Synthesis of TiO₂ nanoparticles using red spinach leaf extract (Amaranthus Tricolor L.) for photocatalytic of methylene blue degradation

Figures & data

Figure 1. Total polyphenol content (TPC) for (a) various of time at temperature of 50°C and (b) various of temperature for 30 min.

Table 1. Compounds detected in the red spinach leaf extract.

Compounds	Chemical formulas	Structures	Retention times
2-amino-5-methyl benzoic acid	C8H9NO2		4.594
3-buten-2-ol	C4H8O		29.864
3’,4’,5,6,7,8-hexamethoxyflavone	C21H22O8		31.664
2,4,4-trimetyl-3-hydroxymetyl-5a-(3-metyl-but-2-enyl)-cyclohexene	C15H26O		32.284
2-(3,4-Dimethoxyphenyl)-5-hydroxy-6,7,8-trimethoxy-4H-chromen-4-one	C20H20O8		33.507
2,6,10-Dodecatrien-1-ol, 3,7,11-trimetil-9-(fenilsulfonil)-, (E,E)-	C21H30O3S		34.631
4,4'-bi-4H-pyran, 2,2’,6,6'-tetrakis(1,1-dimethylethyl)-4,4'-dimethyl	C28H46O2		35.706
β-Amyrin	C30H50O		38.794

Figure 2. (a) XRD pattern, (b) UV-vis spectra, (c) FTIR spectra, and (d) TGA graph of TiO₂ NPs.

Table 2. Crystal properties of TiO₂ NPs.

Sample	Lattice parameters (Å)		Crystallite size (nm)^1	GoF
	a = b	c
TiO2-3	3.7882(4)	9.4971(11)	10.67	2.43
TiO2-5	3.7878(4)	9.4880(12)	11.04	2.91
TiO2-7	3.7910(4)	9.4894(12)	12.20	2.78
TiO2-10	3.7906(3)	9.4917(9)	16.67	3.33
TiO2-15	3.7915(3)	9.4889(10)	16.84	3.54

¹ Calculated using the Scherrer equation from (011).

Figure 3. (a) SEM and (b) TEM image of TiO₂-3.

Figure 4. Particle size distribution of (a) TiO₂-3, (b) TiO₂-5, (c) TiO₂-7, (d) TiO₂-10, and (e) TiO₂-15.

Figure 5. Mechanism of formation green synthesis TiO₂ NPs with red spinach leaf extract.

Figure 6. (a) Photocatalytic activity, (b) kinetics value for all TiO₂ NPs, and (c) photocatalytic activity of TiO₂-3 on different pH for methylene blue degradation.

Table 3. Comparison of the photocatalytic activity with several previous reports of TiO₂ synthesized using plant extracts.

Extract	Pollutant	Time	Constant rate (min^–1)	Efficiency of Degradation (%)	Ref.
Ageratina altissima (L.) King	MB	360 min	–	87	(19)
Carica papaya	RO–4	180 min	0.0088	91	(50)
Aloe vera	RhB	180 min	0.0023	41	(51)
Pulicaria undulata	MO	120 min	–	95	(52)
Mulberry	MB	120 min	0.0240	96	(53)
Lemon	RhB	120 min	–	70	(54)
Amaranthus Tricolor L.	MB	180 min	0.0131	90	This work

*MB: methylene blue, RO–4: reactive orange 4, RhB: rhodamine B, MO: methyl orange.

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