Table 2.

Appliances of biogenic iron-based NPs in degradation of dyes and removal of heavy metals.

Entry	Biogenic source	Nanoparticle size & shape	Dye/metal removed	Refs.
1	Eucalyptus	20–80 nm, spherical	Swine wastewater treatment	(Wang et al., 2014a)
2	Mentha spicata	20–45 nm, core and shell morphology	As(III) & As(V)	(Prasad et al., 2014)
3	Sorghum bran	40–50 nm, amorphous	Bromothymol blue	(Njagi et al., 2010)
4	Green, Oolong and Black tea	20–40 nm, spherical	Monochlorobenzene	(Kuang et al., 2013)
5	Amaranthus dubis	60–300 nm, spherical	MO	(Harshiny et al., 2015)
6	Eucalyptus tereticornis, Melaleuca nesophila, Rosmarinus officinalis	40–60 nm, spherical	Azo dye	(Wang et al., 2014b)
7	Black tea	40–50 nm	Ametryn	(Ali et al., 2016)
8	Oak, mulberry and cherry	10–30 nm, spherical	As(III) & Cr(VI)	(Poguberović et al., 2016)
9	Amaranthus spinosus	58–530 nm, spherical	MB, MO	(Muthukumar and Matheswaran, 2015)
10	Eucalyptus	20–60 nm, spherical agglomerates	Direct black G	(Zhuang et al., 2015)
11	Omani leaf	15 ± 2 in length and 3.0 ± 0.2 nm dia, nanorod	Heavy oil viscosity treatment	(Al-Ruqeishi et al., 2016)
12	Aloe vera	100 × 20 nm, nanorod	As(V)	(Mukherjee et al., 2016)
13	Black tea	40–50 nm, spherical	Fluoride	(Ali et al., 2015)
14	Phyllanthus acidius	4.5–5.8 nm, spherical	AO7	(Gurushantha et al., 2015)
15	Grape leaf	10–100 nm, quasi spherical shape	Orange II dye	(Luo et al., 2016)
16	Eichhornia crassipes (water hyacinth)	20–80 nm, amorphous	Cr(VI)	(Wei et al., 2017)
17	Eucalyptus leaf	20 and 80 nm, amorphous	Cr(VI), Cu(II)	(Weng et al., 2016)
18	Green tea	5–15 nm, spherical	Bromothymol blue	(Hoag et al., 2009)
19	Eucalyptus	50–80 nm, spherical	Cr(VI)	(Madhavi et al., 2013)
20	Eucalyptus	40–60 nm, amorphous	Acid black 194	(Wang, 2013)
21	Green, Oolong and Black tea	40–50 nm, spherical	Malachite green	(Huang et al., 2014a)
22	Pomegranate	100–200 nm	Cr(VI)	(Rao et al., 2013)
23	Vine leaves, black tea, grape marc	15–45 nm	Ibuprofen	(Machado et al., 2013)
24	E. globules	80–90 nm, spherical	Phosphate	(Gan et al., 2018)
25	E. globules	∼80, spherical	Nitrate	(Wang et al., 2014c)
26	Aloe vera	5.5, Rod like	As(V)	(Mukherjee et al., 2016)
27	M. oleifera	250–474, spherical	Nitrate	(Katata-Seru et al., 2018)
28	C. sinensis	5–25, Cuboid/Pyramidal	As(V) & As(III)	(Lunge et al., 2014)
29	M. ferrooxydans	100–130, Rope like	As(III) & As(V)	(Andjelkovic et al., 2017)
30	E. globules	-, spherical	As(V)	(Martínez-Cabanas et al., 2016)
31	C. reticulata	∼50, spherical	Cd(II)	(Ehrampoush et al., 2015)
32	S. thermolineatus	25, distorted spherical	Cu	(Kandasamy, 2017)
33	S. jambos	5–60, Oval, spherical	Cr(VI)	(Xiao et al., 2016)
34	E. globules	50–80, spherical	Cr(VI)	(Madhavi et al., 2013)
35	P. granatum	100–200, irregular	Cr(VI)	(Rao et al., 2013)
36	C. sinensis, S. aromaticum, M. spicata, P. granatum	50–60, spherical	Cr(VI)	(Mystrioti et al., 2016)
37	C. (L.) Cuss	∼45.4, irregular	Cr(III) & Pb(II)	(Lingamdinne et al., 2017)
38	Oolong tea	40–50 nm, spherical	Malachite green	(Huang et al., 2014b)
39	Green tea	70–80 nm, spherical	Malachite green	(Huang et al., 2015)
40	Eucalyptus leaf	80 nm, spherical	Phosphate	(Cao et al., 2016)