Determination of iron, cobalt and nickel ions from aqueous media using the alkali modified miswak

Peer review under responsibility of University of Bahrain.

Figures & data

Table 1 Chemical and physical properties of miswak fibers and alkali treated miswak fibers.

Property	Miswak-F	AT-Miswak-F
Color	Yellow	Brown
Water solubility (g L^−1)	3.27	0.56
Electrical conductivity (mS cm^−1)	1.74	0.19
Bulk density (g cm^−3)	0.52	0.37
pHZPC	5.20	4.62
Iodine number (mmol/g)	3.10	5.15

Table 2 Spectra data of miswak fibers and alkali treated miswak fibers.

Property	Miswak-F	AT-Miswak-F
IR spectra
Main strong stretches absorption band (cm^−1)	3372.9, 2914.9, 1699.9, 1632.5, 1524.7, 1425.2, 1330.3 and 1031.1	3387.35, 2931.06, 1717.3, 1636.3, 1526.53, 1441.53, 1333.54 and 1105.01
UV– spectra
λmax (nm)	381, 219, 212, 205	360, 217, 208, 202
Elemental analysis
C, H, N and S%	34.5, 4.5, 2.2 and 3.8	45.1, 5.8, 0.9 and 1.2

Figure 1 The SEM images of Miswak-F and AT-Miswak-F at magnifications of 400 and 800×.

Figure 2 Surface morphology of AT-Miswak-F using scanning electron microscopy (SEM) at magnifications 800 and 1600×.

Figure 3 (a) pH_ZPC of miswak fiber (Miswak-F) and miswak fibers after alkali treatment (AT-Miswak-F) & (b) effect of initial pH on the Miswak-F and AT-Miswak-F.

Table 3 Composition of miswak fibers and alkali treated miswak fibers.

Property	Miswak-F	AT-Miswak-F
Ash (%)	8.9	1.4
Lignin (%)	31.6	56.7
Cellulose and hemicellulose (%)	59.5	41.9
Total acidity (mmol g^−1)	1.38	3.50
Phenolic (mmol g^−1)	0.69	1.88
Carboxylic acid (mmol g^−1)	0.34	0.87
Lactones (mmol g^−1)	0.35	0.75
Total basisty (mmol g^−1)	0.20	0.50

Figure 4 Effect of initial pH on the sorption of iron (III), cobalt (II) and nickel (II) onto AT-Miswak-F.

Figure 5 Effect of initial platinum concentration on the extraction of iron (III), cobalt (II) and nickel (II) onto AT-Miswak-F.

Figure 6 Effect of interfering metal ions on the sorption of iron (III), cobalt (II) and nickel (II) onto AT-Miswak-F.

Table 4 Conductivity and electronic spectral data and their assignments for Miswak-F, AT-Miswak-F and metal: AT-Miswak-F complexes.

Material	Electronic spectra (λmax/nm)					Conductivity (mS/cm)
	π–π^∗ transition	n-π^∗ overlapped with CT transition	LMCT transition	MLCT transition	d–d transitions
Miswak-F	205, 212, 219	381	–	–	–	1.74
AT-Miswak-F	202, 208, 217	360	–	–	–	0.19
Iron(III): miswak	201, 205, 207, 213	348, 359	373, 384	444	643	0.34
Cobalt(II): miswak	201, 205, 207, 213	342, 350	364, 394	–	422, 646	0.24
Nickel(II): miswak	201, 205, 207, 213	348, 354	375, 390	–	448, 647	0.15

Figure 7 Infrared spectra of AT-Miswak-F: Metal complexes.

Table 5 Recovery of iron (III) from underground water using AT-Miswak fibers.

Added, μg	Found
	μg	%	RSD%
20	20.19	100.95	2.25
50	49.53	99.06
75	74.06	98.75
125	119.49	95.59

Table 6 Determination of iron in certified water samples using batch technique.

Sample	Certified analysis μg mL^−1	Direct method μg mL^−1	Miswak method μg mL^−1	RSD%
Arabian Gulf sea water	0.30	0.35	0.32	0.98
Nestle SA underground water	<0.02	0.19	0.18	1.31

Table 7 Determination of metal ions in wastewater samples using dynamic technique.

Metal ions	Add μg	Found Mg	Recovery %	RSD%
Fe(III)	0	1.64	100	1.69
	20	20.66	103.3
Co(II)	0	0.40	100	0.00
	20	20	100
Ni(II)	0	1.22	100	0.28
	20	18.8	94.1