铀的三元协萃规律研究——HTTA-HPMBP-(C_8H_5)_4AsCl三元协萃高氯酸铀酰的机理

本文研究α-噻吩甲酰三氟丙酮(HTTA)、1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮(HPMBP)与四苯基砷氯(C_6H_5)_4AsCl的氯仿溶液从高氯酸中萃取U(VI).该体系属螯合、离子缔合AAC类,其二元及三元协萃平衡常数分别为:logβ_(A_1C)=3.97[HTTA-(C_6H_5)_4AsCl];logβ_(A_2C)=4.86[HPMBP-(C_6H_5)_4AsCl];logβ_(A_1A_2C)=5.52[HTTA-PMBP-(C_6H_5)_4AsCl].用亚甲基蓝光度法测定了萃合物中ClO_4~-的存在,用斜率法确定二元协萃物组成为(C_6H_5)_4As~+[UO_2(ClO_4)(TTA)_2]~-和(C_6H_5)_4As~+[UO_2(ClO_4)(PMBP)_2]~-,三元协萃配合物为(C_6H_5)_4As~+[UO_2(ClO_4)(TTA)(PMBP)]~-.     

螯合-螯合萃取剂对铀(VI)的协同萃取

有关协同萃取的研究已十分广泛,但文献报道的大多是有关螯合(或酸性磷)-中性萃取剂组成的协萃体系,关于螯合-螯合萃取剂对金属离子的协萃研究报道甚少。Newman[1],Sekine[2.3]以及Sudersanan等[4-6]曾研究过β-二酮类萃取剂之间的协同萃取,但这类体系的协萃机理和规律性尚有待探讨。本文研究了1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮-(PMBP)与噻吩甲酰三氟丙酮(TTA)及PMBP与1-苯基-3-甲基-4-三氟乙酰-5-吡唑啉酮-(PMTFP)两种协萃体系从硝酸介质中对铀(VI)的萃取,这两种协萃体系文献中均未见报道.采用斜率法测求协萃配合物组成,计算了它们的干衡常数,并对协萃反应机理和规律性进行了讨论。     

1-苯基-3-甲基-4-苯甲酰吡唑啉酮-5萃取镓的研究

首次报道了1-苯基-3-甲基-4-苯甲酰吡唑啉酮-5(HPMBP)萃取镓的热力学和动力学, 指出在体系中形成Ga(PMBP)3(H2O)2萃合物, 配体PMBP既有一次溶剂化作用, 又有二次溶剂化作用, 并得到红外光谱和核磁共振谱的证实。镓的萃取过程为水相化学反应控制, 决速步骤为一次溶剂化过程: Ga^3^++HPMBP→Ga(PMBP)^2^++H^+。添加剂三辛基氧化膦(TOPO)不影响HPMBP萃取镓的分配比, 但降低了HPMBP萃取镓的正向速率, 表明动力学抑萃作用与热力学抑萃作用无对应关系。     

PMBP与HEH[EHP]对Fe（Ⅲ）的协同萃取

本文研究了1-苯基-3-甲基-4-苯甲酰基吡唑酮-5(PMBP,HL)和2-乙基己基膦酸单(2-乙基己基)酯(HEH[EHP],HA)的二甲苯溶液对盐酸介质中Fe(Ⅲ)的AA类协同萃取。用斜率法确定二元协萃配合物组成为FeL_2A,计算了协萃反应的平衡常数和热力学函数,讨论了协萃配合物的IR和~1H NMR谱。     

PMBP与中性磷萃取剂对铽(Ⅲ)的协同萃取

本文研究了1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5(PMBP)与丁基膦酸二丁酯(DBBP)或磷酸三丁酯(TBP)的氯苯溶液在硝酸介质中对铽(Ⅲ)的协同萃取。测得了萃合物的组成及其萃取平衡常数,讨论了萃合物的可能结构式及协同萃取机理。     

螯合-酸性磷萃取剂对铀(VI)的协同萃取

本文研究了螯合-酸性磷协同萃取体系─1-苯基-3-甲基-4-(2'-氯苯甲酰基)-5-吡唑啉酮(PMCBP)与磷酸二(2-乙基己基)酯(HDEHP)和2-乙基己基膦酸-单-2-乙基己基酯(HEHEHP)的氯仿溶液从硫酸介质中对铀(VI)的萃取。实验发现均有明显的协同效应存在。采用斜率法测定了协萃配合物的组成为UO2HA2X和UO2HA2HXX'的混合物, 计算了它们的萃取平衡常数, 讨论了协萃机理。     

多元协同萃取的研究 Ⅲ.AAB类三元体系对Nd(Ⅲ)的协同萃取

本文对1-苯基-3-甲基-4-乙酰基吡唑啉酮-5(PMHP文中用HA表示)和2-噻吩甲酰三氟丙酮(TTA用HT表示)与甲基膦酸二异戊酯(DiAMP用B表示)和二戊基亚砜(DASO用S表示)这几种萃取剂的甲苯溶液构成的两组AAB类三元体系,从高氯酸底液中萃取轻稀土元素Nd(Ⅲ)的协萃机理进行了研究。用斜率法测定了Nd~(3+)(≤10~(-4)mol·1~(-1)/NaClO_4(μ=0.1)/PMHP-TTA-DiAMP-C_6H_5CH_3体系的三元协萃物组成分别为NdAT_2·B和NdAT_2·B_2,体系平衡常数分别为K_(ATB)_1=7.0×10~(-2),K_(ATB)_2=20.9(25℃)。同时测定了Nd~(3+)(≤10~(-4)mol·1~(-1)/NaClO_4,HClO_4(μ=0.1)/PMHP-TTA-DASO-C_6H_5CH_3体系协萃物分别为NdA_2T·S和NdA_2T·S_2,测定的平衡常数平均值分别为K_(ATS)_1=5.2×10~(-2),K_(ATS)_2=2.8(25℃,平均值)。     

萃取热力学研究(Ⅰ)——PMBP-DPSO-Er(ClO4)3-C6H5CH3体系

本文研究了1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5(PMBP)与二苯基亚砜(DPSO)的甲苯溶液在高氯酸介质中对铒(Ⅲ)的协同萃取,测得了萃合物的组成和各萃取反应的平衡常数及热力学函数增量.     

PMBP与1,10菲绕啉对希土离子的协同萃取

本文研究了1-苯基-3-甲基-4-苯甲酰基吡唑酮-5(PMBP,HA)及1,10-菲绕啉(B)从高氯酸及醋酸钠构成的缓冲溶液中(pH=4,μ=0.1),对全部希土离子(包括Y~(3 ),不包括Pm~(3 ))的协同萃取。此体系可表示为Ln~(3 )(10~(-4)M)/HClO_4,NaAc(μ=0.1)/PMBP-Phen-CHCl_3。用斜率法确定协萃合物组成为LnA_3B,并求出各希土离子的协萃平衡常数logK_(?)以logK_(?)对原子序数Z作图,表现出四分组效应。相邻希土之间以及轻重希土之间的分离系数比单独用PMBP萃取时来得大。此体系有希望用于轻重希土分离。此外,还用萃取法制得了固体协萃合物,并对其红外光谱进行了分析讨论。     

镧系元素三元协萃规律研究 AAB 类(PMBP-TTA-DPSO)协萃 Tb~(3+)和 Eu~(3+)的机理

本文报道了1-苯基3-甲基4-苯甲酰基吡唑啉酮(PMBP)、2-噻吩甲酰三氟丙酮(TTA)与二苯基亚砜(DPSO)的甲苯溶液,从高氯酸底液中萃取 Tb~(3+)和 Eu~(3+)的机理。该体系属于螯合、中性络合 AAB 类。PMBP+DPSO 体系的二元协萃常数为:1gβ_(301,Tb)=-0.842,1gβ_(302,Tb)=1.04;1gβ_(301,Eu)=-1.00,1gβ_(302,Eu)=0.816。TTA+DPSO 体系为:1gβ′_(301,Tb)=-3.60,1gβ′_(302,Tb)=-1.73;1gβ′_(302,Eu)=-1.84。PMBP+TTA+DPSO 体系的三元协萃平衡常数1gβ_(211,Tb),=-1.06;1gβ_(212,Tb)=0.856;1gβ_(211,Eu)=-1.34,1gβ_(212,Eu)=0.543。     

Synergic extraction of uranyl perchlorate by the ternary system of AAC species composed of HTTA-HPMBP-(C6H5)4AsCl

A new ternary synergic extract system composed of two chelate extract ligands and one ion association ligand, namely AAC species, was studied. Uranyl perchlorate was extracted by the binary system of thenoyltrifluoroacetone (HTTA) and of 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HPMBP) with tetraphenylarsonium chloride [(C₆H₅)₄AsCl] in chloroform solution. It was found that synergic effect occurred during the extraction of uranyl perchlorate with the chloroform solution of a mixture of HTTA, HPMBP and (C₆H₅)₄ AsCl and the principle of minimum density of electric charge plays an important role. The formation of a ternary complex (C₆H₅)₄AsUO₂(ClO₄)(TTA)-(PMBP) was confirmed by the slope method, and the perchlorate was determined by the methylene blue spectrophotometric method. The equilibrium constant was calculated to be log βA₁A₂C = 5.52.     

Structural characterization and reactivity of UO2(salophen)L and [UO2(salophen)]2: dimerization of UO2(salophen) fragments in noncoordinating solvents (salophen = N,N'-disalicylidene-o-phenylenediaminate, L = N,N-dimethylformamide, dimethyl sulfoxide)

The molecular structures of UO2(salophen)L (L = DMF, DMSO) and a uranyl-salophen complex without any unidentate ligands (L) in solid and solution were investigated using single-crystal X-ray analysis and IR, 1H NMR, and UV-visible absorption spectroscopies. As a result, it was found that the uranyl-salophen complex without L is a racemic dimeric complex, [UO2(salophen)]2, in which the UO2(salophen) fragments are held together by bridging between one of the phenoxide oxygen atoms in salophen and the uranium in the other UO2(salophen) unit. Furthermore, it was spectrophotometrically demonstrated that [UO2(salophen)]2 retains its dimeric structure even in the noncoordinating solvents such as CH2Cl2 and CHCl3 and is in equilibrium with UO2(salophen)L {2UO2(salophen)L right arrow over left arrow [UO2(salophen)]2 + 2L}. The equilibrium constants and thermodynamic parameters of this equilibrium were evaluated from UV-visible absorption and 1H NMR spectral changes; log Kdim = -2.51 +/- 0.01 for L = DMF and solvent = CH2Cl2, log Kdim = -1.68 +/- 0.02 for L = DMF and solvent = CHCl3, log Kdim = -4.23 +/- 0.01 for L = DMSO and solvent = CH2Cl2, and log Kdim = -3.03 +/- 0.02 for L = DMSO and solvent = CHCl3. The kinetics of L-exchange reactions in UO2(salophen)L and enantiomer exchange of [UO2(salophen)]2 in noncoordinating solvents were also studied using NMR line-broadening method. As a consequence, it was suggested that the DMF-exchange reaction in UO2(salophen)DMF proceeds through two pathways (dissociative and associative paths) and that the predominant path of DMSO exchange in UO2(salophen)DMSO is the dissociative one. A sliding motion of the UO2(salophen) fragments was considered to be reasonable for the enantiomer-exchange mechanism of [UO2(salophen)]2. On the basis of the kinetic information for UO2(salophen)L and [UO2(salophen)]2, reaction mechanisms including the L-exchange reaction in UO2(salophen)L, the formation of [UO2(salophen)]2 from UO2(salophen)L, and the enantiomer exchange of [UO2(salophen)]2 are proposed.     

HPMBP和二苯胍对Ho~(3+)的协同萃取机理研究

研究了 1-苯基 - 3-甲基 - 4 -苯酰基吡唑酮 - 5(HPMBP)和二苯胍 (DPG)的三氯甲烷溶液对硝酸介质中Ho3+萃取机理。实验结果表明 :在体系Ho3+(～ 10 - 4mol/L)HNO3　NaNO3( μ =0 2 ) /HPMB -DPG -CH3Cl中 ,存在明显的协同效应。利用斜率法测得萃合物的组成为 [HB]+[HoA4 ](HA代表HPMBP ,B代表DPG) ,常温时的萃取平衡常数K =2 7.2 4 ;讨论了协同萃取机理和萃合物的结构。     

Potentiometric and multinuclear NMR study of the binary and ternary uranium(VI)-L-fluoride systems, where L is alpha-hydroxycarboxylate or glycine

Equilibria, structures, and ligand-exchange dynamics in binary and ternary U(VI)-L-F- systems, where L is glycolate, alpha-hydroxyisobutyrate, or glycine, have been investigated in 1.0 M NaClO4 by potentiometry and 1H, 17O, and 19F NMR spectroscopy. L may be bonded in two ways: either through the carboxylate end or by the formation of a chelate. In the glycolate system, the chelate is formed by proton dissociation from the alpha-hydroxy group at around pH 3, indicating a dramatic increase, a factor of at least 10(13), of its dissociation constant on coordination to uranium(VI). The L exchange in carboxylate-coordinated UO2LF3(2-) follows an Eigen-Wilkins mechanism, as previously found for acetate. The water exchange rate, k(aq) = 4.2 x 10(5) s(-1), is in excellent agreement with the value determined earlier for UO2(2+)(aq). The ligand-exchange dynamics of UO2(O-CH2-COO)2F3- and the activation parameters for the fluoride exchange in D2O (k(obs) = 12 s(-1), deltaH(double dagger) = 45.8 +/- 2.2 kJ mo(-1), and deltaS(double dagger) = -55.8 +/- 3.6 J K(-1) mol(-1)) are very similar to those in the corresponding oxalate complex, with two parallel pathways, one for fluoride and one for the alpha-oxocarboxylate. The same is true for the L exchange in UO2(O-CH2-COO)2(2-) and UO2(oxalate)2(2-). The exchange of alpha-oxocarboxylate takes place by a proton-assisted chelate ring opening followed by dissociation. Because we cannot decide if there is also a parallel H+-independent pathway, only an upper limit for the rate constant, k1 < 1.2 s(-1), can be given. This value is smaller than those in previously studied ternary systems. Equilibria and dynamics in the ternary uranium(VI)-glycine-fluoride system, investigated by 19F NMR spectroscopy, indicate the formation of one major ternary complex, UO2LF3(2-), and one binary complex, UO2L2 (L = H2N-CH2COO-), with chelate-bonded glycine; log beta(9) = 13.80 +/- 0.05 for the equilibrium UO2(2+) + H2N-CH2COO- + 3F- = UO2(H2N-CH2COO)F3(2-) and log beta(11) = 13.0 +/- 0.05 for the reaction UO2(2+) + 2H2N-CH2COO- = UO2(H2N-CH2COO)2. The glycinate exchange consists of a ring opening followed by proton-assisted steps. The rate of ring opening, 139 +/- 9 s(-1), is independent of both the concentration of H+ and the solvent, H2O or D2O.     

Solvent Extraction of Uranium(VI), Plutonium(VI) and Americium(III) with HTTA/HPMBP Using Mono- and Bi-Functional Neutral Donors: Synergism and Thermodynamics

Synergistic extraction of hexavalent uranium and plutonium as well as trivalent americium was studied in HNO₃ with thenoyl, trifluoro-acetone (HTTA)/1-phenyl, 3-methyl, 4-benzoyl pyrazolone-5 (HPMBP) in combination with neutral donors viz, DPSO, TBP, TOPO (mono-functional) and DBDECMP, DHDECMP, CMPO (bi-functional) with wide basicity range using benzene as dileunt. A linear correlation was observed when the equilibrium constant log Ks for the organic phase synergistic reaction of both U(VI) and Pu(VI) with either of the chelating agents HTTA or HPMBP was plotted vs. the basicity (log Kh) of the donor (both mono- and bi-functional) indicating bi-functional donors also behave as mono-functional. This was supported by the thermodynamic data (G ⁰, H ⁰, S ⁰) obtained for these systems. The organic phase adduct formation reactions were identified for the above systems from the thermodynamic data. In the Am(III) HTTA system log K _s values of bi-functional donors were found to be very high and deviate from the linear plot (log K _s vs. log K _h ) obtained for mono-functional donors, indicating that they function as bi-functional for the Am(III)/HTTA system studied. This was supported by high +ve S ⁰ values obtained for this system.     

Synergistic extraction of trivalent Am,Cm, Bk and Cf with HTTA+TBP in xylene

The synergistic extraction of trivalent actinides Am, Cm, Bk and Cf with thenoyltrifluoro acetone (HTTA) and tributyl phosphate (TBP) has been studied in xylene at 30°C. Correction for the HTTA-TBP interaction has been applied to get the free TBP concentration in the organic phase. Plots of log D vs. log [HTTA] give straight lines with a slope of 3 only after correcting for the HTTA-TBP interaction; without this correction the slope varies from 3 to 1 with increasing HTTA concentrations. The presence of two synergistic species M(TTA)₃·TBP and M(TTA)₃·2TBP simultaneously has been observed. The equilibrium constants for the organic phase synergistic reactions have been calculated.     

Synergistic extraction of cobalt(II) from cesium containing aqueous solutions with mixtures of 4-acyl-pyrazol-5-ols and crown ethers

The synergistic extraction of cobalt(II) from aqueous solutions loaded with cesium chloride or nitrate, with mixtures of 1-phenyl-3-methyl-4-acyl-pyrazol-5-ols (HL) [acyl = benzoyl (HPMBP), para-tert.-butyl-benzoyl (HPMB'P), stearoyl (HPMSP)] and crown ethers E = B15C5, 18C6, DC18C6, DB18C6 and DB24C8 (DC = dicyclohexano, B = benzo, DB = dibenzo), in CHCl(3), CH(2)Cl(2) and ClCH(2)CH(2)Cl, has been studied. The experimental data agree with the extracted species E(2)CsCoL(3) (E = B15C5), ECsCoL(3), (E = DB18C6) and CoL(2)E (E = DB24C8). The extraction yields follow the orders: 18C6 DC18C6 > DB18C6 > B15C5 > DB24C8, HPMBP > HPMB'P > HPMSP, and ClCH(2)CH(2)Cl > CH(2)Cl(2) > CHCl(3). In spite of the better complexation of potassium than cesium with "18C6" type crown ethers, the extraction of ECsCo (PMBP)(3) is generally higher than the EKCo(PMBP)(3) one. Except in the case of DB24C8, loading the aqueous phase with Cs(+), K(+), Sr(2+) or Ba(2+) improves the synergistic extraction of cobalt.     

Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoylpyrazolone-5 (HPMBP) and diphenyl sulfoxide (DPSO), tri-n-butyl phosphate (TBP) or tri-n-octylphosphine oxide (TOPO)

Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and oxo donors with widely varying basicity, viz. diphenyl sulfoxide (DPSO), tri-n-butyl phosphate (TBP) and tri-n-octylphosphine-oxide (TOPO) has been studied at various fixed temperatures. Results indicate that the equilibrium constants in the organic phase for addition reactions (K_S) with these donors follow their order of basicity (K_H) viz. DPSO (0.033)<TBP (0.16)TOPO (8.9) with log K_S values of 3.70, 4.28 and 6.45, respectively. The thermodynamic parameters associated with the formation of these systems have been evaluted by the temperature coefficient method. The results indicate that the complex in the organic phase for DPSO and TBP is stabilized only by enthalpy, whereas both enthalpy and entropy contribute to the stabilization of the TOPO complex. Also, enthalpy contribution is more prominent as compared with the UO ₂ ²⁺ /HTTA/TOPO system, where both enthalpy and entropy contribute almost equally.     

Binary and ternary uranium(VI) humate complexes studied by attenuated total reflection Fourier-transform infrared spectroscopy

The complexation of U(VI) with humic acid (HA) in aqueous solution has been investigated at an ionic strength of 0.1 M (NaCl) in the pH range between pH 2 and 10 at different carbonate concentrations by attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy. For the first time, the formation of binary and ternary U(VI) humate complexes was directly verified by in situ spectroscopic measurements. The complex formation constants for the binary U(VI) humate complex (UO(2)HA(II)) and for the ternary U(VI) mono hydroxo humate complex (UO(2)(OH)HA(I)) as well as the ternary U(VI) dicarbonato humate complex (UO(2)(CO(3))(2)HA(II)(4-)) determined from the spectroscopic data amount to log β(0.1 M) = 6.70 ± 0.25, log β(0.1 M) = 15.14 ± 0.25 and log β(0.1 M) = 24.47 ± 0.70, respectively, and verify literature data.     

Solvent extraction behaviour of lanthanum(III), cerium(III), europium(III), thorium(IV) and uranium(VI) with 3-phenyl-4-benzoyl-5-isoxazolone

The extraction behaviour of La(III), Ce(III), Eu(III), Th(IV) and U(VI) with 3-phenyl-4- benzoyl-5-isoxazolone (HPBI) in chloroform has been studied. The mechanism of extraction and the species extracted have been identified. Extraction constants for each system have been calculated. The system has been used to separate Th(IV) from U(VI) and from La(III), Ce(III) and Eu(III). A comparison of the extraction constants with those for the 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and thenoyltrifluoroacetone (HTTA) systems indicates that HPBI extracts these metal species better than HPMBP and HTTA do.