5. Performance of the synthesized adsorbents for treatment of electroplating wastewater

The most important part of this work was to evaluate the potential use of both synthesized adsorbents for the treatment of real effluent, via electroplating wastewater. The whole analysis was conducted under the same predetermined conditions (Figure 16). The treatment of paint wastewater utilizing hybrid material is represented in Table 9.

It is obvious that the adsorption rate decreased from 94%–92% to 78%–76% for M1 and 92%–92% to 75%–73% for M2. This pattern might be clarified by the way that in real discharge, organic matter and other pollutants may rival metal ions leading to lessening removal yield.

> great selectivity of both xerogels for Zn (II) ions could be ascribed to their low hydrolysis constant and high covalent index. In this regard, the as-prepared adsor-

Bi-Functionalized Hybrid Materials as Novel Adsorbents for Heavy Metal Removal from…

DOI: http://dx.doi.org/10.5772/intechopen.86802

ions (Pb (II), Cd (II), and Zn (II)) was compared with other stated adsorbents

The uptake efficiency of the as-prepared xerogels for the removal of three metal

bents are relevant for practical application under industrial conditions.

XPS spectra of N1 s and S2p core level spectra before and after metal cation adsorption.

5.2 Comparison with different adsorbents

(Table 10).

145

Figure 14.

#### 5.1 Selectivity of adsorbents

The selectivity of the adsorbent increases its interest for commercial use. In this context, the selectivity of the two xerogels was carried out by removing an aqueous solution containing a mixture of three metal ions (Pb (II), Cd (II), and Zn (II)) under the predetermined optimized conditions, that is, pH = 5, t = 60 min, adsorbent mass = 0.015 g, and T = 20°C.

It is apparent from Figure 17 that the adsorption efficiency of the two adsorbents towards different ions exposed the following order (Cd+2 ˂ Pb+2 ˂ Zn+2). The

Bi-Functionalized Hybrid Materials as Novel Adsorbents for Heavy Metal Removal from… DOI: http://dx.doi.org/10.5772/intechopen.86802

Figure 14. XPS spectra of N1 s and S2p core level spectra before and after metal cation adsorption.

great selectivity of both xerogels for Zn (II) ions could be ascribed to their low hydrolysis constant and high covalent index. In this regard, the as-prepared adsorbents are relevant for practical application under industrial conditions.

#### 5.2 Comparison with different adsorbents

The uptake efficiency of the as-prepared xerogels for the removal of three metal ions (Pb (II), Cd (II), and Zn (II)) was compared with other stated adsorbents (Table 10).

As displayed in Figure 14 a single peak was clearly observed at 398.2 eV, corresponding to the presence of N atom in primary and secondary amine groups. After metal ion adsorption, a new peak with higher binding energy was appeared at about 400.2 eV which may be attributed to the complexation between NH2 and metal ions (R-NH2—M2+). On the other hand, the S2p spectra exhibited a faint peak at 167.3 eV assigned to oxidized sulfur. Another peak was observed at 162.6 eV which corresponds to the unbounded S atom in thiol groups. After metal uptake, the peak ascribed to oxidized sulfur becomes much stronger as well as its ratio area, indicating the ion exchange reaction between (S-H) groups on the M2 xerogel surface and metal ions. Additionally, the XPS spectra of Pb4f, Cd 3d, and Zn2p were

) OH and NH C=N Si▬N S▬H Si▬O M1(pristine) 3343–3325 1557 1174 — 1058-951-460 Pb (loaded) 3303 1559 1170 — 1061-951-464 Cd (loaded) 3310 1561 — — 1060-948-462 Zn (loaded) 3307 1558 — — 1059-950-459 M2(pristine) 3383 1576 — 2680 1134-946-434 Pb (loaded) 3380 1572 — — 1131-947-430 Cd(loaded) 3383 1574 — — 1132-949-433 Zn (loaded) 3380 1577 — — 1135-944-436

As portrayed in Figure 15, the binding energies for Pb 4f7/2, Cd 3d5/2, and Zn2p3/ <sup>2</sup> were 137.9 eV, 404.7 eV, and 1021.1 eV, respectively. This result is in agreement with the FTIR analysis which suggests that metal ions form a bidentate complex on

The most important part of this work was to evaluate the potential use of both synthesized adsorbents for the treatment of real effluent, via electroplating wastewater. The whole analysis was conducted under the same predetermined conditions

It is obvious that the adsorption rate decreased from 94%–92% to 78%–76% for M1 and 92%–92% to 75%–73% for M2. This pattern might be clarified by the way that in real discharge, organic matter and other pollutants may rival metal ions

The selectivity of the adsorbent increases its interest for commercial use. In this context, the selectivity of the two xerogels was carried out by removing an aqueous solution containing a mixture of three metal ions (Pb (II), Cd (II), and Zn (II)) under the predetermined optimized conditions, that is, pH = 5, t = 60 min, adsor-

It is apparent from Figure 17 that the adsorption efficiency of the two adsorbents towards different ions exposed the following order (Cd+2 ˂ Pb+2 ˂ Zn+2). The

5. Performance of the synthesized adsorbents for treatment of

(Figure 16). The treatment of paint wastewater utilizing hybrid material is

also obtained.

ν (cm<sup>1</sup>

Water Chemistry

Table 8.

amino functionalized xerogel.

represented in Table 9.

electroplating wastewater

Band positions before and after metal cation adsorption.

leading to lessening removal yield.

bent mass = 0.015 g, and T = 20°C.

144

5.1 Selectivity of adsorbents

Figure 15. XPS spectra of Pb4f, Cd 3d, and Zn2p after metal ion adsorption.

Figure 16. Efficiency of the as-prepared xerogels for metal ion removal from electroplating wastewater.


It can be remarkably noted that the synthesized xerogels exhibited considerably higher adsorption capacity for metal cations than other sorbents specified previ-

Comparison of adsorption capacity of both mesoporous materials M1 and M2 for Pb(II), Cd(II), and Zn (II)

Adsorbent pH Metal ions qm (mg/g) References SBA15-NH2 5 Pb2+ 54.6 [38] PEG-S 6 Pb2+ 241.36 [39] Amino xerogel 5 Pb2+ 523 This work Sulfhydryl xerogel 5 Pb2+ 509 This work MIONPs-NH2 6 Cd2+ 33.72 [40] MC/Al2O3 3–6 Cd2+ 49.98 [41] Amino xerogel 5 Cd2+ 507 This work Sulfhydryl xerogel 5 Cd2+ 493 This work SiNAL4 6 Zn2+ 86.51 [42] SG-MCF 6 Zn2+ 39.96 [43] Amino xerogel 5 Zn2+ 578 This work Sulfhydryl xerogel 5 Zn2+ 549 This work

Bi-Functionalized Hybrid Materials as Novel Adsorbents for Heavy Metal Removal from…

; contact time: 60 min; pH: 5; temperature:

This pattern might be attributed to high specific surfaces as well as the number of chelating fragments on the surface of the synthesized adsorbents. Besides, the facility of the synthesis method and the lower adsorption parameters such as contact time, pH solution, and adsorbent dosage made them more appropriate for

The primary targets of this work were to synthesize novel functional organicinorganic hybrid materials and to check their ability to remove metal ions from aqueous solution. The structural order, morphology, and texture of the prepared

ously.

147

Table 10.

Figure 17.

20°C).

Selectivity of M1 and M2 xerogels (adsorbent dosage: 0.4 g. L<sup>1</sup>

DOI: http://dx.doi.org/10.5772/intechopen.86802

industrial utilization.

with that of other adsorbents.

6. Conclusion

#### Table 9.

Physicochemical characterization of treated electroplating wastewaters.

Bi-Functionalized Hybrid Materials as Novel Adsorbents for Heavy Metal Removal from… DOI: http://dx.doi.org/10.5772/intechopen.86802

Figure 17.

Figure 15.

Water Chemistry

Figure 16.

TSS (mg.L<sup>1</sup>

COD (mg.L<sup>1</sup>

BOD (mg.L<sup>1</sup>

Zn (mg.L<sup>1</sup>

Pb (mg.L<sup>1</sup>

Cd (mg.L<sup>1</sup>

Table 9.

146

XPS spectra of Pb4f, Cd 3d, and Zn2p after metal ion adsorption.

Efficiency of the as-prepared xerogels for metal ion removal from electroplating wastewater.

Physicochemical characterization of treated electroplating wastewaters.

Parameters Values WHO standard pH 5.8 5.5–6.5 Temperature 27 20–30

) 419 20

) 320 280

) 78 40

) 4.5 5

) 0.15 0.2

) 0.08 0.1

Selectivity of M1 and M2 xerogels (adsorbent dosage: 0.4 g. L<sup>1</sup> ; contact time: 60 min; pH: 5; temperature: 20°C).


#### Table 10.

Comparison of adsorption capacity of both mesoporous materials M1 and M2 for Pb(II), Cd(II), and Zn (II) with that of other adsorbents.

It can be remarkably noted that the synthesized xerogels exhibited considerably higher adsorption capacity for metal cations than other sorbents specified previously.

This pattern might be attributed to high specific surfaces as well as the number of chelating fragments on the surface of the synthesized adsorbents. Besides, the facility of the synthesis method and the lower adsorption parameters such as contact time, pH solution, and adsorbent dosage made them more appropriate for industrial utilization.

#### 6. Conclusion

The primary targets of this work were to synthesize novel functional organicinorganic hybrid materials and to check their ability to remove metal ions from aqueous solution. The structural order, morphology, and texture of the prepared

hybrid gels were studied by FTIR, 13C CP MAS NMR spectroscopy, SEM, and nitrogen adsorption-desorption analysis.

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1000180

The adsorption kinetic studies abide by the pseudo second-order model and exhibit a three-stage adsorption process. Moreover, the adsorption rate of metal cation was controlled by the diffusion rate inside the pore. The Langmuir model showed the best fit for the entire experimental data. The free energy values (E) of metal ion adsorption onto M1 and M2 xerogels generated by the D-R equation revealed that the adsorption proceeded principally by chemisorption. In column studies, the breakthrough efficiencies of both xerogels were comparable to those calculated from batch techniques and can be reused for at least 5 cycles with a slight decrease in the uptake capacity.

Thermodynamic parameters depicted the spontaneity and the exothermic nature of the adsorption process at 20–40°C. The FTIR and XPS analysis revealed that the chelation between the metal ions and the ligating nitrogen atoms of amino functionalized xerogel was the main mechanism involved in cadmium uptake. Otherwise, the proposed mechanism for lead adsorption onto sulfhydryl xerogel was probably through the ion exchange reaction between metal ions and (▬SH) groups. Prior tests accomplished on electroplating wastewater evinced that the xerogel adsorbents possess an exceptional performance in heavy metal uptake from real wastewater. The findings reported in this work showed that the as-prepared xerogels could be widely applied for treatment of industrial wastewater owing to their cost-effectiveness, prominent reusability, good selectivity, and high adsorption efficiency.
