Application of magnetically modified sewage sludge ash (SSA) in ionic dye adsorption

Figures & data

Table 1. Results of chemical analysis and ignition loss of SSA

	Chemical Composition (%)						Ignition Loss
Sample	SiO2	Al2O3	Fe2O3	Na2O	K2O	CaO	(%)
SSA	44.6	16.0	7.3	6.2	6.11	4.5	0.1

Figure 1. X-ray diffraction analysis of sewage sludge and magnetically modified adsorbent. FA0 = SSA not subject to the ferrite process.

Figure 2. Magnetization versus applied magnetic field.

Figure 3. Adsorption of ionic dyes at different pH values for different adsorbents: (a) MB and (b) PR. (Initial dye concentration: 100 mg/L.)

Figure 4. Adsorption of ionic dyes on different adsorbents.

Figure 5. Zeta potentials of SSA, FA2.5, and FA10 from pH 2 to pH 10.

Figure 6. Adsorption percentage versus time for MB and PR.

Figure 7. Results of isotherm adsorption. (a) Fitting of Langmuir equation; (b) fitting of Freundlich equation.

Table 2. Parameters of adsorption isotherm model fitting for MB and PR

Dye	Langmuir			Freundlich
	Q m (mg/g)	K L (L/mg)	r ^2	n	K F	r ^2
MB	22.03	0.13	0.9991	8.81	11.04	0.9392
PR	28.82	0.03	0.9984	3.27	4.42	0.9308

Table 3. Results of kinetic model fitting for MB and PR

	T	Q e,exp	First Order		Second Order		E a
Dye	(°C)	(mg/g)	k 1 (1/min)	r ^2	k 2 (g/mg/min)	r ^2	(kJ/mol)
MB	30	20.20	0.0355	0.9785	0.00072	0.9981	61.71
	45	19.18	0.0532	0.9803	0.00198	0.9959
	60	21.64	0.0629	0.984	0.00654	0.9998
PR	30	23.20	0.0350	0.9758	0.00239	0.9886	9.07
	45	19.96	0.0520	0.9878	0.00276	0.9991
	60	20.42	0.020	0.9936	0.00331	0.9992
Note: Q e,exp = adsorption capacity from experiments.

Table 4. Comparison of MB and PR adsorption on different adsorbents

Adsorbent	Dye	Q m (mg/g)	Well-Fitted Kinetic Model	E a (kJ/mol)	Reference
FA10	MB	22.03	Pseudo-second order	61.71	This study
Fly ash	MB	0.7	Pseudo-second order	5.42	Lin et al., 2008
Fly ash	MB	7.9	Pseudo-second order	NA	Wang et al., 2005
Zeolite	MB	15.9	Pseudo-second order	NA
Unburned carbon	MB	79.9	Pseudo-second order	12.4, 39.3
Zeolite	MB	19.94	Pseudo-second order	16.2–25.1	Han et al., 2009
Sewage sludge	MB	24.9–114.9	Pseudo-second order	NA	Otero et al., 2003
BBAC	MB	454.2	Pseudo-second order	NA	Hameed et al., 2007
FA2.5	PR	28.82	Pseudo-second order	9.07	This study
BWIW	PR	29.37	Pseudo-first order	NA	Binupriya et al., 2008
CNT	PR	39.84	Pseudo-second order	33.35	Wu et al., 2007
Notes: NA = not available; BBAC = bamboo-based activated carbon; BWIW = Bokbunja wine industry waste; CNT = carbon nanotube.

Figure 8. Desorption results of MB and PR.

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