Fabrication of network nanocomposite of polyaniline coating chitosan-graphene oxide-functionalized carbon nanotube and its efficacy in removing dyes from aqueous solution

Figures & data

Figure 1. SEM images of Cross PANI (a), Cross PANI/GO-OXS NCs (b), Cross PANI/Chito-GO OXS NCs (c) NCs, and EDX of Cross PANI/Chito-GO OXS NCs (d).

Figure 2. TEM images of Cross PANI (a), Cross PANI/GO-OXS NCs (b), and Cross PANI/Chito-GO-OXS NCs (c) NCs.

Scheme 1. Illustration of the proposed mechanism for manufacturing Cross PANI/Chito-GO-OXS NCs.

Figure 3. XRD patterns (a) and FTIR spectra (b) of Cross PANI, Cross PANI/GO-OXS, and Cross PANI/Chito-GO-OXS NCs; RAMAN spectra (c) and (d) isotherm curve of Cross PANI/Chito-GO-OXS NCs.

Table 1. The SBET, total pore volumes, and pore size of Cross PANI/Chito-GO-OXS NCs.

Sample	SBET	Vtotal	Pore size
Cross PANI/ Chito-GO-OXS NCs	148.158 m²/g	0.156488 cc/g	2.21124 nm

Figure 4. TGA (a) and DTG (b) curves of Cross PANI, Cross PANI/GO-OXS, and Cross PANI/Chito-GO-OXS NCs, and (c) TGA, DTG and DTA curves of Cross PANI/Chito-GO-OXS NCs.

Table 2. Thermal behavior of Cross PANI, Cross PANI/GO-OXS, and Cross PANI/Chito-GO-OXS NCs.

	Temperature (°C) for various percentage decompositions^a
Sample	T10	T25	T50	PDTmax^b (°C)	CDTfinal^a (°C)
Cross PANI	97	298	407	460	589
Cross PANI/GO-OXS NCs	96	280	403	484	568
Cross PANI/Chito-GO-OXS NCs	133	329	431	476	665

^aThe values were determined by TGA at a heating rate of 10 °C min⁻¹.

^bDetermined from DTG curves.

Figure 5. Efficiency comparison of (a) Cross PANI/GO-OXS NCs and (b) Cross PANI/Chito-GO-OS NCs in removing AR1 and BG dyes from an aqueous phase.

Figure 6. The electronic spectra of (A) Acid Red 1 dye (20 ppm) in the sample solution without Cross PANI/Chito-GO-OXS NCs, (B) after shaking in solution with Cross PANI/Chito-GO-OXS NCs (5 mg) (I), and (A) Brilliant Green dye (5 ppm) in the sample solution without Cross PANI/Chito-GO-OXS NCs (5 mg) and (B) after shaking in solution with Cross PANI/Chito-GO-OXS NCs (5 mg) (II).

Figure 7. The influence of pH on the percentage (I) of adsorption of dyes BG (a) and AR1 (b) from solution samples by (0.005 and 0.0003 g) Cross PANI/Chito-GO-OXS NCs for AR1 and (0.005 and 0.0003 g) Cross PANI/Chito-GO-OXS NCs for BG dyes.

Figure 8. Effect of Cross PANI/Chito-GO-OXS NCs mass on dye adsorption of BG (a) and AR1 (b) at 22 °C temperature and contact period of 120 min.

Figure 9. The effect of shaking duration on the percentage of removal dyes BG (a) and AR (b) by Cross PANI/Chito-GO-OXS NCs at 20 °C.

Figure 10. Temperature effect on the percentage of removal dyes BG (a) and AR1 (b) by Cross PANI/Chito-GO-OXS NCs with a contact time of 120 min.

Figure 11. Effect of KNO₃ concentration on the percentage of removal dyes BG (a) and AR1 (b) on Cross PANI/Chito-GO-OXS NCs at 20 °C.

Table 3. Comparision of Cross PANI/Chito-GO-OXS NCs based on solution pH, equilibrium time, and qe with various other adsorbents for the removal of AR1 and BG dyes from aqueous medium.

Dye	Adsorbents	Equilibrium time	Solution pH	qe calc (mg/g)	Reference
AR1	Halloysite nanoclay	60	2	13.89	[40]
	Aluminium sulfate	15	4	62.5	[41]
	Sunflower seed sheel	100	2	6.81	[42]
	Cross PANI/Chito-GO-OXS NCs	120	2	90.91	This study
BG	Chemically treated Lawsonia inermis	180	6	2.48	[43]
	Areca nut husk	120	7	4.91	[44]
	soybean straw biochar	60	8	12.53	[45]
	Cross PANI/Chito-GO-OXS NCs	120	6	21.27	This study

Figure 12. Lagergren curve for AR1 BG dyes uptake on Cross PANI/Chito-GO-OXS NCs vs. time. The experimental conditions are specified in the batch extraction step.

Figure 13. Pseudo-second order curves for AR1 and BG dye uptake onto Cross PANI/Chito-GO-OXS NCs vs. time. The experimental conditions are specified in the batch extraction step.

Figure 14. Curves of the Elovich model for dye uptake by Cross PANI/Chito-GO-OXS NCs vs. time. The experimental conditions are specified in the batch extraction step.

Table 4. The parameters for several kinetic models for the removal of BG dye and AR1 dye from Cross PANI/Chito-GO-OXS NCs were determined at 22 °C.

The pseudo-first-order kinetic (Lagregen) model
	qe, exp (mg/g)	qe, calc (mg/g)	k1	R^2
BG	16.52	16.98	0.022	0.962
AR1	75.34	74.99	0.025	0.969
The pseudo-second-order kinetic model
	qe, exp (mg/g)	qe, calc (mg/g)	k2	R^2
BG	16.52	21.27	9.2 × 10^–4	0.992
AR1	75.34	90.91	3.4 × 10^–4	0.991
Elovich kinetic model
	α (g/mg min)	β (mg/g min)		R^2
BG	0.058	4.377		0.943
AR1	0.021	18.52		0.957

Figure 15. Intra-particle diffusion model for the AR1 and BG dyes removed from an aqueous solution by Cross PANI/Chito-GO-OXS NCs.

Figure 16. Curves showing ln Kc against 1000/T for BG dye and AR1 dye uptake from aquatic solution by Cross PANI/Chito-GO-OXS NCs.

Table 5. Thermodynamic characteristics for AR1 and BG dye adsorption using Cross PANI/Chito-GO-OXS NCs.

Initial concentration of dye (mg/L)	ln kc	Temperature (K)	1000/T (K^–1)	ΔH (kJ/mol)	ΔS (kJ/mol K)	ΔG (kJ/mol)
5 (BG)	0.92	285	3.50	−15.09 ± 0.53	−45.54 ± 1.69	−1.65 ± 0.06
	0.63	295	3.38
	0.41	303	3.24
	0.24	318	3.14
20 (AR1)	0.503	285	3.50	103.9 ± 4.05	365.5 ± 14.29	−3.833 ± 0.15
	1.15	295	3.38
	2.81	303	3.24
	5.15	318	3.14

Figure 17. The efficiency of AR1 and BG dyes removed by Cross PANI/Chito-GO-OXS NCs from various real three samples, (experimental conditions: 25 mL solution, contact time = 120 min, pH solution = 6, temperature = 295 K, 12.5 mg of Cross PANI/Chito-GO-OXS NCs and 5 mg/L concentration for BG dye, and for the AR1 dye 25 mL solution, contact time = 120 min, pH solution = 2, temperature = 295 K, 12.5 mg of Cross PANI/Chito-GO-OXS NCs and 20 mg/L concentration).

Figure 18. Removal performance of Cross PANI/Chito-GO-OXS NCs towards AR1 and BG dyes over four cycles.

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