The Separation of Metals from Treated Deep-Sea Ferromanganese Nodules by Adsorptive Bubble Techniques Using Salicylaldoxime and Sodium Diethyldithiocarbamate as Organic Precipitating Reagents

Abstract

An adsorptive bubble technique, using two organic precipitating reagents, is applied to separate cobalt, copper, nickel, and manganese from the leach liquors of sulfated deep-sea ferromanganese nodules. Recoveries of the four metal values are studied as a function of pH for each system. The organic precipitating reagents studied are salicylaldoxime and sodium diethyldithiocarbamate.     

A convenient synthesis of novel 1,3-phenylene bridged bis-heterocyclic compounds

Reactions of bis-hydrazonoyl bromide 1 with each of phenyl-5-arylidene-2-thioxo-thiazol-4-one, triazinethiones and 4,6-dimethyl-2,6-dioxocyclohexane-1-thiocarboxanilide as sulfur dipolarophilic reagents led to the formation of the hitherto unreported 1,3-phenylene bis-heterocycles 4, 8 and 10, respectively. The structures of the isolated products were established on the basis of their elemental and spectral analyses. The mechanism and the site selectivity in the studied reactions are discussed.     

Organic Chemistry of Macromolecules

Abstract

Polymers as reagents in organic synthesis may offer certain advantages over low molecular weight reagents. Examples given include cyclization reactions, Dieckmann reactions, acylation and alkylation of active methylene esters, intrapolymeric reactions, hydrogenation of cyclic olefins, and hydrolysis of esters. The influence of cooperative effects and hydrophobicity on the self-acceleration and allosteric effects on some of these reactions is discussed.     

The behavior of some Wittig reagents toward 4,5,6,7-tetrahydro-3H-1,2-benzo[1,2]dithiole-3-thione

ABSTRACT

Novel synthetic route for phosphanylidene-benzothiophenethione, benzothiaphosphinine-4-thione, triphenylphosphoranylidenecyclobutane and benzodithiolylidenephosphonate derivatives has been proposed through reactions of 4,5,6,7-tetrahydro-3H-1,2-benzodithiole-3-thione with different Wittig and Wittig–Horner reagents. All new synthesized compounds were fully characterized with elemental and spectroscopic analysis.     

Xanthan Precipitation from Solutions and Fermentation Broths

Abstract

Precipitation of xanthan from solutions and fermentation broths is studied. The effects of different precipitating agents, initial xanthan concentrations, and salt additions on xanthan solutions are examined. The effect of sodium and calcium chloride concentrations added to isopropanol (IPA) is studied for xanthan solutions. Xanthan precipitation from fermentation broths has been carried out, and the effect of salt addition to IPA is considered.     

POLY-(DIPHENYLPHOSPHINYLMETHYL)ARENES - NEW ORGANOPHOSPHORUS EXTRACTANTS OF TRANS-PLUTONIUM ELEMENTS

ABSTRACT

The extraction properties of poly-(diphenylphosphinylmethyl) arenes in which the fragments of different methyl substituted aromatic compounds serve as hard bridges connecting the P=0 functional groups was studied. The extraction of trivalent transplutonium elements and rare earth elements, uranium (VI), plutonium (IV) by chloroform solutions of these reagents as function of HNO₃, and ligands concentration was investigated. The selectivity of reagents was found to depend only on mutual arrangement of P=0 groups in the bridge regardless of their number. Conformational analysis of the reagents described have been used to establish their structure and cause of their selectivity with respect to one or another element.     

Analytical Applications of Mixed Ligand Complexes. II. Separation-Gravimetric Determination of Cu(II) as Its Mixed Ligand Complex with 1,10-Phenanthroline and p-Cresotic Acid

Abstract

A method is presented for the gravimetric determination of Cu(II) followed by its separation from Ni(II), Co(II), Mn(II), and other anions and cations by precipitating it as its mixed ligand complex with 1,10-phenanthroline and p-cresotic acid (5-methylsalicylic acid). The precipitate is equivalent to 0.184 times its weight of copper. The method has potential for use in the large-scale separation of copper.     

Solvent Extraction of Copper from Nitrate Media with Chelating LIX‐Reagents: Comparative Equilibrium Study

Abstract

Comparative experimental studies were carried out on extraction of copper(II) cations from aqueous acid nitrate media using four LIX‐reagents, representatives of different extractant classes: LIX 984N‐I, LIX 860N, LIX 84‐I and LIX 65N. As a diluent, liquid hydrocarbon undecane was used. The extraction behavior of the LIX‐reagents was compared based on an analysis of the influence of the main factors on the two‐phase mass transfer process: aqueous pH‐value, initial copper and extractant concentrations, and temperature. The experimental data received were used in the calculation of important parameters characterizing the efficiency of copper extraction from nitrate media with different LIX reagents: distribution ratios D, concentration extraction constants K _ex, pH_0.5‐values, and thermodynamic parameters such as enthalpy, entropy, and free energy changes (ΔH ⁰, ΔS ⁰, ΔG ⁰‐values).     

Precipitation of Kraft Black Liquors by Alcohol-Calcium Solutions

Abstract

Industrial and laboratory kraft black liquors were precipitated with a) water-soluble solvents (alcohols and acetone), b) calcium and aluminum salts, and c) alcohol-calcium solutions. Volume of solvent and the amount of Ca (or Al) were varied over wide intervals, and their effect on the amount and composition of precipitate was studied. Alcohol-calcium solutions were the best precipitating agent (90% of the lignin was recovered with good filterability). The pollutant load of the resulting filtrate showed considerable reductions in some parameters. Precipitation of black liquors with alcohol-calcium solution instead of acid precipitation or ultrafiltration may be an alternative to combustion.     

Diluent-Modified Impregnates for the Selective Extraction of Copper

Abstract

Inert diluents were included in resin impregnates of copper selective reagents to improve their selectivity for copper over iron(III). The modified impregnates performed similarly to conventional ones in other respects with the exception that the loading rates were generally slower. This is a problem that can be overcome to some extent by the correct combination of resin matrix, diluent, and reagent. However, there appears to be a trade-off between diluent loss and kinetics.     

STUDY OF KINETIC FACTORS AFFECTING THE EFFICIENCY OF SEPARATION OF TRANSPLUTONIUM AND RARE-EARTH ELEMENTS DURING THE EXTRACTION BY DI-(2-ETHYLHEXYL)PHOSPHORIC ACID

ABSTRACT

The kinetics of the extraction of transplutonium and rare-earth elements with HDEHP from solutions of different complex-forming reagents has been studied. The possibility of the Improvement of intragroup separation of these elements with the use of dynamic factors has been demonstrated     

Synthesis and antioxidant activities of some novel fluorinated spiro[oxindole-thiazolidine] fused with sulfur and phosphorus heterocycles

Facile routes were achieved for the synthesis of novel fluorinated spiro[oxindole-thiazolidinone] fused with some sulfur and phosphorus heterocycles starting from 5-fluoro-3^′-(4-fluorophenyl)-4^′H-spiro[indole-3,2^′-thiazolidine]-2,4^′(1H)-dione (1) via its reaction with trifluoroacetamide, 2-chloro-6-fluorobenzaldehyde and hydrazine hydrate followed by treatment with some suitable sulfur and phosphorus reagents. The antioxidant activities of the synthesized compounds were also evaluated.     

Optimization of NOM Removal during Water Treatment

Abstract

The aim of this paper is to describe the removal efficiency of individual fractions of natural organic matter (NOM) and the aluminum transformation during treatment of two types of surface water with an increased concentration of NOM of various origins. The coagulation conditions (dose of destabilization reagent and reaction pH value) were optimized for the best NOM and aluminum removal. The results show that the NOM removal efficiency depends on the NOM character, using destabilizing reagents and reaction conditions. The optimized doses of destabilization reagents influence especially the removal of hydrophilic charged (CHA) and very hydrophobic acids (VHA) fractions during treatment of both types of raw water. In contrast to this, the removal of hydrophilic neutral (NEU) fraction is very low (? _NEU =0.13–0.22). The optimal destabilization reagent dosage is characterized by the lowest content of the total reactive aluminum concentration and relatively low concentration of dissolved organic aluminum.     

COMPOSITION OF CYANEX® 923, CYANEX® 925, CYANEX® 921 AND TOPO

ABSTRACT

The composition of commercial reagents CYANEX® 923, CYANEX® 925, CYANEX® 921 and TOPO was investigated by GC/MS. CYANEX® 923 contains 18 components. 17 compounds were identified as trialkylphosphine oxides, mainly with normal (92.4) hexyl and octyl groups. CYANEX® 925 consists of 19 components. The reagent contains 65.9% kyphosphine oxides, mainly with isooctyl groups. The reagent contains also trialkylphosphine sulphides, dialkyldithiophosphinic acids and dialkyldisulphides having octyl and butyl groups. Trialkylphosphine sulphides and dialkyldithiophosphinic acids are present in amount of 26.8% be also considered as the active substance. CYANEX® 921 and TOPO are high quality reagents with the content of the active substance of about 99%. Trioctylphosphine oxide is the main component.     

Facilitated Transport of Gold through a Membrane via Complexation to Thiourea-Based Reagents

Abstract

The facilitated transport of Au(III) from hydrochloric acid solutions through double solid supported liquid membranes (SSLMs) is reported. The organic phase consisted of a chloroform solution of thiourea-based extraction reagents, dodecyl-thiourea (DTH) or nonylthiourea (NTH), physically absorbed onto microporous polypropylene films, Celgard 2500 or Celgard 2400 (Celanese Plastic Inc.). A cell composed of three compartments, including a reservoir of organic solution, with double SSLM was used in this study. Aqueous solutions of thiourea, KSCN, or Na₂S₂O₃ were used for removing Au(III) from the membrane phase. The permeability coefficient, P, of the SSLM was determined from the slope of Iog[Au]/[Au]_o or log A/A_o vs time plot. The influences of the stirring rate in aqueous feed and organic solutions, of the stripping reagents and their concentration, of the carrier concentration, and of the concentration of HCl in the aqueous feed on the permeability coefficient were determined. A model describing the transport mechanism consisting of diffusion through a feed aqueous diffusion layer, a fast interfacial chemical reaction, and diffusion through the membranes is reported. The study also demonstrates the suitability of the liquid membrane technique to use reagents with low solubility in organic solutions for the permeation of Au³⁺ without problem of solid-phase formation.

     

Continuous Extraction of Crude Tall Oil

Abstract

A new continuous extraction method for fatty and resinic acids separation from crude tall-oil sodium salts aqueous solutions by countercurrent contact with n-heptane was developed using a bench-scale multistage mixer-settler plant. The data obtained showed good recoveries and high purities, especially for resinic fraction stream, for which the consumption of chemical reagents is virtually obviated with consequent economic advantages.     

Assembly of a water-insoluble strontium metal–organic framework with luminescent properties

A new strontium metal–organic framework, [Sr₂(BTEC)(H₂O)₄]?2H₂O (1) (H₄BTEC = benzene-1,2,4,5-tetracarboxylic acid), has been successfully synthesized by mixing the starting reagents. The single-crystal structure analysis showed that compound 1 displayed three-dimensional structures containing inorganic motifs with two-dimensional layers pillar-connected through organic linkers and forming water-coordinated neutral framework. Further studies revealed that compound 1 was insoluble in water and that it emitted strong luminescence at approximately 437 nm after dehydration.     

Effects of acetic acid addition methods on butyl acetate enzymatic synthesis

Abstract

Butyl acetate is a versatile chemical due to its excellent solvency for polymers, resins, and oils. In this work, the butyl acetate synthesis was studied by the esterification of n-butanol with acetic acid using the commercial immobilized lipase Novozym^® 435. The acetic acid and n-butanol concentrations have to be limited in the enzymatic synthesis of this ester due to the deleterious effects caused by these reagents on the enzyme. Three methods of acetic acid addition (single, stepwise and continuous addition) were investigated to minimize the acid concentration. A significant drop on acid conversion was observed in the presence of a higher concentration of the reagents when single or stepwise acid addition was used. However, a solvent-free system using a continuous addition of acetic acid favored butyl acetate synthesis, reaching a conversion of 84% at 60?°C, employing 5?wt% of enzyme and n-butanol/acetic acid final molar ratio equal to 1/1.     

Study on the Thermooxidative Degradation Kinetics of Tetrafluoroethylene-Ethylene Copolymer Filled with Rice Husks Ash

The thermooxidative degradation kinetics of tetrafluoroethylene-ethylene copolymer (TFE-E) and its composites filled with 10 mass% black rice husks ash (BRHA), white rice husks ash (WRHA) or Aerosil A200 Degussa (AR) in air was studied using the Coats-Redfern calculation procedure. The thermooxidative degradation of these composites occurs in two stages and their most probable kinetic mechanisms were established, as well as the values of the activation energy E, frequency factor A in the Arrhenius equation and the changes of Gibbs free energy Δ G ^≠, enthalpy Δ H ^≠ and entropy Δ S ^≠ for the formation of the activated complex from the reagents, respectively. The thermooxidative degradation of the samples studied was accompanied by kinetic compensation effect. The lifetime values were calculated at different temperatures to conclude that the use of BRHA as filler reduced lifetime to the highest extent.