Application of 2-(octylsulphanyl)benzoic acid as Pb2+ selective ionophore in hybrid membrane system

Article abstract of DOI:10.2478/s11696-011-0101-7

A solution of 2-(octylsulphanyl)benzoic acid in 1,2-dichloroethane was used as a liquid membrane for selective pertraction of Pb²⁺ cations. Transport processes were carried out in a multi-membrane hybrid system (MHS) consisting of two cation-ex

Full text of DOI:10.2478/s11696-011-0101-7

Chemical Papers 66 (1) 26–32 (2012)
DOI: 10.2478/s11696-011-0101-7
ORIGINAL PAPER
Application of 2-(octylsulphanyl)benzoic acid as Pb2+ selective
ionophore in hybrid membrane system
a
b
a
a
´
Andrzej Oberta*, Janusz Wasilewski, Marek Swi a˛ tkowski, Romuald Wódzki
aFaculty of Chemistry, Nicolaus Copernicus University, Gagarin str. 7, 87-100 Toru n´ , Poland
bDepartment of Biochemistry, University of Warmia and Mazury, Faculty of Biology,
Oczapowski str. 1A, 10-719 Olsztyn, Poland
Received 10 May 2011; Revised 7 September 2011; Accepted 9 September 2011
A solution of 2-(octylsulphanyl)benzoic acid in 1,2-dichloroethane was used as a liquid membrane
2+
for selective pertraction of Pb cations. Transport processes were carried out in a multi-membrane
hybrid system (MHS) consisting of two cation-exchange membranes (CEM) and a flowing liquid
membrane (FLM) in the following order: CEM | FLM | CEM. The liquid membrane phase was de-
hydrated continuously using a pervaporation method (PV). The system was capable of transporting
2
+
+
+
2+
2+
Pb ions selectively from a multi-cation aqueous solution composed of Na , K , Ca , Mg , and
2+
Pb nitrates. A comparative study of the carrier efficiency under various feed pH conditions was
performed. It was found that the carrier exhibited sufficient selectivity and transport efficiency un-
2+
der a broad range of operational conditions, with a maximum transport rate of Pb ions attaining
−
10
−2 −1
the value of (1.09 ± 0.03) × 10
mol cm
s
and the selectivity coefficient of up to 40.
ꢀ
c 2011 Institute of Chemistry, Slovak Academy of Sciences
Keywords: pertraction, lead, multi-membrane hybrid system, pervaporation, 2-(octylsulphanyl)benzoic
acid
Introduction
tive (Oberta et al., 2010) and the subsequent separa-
tion of particular cations occurs in the system as a re-
sult of the specific properties of the carrier dissolved in
the liquid membrane solvent. The selective cation car-
riers commonly applied are strong organic acids (e.g.
with a phosphate group) with alkyl chains providing
good solubility in hydrophobic solvents. Conversely,
carboxylic acids are not commonly used because of
their relatively low acidity. However, the introduction
of an electronegative atom, such as sulphur, into the
vicinity of a carboxylic group may result in an in-
crease in the acid dissociation constant (Pasto & Kent,
1965) and the overall liquid membrane transport ca-
pacity. Some of the compounds listed above have al-
ready been examined as the extractants or carriers
The liquid membrane (LM) technique, when ap-
plied in its practical form, i.e. the multi-membrane
hybrid system (MHS), is regarded as one of the
most promising methods of aqueous feeds treatment
(
Kislik, 2010; Oberta et al., 2010). It has recently been
demonstrated that the MHS system can exhibit im-
proved properties in comparison with conventional liq-
uid membranes (Kislik, 2010). In general, the applica-
tion of cation-exchange membranes (CEM) in combi-
nation with a liquid membrane, as presented in Fig. 1,
results in the pre-concentration of cations in the vicin-
ity of a feed polymer and liquid membrane interface
(
Szczepa n´ ska, 2010), and prevents carrier elution from
+
the liquid membrane solution. The process is based on
effective cation-exchange sorption mediated by CEM
in contact with an aqueous solution. However, the
cation-exchange pre-concentration is usually not selec-
of various cations, mainly Ag (Barnes et al., 1971;
Ford et al., 1972; Pettit & Sherrington, 1968; Saito
et al., 1998; Siswanta et al., 1996), Cu2 (Geary &
Malcolm, 1970; Gholivand & Khorsandipoor, 2000), as
+
*Corresponding author, e-mail: oberta@doktorant.umk.pl

A. Oberta et al./Chemical Papers 66 (1) 26–32 (2012)
27
Fig. 1. Scheme of cations’ counter-transport occurring in studied hybrid membrane system.
well as many others (Baba & Inoue, 1984; Bramlett et
al., 2004; Doh et al., 1995; Irving & Fernelius, 1956;
Stypinski-Mis & Anderegg, 2000) The complexation
ability of these acids is associated with the presence
of sulphur atoms, which can create stable but weak
bonds with some cations (Irving & Fernelius, 1956).
Fig. 2. The structure of 2-(octylsulphanyl)benzoic acid (OSBA).
To the best of the authors’ knowledge, the trans-
port properties of 2-(octylsulphanyl)benzoic acid
(
OSBA) as applied to a multi-membrane hybrid sys-
tem are examined and described in this paper for the
water, and air-dried. After crystallisation from aque-
ous ethanol, 39.6 g of the desired product (Fig. 2,
74.3 % yield) was obtained.
The dissociation constant of the carrier (Ka) was
determined using a titration method. A known por-
tion of OSBA was dissolved in a 1 : 1 water–dioxane
mixture (dioxane of reagent grade, POCh, Gliwice,
Poland) with the ionic strength I maintained by the
2+
first time. The ionophore selectivity towards Pb ions
was tested with the model feed solution composed also
+
+
2+
2+
of the competing Na , K , Mg , and Ca
metal
ions. The competing cations were chosen as the rep-
resentatives of common mono- and bivalent cations
present in the environment. In addition, the calculated
values of the output fluxes and selectivity coefficients
were compared with the results recently reported on
various carriers and cations by other authors. The aim
of the work was to prove that there was no need to
use very sophisticated and expensive carriers to ob-
tain reasonable ionic fluxes and selectivity.
−
3
addition of potassium nitrate (I = 0.1 mol dm ).
3
A 30 cm sample of the solution was potentiometri-
−
3
cally titrated with potassium hydroxide (8.19 × 10
−
3
mol dm ). The pKa value was estimated as equal
to the pH value in the middle point of the titration
curve, i.e. at the mid-point between the beginning of
the curve and the end-point of titration. The proce-
dure of determination was repeated and the pKa value
was calculated as an arithmetic mean of three mea-
surements.
Experimental
Lead, potassium, sodium, magnesium, and calcium
nitrates, sodium and potassium hydroxides, as well as
6
5 % nitric acid (all of reagent grade, POCh, Gliwice,
All transport experiments were performed in the
multi-membrane hybrid system (MHS) constructed
as presented in Fig. 3. Two circular cation-exchange
membranes (Nafion-117, Du Pont de Nemours, USA,
Poland) were used for preparation of the aqueous solu-
tions. Extra pure 1,2-dichloroethane (Riedel-de Ha ¨e n,
Germany) was used as the liquid membrane solvent.
All the chemicals were used as received, without fur-
ther purification.
2
each 28.26 cm , 0.20 mm thickness, ion-exchange ca-
pacity equal to 0.997 mol per kg of dry membrane
in acidic form) were clamped in a triple-compartment
cell containing the feed (f), flowing liquid membrane
(FLM), and the stripping solution (s), respectively. In
addition, two circular-shaped Nafion-117 membranes
2
-(octylsulphanyl)benzoic acid (OSBA) was syn-
thesised according to the following procedure: a mix-
ture of 30.8 g (0.2 mol) of thiosalicylic acid, 23.6 g
(0.42 mol) potassium hydroxide, and 38.6 g (0.2 mol)
2
1
-bromooctane (all of reagent grade, POCh, Gliwice,
with a total area of 64.31 cm were used in the perva-
3
Poland) was refluxed in 500 cm of absolute ethanol
under nitrogen atmosphere for more than 5 h. The
mixture was then cooled to room temperature, diluted
with 500 cm of water and acidified with hydrochlo-
ric acid. The white precipitate so formed was filtered,
washed first with cold ethanol and several times with
poration module for continuous liquid membrane de-
hydration. The Nafion-117 membranes were used in
the PV module because of their high mechanical and
chemical resistance as well as their good hydrophilic
3
2
+
properties (Kujawski et al., 1991). The feed (Pb
,
2+
2+
+
+
−3
Ca , Mg , K , Na nitrates, all 0.01 mol dm in

2
8
A. Oberta et al./Chemical Papers 66 (1) 26–32 (2012)
Fig. 3. Scheme of the multi-membrane hybrid system: sodium hydroxide reservoir (1), dosing pump (2), pH controller (3), combi-
nation electrode (4), feed solution (5), stripping solution (6), stirrers (7), piston pump (8), liquid membrane reservoir (9),
pervaporation unit (10), cation-exchange membranes (11), stainless steel porous support (12), vacuum system (13).
3
double-distilled water, 500 cm ) and the stripping so-
CEM-stripping solution interface in time t. The strip-
−
3
−2 −1
) were
lution (HNO3 1 mol dm
6
in double-distilled water,
0 cm ) were mechanically stirred (100 min , dis-
ping rates (output fluxes) Js,Me/(mol cm
s
3
−1
estimated as the slope of the rectilinear fragment of
−
2
tance from CEMs – 5 cm in feed, 0.5 cm in stripping
solution) in order to homogenise the bulk solutions as
well as to minimise the thickness of the diffusion layers
adjacent to CEMs. The feed pH was measured in the
course of the process using a combination of a glass
electrode (HI 1131, Hanna Instruments, France) and
a pH controller (W-252-pH-NL, Walchem, USA). In
several experiments, the feed pH was maintained con-
stant by a pH control system coupled with an electro-
magnetic piston pump (A752-95T, Milton Roy, USA)
appropriate Qs,Me/(mol cm ) vs. t/s curves, corre-
sponding to the pseudo-stationary state of a transport
run according to the following equations
∆Qs,Me
Js,Me =
Qs,Me =
(1)
∆t
∆
[Me] Vs
s,t
∆
(2)
1
000As
−
3
dosing sodium hydroxide solution (0.5 mol dm ).
In Eqs. (1) and (2), [Me]s,t/(mol dm−3) denotes
3
The liquid membrane (65 cm of OSBA solution in
z+
the concentration of Me
cation in the stripping
1
,2-dichloroethane) was pumped with a Teflon piston
3
phase in time t, Vs/(cm ) is the volume of the strip-
3
−1
pump (150 cm min , OSI, France) in a closed circuit
composed of the reservoir, MHS cell, and the perva-
poration unit. Prior to each transport experiment, all
the CEMs were converted to their acidic form by sev-
2
ping solution and As/(cm ) is the area of the poly-
mer membrane-stripping phase interface. The Js,Me
values and their standard deviations were calculated
using the least squares method. The total metal flux
−
3
eral immersions in 1 mol dm nitric acid and then
in water in order to remove free electrolytes. The PV
membranes were supported by stainless steel porous
plates. The pervaporation module was connected to a
glass vacuum system operating at a pressure of 0.5–
−
2
−1
Js,ΣMe/(mol cm
s ) was calculated as the sum of
all particular stripping fluxes – Eq. (3), and the frac-
tional fluxes Ns,Me/% were calculated according to Eq.
(4).
Js,ΣMe = ΣJs,Me
(3)
(4)
1
MPa. Water removed from the system was frozen
in one of two receivers using solid carbon dioxide as
the cooling medium. The amount of permeated wa-
ter was determined by weighing. The aqueous phases
were sampled periodically and the concentrations of
the respective cations in the feed and stripping solu-
tion were determined by the atomic absorption spec-
troscopy method (AAS, SpectrAA-20, Varian Inc.).
Transport of cations was represented quantita-
tively by Qs,Me = f (t) cumulation curves, i.e. the
1
00Js,Me
Ns,Me =
Js,ΣMe
In order to evaluate the improvement in transport
resulting from variation of the carrier concentration or
the feed pH, the facilitation factors FF were calculated
–
Eq. (5).
Js,ΣMe
FF =
(5)
2
blank
amount of moles transported through 1 cm of the
J
s,ΣMe

A. Oberta et al./Chemical Papers 66 (1) 26–32 (2012)
−2 −1
29
In the above equation, Jblank /(mol cm
s
) is
s,ΣMe
the overall metal flux observed in the blank exper-
iment, i.e. without carrier in FLM and with non-
constant feed pH. To evaluate the separation ability
of the system studied, the time-independent selectiv-
ity coefficients were calculated as ratios of the pseudo-
2+
stationary stripping rates of Pb and the other re-
spective cations, as given in Eq. (6).
Js,Pb
Pb
Me
β
= ꢀ
(6)
Js,Me
=Pb
ꢀ
Results and discussion
In a general assumption, the efficiency of the per-
traction process is usually highly dependent on its
mechanism. Two significant steps of the overall trans-
port across the liquid membrane phase involved can be
recognised. The first step is the cation-exchange reac-
tion occurring on the feed–FLM interface which leads
to the formation of a hydrophobic complex which is
able to penetrate the non-aqueous medium. The op-
posite reaction occurs on the second interface where
the transported cations are released into the stripping
CEM due to the reverse cation-exchange reaction. The
second key step is diffusion through the bulk volume of
the membrane. The influence of the diffusion process
can, however, be minimised by vigorous stirring or ef-
ficient pumping of the membrane solution in order to
minimise the thickness of the diffusion layers adjacent
to CEMs in the case of an agitated bulk liquid mem-
brane or flowing liquid membrane, respectively. Nev-
ertheless, it is more difficult to overcome the transport
limitations resulting from the rate of processes occur-
ring at the liquid membrane interfaces. For this pur-
pose, the reaction mechanism should be determined,
i.e. whether the co-transport or counter-transport con-
stitutes the pertraction of cations in the liquid mem-
brane. As described previously (Oberta et al., 2010),
the ionisable carrier operates according to a counter-
transport mechanism and the process is limited by the
reactions occurring at the CEM–FLM phase bound-
Fig. 4. The cations’ cumulation in the experiment performed
−3
under casual pH conditions ([OSBA] = 0.15 mol dm ).
+
The feed pH varied from 4.80 down to 2.84. Na (ꢀ),
+
2+
2+
2+
K
( ), Mg
(
◦
), Ca
(
), Pb
(ꢁ).
Fig. 5. The cations’ cumulation in the experiment performed
under constant pH conditions. The constant feed pH
−3
was equal to 5.00 ± 0.02 ([OSBA] = 0.15 mol dm ).
Na+ (ꢀ), K+ ( ), Mg2+ (◦), Ca2+ ( ), Pb2+ (ꢁ).
aries. Considering the pK value of OSBA calculated
a
as equal to 4.39 ± 0.02, the overall transport process
mediated by this reagent is regarded as being strongly
influenced by the pH in the boundary layer where the
complexation process occurs. As described earlier, at
the beginning of every experiment, the CEMs were al-
ways in their acidic form, and thus, at the zero time of
the transport run, the FLM was contacted from both
sides with the Nafion membrane polyelectrolyte mate-
rial of low pH. Thus, it was concluded that the pH of
the feed CEM–FLM phase boundary is substantially
lower than the value measured in the bulk volume of
the feed. It was observed that in the course of the
transport the feed pH decreased from ≈ 5.0 to ≈ 2.3
within the first hour of a transport run as a result of
the ion-exchange reactions of the CEM membrane; the
lower value should be taken into consideration when
analysing the processes running under casual pH con-
ditions (without pH adjustment). The typical cumu-
lation curves calculated against the results of the ex-
periments running under casual and constant pH con-
ditions are presented in Figs. 4 and 5, respectively.
The curves corresponding to the experiments per-
formed at the constant feed pH exhibit higher max-
imum Qs,Me values than the curves observed when
the casual conditions were applied. The output fluxes
Pb
Me
Js,Me and selectivity coefficients β
calculated from
the results of experiments carried out under various
conditions are summarised in Tables 1 and 2. The re-

3
0
A. Oberta et al./Chemical Papers 66 (1) 26–32 (2012)
Table 1. Results of series of experiments performed with various carrier concentrations
Carrier concentration/(mol dm 3)
−
Parameter
0
(blank)
0.05
0.1
0.15
−
2
−1
−12
−12
−12
−12
−12
−12
Js,ΣMe/(mol cm
s
)
(0.24 ± 0.01) × 10
(0.29 ± 0.1) × 10
(0.48 ± 0.01) × 10
(1.1 ± 0.1) × 10
FF
1
1.2
2
5.6
−
2
−1
−12
−12
−12
Js,Pb/(mol cm
Js,K/(mol cm
Js,Na/(mol cm
Js,Ca/(mol cm
s
)
(0.09 ± 0.02) × 10
(0.275 ± 0.05) × 10
(0.45 ± 0.03) × 10
(0.9 ± 0.1) × 10
−
2
−1
−12
−12
−12
−12
−12
−12
s
)
(0.017 ± 0.003) × 10
(0.02 ± 0.01) × 10
(0.04 ± 0.01) × 10
(0.115 ± 0.05) × 10
−
−
2
−1
−1
a
−12
−12
−12
s
s
s
)
)
)
(0.024 ± 0.003) × 10
–
(0.02 ± 0.01) × 10
(0.02 ± 0.01) × 10
2
(0.055 ± 0.005) × 10
–
–
93.6
6.4
–
–
86.8
8.4
(0.02 ± 0.01) × 10
−
2
−1
Js,Mg/(mol cm
Ns,Pb/%
Ns,K/%
(0.054 ± 0.005) × 10
–
85.7
10.3
38.5
7.3
Ns,Na/%
Ns,Ca/%
10.0
22.5
21.7
0.625
0
0
0
13.8
4.7
0
0
6.43
1.8
1.9
0
6.07
Ns,Mg/%
Pb
β
ΣMe
−
2
−1
−4
−4
−4
−4
JH2O/(g cm
h
)
(34 ± 1) × 10
(40.4 ± 0.3) × 10
(40.4 ± 0.6) × 10
(17.8 ± 0.1) × 10
a) Only trace values with no significant trend found.
Table 2. Results of series of experiments performed with various pH values of the feeding phase; carrier concentration in membrane
−
3
phase was always equal to 0.15 mol dm
pH of the feeding phase
4.0
Parameter
3.2
5.0
−
2
−1
−12
−12
−12
−12
Js,ΣMe/(mol cm
s
)
(13 ± 1) × 10
(52 ± 4) × 10
(111 ± 3) × 10
FF
57
215
460
−
−
−
−
2
−1
−12
−12
−12
Js,Pb/(mol cm
Js,K/(mol cm
Js,Na/(mol cm
Js,Ca/(mol cm
s
−1
)
(13 ± 1) × 10
(51 ± 4) × 10
(109 ± 3) × 10
2
−12
−12
s
)
(0.11 ± 0.01) × 10
(0.5 ± 0.1) × 10
(0.6 ± 0.1) × 10
(0.3 ± 0.1) × 10
(0.3 ± 0.1) × 10
2
−1
−1
−1
a
−12
−12
−12
s
s
s
)
)
)
–
(0.05 ± 0.01) × 10
2
−12
−12
(0.10 ± 0.04) × 10
(0.06 ± 0.01)×10
−
2
−12
−12
Js,Mg/(mol cm
Ns,Pb/%
Ns,K/%
–
98.5
0.8
(0.05 ± 0.03) × 10
(0.35 ± 0.03) × 10
98.6
1.1
98.6
0.5
Ns,Na/%
0.0
0.1
0.3
Ns,Ca/%
0.7
0.1
0.3
Ns,Mg/%
0.0
64.3
0.1
70.8
0.3
70.3
Pb
β
ΣMe
JH2O/(g cm
−
2
−1
−4
−4
−4
h
)
(75.4 ± 0.5 ) × 10
(56.9 ± 0.8) × 10
(91.2 ± 0.8) × 10
a) Only trace values with no significant trend found.
sults indicate that the MHS with the OSBA carrier
exhibits marked selectivity towards Pb2 in compar-
ison with other cations under all the conditions ap-
plied in the experiments. Moreover, it was noticed that
an increase in the carrier concentration improved the
rier. Moreover, similar values were reported after the
investigations on 1,2-dichloroethane (DCE) solutions
of polymeric carriers, i.e. poly(ethylene glycols) or the
+
2+
poly(oxyethylene) phosphates for pertraction of Cu
,
2+
2+
2+
2+
Zn , Mn , Co , and Ni
ions in the MHS sys-
2+
Pb flux across the membranes. This observation is
in agreement with the theory of the carrier-facilitated
transport mechanism. The OSBA application results
tem (Wódzki et al., 2001, 2002). Similar results, re-
lated to the aqueous hybrid liquid membrane, were
reported (Eyal & Kislik, 1999; Kislik & Eyal, 2000)
2+
2+
2+
2+
in the fractional flux of Pb reaching ≈ 90 %. More-
over, it was observed that an increase in the carrier
concentration in FLM impaired the total system selec-
and for the pertraction of Zn , Cu , and Co from
model solutions as well as from industrial waste wa-
ters. The ionic fluxes were improved in one or two or-
ders of magnitude in comparison with these calculated
for OSBA when the commercially available carriers,
i.e. mono- and di-(2-ethylhexyl) phosphorous acids
(M2EHPA and D2EHPA respectively) were applied
(Kislik, 2010). These values were confirmed by Gega
et al. (2001) who examined D2EHPA, Cyanex-272,
Pb
Me
tivity with β varying from 13.8 to 6.1 in the series
of experiments run under casual pH conditions.
The ionic fluxes observed in the system are com-
parable with those reported previously after the study
of the MHS with octylsulphanylacetic acid (OSAA)
2+
(Oberta et al., 2010) as the selective Pb
ion car-

A. Oberta et al./Chemical Papers 66 (1) 26–32 (2012)
31
Cyanex-301, and Cyanex-302 for the selective trans-
above the detection limit of traditional and instrumen-
tal analytical methods. Furthermore, it appears to be
applicable to the decontamination of natural water of
slightly acidic pH.
2+
2+
port of Co over Ni ions under constant pH condi-
tions. In general, all the compounds referred to exhib-
ited satisfactory selectivity coefficients with maximum
values reaching up to 40. This value is comparable
with those observed in this study.
References
2+
With regard to Pb
ion transports achieved in
Baba, Y., & Inoue, K. (1984). Extraction equilibrium of silver
with a sulfur-containing carboxylic acid. Solvent Extraction
and Ion Exchange, 2, 579–590. DOI: 10.1080/0736629840891
systems other than MHS, the fluxes should not be
compared directly with those presented here, because
of the substantial differences in the construction of
the pertractor. However, it is possible to compare the
selectivity coefficients presented here with the results
reported for various ionophores; for example acyclic
polyether carboxylic acids (Hiratani et al., 1994; Kim
et al., 1999). In comparison with these acids, OSBA
8464.
Barnes, D. S., Ford, G. J., Pettit, L. D.,
&
Sherring-
ton, C. (1971). Ligands containing elements of group
VIB. Part V. Thermodynamics of silver complex forma-
tion of some saturated and unsaturated (alkylthio)acetic
and (alkylseleno)acetic acids. Journal of Chemical Society
A: Inorganic, Physical, Theoretical, 18, 2883–2887. DOI:
10.1039/J19710002883.
Bramlett, J. M., Im, H. J., Yu, X. H., Chen, T., Cai, H., Roecker,
L. E., Barnes, C. E., Dai, S., & Xue, Z. L. (2004). Reactions of
thioether carboxylic acids with mercury(II). Formation and
X-ray crystal structure of mercury(II) mercaptoacetate. In-
organica Chimica Acta, 357, 243–249. DOI: 10.1016/S0020-
Pb
exhibits similar or higher β values. Moreover, OSBA
Me
selectivity was much higher than lasalocid A, one of
the natural metal ligands whose selectivity coefficient
2+
towards Pb
over the other ions investigated only
achieved a value of up to 2.37 (Canet et al., 2002).
It was concluded that the presence of an atom of sul-
phur in the vicinity of the carboxylic group may en-
hance the carrier selectivity because of the high affin-
ity of a weak Lewis base (S) towards weak Lewis acid
1693(03)00446-8.
Canet, L., Ilpide, M., & Seta, P. (2002). Efficient facilitated
transport of lead, cadmium, zinc, and silver across a flat-
sheet-supported liquid membrane mediated by lasalocid A.
Separation Science and Technology, 37, 1851–1860. DOI:
2
+
(
Pb ).
10.1081/SS-120003047.
No significant influence of the varied system pa-
Doh, K. M., Kim, I. C., & Choi, B. Y. (1995). Synthesis and
characterization of a di-µ-oxo-bridged molybdeum(V) com-
plexes. Journal of the Korean Chemical Society, 39, 198–203.
Eyal, A., & Kislik, V. (1999). Aqueous hybrid liquid membrane:
A novel system for separation of solutes using water-soluble
polymers as carriers. Journal of Membrane Science, 161,
rameters on the pervaporated water fluxes was found.
However, when the system operated under constant
pH conditions, the water uptake was slightly higher.
This phenomenon probably results from the higher
amount of water transported as the solvation shell of
ions permeating the CEMs.
207–221. DOI: 10.1016/S0376-7388(99)00113-1.
Ford, G. J., Gans, P., Pettit, L. D., & Sherrington, C. (1972).
Ligands containing elements of group VIB. Part VI. Transi-
tion metal complexes of some alkyl- and aryl-thioacetic and
Conclusions
–selenoacetic acids. Journal of Chemical Society A, Dalton
To conclude, 2-(octylsulphanyl)benzoic acid
OSBA) can be applied as an ionophore- mediating
Transactions, 16, 1763–1765. DOI: 10.1039/DT9720001763.
Geary, W. J., & Malcolm, D. E. (1970). Complexes of SSS’S’-
ethanediylidenetetra[(thio)acetic acid] and related ligands
with cobalt(II), nickel(II), and copper(II). Journal of Chem-
ical Society A: Inorganic, Physical, Theoretical, 1970, 797–
(
pertraction in the multi-membrane hybrid system.
This compound exhibits satisfactory selectivity to-
2+
wards Pb transported from feeds containing cations
802. DOI: 10.1039/J19700000797.
+
+
2+
2+
such as Na , K , Ca , Mg . The selectivity coef-
ficients presented in this study were comparable or
higher than the data recently reported by various au-
thors. Irrespective of operational conditions such as
the feed pH as well as OSBA concentration in the
non-aqueous medium, the carrier exhibits adequate
transport properties. The stripping rates are compa-
rable with those reported for ionisable polyethers and
some macromolecular carriers but lower than those
reported for some commercially available organophos-
phorous acids, e.g. di-(2-ethylhexyl)phosphorous acid.
The stripping rates are highly dependent on the feed
pH because of the relatively low dissociation constant
of the carrier investigated. Thus, the system appears
not to be applicable to the treatment of low pH indus-
trial effluents such as acidic electroplating rinse solu-
tions. However, it can be used as an auxiliary labo-
Gega, J., Walkowiak, W., & Gajda, B. (2001). Separation of
Co(II) and Ni(II) ions by supported and hybrid liquid mem-
branes. Separation and Purification Technology, 22–23, 551–
558. DOI: 10.1016/S1383-5866(00)00137-4.
Gholivand, M. B., & Khorsandipoor, S. (2000). Selective and
efficient uphill transport of Cu(II) through bulk liquid mem-
brane using N-ethyl-2-aminocyclopentene-1-dithiocarboxylic
acid as carrier. Journal of Membrane Science, 180, 115–120.
DOI: 10.1016/S0376-7388(00)00523-8.
Hiratani, K., Sugihara, H., Kasuga, K., Fujiwara, K., Hayashita,
T., & Bartsch, R. A. (1994). An acyclic polyether dicar-
boxylic acid ionophore with high selectivity for pH-driven
uphill transport of lead(II) ion. Journal of the Chemical
Society, Chemical Communications, 1994, 319–320. DOI:
10.1039/C39940000319.
Irving, R. J., & Fernelius, W. C. (1956). Formation con-
stants of some metal derivatives: S-alkyl carboxylic acids.
The Journal of Physical Chemistry, 60, 1427–1429. DOI:
10.1021/j150544a022.
Kim, J. S., Cho, M. H., Lee, S. C., Pang, J. H., Lee, J. H.,
& Ohki, A. (1999). Lead selective lipophilic acyclic diion-
2+
ratory device for the pre-concentration of Pb ions

3
2
A. Oberta et al./Chemical Papers 66 (1) 26–32 (2012)
izable polyethers. Talanta, 49, 69–75. DOI: 10.1016/S0039-
140(98)00362-2.
Kislik, V. S. (2010). Bulk hybrid liquid membrane with organic
water-immiscible carriers: application to chemical, biochem-
ical, pharmaceutical, and gas separations. In V. S. Kislik
Saito, K., Taninaka, I., Murakami, S., & Muromatsu, A. (1998).
9
Extraction behaviour of copper(II) and silver(I) with a thi-
acrown ether carboxylic acid, 2-(3,6,10,13-tetrathiacyclote-
tradec-1-oxy)hexanoic acid. Talanta, 46, 1187–1194. DOI:
10.1016/S0039-9140(97)00365-2.
(
Ed.), Liquid membranes – Principles & applications in
Siswanta, D., Nagatsuka, K., Yamada, H., Kumakura, K.,
Hisamoto, H., Shichi, Y., Toshima, K., & Suzuki, K. (1996).
Structural ion selectivity of thia crown ether compounds with
a bulky block subunit and their application as an ion-sensing
component for an ion-selective electrode. Analytical Chem-
istry, 68, 4166–4172. DOI: 10.1021/ac960396q.
Stypinski-Mis, B., & Anderegg, G. (2000). The stability of pal-
ladium(II) complexes with sulphur-containing ligands. An-
alytica Chimica Acta, 406, 325–332. DOI: 10.1016/S0003-
2670(99)00776-X.
chemical separations & wastewater treatment (pp. 201–276).
Amsterdam, The Nederlands: Elsevier.
Kislik, V., & Eyal, A. (2000). Aqueous hybrid liquid mem-
brane process for metal separation: Part II. Selectivity of
metals separation from wet-process phosphoric acid. Journal
of Membrane Science, 169, 133–146. DOI: 10.1016/S0376-
7
388(99)00332-4.
Kujawski, W., Nguyen, T. Q., & Neel, J. (1991). Dehydration
of water-pyridine mixtures by pervaporation. Separation Sci-
ence and Technology, 26, 1109–1121. DOI: 10.1080/0149639
Szczepa n´ ska, G. (2010). Experimental and theoretical modeling
of integrated membrane systems. Ph.D. thesis. Universitas
Nicolai Copernici, Toru n´ , Poland.
9
108050517.
Oberta, A., Wasilewski, J., & Wódzki, R. (2010). Selective
lead(II) transport in liquid membrane system with octylsul-
fanylacetic acid ionophore. Desalination, 252, 40–45. DOI:
´
Wódzki, R., Swi a˛ tkowski, M., Ka lꢀ u z˙ y n´ ski, K., & Pretula, J.
(2002). Pertraction of cations in a hybrid membrane system
containing soluble polymeric ionophores. Journal of Applied
Polymer Science, 84, 99–109. DOI: 10.1002/app.10263.
1
0.1016/j.desal.2009.11.004.
Pasto, D. J., & Kent, R. (1965). Solvent effect studies on the
ionization constants of phenylmercapto-, phenylsulfinyl-, and
phenylsulfoylacetic acids. Journal of Organic Chemistry, 30,
´
Wódzki, R., Swi a˛ tkowski, M., & Lꢀ apienis, G. (2001). Mobile
macromolecular carriers of ionic substances, 2 transport rates
and separation of some divalent cations by poly(oxyethylene)
phosphates. Macromolecular Chemistry and Physics, 202,
145–154. DOI: 10.1002/1521-3935(20010101)202:1<145::AID-
MACP145>3.0.CO;2-M.
2
684–2687. DOI: 10.1021/jo01019a042.
Pettit, L. D., & Sherrington, C. (1968). Ligands contain-
ing elements of group VIB. Part III. The silver com-
plexes of saturated and unsaturated (alkylthio)acetic and
p-(alkylthio)benzoic acids. Journal of Chemical Society A:
Inorganic, Physical, Theoretical, 1968, 3078–3082. DOI:
10.1039/J19680003078.