halfmini and Herrmann DMAs, with classification lengths of 2 and 10 cm) are characterized with these standards, revealing resolving powers considerably higher than previously seen with unipolar electrospray sources. The bipolar source of pure and chemically homogeneous clusters described permits studying size and charge effects in a variety of aerosol instruments in the 1–4 nm size range.

Copyright © 2017 American Association for Aerosol Research     

Reaction of Ozone with Ag(I)—Mechanistic Considerations

Ozone reacts slowly with Ag⁺ (circumneutral pH, k = (11 ± 3) × 10^?2 M^?1 s^?1). After some time, ozone decay kinetics may suddenly become faster with the concomitant formation of silver sol. As primary process, an O-transfer from O₃ to Ag(I) is suggested, whereby Ag(III) is formed [Ag⁺ + O₃ + 2 H₂O → Ag(OH)₃ + O₂ + H⁺]. This conproportionates with Ag(I), which is in large excess, leading to Ag(II) [Ag⁺ + Ag(OH)₃ ? 2 Ag(OH)⁺ + HO^?]. Further, Ag(II) reacts with ozone in a high exergonic reaction [Ag(OH)⁺ + O₃ → Ag + 2 O₂ + H⁺], where ozone acts as a reducing agent. Thereby, a single silver atom, Ag, is formed that can be oxidized by O₂ and O₃ or can aggregate to a silver sol. Aggregation slows down the rate of oxidation. When Ag⁺ is complexed by acetate ions, ozone decay and silver sol formation are speeded up by enhancing Ag(II) formation [Ag(I)acetate + O₃ → Ag(III)acetate → Ag(II) + CO₂ + ?CH₃]. In the presence of oxalate, the formed complex reacts faster with ozone than Ag⁺, and Ag(III)oxalate decarboxylates rapidly [Ag(I)oxalate + O₃ → Ag(III)oxalate → Ag⁺ + 2 CO₂]. This enhances ozone decay but prevents silver sol formation. Quantum chemical calculations have been carried out for substantiating mechanistic suggestions.     

UNIFAC model for ionic liquid‐CO (H2) systems: An experimental and modeling study on gas solubility

The universal quasichemical functional‐group activity coefficients (UNIFAC) model for ionic liquids (ILs) has become notably popular because of its simplicity and availability via modern process simulation softwares. In this work, new group binary interaction parameters (α_mn and α_nm) between CO (H₂) and IL groups were obtained by correlating the solubility data in pure ILs at high temperatures (above 273.2 K) collected from the literature. the solubility of CO in [BMIM]⁺[BF₄]^?, [OMIM]⁺[BF₄]^?, [OMIM]⁺[Tf₂N]^?, and their mixtures, as well as that of H₂ in [EMIM]⁺[BF₄]^?, [BMIM]⁺[BF₄]^?, [OMIM]⁺[Tf₂N]^?, and their mixtures, at temperatures from 243.2 to 333.2 K and pressures up to 6.0 MPa were measured. The UNIFAC model was observed to well predict the solubility in pure and mixed ILs at both high (above 273.2 K) and low (below 273.2 K) temperatures. Moreover, the selectivity of CO (or H₂) to CO₂ in ILs increases with decreasing temperature, indicating that low temperatures favor for gas separation. © 2014 American Institute of Chemical Engineers AIChE J 60: 4222–4231, 2014     

Mineralizer effect on the synthesis of two types of one-dimensional chains silver-selenogermanate and selenostannate

Two type of one-dimensional compounds, K₂Ag₂GeSe₄(2) and K₃AgSn₃Se₈(4), were synthesized with thiophenol as a mineralizer, whilst two oligomers, Cs₄Ge₂Se₆ (1) and K₄Sn₃Se₈(3), were obtained in absence of thiophenol. Compounds 1 and 3 contain dimeric [Ge₂Se₆]^4? and trimeric [Sn₃Se₈]^4? anions, respectively. Compound 2 contains isolated GeSe₄ tetrahedra connected by linear-coordinated Ag⁺ ions to form an infinite anionic chains [Ag₂GeSe₄]^2?. The building blocks [Sn₃Se₈]^4? are linked by tetrahedral coordinated Ag⁺ ions to generate infinite chain [AgSn₃Se₈]^3? of 4.     

Zinc(II)-bound thiolate complexes-containing cysteine derivatives modeling of methionine synthase alkylating enzyme

The reaction of thioimidazolylborate-zinc(II)-perchlorate complex [Tt^xyly·Zn? OClO₃] 1 (Tt^xyly=hydrotris[N-xylyl-thioimidazolyl]borate) with cysteine and its derivative N-acetyl cysteine and S-methyl cysteine leads to the formation of three new monomeric and dimeric thiolate complexes: [Tt^xyly·Zn? Cys? Zn·Tt^xyly] 2, [Tt^xyly·Zn? Cys(NAc)? Zn·Tt^xyly] 3, and [Tt^xyly·Zn? Cys(SMe)] 4. The attachment of the cysteine derivatives to the Tt·Zn unit serves as structural models for the active site of methionine synthase. Methylation of the coordinated thiolate in the dinuclear zinc(II) complex 2 with methyl iodide appears to occur intramolecularly at the zinc-bound thiolates, forming methyl thioether-containing zinc(II) complex [Tt^xyly·Zn? Cys(SMe)] 4 and iodo complex [Tt^xyly·Zn? I] 5 with a clean second-order reaction of k=1.0×10^?5 M^?1 s^?1.     

Ionic liquid-based extraction and separation trends of bioactive compounds from plant biomass

Ionic liquids have been projected as the best solvent for extraction and separation of bioactive compounds from various origins. This review offers a collection of the published results, using ionic liquids for the extraction and purification of biomolecules. Ionic liquids have been studied as solvents, co-solvents and supported materials for separation of bioactive compounds. The ionic liquids-based extraction procedures were previously reported, such as ionic liquids-based solid-liquid extraction, liquid-liquid extraction and ionic liquids-modified materials are reviewed and compared to their performance. In this review, the main activities and future challenges are discussed, with major gaps identified using ionic liquids in extraction procedures and by advancing few steps to overcome these drawbacks.

Abbreviation: [(HSO₃)C₄MIM]⁺: 1-(4-sulfonylbutyl)-3-methylimidazolium; [(C₆H₃OCH₂)₂im]⁺: 1,3-dihexyloxymethylimidazolium; [C_nC₁MIM]⁺: 1-alkyl-2,3-dimethylimidazolium; [C_nMIM]^{+; [Cn, 2, 3, 4, 6, 8, 10, 12]}: 1-alkyl-3-methylimidazolium; [C_nC₁pyr]⁺: 1-alkyl-3-methylpyridinium; [C_nim]⁺: 1-alkylimidazolium; [C_npyr]⁺: 1-alkylpyridinium; [aC_nim]⁺: 1-allyl-3-alkylimidazolium; [C₇H₇MIM]⁺: 1-benzyl-3-methylimidazolium; [C₄(C₁C₁C₁Si)im]⁺: 1-butyl-3-trimethylsilylimidazolium; [(HOOC)C₂MIM]⁺: 1-carboxyethyl-3-methylimidazolium; [(OH)C_nMIM]⁺: 1-hydroxyalkyl-3-methylimidazolium; [(C₂H₅O)₃SiC₃MIM]⁺: 1-methyl-3-(triethoxy)silypropyl imidazolium; [(NH₂)C₃MIM]⁺: 1-propylamine-3-methylimidazolium; [C_wH_xN_yO_z]⁺: Chirally functionalized methylimidazolium; [P_{10(3OH)(3OH)(3OH)}]⁺: Decyltris(3-hydrox- ypropyl) phosphonium; [N_111(2OH)]⁺: N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium (cholinium); [N_00nn]⁺: N,N-dialkylammonium; [N_0nn(2OH)]⁺: N,N-dialkyl-N-(2-hydroxyethyl) ammonium; [C₁₀C₁₀C₁gluc]⁺: N,N-didecyl-N-methyl-d-glucaminium; [N_11(2(O)1)0]⁺: N,N-dimethyl(2-methoxyethyl) ammonium; [N_{11(2OH)(C7H7)}]⁺: N-benzyl-N,N-dimethyl-N-(2-hydroxyethyl) ammonium; [P₆₆₆₁₄]⁺: Trihexyltetradecylph- osphonium; [P_i(444)1]⁺: Triisobutyl (methyl) phosphonium; P.minus: Polygonum minus; NPs: Nanoparticle; ZnO : Zinc oxide nanoparticles ; Ni NPs: Nickel nanoparticles; MO: Methyl orange; UAE: Ultrasonic-assisted extraction; LLE: Liquid-liquid extraction; ABS: Aqueous biphasic system ; [Ace]^?: Acesulfamate; [Ala]^?: alalinate; [TMPP]^?: bis(2,4,4-trimethylpentyl)phosphinate; : ; [NTf₂]^?: bis(trifluoromethylsulfonyl)imide; [[Br]^–]: [Br]omide; [Calc]: calkanoate; [Cl]^–: chloride; [Bz]^?: benzoate; [PF₆]^?: hexafluorophosphate; [HSO₄]^?: hydrogenosulfate; [OH]^?: hydroxide; I^–: iodide; [Lac]^?: lactate; [NO₃]^?: nitrate; [[Cl]O₄]^?: perchlorate; [Phe]^?: phenilalaninate; [BF₄]^?: tetrafluoroborate; [SCN]^?: thiocyanate; [C(CN)₃]^?: tricyanomethanide; [CF₃CO₂]^?: trifluoroacetate; [CF₃SO₃]^?: trifluoromethanesulfonate; [FAP]^?: tris(pentafluoroethyl)trifluorophosphate; ILs: Ionic liquids; Ag NPs: Silver nanoparticle; Cu NPs: Copper nanoparticle; MB: Methylene blue; MR: Methyl red ; MAE: Microwave-assisted extraction; SLE: solid-liquid extraction.     

Sorption of Silver Cations by Natural and Na-Exchanged Mordenite

Sorption of Ag⁺ by natural mordenite and its Na-exchanged form was investigated by the batch method. Maximum Ag⁺ uptake was observed at initial pH > 3.0 and contact time 90 min. The kinetic data fitted very well to the pseudo-second-order rate model with values of k ₂ from 37.31 to 0.487 and 48.32 to 0.491 g/meq min for the natural and Na-exchanged mordenite, respectively. The Langmuir model is in good correlation with the isotherm data up to initial concentration of 500 mg Ag⁺/L (q _m = 57.41 (natural sample) and 87.72 mg/g (Na-exchanged sample). The obtained data are promising for clean-up of polluted water.     

Synthesis and Structure Determination of the Adducts of Dibenzo[a,l]pyrene Diol Epoxides and Deoxyadenosine or Deoxyguanosine

Abstract

(±)?Syn?dibenzo[a,l]pyrene diol epoxide (DB[a,l]PDE) and (±)?anti?DB[a,l]PDE were reacted with deoxyadenosine (dA) or deoxyguanosine (dG) in dimethylformamide at 100 °C for 30 min. The crude products were purified by reverse phase HPLC under gradient and isocratic conditions. The structure of each adduct was assigned by 1D and 2D NMR spectra and by fast atom bombardment mass spectrometry. Five adducts were isolated from the reaction of (±)?syn?DB[a,l]PDE and dA: syn?DB[a,l]PDE?N⁶dA?1, syn?DB[a,l]PDE?N⁶dA?2, syn?DB[a,l]PDE?N⁶dA?3, syn?DB[a,l]PDE?N⁶dA?4 and syn?DB[a,l]PDE?N7Ade. Four adducts were isolated from the reaction of (±)?anti?DB[a,l]PDE and dA: anti?DB[a,l]PDE?N⁶dA?1, anti?DB[a,l]PDE?N⁶dA?2, anti?DB[a,l]PDE?N⁶dA?3 and anti?DB[a,l]PDE?N⁶dA?4. Two adducts were isolated from the reaction of (±)?syn?DB[a,l]PDE and dG: (±)?11,12,13?trihydroxy?tetrahydroDB[a,l]P?14?N²dG and (±)?11,12,13?trihydroxy?tetrahydroDB[a,l]P?14?N7Gua. Two adducts were isolated from the reaction of (±)?anti?DB[a,l]PDE and dG: (±)?11,12,13?trihydroxy?tetrahydroDB[a,l]P?14?N²dG and (±)?11,12,13?trihydroxy?tetrahydroDB[a,l]P?14?N7Gua.     

Ion interaction chromatography of anions in alkaline solutions: effect of temperature and the kind of stationary phase

Effect of temperature (5°–65°C) on the separation of 11 inorganic anions by ion interaction chromatography (IIC) was studied employing RP C₁₈ and C _PhenylHexyl columns and aqueous mobile phase: 2.8 mM NaHCO₃ + 0.7 mM TBAOH (tetra-n-butylammonium hydroxide). The apparent enthalpy changes, ΔH for hydrophobic ions like I^?, SCN^?, and ClO₄ ^? largely exceeded 3 kcal/mole suggesting that added to ion exchange they are retained by hydrophobic adsorption. Unlike conventional strongly basic anion exchangers, our system can be used at elevated temperatures with alkaline eluents without irreversible damaging the column.     

Dendrimer-like cyanoruthenate anions with high potential connectivity derived from a [Ru(bpym)3]2+ core

Reaction of [Ru(bpym)₃]²⁺ (bpym = 2,2′-bipyridmidine) with hexacyanoruthenate under forcing conditions affords a mixture of the trinuclear species [(bpym)Ru{(µ-bpym)Ru(CN)₄}₂]^2?, [1]^2?, and the tetranuclear species [Ru{(µ-bpym)Ru(CN)₄}₃]^4?, [2]^4?, in which two or three (respectively) of the peripheral vacant bpym binding sites of [Ru(bpym)₃]²⁺ are occupied by {Ru(CN)₄}^2? fragments. Thus, [1]^2? and [2]^4? have eight and twelve externally-directed cyanide groups respectively for use in forming high connectivity coordination networks. The crystal structure of HK[1]·2MeOH·6.5H₂O reveals a one-dimensional ladder structure in which [1]^2? anions are connected by (i) cyanide/K⁺ and (ii) bpym/K⁺ coordination interactions.     

Synthesis,Characterization, Crystal Structures and Thermal and Fluorescence Studies of Dinuclear and Polymeric Silver(I) Complexes of 5,5-Diethylbarbiturate with 2,5-Dimethylpyrazine and Piperazine Involving Ag–Ag Interactions

Two silver(I) complexes, [Ag(dmpyz)₂][Ag(barb)₂] (1) and {[Ag(ppz)][Ag(barb)₂]·H₂O} _n (2) (barb = 5,5-diethylbarbiturate, dmpyz = 2,5-dimethylpyrazine and ppz = piperazine), have been synthesized and characterized by elemental analyses, IR, thermal analysis (TG-DTA) and single-crystal X-ray diffraction. Complex 1 consists of [Ag(dmpyz)₂]⁺ and [Ag(barb)₂]^? ions in which the silver(I) ions are linearly coordinated by two dmpyz or two barb ligands. These two ions are connected by strong Ag–Ag interactions (Ag–Ag = 2.896 (1) Å). Complex 2 is a 1D coordination polymer in which the silver(I) ions are bridged by the ppz ligands in a linear fashion, leading to a zigzag chain of [Ag(ppz)] _n ⁺ , which interacts with the [Ag(barb)₂]^? units by Ag–Ag interactions of 3.183 (1) Å. The 1D chains are further assembled to form 3D networks by strong N–H···O and OW–H···O hydrogen bonds. IR spectra and TG-DTA data are in agreement with the crystal structures. The fluorescent properties of 1 were also evaluated.     

Effect of doping with different sulphur group elements on the performance of silver ion-conducting glass

Ion-conducting glasses of AgI-based Ge-Ga-S, Ge-Ga-Se and Ge-Ga-Te with different sulphur group elements were prepared by melt quenching technique. The electrical properties and thermodynamic stability were investigated and compared. Glass transition temperatures and crystallisation temperatures of the samples were measured using differential scanning calorimetry. Results showed that Ge-Ga-S-AgI had the best thermodynamic stability and glass-forming ability, highest ionic conductivity (1.33 × 10^?7 S/cm) at room temperature and lowest conductivity activation energy of 0.41 eV. Raman spectroscopy analysis showed that the [GeI_nS_4-n] (n = 1,2,3) structural units in the S series glasses provided a good environment for the effective transport of Ag⁺ and formed an active ion transport channel. By contrast, the structural units in the Se and Te series contributed less to the transport of Ag⁺. This work systematically explored the effects of three elements in the sulphur main group on the performance of Ag⁺ conductive glasses. This study provides a reference for the rational formulation of sulphur-based Ag⁺ conductive glass components with enhanced comprehensive properties.     

Extraction of iridium(III) by ion-pair formation with 2-octylaminopyridine in weak organic acid media

To extract iridium(III), various physicochemical parameters were studied. 2-Octylaminopyridine was used for the extraction of iridium(III) from acetate medium at 8.5 pH. Quantitative extraction of iridium(III) was achieved via ion-pair formation of cation [2-OAPH⁺] and anion [Ir(CH₃COO)₄]^?. The stripping of iridium(III)-laden organic phase was carried out 2 M HCl (3 × 10 mL) . The stoichiometry of the extracted ion–pair complex was found to be 1:4:1 (metal: acetate: extractant). The extracted species [2-OAPH⁺. Ir(CH₃COO)₄^?] is assumed to be an ion association product of [Ir(CH₃COO)₄] ^? and [2-OAPH]⁺. The proposed method was successfully used in the separation of iridium(III) from binary and ternary mixtures. Analysis of various alloy samples was also carried out.     

Ionization equilibria in solutions of nickel(II) chloride in dimethyl-sulphoxide

Visible absorption spectra and the molar conductance curve of NiCl₂ dissolved in dimethyl-sulphoxide (DMSO) have been determined at 25°C. The results indicate the formation of the [NiCl(DMSO)₅]⁺ inner-sphere complex followed by the formation of the {NiCl(DMSO)₅]⁺Cl^?} outersphere ion-pair as the concentration of NiCl₂ increases. The [NiCl₂(DMSO)₄] inner-sphere complex in pure dimethyl sulphoxide at 25°C is formed to but a small extent, but its relative content increases upon addition of the non-coordinating diluent, chlorobenzene. Dilutions with chlorobenzene also enhance coordination disproportionation producing the [NiCl₃ DMSO]^? tetrahedral complex. The stability constant of the monochloro complex derived from the conductometric data has the value of 297 (^±10)M^?2 at 25°C, and the estimated value of the association constant of the [NiCl (DMSO)₅]⁺Cl^? complex electrolyte, dominating in moderately concentrated solutions at room temperature, is 7(±3)M^?1.     

Optimisation of the biological treatment of hypersaline wastewater from Dunaliella salina carotenogenesis

The reutilisation of Dunaliella salina carotenogenesis medium, after microalgal biomass separation by centrifugation, was assessed. The wastewater had an NaCl concentration between 174 g dm^?3 and 254 g dm^?3 and an average total organic matter concentration of 1540 mg dm^?3 ash‐free dry weight, of which 41% (w/v) was glycerol. The biological treatment was established at laboratory scale and batch operations used halophilic bacteria from the wastewater itself. The wastewater was supplemented with NH₄⁺,PO₄^3?, K⁺ and Mg²⁺ ions to enhance growth. The effect of each ion added per se was initially investigated and a response surface methodology (RSM) used to identify the optimal conditions for maximisation of glycerol removal from the wastewater, which was considered to be the main objective. Addition of NH₄⁺ ions alone achieved 79% glycerol removal compared with only 59% in the absence of supplement, after 8 days incubation. The combined addition of ions ([NaCl] = 214 g dm^?3, [Mg²⁺] = 114 mg dm^?3, [K⁺] = 131 mg dm^?3, [NH₄⁺] = 113 mg dm^?3, [PO₄^3?] = 40 mg dm^?3) increased glycerol removal from the wastewater such that, after 2 days incubation, no residual glycerol was apparent in cultures. These ion combinations enabled the halophilic bacteria to efficiently remove glycerol from the wastewater and consequently reduce organic matter. This treated wastewater should be appropriate for reutilisation as a carotenogenesis medium for β‐carotene production from D salina. © 2001 Society of Chemical Industry     

Homogeneous Liquid–Liquid Extraction and Determination of Cobalt,Copper, and Nickel in Water Samples by Flame Atomic Absorption Spectrometry

Abstract

A simple and effective homogeneous liquid–liquid extraction method has been used for the simultaneous extraction and preconcentration of cobalt, copper, and nickel after the formation of complex with 4‐benzylpiperidinedithiocarbamate potassium salt (K‐4‐BPDC), and later they were determined by flame atomic absorption spectrometry (FAAS) using (water/tetrabutylammonium ion (TBA⁺)/chloroform) as a ternary component system. The phase separation phenomenon occurred by an ion‐pair formation of TBA⁺ and perchlorate ion. After the optimization of complexation and extraction conditions ([K‐4‐BPDC]=2.0×10^?4 mol l^?1, [TBA⁺]=2.0×10^?2 mol l^?1, [CHCl₃]=60.0 µl, [ClO₄ ^?]=2.0 ×10^?2 mol l ^?1 and pH=6.0), a preconcentration factor of 200 was obtained for only 10 ml of the sample.

The analytical curves were linear in the range of 20–1500, 15–2000, 35–1600 µg l^?1 and the limits of detection were 10, 5, and 15 µg l^?1 for Co²⁺, Cu²⁺, and Ni²⁺, respectively. The proposed method was applied for the extraction and determination of Co²⁺, Cu²⁺, and Ni²⁺ in natural water samples with satisfactory results.     

Thioether‐Functionalized Corn Oil Biosorbents for the Removal of Mercury and Silver Ions from Aqueous Solutions

Heavy‐metal contamination is one of the most important environmental problems faced in the world, particularly in developing countries. Metals such as silver and mercury from drinking water, food, and air sources can accumulate in living organisms and present significant health concerns. Meanwhile, the demand for these metals in many industries continues to increase. In the present study, thioether‐functionalized corn oil (TFCO) from a photoinitiated thiol‐ene synthesis was utilized to remove Ag⁺ and Hg²⁺ ions from an aqueous solution. An aqueous solution containing AgNO₃ and Hg[NO₃]₂ was prepared and contacted directly with TFCO. After vortex mixing for 60 s, the experiment ran for 351 min with the aqueous phase being periodically sampled for the analysis of metal ions (M ⁿ⁺). Results showed that 88.9% of Ag⁺ and 99.6% of Hg²⁺ ions were removed from the aqueous phase by the TFCO. Mass balances indicated that the total M ⁿ⁺ concentration in the oil phase was 13.890 g kg^?1 under the conditions studied. TFCO exhibited higher selectivity for removing Hg²⁺ than for Ag⁺ ions. Analysis of the adsorption kinetics showed that a pseudosecond‐order model may be used to determine the rate of Ag⁺ ion sorption by the oil phase. The presence of the Hg²⁺ ions interfered with the adsorption of Ag⁺ ions from the aqueous solution.     

Mass transfer kinetics of neodymium(III) extraction by calix[4]arene carboxylic acid using a constant interfacial area cell with laminar flow

BACKGROUND: Thermodynamics and kinetics data are both important to explain the extraction property. In order to develop a novel separation technology superior to current extraction systems, many promising extractants have been developed including calixarene carboxylic acids. The extraction thermodynamics behavior of calix[4]arene carboxylic acids has been reported extensively. In this study, the mass transfer kinetics of neodymium(III) and the interfacial behavior of calix[4]arene carboxylic acid were investigated. RESULTS: The rate constant (K_ao) becomes constant when the stirring speed was controlled between 250 rpm and 400 rpm. The activation energy (E_a) was calculated to be 21·41 kJ mol^?1 or 88·17 kJ mol^?1 (dependent on temperature) from the slope of log K_ao against 1000/T. The linear relationship between the specific area and the extraction rate is the characteristic of an interfacial reaction control. The minimum bulk concentration of the extractant necessary to saturate the interface (C_min) is lower than 4·19 × 10^?4 mol L^?1. CONCLUSION: The effect of stirring speed, temperature, and species concentration on the extraction rate demonstrates that the extraction regime depends on the extraction conditions. The chemical reaction control governs the extraction regime at temperatures below 303 K and a mixed control regime occurs when the temperature is between 303 K and 318 K. The probable locale for the chemical reaction is at the liquid–liquid interface and the rate equation is deduced to be: ? d[Nd³⁺]_(a)/dt = k_f[Nd³⁺]_(a)[H₄A]_(o)^0·727[H⁺]_(a)^?0·978. The rate‐controlling step was suggested by the analysis of the experimental results. Copyright © 2008 Society of Chemical Industry     

Electrocoated Films of Poly(N-Methylpyrrole-co-2,2′-Bithitiophene-co-3-(Octylthiophene)), Characterizations,and Capacitor Study

N-Methylpyrrole (N-MPy), 2,2′-bithiophene (BTh), and 3-(Octylthiophene) (OTh) were electrocopolymerized in 0.2 M NaClO₄/CH₃CN on glassy carbon electrode (GCE). The resulting terpolymers of N-MPy, BTh and OTh in different initial monomer feed ratios such as [N-MPy]₀/[BTh]₀/[OTh]₀ = 1/1/1 and 1/2/5 were characterized by cyclic voltammetry (CV), Fourier-transform infrared attenuated total reflectance spectroscopy (FTIR-ATR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and electrochemical impedance spectroscopy (EIS). The capacitive behaviors of the modified electrodes were defined via Nyquist, Bode-magnitude, Bode-phase, and Admittance plots. The equivalent circuit model of Rs(C _dl1 (R ₁ (QR ₂ )))(C _dl2 R ₃ ) was performed to fit the theoretical and experimental data. The low-frequency capacitance (C_LF) were obtained from initial monomer concentrations of 50 mM as C_LF = ～2.34 × 10^?4 mFcm^?2 for P(N-MPy), C_LF = 5.06 × 10^?4 mF cm^?2 for P(BTh), C_LF = 5.07 m F cm^?2 for P(OTh), and C_LF = ～3.78 m Fcm^?2 for terpolymer for [N-MPy]₀/[BTh]₀/[OTh]₀ = 1/1/1. The terpolymer may be used as energy storage devices.