KINETICS OF THE EXTRACTION OF COBALT WITH EXTRACTANT P5709

The kinetics of extraction of cobalt with P5709 was studied in a Lewis cell. In the extraction system the aqueous phase was the solution of CoSO_4 (8.8×10~(-4)—3.4×10~(-2)M) and Na_2SO_4 (0.63M.) at pH 5.5; the organic phase was 15% (v/v) P5709 in kerosene (saturated with hydrogen).In order to determine the control regime of extraction of cobalt, the stirring speed, the interracial area between the two phases and the operating temperature were varied in the experiments. Experimental results showed that the extraction process of cobalt was predominantly governed by the diffusion process, and the overall mass transfer coefficients were found to be as follows:_((a)): (2-5)×10~(-3)cm/s, _((o)): (0.3-1)×10~(-3)cm/s.The results of the experiments and calculations indicated that K did not remain constant during the extraction process, Reasons for the variations in K were discussed.     

A NEW PROCESS FOR THE EXTRACTION OF PENICILLIN G FROM THE FILTRATE OF FERMENTATION BROTH WITH TBP IN BUTYL ACETATE

The mixture of neutral phosphorus esters and butyl acetate (BA) can be used, as the extractant for the extraction of penicillin G. The extraction equilibrium pH can be increased to pH3—4 due to the stronger extraction capability of the solvent mixture, instead of pH1.8—2.2 with butyl acetate as solvent. The experimental results indicate that the total recovery of penicillin G can reach 96.6% with the new extraction process, which is 5—6% higher than that obtained with the traditional process using BA as solvent at pH1.8—2.2.     

COBALT–NICKEL SEPARATION: THE EXTRACTION OF COBALT(II) AND NICKEL(II) WITH BIS(2-ETHYLHEXYL) PHOSPHINIC ACID (PIA-8) IN TOLUENE

The extraction behaviour of cobalt(II) and nickel(II) from sulfate solutions with bis(2-ethylhexyl) phosphinic acid (PIA-8) in toluene has been studied. Quantitative extraction of Co(II) was observed at pH 5.0–5.9 while that of Ni(II) at pH 6.8–7.0 with 0.03 M PIA-8 in toluene. The difference in pH_0.5 for Co(II) and Ni(II) was 1.9. The stoichiometry of the extracted species were determined by slope analysis method. The extraction reaction proceeds by cation exchange mechanism and the extracted species were Co · R₂(HR)₂ and Ni · R₂ · 2(HR)₂. Temperature dependance of the extraction equilibrium constants were determined to estimate the apparent thermodynamic functions (ΔG, ΔS and ΔH). The method was used for separation of cobalt(II) and nickel(II). Cobalt(II) was separated from nickel even at 1:20 (Co:Ni) ratio. The separation of cobalt(II) from nickel(II) was favoured with the increase in temperature.     

SYNERGISM IN THE EXTRACTION OF ZINC(II)AND CADMIUM(II) WITH SOME LOWER FATTY ACIDS IN THE PRESENCE OF AMINES AND THEIR SEPARATIONS∗

Abstract

Synergism in the extraction of Zn(Il) and Cd(II)with chloroform solution of propionic, butyric and valeric acids in the presence of n-butylamine, dibutylamine, tributylamine, β-picoline, pyridine and quinoline is reported The effect of various parameters affecting extractions has been investigated The compositions of synergistic adduct extracted into the organic phase have been proposed on the basis of slope analysis method. In general the species have been represented as MA2.2HA.B (aliphatic amine system and MA₂.2HA.2B (heterocyclic amine system), where M = zn(Il)/CdII), HA = acid and B = amine. On the basis of extraction constant (K_ex) values the relative effectiveness of different amines as synergists has been compared. Based on the extraction data some separations of metal ions have also been reported with fairly high separation factor (β).     

THE SEPARATION OF NEPTUNIUM AND PLUTONIUM FROM NITRIC ACID USING n-OCTYL(PHENYL)-N,N DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE EXTRACTION AND SELECTIVE STRIPPING†

The extraction of neptunium and plutonium in several oxidation states was studied as a function of nitric acid concentration for 0.1M n-octyl(phenyl)-N, N-diisobutylcarbamoyl -methylphosphine oxide in 1.4M tributylphosphate with dodecane diluent. Np(V) is only weakly extractable over the range of acid concentrations studied while Np(IV) and Np(VI) are highly extractable. Pu(IV) and Pu(VI) are also highly extractable while Pu(III) was extracted but with lower efficiency. An Fe(II) reductant was used to reduce neptunium to Np(IV) and plutonium to Pu(III) for the initial extraction. Pu(III) was then stripped with dilute HNO₃ in the presence of a holding reductant leaving the Np(IV) in the organic phase. Neptunium may then be recovered to an aqueous phase with one of a number of complexing agents.     

THE DIFFUSION COEFFlCIENT OF HEHEHP IN HEPTANE MEASURED BY THE MODIFIED STOKES CELL TECHNIQUE AT TEMPERATURES BETWEEN 25 AND 55°C.

The diffusion coefficient of HEHEHP in heptane has been measured by the modified Stokes cell technique at temperatures between 25 and 55^°C. The Stokes cell was calibrated by measuring acetic acid diffusion with the pH-stat technique. The average diffusion coefficient of HEHEHP in heptane was determined to be 0.97 × 10 ^?9 m²/s at 25 ^°C for HEHEHP concentrations of 0 - 0.1 kmol/m³. The diffusion coefficient did not vary significantly with HEHEHP concentration. The Wilke-Chane relationship was used to predict D values of 1.53 × lO^?9m²/s and 1.01 × 10 ^?9m²/s for the monomelic and dimeric species respectively. Comparison of the measured and predicted diffusion coefficients led to the conclusion that the HEHEHP was substantially dimenzed over the concentration range studied

An activation energy of 6.90 kJ/mol was calculated from the diffusion coefficient measurements at elevated temperature.     

POLYMERIZATION OF BUTADIENE IN TOLUENE WITH NICKEL(II) STEARATE-DIETHYL ALUMINUM CHLORIDE CATALYST†

A bench-scale batch reactor was used to study the polymerization of butadiene with nickel(II) stearate Et₂AlCl catalyst. In particular, the effects of moisture on polymerization were investigated. The initiation reaction is sensitive to temperature. At 0°C an induction period was observed, but at room temperature initiation can be assumed instantaneous. Water enhances catalytic reactivity, however at water concentrations greater than 10 mmol/L, termination reactions become significant. Maximum conversion is obtained in the 6 to 15 mmol/L range of water. The determining step for the molecular weight of polymer is the chain transfer to monomer. At low H₂O concentration the molecular weight increases with water concentration, however it becomes independent of water concentration at high moisture content. With the help of statistical analysis of the experimental data, a two-active-species model was developed to describe the kinetics of the system and to explain certain polymerization characteristics.     

EFFECT OF SELECTED β-DIKETONES ON THE SYNERGICEXTRACTION OF COBALT(II) BY TRIPHENYL-PHOSPHINE OXIDE IN BENZENE

Abstract

Synergic extraction of Co(ll) by thenoyltrifluoroacetone (HTTA), Pivaroyltrilluoioacetone (HPvTA) or hexafiuoroacetylacetone (HHFA) mixed with triphenyiphosphine oxide (ph₃PO) in benzene from perchlorate media has been investigated. It ’ was found that in all the systems studied, Co(ll) is synergistically extracted as CoL₂.ph₃PO, where L stands for the different chelating ligands. The obtained equilibrum constants for the chelating and adduct systems indicated that: i- the weaker the acidity of the chelating ligand, the higher the overall aqueous phase formation constant of the metal chelate (β₂ ), ii- the sequence of the extraction constants (K_2,1 ) and the organic phase formation constants for the adduct ( β_2,1) as related to the chelating ligands is TTA> HFA > PvTA, iii- the stability of the adduct is related to both the structure and the pK_avalues of the chelating ligands.     

KINETICS OF METHANOL SYNTHESIS IN THE PRESENCE OF C301 Cu-BASED CATALYST (Ⅰ) INTRINSIC AND GLOBAL KINETICS

The intrinsic and global kinetics of methanol synthesis from carbon monoxide, carbon dioxide and hydrogen in the presence of C301 commercial catalyst is studied. The investigation is performed under typical commercial conditions in an isothermal plug-flow integral reactor and an     

EQUILIBRIUM AND KINETIC STUDIES FOR THE ADSORPTION OF MN(II) AND CO(II) FROM AQUEOUS MEDIUM USING AGAR–AGAR AS SORBENT

An extensive increase in industrial activities and environmental accidents in recent years have greatly contributed to increasing metal pollution in water resources, thereby causing threats to terrestrial as well as aquatic life. The toxicity of metal pollution is slow and long lasting, as these metal ions are nonbiodegradable. The most appropriate solution for controlling the biogeochemistry of metal contaminants to produce high-quality treated effluents from polluted wastewaters is sorption technique. Agar–agar, a readily available seaweed, was used as sorbent for the removal of Mn(II) and Co(II) from aqueous media. Batch experiments were performed to study adsorption as a function of process parameters: sorption time, initial pH, concentration of sorbate and sorbent. The Freundlich model fitted best with the experimental equilibrium data between the two adsorption isotherm models tested. The kinetic data correlated well with the Lagergren pseudo-second-order kinetic model for the sorption of both Mn(II) and Co(II) using agar–agar. Adsorbed metal ions were quantitatively recovered from the spent adsorbent using 5.0 mol L^?1 HCl. The efficiency of agar–agar for decontaminating Mn(II) and Co(II) from electroplating effluent has also been evaluated. The results proved agar–agar to be a favorable adsorbent to remove and recover Mn(II) and Co(II) from waste effluent for further use in diversified industrial applications.     

THE EXTRACTION OF SELECTED ACTINIDES IN THE ( III) (IV) AND ( VI) OXIDATION STATES FROM HYDROCHLORIC ACID BY Oπ D( iB) CMPO: THE TRUEX-CHLORIDE PROCESS∗

The extraction of tetravalent Th, Np, and Pu and hexavalent U from hydrochloric acid was studied using octyl(phenyl)-N,N-diiso-butylcarbamoylmethylphosphine oxides, 0π D(iB)CMP0 or CMPO, dissolved in tetrachloroethylene (TCE). A 0·5 MCMPO solution in TCE was found to be an extremely effective extractant for the tetravalent actinides and U(VI) from moderate to concentrated HC1. Extractant dependencies of the distribution ratios of Th(IV), U(VI), and Pu(IV) were 3rd, 2nd, and 3rd power, respectively, indicating the following species: ThCl₄’3CMPO, UO₂Cl₂2CMP0, and PuCl₄»3CMPO. The distribution ratios of a variety of non-actinide elements, including selected alkali, alkaline earths, Al, transition and post-transition metal ions were also measured from 2 Mand 6 M_ HC1. Based on the distribution ratios of tri-, tetra-, and hexavalent actinides from chloride media, a generic actinide extraction/recovery process was developed for the removal of actinides from chloride salt wastes. The process is called TRUEX-Chloride.     

THE EXTRACTION OF CATIONIC RUTHENIUM COMPLEXES FROM AQUEOUS MEDIA BY α-TIN(IV) HYDROGEN PHOSPHATE

ABSTRACT

The ruthenium species [Ru(NH₃)₆]³⁺ was adsorbed by the surface of (α-Sn(HPO₄)₂.2H₂O [SnP]) α-tin(IV) hydrogen phosphate. The ruthenium(II)-containing cation [Ru(NH₃)₆]²⁺, however, has been directly intercalated into (SnP). Since the corresponding ruthenium(III) complex cation was not so intercalated, a new self-catalysed intercalation mechanism involving labile ammonia ligands from the ruthenium(II) has been proposed. At high loadings, guest ruthenium(II) species were oxidised to ruthenium(III).     

KINETICS OF METHANOL SYNTHESIS IN THE PRESENCE OF C301 Cu-BASED CATALYST (Ⅱ) EFFECTIVENESS FACTORS OF PARALLEL REACTIONS

For multiple reaction system of methanol synthesis in the presence of Cu-based catalyst, hydrogenation reactions of CO and CO_2 are selected as key reactions. A diffusion model, taking CO and CO_2 as key components, is presented for the calculation of the intraparticle effectiveness factors of the two parallel key reactions over C301 Cu-based catalyst. Numerical solutions of the effectiveness factors     

SEPARATION OF COBALT(II) AND NICKEL(II) IONS FROM ACID AQUEOUS SOLUTIONS BY Co IT ION-EXCHANGE INTO γ-TITANIUM PHOSPHATE

ABSTRACT

The Co²⁺-2H⁺, Ni²⁺-2H⁺, and Co²⁺-Ni²⁺-2H⁺ ion exchange processes into γ-Ti(H₂PO₄)(PO₄)2H₂O were studied. Exchange isothenns and titration curves were obtained. Monometallic half ion exchange phases were formed by using MC₂+HCl (M=Co,Ni) solutions. Equilibrium constants, free energy, enthalpy, and entropy of the Co²⁺-2H²⁺ ion exchange reaction were determined. In (Co,Ni)Cl₂ solutions, bimetallic a half ion exchange substitution solid solution is detected. Equilibrium constant of the Co²⁺-Ni²⁺ substitution process in the γ-Ti(Co_xNi_0.5?x.HPO₄)(PO₄)nH₂O phase at 85°C was determined. In (Co,Ni)Cl₂+HCl solutions, total separation of Co²⁺ and Ni²⁺ is obtained.     

SOLVENT EXTRACTION OF COBALT AND NICKEL IN BIS (2,4,4-TRI-METHYLPENTYL) PHOSPHINIC ACID, “CYANEX -272”

ABSTRACT A study has been made of the extraction of cobalt and nickel from sulfate solutions into bis(2,4,4 tri-methylpentyl) Phosphinic acid - “Cyanex 272”, diluent Esso solvent DX 3641, for both high and low metal loading in the organic phase. In dilute solution, 0.01 M, extraction constants and enthalpies were determined for both metals. The extraction of cobalt was always favored over that of nickel, increasing with increase in temperature. No structure change with temperature was found for the cobalt-Cyanex complex. Phase modifiers were found to effect the selectivity of “Cyanex 272” for cobalt.

At high metal loading, equilibrium curves for cobalt were fitted using semi-empirical curve fitting, while for nickel a straight line variation was observed. Organic phase polymerization was observed for both metals the degree of aggregation increasing with increase in loading. A step change increase in the viscosity of the organic phase was observed at high cobalt loading. Phase modifiers proved to be ineffective In reducing the increase in organic phase viscosity.     

STUDIES ON KINETICS OF DESORPTION OF CO_2 FROM HOT CARBONATED POTASH SOLUTION WITH DETA (DIETHYLENETRIAMINE) AS A CATALYST

Under atmosphe()e press()ne, rates of deseption of CO() from unmod()ed carbonated potash solutior (27 wt%)and modified carbonated potash solution(27 wt%) containing DETA as a catalyst, have been measured in a laboratory stirred reactor. Experiments were carried out with concentrations of DETA from 0—40g/L and temperatures from 90—104℃The results, show that the desorption of CO_2 from hot carbonated solutions with and without the addition of DETA, may be considered a pseudo-first order reversible reaction, and that the desorption of CO_2 from carbonated potash solution calalysed by DEIA is in agreement with the mechanism of simultancous reactions of CO_2 with amine molecules and with hydroxyl ions in solution. Mathematical models for desorptions rate cocflicient have been cstablished, and optimum concentration of DETA is proposed.     

SOLVENT EXTRACTION OF Au(III), Pd(II) AND Pt(lV) WITH SULFUR-CONTAINING METHYLPHOSPHONATES AND β-KETOPHOSPHONATE

Three sulfur-containing methylphosphonates, dibutyl propylthiomethylphosphonate, (C₄H₈O)₂P(0)CH₂SC₃H₇,(DBPTMP),dibutyl propylsulfinylmethylphosphonate, (C₄H₉0)₂P(0)CH₂S(0)C₃H₇, (DBPSiMP) and dibutyl propylsulf onylmethylphosphonate, (C₄H₈O)₂P(0)CH₂S(0) C₃H₇ (DBPSiMP) were synthesized. The extraction of gold(III), palladium(II) and platinum(IV) from HCl media with the synthesized compounds and dibutyl 2-keto-3-methylbutyl-phosphonate, (C₄H₈O)₂P(0)CH₂C (0) CH(CH₃) CH₃, (DBKPP) was investigated at various mixing times and acidities. DBPTMP and DBPSiMP were found to provide nearly quantitative extraction of Au(III) and Pd(II) with short equilibration times for Pd(II) extraction. DBKPP was selective for Au(TII) over Pt(IV) and Pd(II) at high acidity. The behavior of these extractants was also examined in comparison with the corresponding monofunctional extractants, dibutyl butylphosphonate(DB‘BP’), tributyl-phosphate(TBP), dioctylsulphide(DOS) and dioctyl-sulphoxide(DOSO).     

LIQUID AND SOLID PHASE REACTION KINETICS OF PHOSPHORIC ACID COMPLEX SYSTEM(Ⅰ) DIFFUSION AND REACTION MECHANISM IN FRACTAL MEDIA

采用随机过程理论导出了液相在固体颗粒分形介质中的扩散方程 ,得到了分形扩散系数与自由空间扩散系数的关系式 .同时研究了以磷酸与具有丰富内孔隙的磷矿颗粒为代表的液固两相反应的机理和动力学模型 .发现已反应完毕的区段与尚未反应的区段之间的反应界面不是一个面 ,而是一个过渡区段 ,这一反应区段将逐步向颗粒中心移动 .根据固相物质的分形结构与反应机理 ,导出了描述这一过程的理论模型 .     

DESENSITIZING EFFECT OF ISOMERIC METALLORGANIC PALLADIUM (II) COMPOUNDS WITH THIOSEMICA-RBAZIDE ON THE DEVELOPMENT PROCESS OF SILVER HALIDE PHOTOGRAPHIC MATERIALS

Some chemical compounds can be used in the chemical photographic development process of silver halide panchromatic motion picture materials to decrease their sensitivity upon exposure whereby their development is possible at relatively bright illumination. Such compounds can be the organic compounds of o-elements with complanar structure. It was observed, in particular, the pronounced desensitizing effect of bis (thiosemicarbazido) palladium (Ⅱ) dichloride of the formula:     

SIMPLIFIED FRAMEWORK FOR DESCRIPTION OF MIXING WITH CHEMICAL REACTIONS (Ⅱ) CHEMICAL REACTIONS IN THE DIFFERENT MIXING REGIONS

1 INTRODUCTIONIn Part Ⅰ of this study,the physical aspects for micro-and macromixing were outlined,a shrinkage slab model for micromixing was presented and a three-region picturecharacterizing interaction between micro-and macromixing was sketched.The feed ma-terial from a point source was shown to successively undergo the dispersion,micromixing and macromixing regions before achieving homogeneity on the molecular