Materials Letters 215 (2018) 121–124

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Materials Letters
journal homepage: www.elsevier.com/locate/mlblue

Biosynthesis of tin oxide nanoparticles using Psidium Guajava leave

extract for photocatalytic dye degradation under sunlight
Mandeep Kumar a,1, Akansha Mehta b,1, Amit Mishra b, Jagpreet Singh a, Mohit Rawat a,⇑, Soumen Basu b,⇑
a
Dept. of Nanotechnology, Sri Guru Granth Sahib World University, India
b
School of Chemistry and Biochemistry, Thapar University, India

a r t i c l e i n f o a b s t r a c t

Article history: In present investigation green synthesis of tin oxide (SnO2) nanoparticles has been carried out by simple,
Received 15 September 2017 eco-friendly and low cost process using guava (Psidium Guajava) leaf extract. The as-synthesized SnO2
Received in revised form 1 December 2017 nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy,
Accepted 17 December 2017
X-ray powder diffraction, Transmission electron microscopy, Field emission scanning electron micro-
Available online 18 December 2017
scope and Energy-dispersive spectroscopy. The photocatalytic activity of the nanoparticles was analyzed
for the photodegradation of reactive yellow 186 dye under sunlight. SnO2 nanoparticles within size range
Keywords:
8–10 nm effectively degraded 90% of the dye within 180 min at a rate constant of 0.00476 min
1.
Green synthesis
Tin oxide nanoparticles
Ó 2017 Elsevier B.V. All rights reserved.
Photocatalysis
Reactive yellow 186 dye

1. Introduction few reports are available throughout the literature regarding green
synthesis of SnO2 NPs [16]. Here in this paper, we have synthesized
The industrial and domestic water effluents have become major SnO2 NPs using guava (Fig. 1) (Psidium Guajava) leaf extracts by a
concern as threat to human health. Wastewater generated from simple and economical synthesis method. Guava leaf extracts have
various industrial processes consists of organic pollutants of toxic found to contain phenolic compounds, flavonoids, sesquiterpene
and carcinogenic nature [1]. Remediation of such toxic wastes is alcohols and triterpenoid acids which possess antioxidant, antimi-
one of the prime challenges worldwide [2]. There are many efforts crobial as well as antitumor properties [18]. The as-synthesized
being made for treating these effluents such as electrolytic method SnO2 NPs were then used as photocatalysts to degrade Reactive
[3], electron beam treatment [4], activated carbon [5,6], photo- Yellow 186 dye (Vinyl Disulphone, RY186) as model pollutant
catalysis [7] and photo electrochemical [8,9] methods respectively. obtained from a local textile industry (Fig. 2).
Photocatalytic or advanced oxidation process has been highly
investigated in this regard. Among many photoactive materials
2. Experimental
metal oxides have been widely studied for such purpose. SnO2
has been found to be one of the highly promising photocatalysts
2.1. Materials
with a band gap of 3.6 eV and a tetragonal n-type crystal structure
[10–13]. SnO2 has a key advantage over other materials such as
Guava leaves were collected from university campus garden.
TiO2 since it offers high electron mobility (100–200 cm2 V
1 s
1)
SnCl4 was purchased from Sigma Aldrich. Reactive Yellow 186
leading to faster photo generated electron transport [14]. There
dye (RY186) was obtained from a local textile industry. All the
are many methods for preparation of SnO2 nanoparticles (NPs)
solutions were prepared in deionized water.
[15,16] but bio-based green synthesis approach has gained consid-
erable interest [16]. Bio-based green synthesis methods using plant
extracts are considered eco-friendly, safe and cheap [17] but, only 2.2. Preparation of guava leaf extract

The as-collected guava leaves were first cleaned and washed to

⇑ Corresponding authors. remove dust particles and placed under sunlight. The dried leaves
E-mail addresses: mohitnano.nit@gmail.com (M. Rawat), soumen.basu@thapar.
were grinded and dissolved in 500 mL water with continuous stir-
edu (S. Basu). ring and heating at 60 °C for 4 hrs. The brownish extract was
1
Contribution of first and second author is equal. obtained by filtering the as-treated material using filter paper.

https://doi.org/10.1016/j.matlet.2017.12.074
0167-577X/Ó 2017 Elsevier B.V. All rights reserved.
122 M. Kumar et al. / Materials Letters 215 (2018) 121–124

Fig. 1. Schematic representation of SnO2 nanoparticles by Psidium Guajava leaf.

Fig. 2. (a) XRD Pattern, (b) FTIR spectra and (c) and (d) TEM images of SnO2 nanocrystallites.
 M. Kumar et al. / Materials Letters 215 (2018) 121–124 123

Fig. 3. (a) Time course study, (b) pseudo-first order fit of photocatalytic degradation of reactive yellow 186 dye by SnO2 nanoparticles, (c) reusability of SnO2 NPs and (d)
plausible mechanism of dye degradation.

2.3. Synthesis of SnO2 NPs 83.71° which are related to planes having miller indices (1 1 0),
(1 0 1), (2 0 0), (2 1 1), (2 2 0), (1 1 2), (3 0 1), (3 2 1) and (2 2 2)
About 2.1 M SnCl4 (Fig. 3) was added drop wise to guava leaf respectively corresponds to tetragonal rutile structure with lattice
extracts in the ratio 1:1 (w/w %) and stirred for 4 hrs at 60 °C. After parameters a = 4.739 Å and c = 3.186 Å (JCPDS File No. 41-1445).
4 hrs, the stirring was continued at room temperature until the The crystallite size was calculated using Debye-Scherrer equa-
mixture was transformed to jelly form which was then calcined tion [19],
at 400 °C for 4 hrs to obtain SnO2 NPs.
Kk
D¼
2.4. Photocatalytic activity of SnO2 NPs
b cos h

Where k is constant (0.9), k is the wavelength having value 1.540 Å

In a typical process, 10 mL (40 ppm) of RY186 dye was taken in
corresponding to Cu Ka source, h is the Bragg angle and b is full
a beaker. About 10 mg of as prepared SnO2 NPs was added to the
width of the half maxima. The crystallite size of as-prepared SnO2
dye solution and the reaction mixture was stirred in dark for
NPs was found to be 8.44 nm corresponding to (1 1 0) plane.
30 min to establish adsorption-desorption equilibrium. The reac-
The FTIR spectrum of SnO2 NPs (Fig. 2(b)) have the bands at
tion mixture was then irradiated by sunlight for 30, 60, 90, 120,
3742 cm
1, 3212 cm
1, 2888 cm
1, 1693 cm
1, 1647 cm
1, 1521
150 and 180 min respectively. The experiment was also carried
cm
1 and 663 cm
1. The band at 3212 cm
1 is attributed to OAH
out under sunlight on July 30, 2016 (Solar flux = 637 W/m2). After
bending of bound water molecules present on SnO2 surface. The
the reaction, the photocatalyst was separated from the solution by
strong band at 2888 cm
1 and 1640–1693 cm
1 is due to C–H
centrifugation and concentration of remaining dye was monitored
stretching and stretching of amide C@O bond. The band between
from UV-Visible spectrophotometer. Absorbance spectrum of
450 and 790 cm
1 are attributed to the anti-symmetric SnAOASn
RY186 was recorded after particular time interval by monitoring
stretching [18].
change in its absorption intensity at 425 nm.
FESEM images of SnO2 NPs (Fig. S2) show fine flaky structures
containing spherical NPs and their agglomerates. The presence of
3. Result and discussions 8–10 nm spherical NPs was further confirmed from TEM images
(Fig. 2c). Presence of few large NPs can also be observed may be
UV-Vis absorption spectrum of SnO2 NPs (Fig. S1) have an due to aggregation. The presence of only Sn and O atoms in EDS
absorption peak at 314 nm. The corresponding band gap energy spectra (Fig. S3) confirms the absence of other elemental impuri-
(Eg) has been calculated using the equation Eg = 1240/kg, where ties and formation of pure SnO2 phase.
kg wavelength corresponding to absorption peak of SnO2 and it As observed from control experiments that SnO2 is not able to
has been found to be 3.64 eV. The XRD pattern of SnO2 NPs degrade dye in dark neither dye degrades by irradiating it in the
(Fig. 2a) shows a number of diffraction peaks at 2h = 26.61, absence of SnO2. This clearly establishes the fact that both light
33.89, 37.95, 51.78, 54.75, 61.87, 64.71, 65.93, 71.27, 78.71 and and SnO2 are necessary for dye degradation. The dye degradation
124 M. Kumar et al. / Materials Letters 215 (2018) 121–124

process follows the pseudo-first order rate law ln(C/C0) =
kt, Appendix A. Supplementary data
where k and C0 are the rate constant and initial concentration at
time t = 0 respectively and C is the concentration at time t during Supplementary data associated with this article can be found, in
the reaction. The UV-visible spectra of RY186 dye representing the online version, at 10.1016/j.matlet.2017.12.074.
its degradation by SnO2 NPs (Fig. S4). SnO2 NPs degrade 90% of
dye within 180 min with a rate constant of 0.00465 min
1 as evi- References
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