共查询到20条相似文献,搜索用时 15 毫秒
1.
Daniela de Araújo Viana Carolina de Albuquerque Lima Rejane Pereira Neves Cristina Souza Mota Keila Aparecida Moreira José Luiz de Lima-Filho Maria Taciana Holanda Cavalcanti Attilio Converti Ana Lúcia Figueiredo Porto 《Applied biochemistry and biotechnology》2010,162(3):830-842
Cow raw milk from dairy cooperatives was examined for its microbial composition. Among the isolates identified, 17.6% were
yeasts. The most frequent genus was Candida, although members belonging to the genera Brettanomyces, Dekkera, and Geotricum were also identified. Although qualitative and quantitative tests for extracellular proteolytic activity were positive for
all the species isolated, Candida buinensis showed the highest response (23.5 U/mg); therefore, it was selected for subsequent investigation. The results of fermentations
carried out at variable temperature, pH, and soybean flour concentration, according to a 23 full factorial design, demonstrated that this yeast ensured the highest production of extracellular proteases (573 U/mL)
when cultivated at 35 °C, pH 6.5, and using soybean flour concentrations in the range 0.1–0.5% (w/v). The cell-free supernatants showed the highest activity at 25 °C and pH 7.0, and satisfactory stability in the ranges 25–30 °C
and pH 7–9. The first-order rate constants of protease inactivation in the cell-free supernatants were calculated at different
temperatures from semi-log plots of the residual activity versus time and then used in Arrhenius and Eyring plots to estimate
the main thermodynamic parameters of thermoinactivation (E* = 40.0 kJ/mol; ΔH* = 37.3 kJ/mol; ΔS* = −197.5 J/mol K; ΔG* = 101 kJ/mol). 相似文献
2.
Abdel-Aziz Youssef El-Sayed Ebtesam Ahmad Saad Basheer Mohamed Mohamed Ibrahime Mohamed Tarek Mohamed Zaki 《Mikrochimica acta》2000,135(1-2):19-27
Simple, rapid, sensitive and selective methods for the determination of Cr(III) and W(VI) with flavonol derivatives in the
presence of surface-active agents are proposed. In the pH ranges 3.4–4.2 and 1.9–2.5, the molar absorptivities of Cr(III)-morin-emulsifier
S (EFA) and W(VI)-morin-polyvinylpyrrolidone (PVP) systems are 1.13×105 and 2.13×104 L mol−1 cm−1 at 435 and 415 nm, respectively. The Cr(III)-quercetin-PVP and W(VI)-quercetin-cetylpyridinium bromide (CPB) systems are
formed in the pH ranges 4–4.6 and 2.2–2.8 with molar absorptivities 1.02×105 and 9.02×104 L. mol−1 cm−1 at 441 and 419 nm, respectively. The linear dynamic ranges for the determination of Cr(III) and W(VI) with morin in the presence
of EFA and PVP are 0.03–0.46 and 0.71–8.1 μg mL−1, respectively. The corresponding ranges with quercetin are 0.04–0.54 and 0.14–2.1 μg mL−1 of Cr(III) and W(VI), respectively. The r.s.d (n = 10) for the determination of 0.25 and 3.7 μg mL−1 of Cr(III) and W(VI) with morin and their detection limits are 0.88 and 0.99% and 0.016 and 0.63 μg mL−1, respectively. Using quercetin, the r.s.d (n = 10) for 0.22 and 1.2 μg mL−1 of Cr(III) and W(VI) and their detection limits are 0.92 and 0.91% and 0.015 and 0.08 μg mL−1, respectively. The critical evaluation of the proposed methods is performed by statistical analysis of the experimental data.
The proposed methods are applied to determine Cr in steel, non-ferrous alloys, wastewater and mud filtrate and to the determination
of W in steel.
Received March 8, 1999. Revision January 21, 2000. 相似文献
3.
Rabindra N. Roy Lakshmi N. Roy Michael S. Fuge Chandra N. Roy Curtis A. Himes Paul A. Bryant Kyle T. Robinson Daniel A. Kaufmann II Colby H. Grove Toshi Gosh Adonis Bwashi 《Journal of solution chemistry》2009,38(4):471-483
The values of the second dissociation constant, pK
2, and related thermodynamic quantities of [N-(2-acetamido)-2-aminoethanesulfonic acid] (ACES) have already been reported over
the temperature range 5 to 55 °C including 37 °C. This paper reports the pa
H values of four chloride ion free buffer solutions and eight buffer solutions with I=0.16 mol⋅kg−1, matching closely that of the physiological sample. Conventional pa
H values for all twelve buffer solutions from 5 to 55 °C are reported. The residual liquid-junction potential correction for
two widely used temperatures, 25 and 37 °C, has been made. The flowing-junction calomel cell method has been utilized to measure
E
j
, the liquid-junction potential. The operational pH values for four buffer solutions at 25 and 37 °C are calculated using
the physiological phosphate buffer standard based on the NBS/NIST convention. These solutions are recommended as pH standards
in the pH range of 6.8 to 7.2 for physiological fluids. 相似文献
4.
Mário A. P. Nunes Hélder Vila-Real Pedro C. B. Fernandes Maria H. L. Ribeiro 《Applied biochemistry and biotechnology》2010,160(7):2129-2147
A synthetic polymer, polyvinyl alcohol (PVA), a cheap and nontoxic synthetic polymer to organism, has been ascribed for biocatalyst
immobilization. In this work PVA–alginate beads were developed with thermal, mechanical, and chemical stability to high temperatures
(<80 °C). The combination of alginate and bead treatment with sodium sulfate not only prevented agglomeration but produced
beads of high gel strength and conferred enzyme protection from inactivation by boric acid. Naringinase from Penicillium decumbens was immobilized in PVA (10%)–alginate beads with three different sizes (1–3 mm), at three different alginate concentrations
(0.2–1.0%), and these features were investigated in terms of swelling ratio within the beads, enzyme activity, and immobilization
yield during hydrolysis of naringin. The pH and temperature optimum were 4.0 and 70 °C for the PVA–alginate-immobilized naringinase.
The highest naringinase activity yield in PVA (10%)–alginate (1%) beads of 2 mm was 80%, at pH 4.0 and 70 °C. The Michaelis
constant (K
Mapp) and the maximum reaction velocity (V
maxapp) were evaluated for both free (K
Mapp = 0.233 mM; V
maxapp = 0.13 mM min−1) and immobilized naringinase (K
Mapp = 0.349 mM; V
maxapp = 0.08 mM min−1). The residual activity of the immobilized enzyme was followed in eight consecutive batch runs with a retention activity
of 70%. After 6 weeks, upon storage in acetate buffer pH 4 at 4 °C, the immobilized biocatalyst retained 90% of the initial
activity. These promising results are illustrative of the potential of this immobilization strategy for the system evaluated
and suggest that its application may be effectively performed for the entrapment of other biocatalysts. 相似文献
5.
In-situ measurement of pH at elevated temperatures and pressures is of major importance for investigating chemical and biochemical
systems in extreme environments. Based on the performance of the newly developed IrO
x
electrode at 25 °C, we initiated a series of experiments to test the electrode at elevated temperatures (100 to 175 °C) and
high pressure (25 MPa). The experiment was carried out in a titanium flow-through reactor. Our results revealed good pH response
at 100, 150 and 175 °C, with good Nernstian slopes at 100 and 150 °C. Although a greater-than-Nernstian response was observed
at 175 °C, the factors that cause this difference are attributed to the accuracy of calculations of the distribution of aqueous
species rather than alteration of the IrO
x
surface. A key problem that may limit applications of the IrO
x
electrode at elevated temperatures and pressures is the noticeable shift in E° during the 175 °C (25 MPa) experiments and between experiments with similar conditions at 150 °C. The results of tests from
25 °C to elevated temperatures provide highly useful information on the reversibility and functionality of the IrO
x
-pH sensor with implications for the suitability of its use under challenging chemical and physical conditions. 相似文献
6.
A novel surfactant peptide consisting of an arginine cation with laurate anion has been synthesized, purified and characterized.
The critical micellar concentration (cmc) of peptide in aqueous solutions has been determined using spectroscopic techniques
and is found to increase from 0.06 to 0.11 mM with increasing temperature (15–45 °C). Cmc is also determined in the presence
of salts like NaCl, KCl and sodium acetate and it is found that these electrolytes hinder aggregation with a significant increase
in the case of sodium acetate. The aggregation number of the surfactant peptide has been determined using fluorescence quenching
measurements and is observed to decrease from 14 to 6 with increasing temperature (15–45 °C). The standard free energy change
(ΔG
0
m) and standard enthalpy change (ΔH
0
m) of the peptide aggregate are found to be negative with a small positive value for standard entropy change (ΔS
0
m). The peptide aggregate seems to undergo phase transition above 50 °C as observed from UV–vis and fluorescence spectroscopy.
From pyrene binding studies, it is shown that the interior dielectric constant increases from 5.08 at 34 °C to 8.77 at 50 °C
and further decreases with increase in temperature indicating a phase change at 50 °C. Also, the ratio of excimer intensity
to monomer intensity, which is a measure of microviscosity of the aggregate, decreases with increase in temperature with a
change at 50 °C indicating a phase change.
Received: 14 February 1997 Accepted: 13 August 1997 相似文献
7.
The solubility of industrially produced titanium dioxide nanoparticles has been studied in aqueous sodium chloride media in
the pH range 1 to 13 at 25 °C by using adsorptive stripping voltammetry (AdSV). Kinetic dissolution curves have been obtained
as well as long-term solubilities that provide an approximation of the equilibrium solubilities. The titania nanoparticles
used in the dissolution experiments have been characterized by nitrogen sorption measurements, XRD and colloid titration.
The equilibrium solubilities and titanium(IV) speciation and their dependences on pH have been modelled by assuming the formation
of the mononuclear titanium hydroxo complexes [Ti(OH)
n
](4−n)+ (n=2 to 5) to be the only titanium species present. The solubility product of titanium dioxide and equilibrium constants for
titanium(IV) hydrolysis, calculated from the AdSV solubility data, are presented. 相似文献
8.
Farrokh Gharib Ali Shamel Sahar Mohajeri 《Russian Journal of Inorganic Chemistry》2010,55(10):1651-1656
The dependence on ionic strength of protonation of nitrilotriacetic acid and its complexation with W(VI) is reported in sodium
perchlorate, sodium nitrate and sodium chloride solutions as background salts. The measurements have been performed at 25°C
and various ionic strengths in the range 0.1–1.0 mol dm−3, using a combination of potentiometric and spectrophotometric techniques. The overall analysis of the present and the previous
data dealing with the determination of stability constants at different ionic strengths allowed us to obtain a general equation,
by which a formation constant determined at a fixed ionic strength can be calculated, with a good approximation, at another
ionic strength, if 0.1 ≤ ionic strength ≤ 1.0 mol dm−3 sodium perchlorate, sodium nitrate or sodium chloride. 相似文献
9.
The competitive sorption of Cu(II) and Eu(III) ions from aqueous solutions by olive-cake carbon, has been investigated by
potentiometry at pH 6, I=0.1 M NaClO4, 25°C and under normal atmospheric conditions. Evaluation of the experimental data supports the formation of inner-sphere
surface complexes and results in the calculation of the formation constant of the surface complexes ((=S–O)2Cu), which is found to amount log β
Cu=5.3±0.3. Addition of competing Eu(III) ions in the aqueous system leads to replacement of the Cu(II) by the competitor metal
ion. Evaluation of the potentiometric data obtained from competition experiments indicates an ion-exchange mechanism. The
formation constant of the Eu(III) species sorbed on olive cake carbon is found to be log β
Eu=5.1±0.5. Comparison of the complex formation constants of the olive-cake carbon with the corresponding complex formation
constants for of olive cake and humic acid with the two metal ions, indicates that the same type of active sites is responsible
for the metal ion complexation on the surface of the different types natural organic matter (e.g. olive-cake carbon, olive-cake
and humic acid). 相似文献
10.
Lakshmi N. Roy Rabindra N. Roy Sean R. LeNoue Cole E. Denton Michael S. Fuge Craig D. Dunseth Chandra N. Roy Shawn M. Hayden Joshua T. Wollen Kripa Sreepada 《Journal of solution chemistry》2009,38(4):459-469
The values of the second dissociation constant, pK
2, and related thermodynamic quantities of 3-[N,N-bis (2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO) have already
been reported over the temperature range 5 to 55 °C including 37 °C. This paper reports the pH values of four NaCl-free buffer
solutions and four buffer composition containing NaCl salt at I=0.16 mol⋅kg−1. Conventional pa
H values are reported for all eight buffer solutions. The operational pH values have been calculated for four buffer solutions
recommended as pH standards, at 25 and 37 °C after correcting the liquid junction potentials with the flowing junction cell. 相似文献
11.
Many semicrystalline polymers undergo a process of aging when they are stored at temperatures higher than their glass-transition
temperature (T
g). Syndiotactic polypropylene was quenched from the melt to −40 °C, crystallized from the glassy state at 20 or 40 °C and
stored at the respective temperature for different aging times up to 7200 h. A significant increase in the tensile modulus
and stress at yield and a decrease in strain at yield were observed for both aging temperatures. Differential scanning calorimetry
(DSC) scans of aged material showed an endothermic annealing peak 15–30 °C above the previous aging temperature, the maximum
temperature and enthalpic content of which increased with aging time. The position and the shape of the melting peak were
not affected by aging. Scans of the storage modulus obtained from dynamic mechanical analyser measurements indicated a softening
process starting at about 20 °C above the aging temperature and correlating with the annealing peak detected by DSC. Density
measurements and wide-angle X-ray scattering investigations revealed that neither the crystallinity increased significantly
nor did the crystal structure change. So the observed property changes induced by aging are attributed to microstructural
changes within the amorphous phase. Furthermore, it could be shown by annealing experiments carried out at 60 °C, that aging
above T
g is, analogous to aging below T
g (physical aging), a thermoreversible process.
Received: 18 September 2000 Accepted: 2 January 2001 相似文献
12.
Prenesti E Ferrara E Berto S Fisicaro P Daniele PG 《Analytical and bioanalytical chemistry》2007,388(8):1877-1883
A method that uses a Harned cell to perform potentiometric pH measurements has been optimized and applied to an aqueous solution
of simulated seawater that contains sodium perchlorate, sodium sulfate, sodium hydrogen carbonate and boric acid and has an
ionic strength I of 0.57 mol kg−1. The standard metrological approach developed for the measurement of pH in low ionic strength aqueous solutions was maintained,
but a few modifications were necessary, and measurement procedures and calculations were modified ad hoc from those adopted
in conventional protocols. When determining the standard potential of the cell, E°, NaClO4 salt was added to a 0.01 mol/kg HCl solution to attain the same ionic strength as the test solution and to investigate possible
specific effects related to the high levels and the nature of the background electrolyte. An appropriate value of γ
±HCl (0.737) was then selected from the literature, based on a realistic value for I. Finally, in order to convert the acidity function at zero chloride molality into pH, a suitable value of γ
Cl (0.929) was calculated. As a result, we obtained pH = 8.18 (T = 25 °C) with an associated expanded uncertainty U = 0.01 (coverage factor k = 2). The aim was to establish a sound basis for the pH measurement of seawater by identifying the critical points of the
experimental and theoretical procedure, and to discuss further possible developments that would be useful for achieving a
reference solution. 相似文献
13.
D. Ranjan P. Srivastava M. Talat S. H. Hasan 《Applied biochemistry and biotechnology》2009,158(3):524-539
The potential use of biomass of Aeromonas hydrophila for biosorption of chromium from aqueous solution was investigated. The variables (pH, initial Cr(VI) concentration, biomass
dose, and temperature) affecting process were optimized by performing minimum number of experimental runs with the help of
central composite design. The results predicted by design were found to be in good agreement (R
2 = 99.1%) with those obtained by performing experiments. Multiple regression analysis shows that uptake decreases with increase
in pH and biomass dose, whereas it increases with increase in temperature and concentration. The maximum removal of Cr(VI)
predicted by contour and optimization plots was 184.943 mg/g at pH 1.5, initial Cr(VI) concentration 311.97 mg/L, temperature
60 °C, and biomass dose 1.0 g. The removal of Cr(VI) was governed by adsorption of Cr(VI) as well as its reduction into Cr(III),
which further gets adsorbed. The sorption capacity of biomass was calculated from experimental data using Langmuir sorption
model and was found to be 151.50 mg/g at 40 °C and pH 1.5, which is comparable to other biosorbents. In addition to this,
Dubinin–Radushkevich model was applied, and it was found that nature of sorption was chemisorption. 相似文献
14.
M. Teresa Barros João Martins Rui M. Pinto Mónica S. Santos Helena M. V. M. Soares 《Journal of solution chemistry》2009,38(12):1504-1519
As part of a search for environmentally friendly metal chelating ligands, the stability constants of N, N′-ethylenedi-L-cysteine
(EC) complexes with Ca(II), Cu(II), Mg(II) and Mn(II) were determined by potentiometry with a glass electrode in aqueous solutions
containing 0.1 mol⋅L−1 KCl at 25 °C. Final models are proposed. For the Ca(II)–EC system, the overall stability constants are log 10
β
CaHL=14.53±0.03, log 10
β
CaL=4.79±0.01 and log 10
β
CaL2=8.38±0.04. For the M(II)–EC systems, where M=Cu(II) or Mg(II), the overall stability constants are log10
β
CuHL=31.19±0.02 and log 10
β
CuL=27.02±0.06 for Cu(II), and are log 10
β
MgHL=14.84±0.02 and log 10
β
MgL=6.164±0.008 for Mg(II). For the Mn(II)–EC system, the overall stability constant is log 10
β
MnL=10.12±0.01.
Metal–chelate speciations simulations showed that EC is an efficient chelating agent for Cd(II), Co(II), Cu(II), Ni(II), Pb(II)
and Zn(II) for pH≥7. 相似文献
15.
A novel polymer-forming diimide–diacid, 5,5′-bis[4-(4-trimellitimido phenoxy)phenyl]-hexahydro-4,7-methanoindan (II), was prepared by the condensation reaction of 5,5′-bis[4-(4-aminophenoxy)phenyl]-hexahydro-4,7-methanoindan with trimellitic
anhydride. A series of novel aromatic poly(amide–imide)s (PAIs) containing polycyclic cardo groups was prepared by the direct
polycondensation of II with various aromatic diamines using phosphorylation techniques. The polymers had inherent viscosities between 0.71 and 0.96 dl/g.
The polymers were soluble in polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide, and could be cast from their DMAc solutions into transparent, flexible, and tough films, except for III
a
. These films had yield strengths of 85–114 MPa, tensile strengths of 77–102 MPa, an elongation at break of 8–17%, and initial
moduli of 2.0–2.7 GPa. Wide-angle X-ray diffraction revealed that the polymers are amorphous. The glass-transition temperatures
of the polymers were in the range 242–312 °C. All the PAIs exhibited no appreciable decomposition below 430 °C, and their
10%-weight-loss temperatures were in the range 484–507 °C in nitrogen and 494–515 °C in air.
Received: 26 January 1999 Accepted in revised form: 11 May 1999 相似文献
16.
The temperature and pressure dependences of pK for acridine ion ionization were determined up to 200 °C and 2000 bar. The UV-Vis measurements at high temperatures and pressures
were conducted in flow-through spectrophotometric cells. Two independent series of experiment were performed: one in a Ti–Pd
cell with silica quartz windows for measurements in the ultraviolet region, and another in a Ti grade 5 cell with sapphire
windows for use at higher pressures, which permitted measurements in the visible region. Combined chemometric and thermodynamic
analyses of the UV-Vis spectrophotometric data were used to extract the ionization constants as well as the changes in molar
volume ΔV° for acridine protonation as functions of temperature and pressure. Values of pK decrease from 5.52 to 3.74 with increasing temperature from 25 to 200 °C at saturated water-vapor pressure. The pressure
dependence of acridinium ion ionization is small (e.g., pK=5.5 at 25 °C and 2000 bar) and is characterized by positive ΔV°≤1.2 cm3⋅mol−1, which is not surprising for this type of isocoulombic reaction involving a large molecule. 相似文献
17.
A new dicarboxylic acid monomer containing the N-methylcarbazole and imide structures, 3,6-bis(trimellitimido)-N-methylcarbazole (I), was prepared from the condensation of 3,6-diamino-N-methylcarbazole (c) and trimellitic anhydride. The diamine c was synthesized in three steps starting from the methylation of carbazole, followed by nitration and catalytic hydrazine
reduction. A series of N-methylcarbazole-containing poly(amide–imide)s were synthesized by direct polycondensation from the diimide–diacid I with various aromatic diamines. These poly(amide–imide)s had inherent viscosities of 0.66–1.47 dl/g and were readily soluble
in a variety of organic solvents, including N-methyl-2-pyrrolidone and N,N-dimethylacetamide (DMAc). Transparent, flexible, and tough films of these polymers could be cast from DMAc solutions, and
these films exhibited excellent mechanical strength. The glass-transition temperatures of these poly(amide–imide)s were in
the range 317–362 °C. All the poly (amide–imide) did not degrade noticeably below 480 °C in nitrogen, and the 10% weight loss
temperatures and char yields at 800 °C were above 520 °C and 60% in nitrogen, respectively, indicating high thermal stability.
Received: 8 February 2000/Accepted: 23 March 2000 相似文献
18.
S. Yamaguchi 《Colloid and polymer science》1998,276(8):715-722
Phase behavior of water/hexaethyleneglycol dodecyl ether (C12EO6)/propanol/heptane system was investigated in a composition–temperature space (25–30 °C) at atmospheric pressure. A cone-like three-phase body consisting of aqueous (W), surfactant (Dp), and oil (O) phases is
formed in the two-phase body of Wm (aqueous micellar phase)+O at 30.0 °C. With decreasing temperature the three-phase body becomes thinner and finally disappears at a critical double end point
(CDEP) where the two critical end points of W and Dp phases are merged. The CDEP exists at about 26.2 °C (T
CDEP). The hydrophile–lipophile balance (HLB) of the mixed amphiphile changes towards lipophilic on addition of propanol. As a
result, the Wm phase separates into two phases W+Dp above the T
CDEP. Further addition reduces the lipophobicity of aqueous media (or the solvophobicity of the mixed amphiphile), and the W and
Dp phases are merged again. Below T
CDEP, since C12EO6 becomes much hydrophilic, the change of HLB lurks and a middle phase (Dp) cannot be observed.
Received: 19 June 1997 Accepted: 20 March 1998 相似文献
19.
In this work, we studied the adsorption of butane, toluene and nitric oxide on NaMordenite exchanged with different amounts
of silver. The reactions that occurred when the adsorbed hydrocarbons interacted with NO and the effect of water adsorption
were also addressed. Different silver species were formed after ion exchange and they were detected by TPR analysis. Highly
dispersed Ag2O particles were reduced at temperatures lower than 300 °C whereas Ag+ exchanged ions showed two TPR peaks, which can be ascribed to species exchanged at different mordenite sites. The TPD experiments
after adsorption of NO at 25 °C showed that the only desorbed species was NO2 which was formed by the total reduction of Ag2O particles. When the adsorbed butane was exposed to NO (1000 ppm), isocyanate species were formed on Ag+ ionic sites as well as Ag+–(NOx)–CO species. Toluene adsorption was stronger than butane since adsorbed toluene molecules were held even at 400 °C.
The characteristic bands of the aromatic ring C=C bond was observed as well as that of methyl groups interacting with Ag+ and Na+ ions. However, the appearance of carboxylic groups at temperatures above 300 °C in inert flow indicated the partial oxidation
of toluene due to Ag2O species present in the samples. After contacting adsorbed toluene with NO, different FTIR bands correspond to organic nitro-compounds,
isocyanate, cyanide and isocyanide species adsorbed on Ag+ ions, were detected. The presence of water inhibited the formation of NO2 species and the hydrocarbon adsorption on Na+ sites but did not affect the toluene-Ag+ interaction. 相似文献
20.
Carina M. M. Machado Paula Gameiro Helena M. V. M. Soares 《Journal of solution chemistry》2008,37(5):603-617
The complexation behavior of eight M–(buffer)
x
–(OH)
y
systems involving two divalent ions (cobalt and nickel) and four zwitterionic biological buffers (AMPSO, DIPSO, TAPS and
TAPSO) were characterized. Complex formation was detected for all eight M–(buffer)
x
–(OH)
y
systems studied, but fully defined final models were obtained for only four of these systems. For systems involving cobalt
or nickel with AMPSO or TAPS, a complete characterization of the systems was not possible in the studied buffer pH-range.
Metal complexation was studied by glass-electrode potentiometry (GEP) and UV-Vis spectroscopy at 25.0 °C and I=0.1 mol⋅dm−3 KNO3 ionic strength. For the Ni–(L)
x
–(OH)
y
and Co–(L)
x
–(OH)
y
systems, with L = TAPSO or DIPSO, the proposed final models and overall stability constants were obtained by combining results
from both techniques. For the Ni–(L)
x
–(OH)
y
systems, the measured values of the stability constants are log 10
β
NiL=3.0±0.1 and log 10
β
NiL2=4.8±0.1 for L = TAPSO, and log 10
β
NiL=2.7±0.1 and log 10
β
NiL2=4.6±0.1 for L = DIPSO. For the Co–(L)
x
–(OH)
y
systems, the overall stability constants are log 10
β
CoL=2.2±0.1, log 10
β
CoL2=3.6±0.2 and log 10
β
CoL(OH)=7.6±0.1 for L = TAPSO, and log 10
β
CoL=2.0±0.1 and log 10
β
CoL(OH)=7.8±0.1 for L = DIPSO. For both buffers, the CoL(OH) species is characterized by a major structural rearrangement. 相似文献