**16. Characteristics of the chelating ion exchange resins**

The chelating ion exchange resins Dowex M 4195 and Diphonix Resin® were tested. Their short characteristics are presented in Table 2.


**Table 1.** Physicochemical properties of IDA and MGDA.


**Table 2.** Physicochemical properties of Dowex M 4195 and Diphonix Resin®.

220 Ion Exchange Technologies

**15. Experimental** 

(SPE) process with the application of such materials is characterized by important advantages such simplicity, flexibility, economical, rapid, higher enrichment factors, absence of emulsion

In general, sorption selectivity of a resin can be affected by both sorbate-sorbent and sorbate-solvent interactions. It has been well recognized that resin matrix and functional groups can strongly affect ion exchange capacity and selectivity. Therefore in the presented paper the chelating ion exchangers Diphonix Resin® containing diphosphonic, sulphonic and carboxylic acid groups and Dowex M 4195 with the bis(2-pyridylmethyl) amine functional group were used for the sorption of Cu(II), Zn(II), Co(II), Pb(II) complexes with Baypure CX 100 (IDS) and Cu(II), Zn(II), Cd(II), Pb(II) complexes with Trilon M (MGDA). The presence of the sulphonic functional groups determines better hydrophilic properties of

In the paper the results of the sorption of heavy metal ions such as Cu(II), Zn(II), Cd(II) and Pb(II) in the presence of the complexing agents of a new generation Baypure CX 100 (IDS) and Trilon M (MGDA) on commercially available chelating ion exchangers are presented.

The chelating ion exchange resins Dowex M 4195 and Diphonix Resin® were tested. Their

<sup>N</sup> COOH <sup>H</sup>

COOH

N

COOH

COOH

HOOC

The essential physicochemical properties of these chelating agents are given in Table 1.

**Properties IDS MGDA**

Form supplied liquid liquid Molecular weight 337.1 271.0

Appearance colourless to light yellow clear yellowish pH 10.3-11.4 11.0 Density [g mL-1] 1.32-1.35 g/mL 1.31 g/mL Solubility in H2O in any ratio in any ratio Solubility in NaOH in any ratio in any ratio Biodegradability [%] > 80% > 68% Termal stability in any range in any range

**16. Characteristics of the chelating ion exchange resins** 

HOOC

short characteristics are presented in Table 2.

Structure HOOC

**Table 1.** Physicochemical properties of IDA and MGDA.

Diphonix Resin® compared to the traditional monofunctional ion exchangers.

and low cost because of lower consumption of reagents.

Before the experiments, the resins were washed with hydrochloric acid (0.1 M) or sulphuric acid (0.5 M) to remove impurities from their synthesis. After pre-treatment they were washed with deionised water.

The solutions of Cu(II), Zn(II), Cd(II) and Pb(II) complexes with Baypure CX 100 and Trilon M with the desirable concentrations were prepared by mixing appropriate metal chlorides or nitrates with the complexing agents solutions, respectively. For the studies the obtained solutions were used without pH adjustment. The pH values of the solutions of Cu(II), Zn(II), Cd(II) and Pb(II) complexes with IDS were as follows: 6.7, 6.5, 69 and 7.3, respectively. For the Cu(II), Zn(II), Cd(II) and Pb(II) complexes with MGDA these values were equal to 8.3, 9.8, 10.5 and 10.4. The other chemicals used were of analytical grade.

In batch experiments, 50 cm3 of sample solution and ion exchanger (0.5 g) were put into a conical flask and shaken at different time intervals using the laboratory shaker Elpin type 357, (Elpin-Plus, Poland). After the pH of solutions was stabilized and equilibrated, the ion exchangers were filtered. The experiments were conducted in three parallel series. The reproducibility of the measurements was within 5%. Adsorption isotherms were obtained with different initial concentrations varying from 1×10-3 M to 2.5 ×10-2 M of metal ions and ligands while keeping the constant amount of resins at room temperature (295 K). The equilibrium between the solid and liquid phases was modelled by the Langmuir and Freundlich equations as presented earlier (Kołodyńska, 2010a; Kołodyńska 2010b; Kołodyńska 2010c). Kinetic studies were carried out at different time intervals varying from 1 to 120 min keeping the constant amount of resins at room temperature (295 K). The shaking speed was 180 rpm to maintain resin particles in suspension.

The amount of heavy metal complexes sorbed onto the resins was calculated by the difference between the amounts added and already present in the solution and that left in the solution after equilibrium.

The pH values were measured with a PHM 84 pH meter (Radiometer, Copenhagen) with the glass REF 451 and calomel pHG 201-8 electrodes. The concentrations of heavy metals were measured with the AAS spectrometer Spectra 240 FS (Varian, Australia).
