**2. Experimental**

#### **2.1. Reagents and materials**

All chemicals used were of A.R. grade and were used without further purification. Stock solution (1000 μg mL-1) of bismuth (III) was prepared from bismuth (III) nitrate (Aldrich Chemical Co Ltd, Milwaukee, WC, USA). More diluted solutions of bismuth (III) (0.1 – 100 μg mL-1) were prepared by diluting the stock solution with diluted nitric acid. Stock solutions of procaine [2-(diethylamino)ethyl 4 aminobenzoate] hydrochloride, PQ+.Cl- (1.0 %w/v), Fig.1 and KI (10%w/v) were prepared by dissolving the required weight in water (100 mL). A stock solution (1%v/v) of trioctylamine (Aldrich) was prepared in water in the presence of few drops of concentrated HNO3. Sodium bismuthate

Fast, Selective Removal and Determination of Total Bismuth (III) and (V) in Water by Procaine Hydrochloride Immobilized Polyurethane Foam Packed Column Prior to Inductively Coupled… 283

(NaBiO3, 85% purity) (BDH, Poole, England) was used for preparation of stock solution (50 μg mL-1) of bismuth (V) in dark bottle [30] as follows: an accurate weight of NaBiO3 was heated in a suitable volume of HClO4 (20 mL, 0.5 mol L-1) filtered and the solution was made up to 250 mL with deionized water and finally analyzed under the recommended conditions of bismuth determination by ICP-OES (Table 1). The measured concentration was taken as a standard stock solution of bismuth (V) in the next work. Bismuth (V) solution was finally stored in low density polyethylene bottles (LDPE) in dark. Stock solutions (0.1-1% w/v) of

(BDH) and trioctylamine (Merck, Darmstadt, Germany) abbreviated as TOA were

(1% w/v) were purchased from Fluka, AG

(1.0 % w/v) was dissolved in water, shaken

of bismuth (III) at 420 nm

prepared in deionized water containing few drops of concentrated HNO3. Sodium

(Buchs, Switzerland). Commercial white sheets of PUFs were cut as cubes (10 -15 mm),

with the PUFs cubes in the presence of TOA (1% v/v) with efficient stirring for 30 min, squeezed and finally dried as reported [21].. The certified reference material (CRM) i.e. trace metal in drinking water standard (CRM-TMDW) was obtained from High-Purity Standard Inc. Sulfuric acid (0.5mol L-1) was used as an extraction medium in the sorption process of bismuth (III) by the PUFs. Commercial white sheets of open cell polyether type polyurethane foam were purchased from the local market of Jeddah City, Saudi Arabia and were cut as cubes (10-15 mm). The PUFs cubes were washed and dried as reported [21, 27].

\*ICP –MS operational parameters are given in parentheses. Other parameters are: lens voltage =9.0; analog stage voltage 1750 V; pulse stage voltage =750 V; quadrupole rod offset std = =0.0; cell rod offset =-18.0; discriminator threshold =17.0; cell path voltage

A Perkin \_ Elmer (Lambda 25, Shelton, CT,USA) spectrophotometer (190 \_ 1100 nm) with 10 mm (path width) quartz cell was used for recording the electronic spectra and measuring

treated PUFs. A

**Table 1.** ICP-OES operational conditions and wavelength (nm) for bismuth determination\*

A series of Britton- Robinson (B-R) buffer (pH 2-11) was prepared as reported [31].

Rf power (kW) 1050 (900.0) Plasma gas (Ar) flow rate, L min 15 (15) -1 Auxiliary gas (Ar) flow rate, L min 0.2 (1.2) -1 Nebulizer gas (Ar) flow rate, Lmin 0.80 (0.93) -1

Wavelength, nm Bi 223.061

Pump rate, mL min 1.5 -1 Observation height, mm 15 Integration time, s 10

the absorbance of the ternary complex ion associate PQ+. BiI4-

before and after extraction with the reagent PQ+.Cl-

Std = -13.0 V and atomic mass 208.98 am.

*2.2.* **Instrumental and apparatus** 

PQ+.Cl-

Parameter

diethyldithiocarbamate (Na-DDTC) and PQ+ .Cl-

washed, treated and dried. The reagent PQ+ .Cl-

**Figure 1.** Chemical structure of procaine hydrochloride.

(NaBiO3, 85% purity) (BDH, Poole, England) was used for preparation of stock solution (50 μg mL-1) of bismuth (V) in dark bottle [30] as follows: an accurate weight of NaBiO3 was heated in a suitable volume of HClO4 (20 mL, 0.5 mol L-1) filtered and the solution was made up to 250 mL with deionized water and finally analyzed under the recommended conditions of bismuth determination by ICP-OES (Table 1). The measured concentration was taken as a standard stock solution of bismuth (V) in the next work. Bismuth (V) solution was finally stored in low density polyethylene bottles (LDPE) in dark. Stock solutions (0.1-1% w/v) of PQ+.Cl- (BDH) and trioctylamine (Merck, Darmstadt, Germany) abbreviated as TOA were prepared in deionized water containing few drops of concentrated HNO3. Sodium diethyldithiocarbamate (Na-DDTC) and PQ+ .Cl- (1% w/v) were purchased from Fluka, AG (Buchs, Switzerland). Commercial white sheets of PUFs were cut as cubes (10 -15 mm), washed, treated and dried. The reagent PQ+ .Cl- (1.0 % w/v) was dissolved in water, shaken with the PUFs cubes in the presence of TOA (1% v/v) with efficient stirring for 30 min, squeezed and finally dried as reported [21].. The certified reference material (CRM) i.e. trace metal in drinking water standard (CRM-TMDW) was obtained from High-Purity Standard Inc. Sulfuric acid (0.5mol L-1) was used as an extraction medium in the sorption process of bismuth (III) by the PUFs. Commercial white sheets of open cell polyether type polyurethane foam were purchased from the local market of Jeddah City, Saudi Arabia and were cut as cubes (10-15 mm). The PUFs cubes were washed and dried as reported [21, 27]. A series of Britton- Robinson (B-R) buffer (pH 2-11) was prepared as reported [31].


\*ICP –MS operational parameters are given in parentheses. Other parameters are: lens voltage =9.0; analog stage voltage 1750 V; pulse stage voltage =750 V; quadrupole rod offset std = =0.0; cell rod offset =-18.0; discriminator threshold =17.0; cell path voltage Std = -13.0 V and atomic mass 208.98 am.

**Table 1.** ICP-OES operational conditions and wavelength (nm) for bismuth determination\*

#### *2.2.* **Instrumental and apparatus**

282 Polyurethane

PQ+.Cl-

**2. Experimental** 

determination step [14 -18].

treated PUFs sorbent.

**2.1. Reagents and materials** 

Solvent extraction in the presence of co-extractant ligands e.g. bis (2, 4, 4-trimethyl pentyl) monothiophosphinic acid [11], pyrolidine dithocarbamate [12] etc has received considerable attention. However, these methods are too expensive, suffer from the use of large volumes of toxic organic solvents, and time-consuming. Thus, recent years have seen considerable attention on preconcentration and/ or monitoring of trace and ultra trace concentrations of bismuth by low cost procedures in a variety of samples e.g. fresh, marine and industrial wastewater [13]. Solid phase extraction (SPE) techniques have provided excellent alternative approach to liquid – liquid extraction for bismuth preconcentration prior to analyte

Polyurethane foams (PUFs) sorbent represent an excellent solid sorbent material due to their high available surface area, cellular and membrane structure and extremely low cost [19]. Thus, several liquid solid separation involving PUFs methods have been employed successfully for separation and sensitive determination of trace and ultra trace levels of metal ions including bismuth (III) [19-29]. The membrane like structure and the available surface area of the PUFs make it a suitable stationary phase and a column filling material [25, 27]. Thus, the main objectives of the present chapter are focused on: i. developing of a low cost method for the removal of bismuth(III) and (V) species after reduction of the latter

thermodynamic characteristics of bismuth (ІІІ) sorption by trioctylamine plasticized PQ+.Cltreated PUFs and finally iii. Application of the developed method in packed column for complete removal and / or determination of bismuth (III &V) species in wastewater by

All chemicals used were of A.R. grade and were used without further purification. Stock solution (1000 μg mL-1) of bismuth (III) was prepared from bismuth (III) nitrate (Aldrich Chemical Co Ltd, Milwaukee, WC, USA). More diluted solutions of bismuth (III) (0.1 – 100 μg mL-1) were prepared by diluting the stock solution with diluted nitric acid. Stock solutions of procaine [2-(diethylamino)ethyl 4 aminobenzoate] hydrochloride, PQ+.Cl-

%w/v), Fig.1 and KI (10%w/v) were prepared by dissolving the required weight in water (100 mL). A stock solution (1%v/v) of trioctylamine (Aldrich) was prepared in water in the

N

CH2 CH3

CH2 CH3

; ii. Studying the kinetics, and

.HCl

(1.0

to tri valence state employing PUFs impregnated PQ+.Cl-

presence of few drops of concentrated HNO3. Sodium bismuthate

O

O

**Figure 1.** Chemical structure of procaine hydrochloride.

H2N

A Perkin \_ Elmer (Lambda 25, Shelton, CT,USA) spectrophotometer (190 \_ 1100 nm) with 10 mm (path width) quartz cell was used for recording the electronic spectra and measuring the absorbance of the ternary complex ion associate PQ+. BiI4 of bismuth (III) at 420 nm before and after extraction with the reagent PQ+.Cl treated PUFs. A

Perkin Elmer inductively coupled plasma – optical emission spectrometer (ICP- OES, Optima 4100 DC (Shelton, CT, USA) was used and operated at the optimum operational parameters for bismuth determination (Table 1). A Perkin Elmer inductively coupled plasma – mass spectrometer (ICP – MS) Sciex model Elan DRC II (California, CT, USA) was also used to measure the ultra trace concentrations of bismuth in the effluent after extraction by the developed PUFs packed column at the operational conditions (Table 1). A Corporation Precision Scientific mechanical shaker (Chicago, CH, USA) with a shaking rate in the range 10 – 250 rpm and glass columns (18 cm x 15 mm i.d) were used in batch and flow experiments, respectively. De-ionized water was obtained from Milli-Q Plus system (Millipore, Bedford, MA, USA). A thermo Orion model 720 pH Meter (Thermo Fisher Scientific, MA, USA) was employed for pH measurements with absolute accuracy limits being defined by NIST buffers.

#### **2.3. General batch procedures**

#### *2.3.1. Preparation of the immobilized reagent (PQ+ .Cl- ) polyurethane foams.*

The reagent PQ+ .Cl- (1% w/v)in water was shaken with the PUFs cubes in the presence of the plasticizer TOA (1% v/v) with efficient stirring for 30 min. The loaded PQ+.Cl- PUFs cubes were squeezed and dried between two filter papers [20, 21]. The amount of PQ+.Cl retained onto the PUFs sorbent was calculated using the equation [21]:

$$a = \left(\text{C} \text{} \text{} \text{} \text{} \text{} \text{} \right) \frac{\text{v}}{\text{w}} \tag{1}$$

Fast, Selective Removal and Determination of Total Bismuth (III) and (V) in Water by Procaine Hydrochloride Immobilized Polyurethane Foam Packed Column Prior to Inductively Coupled… 285

An aqueous solution (100 mL) of bismuth (ІІІ) ions at concentration (5 – 100 μg L-1), KI (10%) and H2SO4 (1.0 mol L-1) was percolated through the PQ+.Cl- loaded PUFs (1.0 ± 0.002 g) column at 2.0 mL min-1 flow rate. A blank experiment was also performed in the absence of bismuth (ІІІ) ions. Bismuth (III) sorption took place quantitatively as indicated from the analysis of bismuth species in effluent solutions by ICP- OES. After extraction, the ultra trace concentrations of bismuth (III) remained in the test aqueous solutions were estimated by ICP-MS. Bismuth (III) species were recovered quantitatively with HNO3 (3.0 mol L-1, 10

An aqueous solution (100.0 mL) of bismuth (V) at concentration < 10 μg L-1 was allowed to react with an excess of KI (10% w/v) - H2SO4 (1.0 mol L-1). The solution was then percolated through PQ+ .Cl- loaded PUFs (1.0 ± 0.002 g) packed column at 2.0 mL min-1 flow rate of 2.0 mL min-1. The retained bismuth (III) species were recovered with HNO3 (10.0 mL, 1.0 mol L-

An aqueous solution (100 mL) containing bismuth (III) and (V) at a total concentration ≤ 10 μg L-1 was analyzed according to the described procedure for bismuth (V) retention and recovery. Another aliquot portion (100 mL) was adjusted to pH 3 - 4 with acetate buffer and then shaken with Na-DDTC (5 0 mL, 1%w/v) for 2-3 min. Bismuth (III) ions were then extracted with methylisobutylketone (5.0 mL) as Bi (DDTC)3after 2 min [24]. Bismuth (V) remained in the aqueous solution was reduced to bismuth (III) by an excess of KI (10% w/v) in the presence of H2SO4 (0.5 mol L-1) and then percolated through the PQ+.Cl- loaded PUFs column at 2 ml min -1 flow rate at the optimum experimental conditions. The retained bismuth species were recovered and finally analyzed following the recommended procedures for bismuth (III). Thus, the net signal intensity of ICP- OES ( or ICP-MS) at ultra trace concentrations of the first aliquot (I1) will be a measure of the sum of the bismuth (III) and (V) ions in the mixture, while the net signal intensity of the of the second aliquot (I2) is a measure of bismuth (V) ions. The difference (I1-I2) of the net signal intensity is a measure of

The TMDW water sample (2 mL) was digested with nitric acid (10 mL, 3.0. mol L-1) and hydrogen peroxide (10 mL, 10% v/v), boiled for 5 min and diluted by an excess of KI (10% w/v) - H2SO4 (1.0 mol L-1) to 100 mL. After cooling, the test solution was percolated through the PQ+.Cl- loaded PUFs column at 2 ml min -1 flow rate. The retained bismuth species were recovered with HNO3 (10.0 mL, 1.0 mol L-1) at 2.0 mL min-1 flow rate and nalyzed by ICP-

*2.3.3. Retention and recovery of bismuth (ІІІ)* 

*2.3.4. Retention and recovery of bismuth (V)* 

bismuth (III) ions in the binary mixture.

*2.4.1. Analysis of certified reference material TMDW* 

OES following the recommended procedures for bismuth (III).

**2.4. Analytical applications** 

1) at 2.0 mL min-1 flow rate and analyzed by ICP- OES.

*2.3.5. Sequential determination of total bismuth (ІІІ) and (V)* 

mL) at 2.0 mL min-1 flow rate.

where, Co and C are the initial and final concentrations (mol L-1) of the reagent (PQ+.Cl- ) in solution, respectively, v = volume of the reagent solution (liter) and w is the mass (g) of the PUFs sorbent. The reproducibility of PQ+.Cl treated PUFs is fine and the PUFs can be reused many times without decrease in its efficiency.

#### *2.3.2. Batch extraction step*

An accurate weight (0.1 ± 0.002 g) of unloaded- or PQ+.Climmobilized PUFs was equilibrated with an aqueous solution (100 mL) containing bismuth (10 μg mL-1) in the presence of KI (10% w/v) , H2SO4 ( 0.5 mol L-1 )and ascorbic acid (0.1%w/v) to minimize the aerial oxidation of KI. The test solution was shaken for 1 h on a mechanical shaker. The aqueous phase was then separated out by decantation and the amount of bismuth (ІІІ) remained in the aqueous phase was then determined spectrohotometrically against reagent blank [32] or by ICP-OES at ultra trace concentrations. The amount of bismuth (ІІІ) retained on the foam cubes was then calculated from the difference between the absorbance of [BiI4] in the aqueous phase before (Ab) and after extraction (Af). The sorption percentage (%E) , the distribution ratio (D), the amount of bismuth (ІІІ) retained at equilibrium (qe) per unit mass of solid sorbent (mol/g) and the distribution coefficient (Kd) of sorbed analyte onto the foam cubes were finally calculated as reported. The %E and Kd are the average of three independent measurements and the precision in most cases was ±2%. Following these procedures, the influence of shaking time and temperature on the retention of bismuth (III) by the PUFs sorbents was fully studied.

#### *2.3.3. Retention and recovery of bismuth (ІІІ)*

284 Polyurethane

**2.3. General batch procedures** 

The reagent PQ+ .Cl-

*2.3.1. Preparation of the immobilized reagent (PQ+ .Cl-*

PUFs sorbent. The reproducibility of PQ+.Cl-

by the PUFs sorbents was fully studied.

*2.3.2. Batch extraction step* 

many times without decrease in its efficiency.

onto the PUFs sorbent was calculated using the equation [21]:

An accurate weight (0.1 ± 0.002 g) of unloaded- or PQ+.Cl-

plasticizer TOA (1% v/v) with efficient stirring for 30 min. The loaded PQ+.Cl-

were squeezed and dried between two filter papers [20, 21]. The amount of PQ+.Cl-

<sup>o</sup> <sup>v</sup> ( C - C )

where, Co and C are the initial and final concentrations (mol L-1) of the reagent (PQ+.Cl-

solution, respectively, v = volume of the reagent solution (liter) and w is the mass (g) of the

equilibrated with an aqueous solution (100 mL) containing bismuth (10 μg mL-1) in the presence of KI (10% w/v) , H2SO4 ( 0.5 mol L-1 )and ascorbic acid (0.1%w/v) to minimize the aerial oxidation of KI. The test solution was shaken for 1 h on a mechanical shaker. The aqueous phase was then separated out by decantation and the amount of bismuth (ІІІ) remained in the aqueous phase was then determined spectrohotometrically against reagent blank [32] or by ICP-OES at ultra trace concentrations. The amount of bismuth (ІІІ) retained on the foam cubes was then calculated from the difference between the absorbance of [BiI4] in the aqueous phase before (Ab) and after extraction (Af). The sorption percentage (%E) , the distribution ratio (D), the amount of bismuth (ІІІ) retained at equilibrium (qe) per unit mass of solid sorbent (mol/g) and the distribution coefficient (Kd) of sorbed analyte onto the foam cubes were finally calculated as reported. The %E and Kd are the average of three independent measurements and the precision in most cases was ±2%. Following these procedures, the influence of shaking time and temperature on the retention of bismuth (III)

w

Perkin Elmer inductively coupled plasma – optical emission spectrometer (ICP- OES, Optima 4100 DC (Shelton, CT, USA) was used and operated at the optimum operational parameters for bismuth determination (Table 1). A Perkin Elmer inductively coupled plasma – mass spectrometer (ICP – MS) Sciex model Elan DRC II (California, CT, USA) was also used to measure the ultra trace concentrations of bismuth in the effluent after extraction by the developed PUFs packed column at the operational conditions (Table 1). A Corporation Precision Scientific mechanical shaker (Chicago, CH, USA) with a shaking rate in the range 10 – 250 rpm and glass columns (18 cm x 15 mm i.d) were used in batch and flow experiments, respectively. De-ionized water was obtained from Milli-Q Plus system (Millipore, Bedford, MA, USA). A thermo Orion model 720 pH Meter (Thermo Fisher Scientific, MA, USA) was employed for pH measurements with absolute accuracy limits being defined by NIST buffers.

*) polyurethane foams.* 

*a* (1)

treated PUFs is fine and the PUFs can be reused

PUFs cubes

immobilized PUFs was

retained

) in

(1% w/v)in water was shaken with the PUFs cubes in the presence of the

An aqueous solution (100 mL) of bismuth (ІІІ) ions at concentration (5 – 100 μg L-1), KI (10%) and H2SO4 (1.0 mol L-1) was percolated through the PQ+.Cl- loaded PUFs (1.0 ± 0.002 g) column at 2.0 mL min-1 flow rate. A blank experiment was also performed in the absence of bismuth (ІІІ) ions. Bismuth (III) sorption took place quantitatively as indicated from the analysis of bismuth species in effluent solutions by ICP- OES. After extraction, the ultra trace concentrations of bismuth (III) remained in the test aqueous solutions were estimated by ICP-MS. Bismuth (III) species were recovered quantitatively with HNO3 (3.0 mol L-1, 10 mL) at 2.0 mL min-1 flow rate.

## *2.3.4. Retention and recovery of bismuth (V)*

An aqueous solution (100.0 mL) of bismuth (V) at concentration < 10 μg L-1 was allowed to react with an excess of KI (10% w/v) - H2SO4 (1.0 mol L-1). The solution was then percolated through PQ+ .Cl- loaded PUFs (1.0 ± 0.002 g) packed column at 2.0 mL min-1 flow rate of 2.0 mL min-1. The retained bismuth (III) species were recovered with HNO3 (10.0 mL, 1.0 mol L-1) at 2.0 mL min-1 flow rate and analyzed by ICP- OES.

#### *2.3.5. Sequential determination of total bismuth (ІІІ) and (V)*

An aqueous solution (100 mL) containing bismuth (III) and (V) at a total concentration ≤ 10 μg L-1 was analyzed according to the described procedure for bismuth (V) retention and recovery. Another aliquot portion (100 mL) was adjusted to pH 3 - 4 with acetate buffer and then shaken with Na-DDTC (5 0 mL, 1%w/v) for 2-3 min. Bismuth (III) ions were then extracted with methylisobutylketone (5.0 mL) as Bi (DDTC)3after 2 min [24]. Bismuth (V) remained in the aqueous solution was reduced to bismuth (III) by an excess of KI (10% w/v) in the presence of H2SO4 (0.5 mol L-1) and then percolated through the PQ+.Cl- loaded PUFs column at 2 ml min -1 flow rate at the optimum experimental conditions. The retained bismuth species were recovered and finally analyzed following the recommended procedures for bismuth (III). Thus, the net signal intensity of ICP- OES ( or ICP-MS) at ultra trace concentrations of the first aliquot (I1) will be a measure of the sum of the bismuth (III) and (V) ions in the mixture, while the net signal intensity of the of the second aliquot (I2) is a measure of bismuth (V) ions. The difference (I1-I2) of the net signal intensity is a measure of bismuth (III) ions in the binary mixture.

#### **2.4. Analytical applications**

#### *2.4.1. Analysis of certified reference material TMDW*

The TMDW water sample (2 mL) was digested with nitric acid (10 mL, 3.0. mol L-1) and hydrogen peroxide (10 mL, 10% v/v), boiled for 5 min and diluted by an excess of KI (10% w/v) - H2SO4 (1.0 mol L-1) to 100 mL. After cooling, the test solution was percolated through the PQ+.Cl- loaded PUFs column at 2 ml min -1 flow rate. The retained bismuth species were recovered with HNO3 (10.0 mL, 1.0 mol L-1) at 2.0 mL min-1 flow rate and nalyzed by ICP-OES following the recommended procedures for bismuth (III).

#### *2.4.2. Analysis of total bismuth in wastewater*

Wastewater samples (1.0 L) were collected and filtered through a 0.45 μm membrane filter (Milex, Millipore Corporation). The test solution was digested with nitric acid (10 mL, 3.0. mol L-1) and hydrogen peroxide (10 mL, 10% v/v), boiled for 5 min and spiked with different amounts (0.05- 0.5 μg ) of bismuth (ІІІ) in presence of an excess of KI (10% w/v). After centrifugation for 5 min, the sample solutions were percolated through PQ+.Cl loaded PUFs packed columns at 5 mL min-1 flow rate. The concentration of bismuth in the effluent solution was determined by ICP - MS. The retained bismuth (III) species on the PUFs were then recovered and analyzed as described above.

Fast, Selective Removal and Determination of Total Bismuth (III) and (V) in Water by Procaine Hydrochloride Immobilized Polyurethane Foam Packed Column Prior to Inductively Coupled… 287

treated

sorption onto the PUFs markedly decreased on increasing solution pH and maximum

PUFs towards bismuth (III) decreased markedly (Fig.2). This behavior is most likely attributed to the deprotonation of the ether oxygen (-CH2 – O– CH2 –) and/or urethane nitrogen (- NH– CO–**)** of PUFs, instability, hydrolysis, or incomplete extraction of the

**Figure 2.** Effect of pH on the sorption percentage of bismuth (III) from aqueous solutions containing KI

0 2 4 6 810

**pH**

The retention of bismuth (ІІІ) at low pH of aqueous media is most likely attributed to sorbent membranes. The pKa values of protonation of oxygen atom of ether group (\_ CH2\_ OH+\_ CH2\_) foam and nitrogen atom of the amide group (- N+H2 - COO-) foam are \_ 3 and \_ 6, respectively [32]. Thus, in extraction media containing H2SO4 (0.50 mole L-1) and KI, the complexed species of bismuth [BiI4]- are easily retained onto the protonated ether group of the PUFs than amide group of PUFs sorbent. The stability constants of the binding sites of

( )

of bismuth bound to foam (g)

*weight <sup>n</sup>* (3)

*i <sup>n</sup> Kn n*

weight of foam (g)

where, K = stability constant of bismuth (III) on PUF, ni = maximum concentration of sorbed bismuth (III) by the available sites onto the PUFs, and [Bi] is the equilibrium concentration of bismuth (III) in solution (mol L-1). The plot of n /[Bi] versus *n* is shown in Fig. 3. The curvature of the Scatchard plot demonstrated that more than one class of complex species of

the PUFs with [BiI4]- were calculated using the Scatchard equation [33]:

[ ]

immobilized PUFs (0.1 ± 0.002 g) at 25 ± 0.10C**.**

*Bi* (2)

(10 % m/v) - H2SO4 (2.0 mol L-1) onto PQ+ .Cl-

0

30

**%E**

60

90

and n is given by the equation:

uptake was achieved at pH zero. At pH >1, the sorption of bismuth (III) by PQ+.Cl-

produced ternary complex ion associate of PQ+.[BiI4]-. on/ in the PUFs sorbent.
