In this research, a simple oxidation chemical process was applied for the synthesis of novel PANI@ZnO nanocomposite. The prepared nanocomposites were characterized by XPS, XRD, FTIR, SEM, TGA and N2 adsorption-desorption isotherms. Thereby, PANI@ZnO highest SBET values (about 40.84 m2.g− 1), total mesoporous volume (about 3.214 cm3.g− 1) and average pore size (about 46.12 nm). Afterwards, the prepared nanomaterial was applied as novel nanoadsorbent for the adsorption of Congo Red (CR) and Methylene Blue (MB) dyes from aqueous solutions at 298 K and pH 5.0. Besides, the pseudo-second-order model was obtained the best for the adsorption of both dyes. In the case of isotherm models, the Freundlich model showed the best fit. After removal, the spent adsorbent was regenerated. With the regeneration repeated five cycles, the PANI@ZnO regeneration efficiency remained at a very adequate level.
Research Article
Synthesis of PANI@ZnO Hybrid Material and Evaluations in Adsorption of Congo Red and Methylene Blue Dyes: Structural Characterization and Adsorption Performance
https://doi.org/10.21203/rs.3.rs-661310/v1
This work is licensed under a CC BY 4.0 License
Journal Publication
published 07 Aug, 2021
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Table 1. XPS data of Binding Energy (BE) for: (A) ZnO, (B) PANI and (C) PANI@ZnO samples.
|
Species |
Samples and BE (eV) |
Observation |
||
|
(A) |
(B) |
(C) |
||
|
Zn2p3 |
1021.69 |
// |
1021.62 |
Zn metal |
|
1022.45 |
// |
1022.35 |
Zn–O |
|
|
1023.62 |
// |
1023.64 |
Zn(OH)2 |
|
|
O1s |
529.87 |
531.79 |
530.96 |
C=O, O=C–OH |
|
531.09 |
533.55 |
531.89 |
C–OH |
|
|
532.14 |
// |
532.92 |
Zn–OH, H2O |
|
|
C1s |
// |
284.60 |
284.67 |
C–H, C–C, C=C |
|
286.14 |
285.92 |
286.01 |
C–O, C–N |
|
|
// |
287.22 |
287.37 |
N–C=N |
|
|
288.43 |
// |
288.56 |
C=O |
|
|
N1s |
// |
399.70 |
399.56 |
=N– |
|
// |
400.74 |
400.43 |
–NH– |
|
Table 2. Textural properties of PANI and PANI@ZnO materials.
|
Materials |
SBET m2.g−1 |
Pore volume cm3.g−1 |
Average pore size nm |
|
PANI |
14.21 |
1.784 |
26.07 |
|
PANI@ZnO |
40.84 |
3.214 |
46.12 |
Table 3. PFO and PSO sorption rate constants and Qeq value for the elimination of CR and MB by PANI@ZnO adsorbent at 298K, pH:5.0 and Co:150mg.L−1.
|
Dyes |
Qeq.Exp (mg.g−1) |
Pseudo first order (PFO) |
Pseudo second order (PSO) |
||||
|
k1 min−1 |
Qeq.Cal mg.g−1 |
R2 |
k2.ads g.mg−1.min−1 |
Qeq.Cal mg.g−1 |
R2 |
||
|
CR |
69.82 |
0.028 |
62.57 |
0.948 |
0.0004 |
87.71 |
0.977 |
|
MB |
59.23 |
0.053 |
62.47 |
0.915 |
0.0009 |
68.49 |
0.991 |
Table 4. 
Langmuir & Freundlich isotherm constants and their correlation coefficients for the elimination of CR and MB on PANI@ZnO adsorbent at 298K and pH:5.0.
|
Dyes |
Langmuir |
Freundlich |
|||||
|
Qm (mg.g−1) |
KL (L.mg−1) |
RL |
R2 |
KF (mg1−1/nL1/ng−1) |
n |
R2 |
|
|
CR |
76.92 |
0.069 |
0.159 |
0.972 |
8.231 |
2.21 |
0.819 |
|
MB |
59.88 |
0.157 |
0.095 |
0.996 |
19.96 |
4.38 |
0.806 |
Table 5. Adsorption capacities (Qeq) of Congo Red (CR) and Methylene Blue (MB) dyes on several adsorbents.
|
Dyes |
Adsorbents |
Qeq (mg.g−1) |
pH |
Ref. |
|
CR |
CMC-MMT |
74.13 |
5.0 |
[45] |
|
Al2O3–ZrO2 |
57.50 |
5.0 |
[46] |
|
|
CoFe2O4–Chit |
15.60 |
2.2 |
[47] |
|
|
Fe3O4@SiO2@ZnTDPAT |
12.68 |
7.0 |
[48] |
|
|
MgFe2O4-NH2 NPs |
71.4 |
6.0 |
[49] |
|
|
PANI |
50 |
6.5 |
[50] |
|
|
pTSA doped PANI@graphene oxide |
66.66 |
5.0 |
[51] |
|
|
PVC@graphene-polyaniline |
40.00 |
4.5 |
[52] |
|
|
PANI/ZTO |
64.51 |
5.6 |
[53] |
|
|
PANI@ZnO |
69.82 |
5.0 |
This work |
|
|
MB |
SW–ZnO–PANI hybrid composite |
20.55 |
7.0 |
[1] |
|
Al2O3–ZrO2 |
53.44 |
5.0 |
[46] |
|
|
Fe3O4@SiO2@ZnTDPAT |
20.83 |
7.0 |
[49] |
|
|
α-chitin nanoparticles |
6.90 |
6.0 |
[54] |
|
|
Rice husk (physically activated) |
56.40 |
11 |
[55] |
|
|
AC from Ackee apple pods |
49.99 |
6.2 |
[56] |
|
|
PProDOT/MnO2 (1:2) |
13.94 |
7.0 |
[57] |
|
|
PANI nanotubes |
9.21 |
6.8 |
[58] |
|
|
Nanostructured cross linked PANI |
13.85 |
7.0 |
[59] |
|
|
PANI@ZnO |
59.23 |
5.0 |
This work |