Chitosan functionalized recyclable and eco-friendly nanoadsorbent for Pb(II) adsorption from water

Figures & data

Figure 1. FTIR spectra of chitosan, MNPs, Ch-MNPs, and Pb (II) loaded Ch-MNPs [16].

Figure 2. HR-TEM analysis represented the size and shape of Ch-MNPs (a–b). Arrows indicate the lattice fringes (b), (c) SAED pattern [16].

Figure 3. HR-SEM micrographs of Ch-MNPs before (a) and after Pb (II) adsorption (b) [16].

Figure 4. EDX analysis (a) and elemental mapping representing the distribution of all elements (b), carbon (c), nitrogen (d), oxygen (e), manganese (f), and Pb (g).

Figure 5. Effect of pH (a), initial Pb(II) concentration (b), Ch-MNPs dosage (c), temperature (d), contact time (e), and agitation rate (f) for Pb(II) adsorption onto Ch-MNPs.

Figure 6. Langmuir (a), Freundlich (b), Temkin (c), and Halsey (d) isotherms of Pb(II) adsorption on Ch-MNPs.

Table 1. The isotherm parameters of Pb(II) adsorption at various temperature.

Isotherms	Parameters	20 °C	35 °C	50 °C
Langmuir	B	0.34	0.031	0.23
	Q^0	0.06	0.06	0.06
	R^2	0.99	0.99	0.99
	RSS	0.013	0.016	0.010
Freundlich	kf	0.36	0.35	0.34
	N	0.60	0.63	0.68
	R^2	0.98	0.98	0.98
	RSS	0.002	0.0018	0.0029
Temkin	AT	2.59	3.23	4.14
	bT	3.39	3.25	3.20
	R^2	0.99	0.98	0.99
	RSS	0.56	0.67	0.09
Halsey	KH	0.37	0.36	0.34
	nH	1.38	1.45	1.56
	R^2	0.98	0.98	0.98
	RSS	0.012	0.009	0.015

Figure 7. PFO (a), PSO (b), and Elovich (c) kinetic models of Pb(II) adsorption onto Ch-MNPs.

Table 2. Kinetics of Pb(II) adsorption.

PFO				PSO				Elovich kinetics
ks	qe	R^2	RSS	${k\prime }_2$	qe′	R^2	RSS	ɑ	β	R^2	RSS
4.4 × 10^−3	0.42	0.98	0.01	1.76	0.10	0.99	4.8 × 10^−3	0.81	4.52	0.95	0.49

Figure 8. Thermodynamics of Pb(II) adsorption.

Table 3. Thermodynamic data for adsorption of Pb(II) on to Ch-MNPs.

T (°C)	ΔG° (kJ mol^−1)	ΔH° (kJ mol^−1)	ΔS° (J K^−1 mol^−1)
20	−0.21	4.45	1.29
35	−0.43
50	−1.37

Table 4. Comparison of Pb(II) removal capacity of Ch-MNPs with other nanoparticles.

Nanoparticle	Initial Pb (II) concentration (mg/L)	pH	Temperature (°C)	Adsorption capacity (mg/g)	Removal (%)	References
Multiwall carbon nanotubes (MWCNTs)	20	6.40	–	0.05	96.03	[48]
ZnO nanoparticle	100	7	41 °C	58.88	98.43	[49]
MnFe2O4	100	5.3	25	75.75	88.00	[50]
nanoparticles					66.00	[51]
Al2O3–SiO2 nanoparticles	100	8	25	36.03	98.00	[52]
Ch-MNPs	100	6	35	0.06	94.40	Present study

Figure 9. Pb(II) adsorption–desorption on Ch-MNPs.

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