Abstract

The present study demonstrates an intensive experimental work based on the tin oxide (SnO2) nanoparticle synthesis which was successfully carried out by a simple conventional precipitation method followed by calcination at 700 °C. The synthesized nanoparticles were characterized by X-ray powder diffraction (XRD), UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDAX). The XRD pattern proves that tetragonal rutile structure SnO2 nanoparticles were formed. The crystallite particle size calculation from Scherer's equation revealed the average size of 28.5 nm. The absorption spectrum of SnO2 nanoparticles showed absorption band at about 290 nm and the band gap energy (Eg) from Tauc plot was obtained at 3.8 eV. The photocatalytic degradation of pharmaceutical compound, 4-aminopyridine (5 ppm) using synthesized SnO2 nanoparticle, was assessed. The effect of variable catalyst dosage, pH and irradiation sources, were studied. The optimum catalyst dosage and pH were found to be 1.5 gm/L and 6.5, respectively. The degradation efficiency of water contaminant 4-aminopyridine under UV light and solar light irradiation for 120 min were found to be 97% and 11%, respectively. The reusability of the catalyst was checked and has been found stable after three photocatalytic runs.

INTRODUCTION

Pharmaceutical, textile and chemical industries being the cradle of all scientific and technical progress imparts majorly for the advancement of human society. However, these chemicals, when they find their way to the aqueous environment, results in severe environmental pollution that negatively effects the entire ecosystem. To get rid of these toxic effluents, biodegradation was used traditionally. The cost-effectiveness and low efficacy are the major disadvantages of the biodegradation process (Li et al. 2018). In the field of wastewater treatment, employment of nanostructured materials has fascinated the researchers due to its outstanding physico-chemical properties (An et al. 2005; Ali et al. 2010; Al-Hamdi et al. 2015) which are dissimilar from the bulk state (Bagheri-Mohagheghi et al. 2008).

The most widely used metal oxides such as zinc oxide (ZnO) and titanium dioxide (TiO2) with wide band gap semiconductors are used currently in the decontamination of wastewater. Quite a number of previously published works were centered on TiO2 and ZnO for degradation of organics. Many researchers reported that TiO2, ZnO and tin dioxide (SnO2) are the most active catalysts for the degradation of dyes, phenols and pesticides (Al-Hamdi et al. 2015).

In this regard, there are few literature reports showing the study of tin oxide (SnO2) of rutile-type crystal structure making it a topic of immense interest for the researchers. SnO2 is a typical n-type semiconductor with a wide band gap of about 3.6 eV (Viet et al. 2016). This low cost material shows high electron mobility excellent optical, gas-sensing properties and chemical stability (Hu et al. 2017) which was widely used in sensors (Tripathy et al. 2013), solar cells (Hara et al. 2011; Chen et al. 2012) and lithium ion batteries (Lin et al. 2012). However, for the degradation of organic pollutants, water splitting and hydrogen production, SnO2 has proved to be an excellent photocatalyst (Prakasha et al. 2016). SnO2 is poorly absorbed by the human body when injected or inhaled (Kim et al. 2016). So it has no adverse health impacts on the human body. Thus, it can be stated that SnO2 is an ideal photocatalyst to work with. Few literature reports the use of pure SnO2 nanoparticle in the photocatalysis (Singh & Nakat 2013).

Various synthetic methods are there for preparing SnO2 nanoparticles which includes sono-chemical method (Yu et al. 2011), sol-gel (Lin et al. 2008), two-step solid state reaction (Li et al. 2002) and spray pyrolysis (Begum et al. 2016b). Precipitation method is simple, inexpensive and does not require high temperature and pressure. A huge amount of photocatalyst could be synthesized without using many reagents. Impurities in the precipitate can easily be eliminated by filtration and repeated washing (Patil et al. 2012; Pan et al. 2014; Nadaf & Venkatesh 2016).

Different research groups have synthesized SnO2 nanoparticles and studied their applicative perspectives towards reduction and photo degradation of aromatic compounds (Begum et al. 2016a), photo degradation of methyl violet 6B dye and reduction of p-nitrophenol to p-aminophenol (Bhattacharjee et al. 2015), photocatalytic activity in methylene blue degradation (Kim et al. 2016), photocatalytic removal of NO gas (Huy et al. 2018) and degradation of carbamazepine from aqueous phase (Begum & Ahmaruzzaman 2018), etc.

4-Aminopyridine (4-AP) showed agricultural use as Avitrol and is used for repelling and killing bird pests (Takenaka et al. 2013). 4-AP is used by people with multiple sclerosis (Kenneth et al. 2000). In the laboratory of physics and biophysics, it is used in the pharmacology of various potassium conductances. But overdoses with 4-AP can lead to parenthesis, seizure and some common side effects like kidney or bladder infections, headache, nausea, weakness and back pain. The discharge of this toxic chemical as industrial effluent, agricultural, laboratory and hospital wastes contaminates the water sources. Although low in concentration, a continuous release of 4-AP, a highly stable chemical, to the aquatic environment can lead to undesirable effects causing harm to aquatic life and human health (Ljubas et al. 2018).

In the past few decades, advanced oxidation processes (AOPs) including semiconductor powders as photocatalysts have been engaged to treat a variety of industrial wastewaters carrying a number of products such as dyes, plastics, resin, pharmaceuticals, pesticides, etc. (ChangSong et al. 2000; Taib & Sorrell 2007; Saleh & Gupta 2012). Recently, researchers have focused their attention to apply semiconductor nanomaterials for the degradation of these water contaminating industrial wastes under the irradiation of UV light, visible light or even under solar light (Regmi et al. 2018).

Previous study reports that Fenton and photo-Fenton degradation process has been applied for removal of 3-aminopyridine (Karale et al. 2014). There is only a report demonstrating degradation of 4-AP using bulk ZnO photocatalyst (Chakraborty et al. 2017).

To the best of our knowledge, there are no previous reports focused on the photocatalytic application of synthesized SnO2 nanoparticle towards the degradation of 4-AP under UV irradiation and solar light irradiation separately.

EXPERIMENTAL

Materials

Analytical reagent (AR) grade chemicals such as tin dichloride dihydrate (SnCl2.2H2O) and ammonia (Merck, India), were used for synthesis of SnO2 nanoparticles without any further purification. 4-AP of 99.9% purity was purchased from Sigma Aldrich, India. The double distilled water was used as a solvent during the reaction process.

Synthesis of SnO2 nano-powders

In the typical synthesis process, at first 2 g (0.1 M) stannous chloride dihydrate (SnCl2.2H2O) was dissolved in 100 mL water, when the pH of the solution was found to be acidic (pH = 3). Complete dissolution was followed by addition of 4 mL ammonia solution to the above aqueous solution with magnetic stirring. Nonstop stirring was continued for 20 min. Immediately, white gel precipitate was formed. It was allowed to settle for 12 h. Then it was filtered and washed with water 2–3 times by using deionized water. The obtained precipitate was mixed with 0.27 g carbon black powder (charcoal activated). The obtained mixer was kept in vacuum oven at 70 °C for 24 h so that the mixer turns completely in to dried powder. Then this dry product was crushed into a fine powder by grinder. Now the obtained product of fine nano-powder of SnO2 was calcinated at 700 °C up to 6 h in the auto controlled muffle furnace (Gayatri Scientific, Mumbai, India) so that the impurities from the product were completely removed.

Particle characterization

Optical absorption spectrum was recorded in a double beam spectrophotometer. To study the surface morphology of the prepared SnO2 nanoparticle, field emission scanning electron microscopy (FESEM) was carried out. The crystalline phase was analyzed by X-ray powder diffraction (XRD) using Pan Analytical Expert Pro Diffractometer with copper k a radiation and a graphite monochromator to produce X-rays of wavelength 1.54 A. Diffractogram of powders were recorded in 2Ө scan configuration, in the 20–80 °C 2Ө range. Infrared spectrum was recorded in the wave number range from 500 to 4,000 cm−1 by Bruker Hyperion 3,000 Fourier transform infrared (FTIR) spectrometer.

Photocatalytic experiment

The photocatalysis of the synthesized SnO2 nanoparticle observed under UV and direct sunlight was investigated by the degradation of 4-AP (5 ppm) compound analyzed spectrophotometrically at room temperature. The degradation was carried out for 2 h. For the UV irradiation, the above method was followed but a photo-reactor was designed for the UV photocatalytic activity. The reactions were conducted in a batch process in a cylindrical photo reactor with a total volume of 1.0 L (diameter 12 cm and height 13.3 cm). The catalyst (SnO2 nanoparticle) was added to the reactor containing the sample. To house UV light (λ = 240 nm) source, the unit was set up with an annular cylindrical glass reactor consisting of a quartz tube at the center and a jacket was provided for cooling purpose. A continuous circulation of cooling media (water) was provided. The reactor was provided with inlets for intake of reactants, and outlets for collecting samples. The reactor was open to air with a magnetic stirring bar placed in the bottom for homogenization. The reactor was covered with a wooden box to prevent the exposure of UV light. Samples were periodically withdrawn for recording the absorbance of the selected compound (4-AP).

The degradation of 4-AP solution was resulted by the photocatalytic activities of synthesized SnO2 nanoparticle. The experiments of photocatalysis were done under solar light during summer days in the month of May, in NIT Durgapur campus between 12:00 pm and 3:00 pm (atmospheric temperature 33–40 °C). Before irradiation, 500 mL aqueous solution of 4-AP (5 ppm) containing different dosage of catalyst (0.5–2 g/L) was taken in a beaker and subjected to continuous stirring in the dark for 30 min. At specified pre-selected time intervals, some aliquot of solution was taken from the solution and filtered by GF/C (25 mm) filter paper for determining the concentration, absorbance peak of 4-AP was observed at wavelength 261.5 nm using UV-Vis spectrophotometer (Shimadzu UV-1601). A standard absorbance verses 4-AP concentration calibration curve was prepared by single wavelength mode (261.5 nm) using 4-AP standard. This curve was used to determine residual 4-AP concentrations in aqueous solution at different time intervals during the photocatalytic treatment. The percentage degradation of 4-AP was calculated according to the following equation: 
formula
(1)
where C0 is the initial 4-AP concentration and Ct is the 4-AP concentration after photocatalytic irradiation of t minutes.

RESULTS AND DISCUSSION

XRD pattern

XRD analysis was performed to determine the size and structural properties of the synthesized SnO2 nanoparticle. Structural identification of SnO2 nanoparticle was carried out with X-ray diffraction in the range of angle 2 theta between 20 °C and 80 °C. Figure 1 shows the XRD pattern of synthesized SnO2 nanoparticle formed at 700 °C which was crystalline in nature. XRD pattern showed peak at 2Ө values of 26.8 °C, 34.1 °C, 39.2 °C, 52.05 °C, 54.9 °C, 58.2 °C, 62.04 °C, 65 °C and 66.16 °C which corresponded to the (110), (101), (200), (211), (220), (002), (310), (112) and (301) planes respectively. The obtained peaks coincided well with previous similar observations of tetragonal rutile structure of SnO2 nanoparticle (JCPDS 41-1445) [35].

Figure 1

XRD pattern synthesized SnO2 nanoparticle at 700 °C.

Figure 1

XRD pattern synthesized SnO2 nanoparticle at 700 °C.

Using Debye-Scherer's formula, the average size of the crystallite SnO2 nanoparticle can be calculated by the equation as follows: 
formula
(2)
where the λ, the X-ray wavelength, β, the full width at half maximum of the diffraction peak (fwhm) and Ө, the Bragg diffraction angle. The average crystalline size of SnO2 nanoparticles formed at 700 °C was calculated from the above equation and found to be 28.4 nm.

UV-Visible spectrophotometric analysis

The synthesized SnO2 nanoparticle showing UV-Vis spectrum has been depicted in Figure 2. The figure shows that the absorption onset of SnO2 nanoparticle was about 290 nm at 700 °C calcination temperature.

Figure 2

(a) UV–Vis absorption spectrum of SnO2 nanoparticles and (b) plot of (αhv)2 vs incident photon energy (hv) for the synthesized SnO2 nanoparticle.

Figure 2

(a) UV–Vis absorption spectrum of SnO2 nanoparticles and (b) plot of (αhv)2 vs incident photon energy (hv) for the synthesized SnO2 nanoparticle.

The Tauc plot was conducted to obtain the band gap energy (Eg) of semiconductor SnO2 nanoparticles which was found to be 3.8 eV by calculating the absorption spectra. To show the relationship between the absorption co-efficient and incident photon energy, the following equation has been used: 
formula
(3)
where hυ was the incident photon energy, K, the constant, Eg, the band gap energy, α (υ), the absorption co-efficient which can be defined by the Beer-Lambert's law.

FESEM

The morphology and particle size of the prepared SnO2 sample was determined by FESEM analysis as shown in Figure 3(a). The figure shows the FESEM picture of SnO2 nanoparticles synthesized by using aqueous-phase method via conventional precipitation. It was observed from micrographs, particles were found to be spherical in shape and the maximum particle size distribution found in the range about 25–50 nm from Figure 3(b). The average particle size observed in both FESEM and XRD measurement was found to be nearly equal. The composition of the powders was confirmed by EDAX analysis from Figure 3(c).

Figure 3

(a) FESEM picture of the SnO2 nanoparticle. (b) Particle size distribution of SnO2 nanoparticles. (c) The composition of SnO2 nanoparticles by EDAX analysis.

Figure 3

(a) FESEM picture of the SnO2 nanoparticle. (b) Particle size distribution of SnO2 nanoparticles. (c) The composition of SnO2 nanoparticles by EDAX analysis.

FTIR

The idea of the chemical composition can be obtained from the FTIR spectra. Figure 4 has given the FTIR spectrum of SnO2 nanoparticle. The bands acquired at around 554 cm−1 and 618 cm−1 were recognized as the Sn-O stretching modes of Sn-OH and Sn-O-Sn, respectively. The bands at around 1,630 cm−1 and 3,410 cm−1 were due to the bending vibrations of absorbed water molecule on the SnO2 nanoparticle and the stretching vibrations of –OH, respectively. These bands were generally due to the moisture acquired during sample preparation.

Figure 4

FTIR spectra of synthesized SnO2 nanoparticle.

Figure 4

FTIR spectra of synthesized SnO2 nanoparticle.

Formation mechanism of SnO2 nanoparticle

The two forms of ammonia present in water are ammonium hydroxide (NH3) or as the ammonium ion (NH4+). Ammonia is present as ammonium ion when pH of the water is less than 7.

It should be noted that when SnCl2.5H2O was dissolved in water, the pH of the medium became acidic (pH = 3). On addition of ammonia to this solution, a milky white precipitate was formed. Ammonia played a pH adjusting role due to the formation of hydroxyl ion. The formed hydroxyl ion led to the formation of Sn(OH)3 complex followed by the precipitation of Sn(OH)2. This precipitate on annealing at 700 °C decomposed to produce SnO2 nanoparticles.

For SnO2 nanoparticles synthesis, the probable chemical reactions involved are as follows: 
formula
 
formula
 
formula
 
formula
 
formula

Photocatalytic degradation of 4-aminopyridine

The degradation of toxic 4-AP water solution (5 ppm) using synthesized SnO2 nanoparticle was studied. The catalyst dosage and the pH were fixed at 1.5 gm/L and 6.5, respectively. In this case, UV light and direct sunlight was used as irradiation sources, separately as shown in Figure 5(i). As the illumination time increased, the degradation of 4-AP has also increased under UV light and solar irradiation both. The figure depicts the degradation rate under UV radiation was 33%, 76%, 92%, 97% and 3%, 5%, 8%, and 11% under direct sunlight.

Figure 5

(i) Photocatalytic degradation of 4-AP under UV and solar light separately, (ii) the possible mechanism for photodegradation of 4-AP, (iii) degradation of 4-AP by SnO2 photocatalyst at varied pH, (iv) degradation of 4-AP by different dosages of SnO2 under UV radiation.

Figure 5

(i) Photocatalytic degradation of 4-AP under UV and solar light separately, (ii) the possible mechanism for photodegradation of 4-AP, (iii) degradation of 4-AP by SnO2 photocatalyst at varied pH, (iv) degradation of 4-AP by different dosages of SnO2 under UV radiation.

In the solar spectrum, only 4% of UV light is present. Thus, it can be said that as the amount of UV light is very less, few upon it was absorbed for degradation. For this reason, the degradation was much lower under solar irradiation than that of UV irradiation. So, experiment under UV irradiation has been continued further but neglected under solar light.

The possible mechanism for photodegradation of 4-AP can be explained from Figure 5(ii). SnO2 photocatalyst was excited when light with greater energy than the band gap energy was irradiated resulted in the formation of hole-electron pair in the valence band (VB) and conduction band (CB) of SnO2 nanoparticle. Consequently, hole (h+) may react with H2O adsorbed on the surface of SnO2 to form hydroxyl radicals (°OH). In the VB, photo-oxidation occurred where the holes are trapped by water molecules to form °OH. At the same time, photo-reduction also occurred where the electrons in the CB of the SnO2 semiconductor react with dissolved molecular oxygen present in water to produce superoxide radical anion O2°. This O2° reacted with H2O to furnish °OH and HOO° having powerful oxidizing ability. The °OH is the strong oxidizing agent which helped in the degradation of the organic compound, 4-AP (Begum et al. 2016a).

The physico-chemical factors (like pH of the medium and catalyst dosage) that influences photocatalytic degradation has been discussed below.

Change in pH

It is believed that pH plays a key role in the photocatalytic degradation of 4-AP using SnO2 photocatalyst. The effect of variable pH has been shown in Figure 5(iii). The study was performed using SnO2 dosage of 1.5 gm/L under UV light irradiation. The figure depicts catalytic degradation of 4-AP by SnO2 at pH 3 (acidic), 6.5 (neutral) and 10 (basic) medium by adjusting the pH with the help of 0.1 M HCl or 0.1 M NaOH. The removal efficiency of 4-AP by SnO2 was 99% at basic, 98% at neutral and 81% at acidic medium. The above results revealed that the degradation of SnO2 in acidic pH was appreciably lower than that in the neutral as well as in the alkaline medium, which showed almost similar removal efficiency. So the degradation study had been done at neutral pH.

The influence of pH on degradation rates of 4-AP can be explained by the electrical double-layer of a solid electrolyte interface (Soltani et al. 2012). Under acidic condition the SnO2 nanoparticle surface as well as 4-AP molecules were protonated (Uddin et al. 2016). Hence protonated SnO2 surface hinders the adsorption of cationic 4-AP, thus explaining the lower removal efficiency in acidic pH.

Effect of catalyst dosage

To study the effect of catalyst on degradation efficiency, the SnO2 nanoparticle with different dosage ranges from (0.5–2) gm/L was added to the 5 ppm 4-AP solution and kept under ultra-violet radiation. Figure 5(iv) shows the photocatalytic activity of SnO2 under UV light illumination condition. The performance of the photocatalytic degradation depended immensely on the variation of catalyst loading. The degradation efficiency under catalyst dosage 0.5 gm/L, 1 gm/L, 1.5 gm/L and 2 gm/L were found to be 88, 95, 97 and 99, respectively. Up to 60 min, degradation had shown a sharp increase but after 60 min of degradation, the efficiency found to become stable. The optimum catalyst dosage was 1.0 gm/L.

This phenomenon could be explained as the low dosage of catalyst leads to the less absorption of photons by SnO2 thereby little utilization for the photocatalytic activity. When the catalyst loading increases, the photon absorbed also increases followed by the increase in active centers on the surface of the catalyst (Hao & Jiaqiang 2010). Thus, the degradation efficiency also increased with catalyst loading.

A comparison between the present study and the previous study has been shown in Table 1. The SnO2 nanoparticle had shown its high degradation efficiency under the UV radiation.

Table 1

Comparison of photocatalytic degradation of targeted compound by SnO2 nanoparticles

Catalysts (shape and particle size)Light sourceTarget compound (initial conc.)% degradationIrradiation time (mins)Catalyst dosage (g/L)Reference
SnO2 NPs (∼3 nm) 7 W UV lamp, visible light λ = 350 nm
Direct sunlight 
MB, 10 mg/L 90.0 120 0.5 Viet et al. (2016)  
SnO2 NPs (15–40 nm) Low pressure 125 W UV lamp, visible light λ = 254 nm MB, 20 mg/L 93.3 120 2.0 Srivastava & Mukhopadhyay (2014)  
SnO2 NPs (∼4 nm) UV lamp, λ = 365 nm lamp power not determined)

 
Phenol red, 1 mL,
10−4
100 120 250 Elango et al. (2015)  
Microspherical (0.4–1.8 μm diameter) Four 8 W UV lamps (Philips UV-A, λ = 350 nm) Aniline, (20 mg/L)
4-Nitroaniline, (20 mg/L)
2,4-Dinitroaniline (20 mg/L) 
80
70
50 
120 10 Talebian & Jafarinezhad (2013)  
Spherical SnO2 quantum dots (∼2.5–4.5 nm) Direct sunlight Rhodamine B (10−4 M)
MB (10−4 M) 
83.9
56.8 
420
360 
0.05 Bhattacharjee et al. (2014)  
SnO2 NPs (∼25–50 nm) UV lamp, λ = 240 nm 4-Aminopyridine, 5 mg/L 97 120 1.5 This work 
SnO2 NPs (∼25–50 nm) Direct sunlight 4-Aminopyridine, 5 mg/L 11 120 1.5 This work 
Catalysts (shape and particle size)Light sourceTarget compound (initial conc.)% degradationIrradiation time (mins)Catalyst dosage (g/L)Reference
SnO2 NPs (∼3 nm) 7 W UV lamp, visible light λ = 350 nm
Direct sunlight 
MB, 10 mg/L 90.0 120 0.5 Viet et al. (2016)  
SnO2 NPs (15–40 nm) Low pressure 125 W UV lamp, visible light λ = 254 nm MB, 20 mg/L 93.3 120 2.0 Srivastava & Mukhopadhyay (2014)  
SnO2 NPs (∼4 nm) UV lamp, λ = 365 nm lamp power not determined)

 
Phenol red, 1 mL,
10−4
100 120 250 Elango et al. (2015)  
Microspherical (0.4–1.8 μm diameter) Four 8 W UV lamps (Philips UV-A, λ = 350 nm) Aniline, (20 mg/L)
4-Nitroaniline, (20 mg/L)
2,4-Dinitroaniline (20 mg/L) 
80
70
50 
120 10 Talebian & Jafarinezhad (2013)  
Spherical SnO2 quantum dots (∼2.5–4.5 nm) Direct sunlight Rhodamine B (10−4 M)
MB (10−4 M) 
83.9
56.8 
420
360 
0.05 Bhattacharjee et al. (2014)  
SnO2 NPs (∼25–50 nm) UV lamp, λ = 240 nm 4-Aminopyridine, 5 mg/L 97 120 1.5 This work 
SnO2 NPs (∼25–50 nm) Direct sunlight 4-Aminopyridine, 5 mg/L 11 120 1.5 This work 

Reusability of the catalyst

Recycling and stability performance had been studied for SnO2 photocatalyst. The recycling performance of catalytic efficiency was checked for three cycles (Figure 6(i)). The experimental conditions, i.e. initial concentration of pollutant solution was 5 ppm, catalyst dosage, 1.0 g/L and pH was neutral. The synthesized SnO2 nanoparticle showed almost same degradation performance in three consecutive runs.

Figure 6

(i) Bar plot representing the degradation efficiency, (ii) XRD, (iii) FTIR, (iv) FESEM of SnO2 after photocatalytic degradation of 4-AP in three consecutive cycles.

Figure 6

(i) Bar plot representing the degradation efficiency, (ii) XRD, (iii) FTIR, (iv) FESEM of SnO2 after photocatalytic degradation of 4-AP in three consecutive cycles.

To check the stability of the synthesized SnO2 photocatalyst after degradation of 4-AP in three consecutive cycles, the photocatalyst was characterized by XRD (Figure 6(ii)), FTIR (Figure 6(iii)) and FESEM (Figure 6(iv)). The figure demonstrats that there was no such change as compared to synthesized fresh SnO2 nanoparticles.

CONCLUSION

In this paper, we developed a simple chemical precipitation method for synthesizing SnO2 nanoparticles. The XRD pattern proved the tetragonal rutile structure of SnO2 nanoparticles. The formation of spherical shape was evident from the FESEM images and XRD pattern. The maximum particle size distribution found in the range about 25–50 nm. The band gap energy of SnO2 nanoparticles was obtained at 3.8 eV. The degradation efficiency of water contaminant 4-AP under UV light and solar light irradiation for 120 min were found to be 97% and 11%, respectively. These SnO2 nanoparticles were also found to be stable photocatalysts after photocatalytic degradation. The reusability of the catalyst was checked and has been found stable after three photocatalytic runs.

ACKNOWLEDGEMENT

We, the authors, express our heartfelt thanks and gratitude to the Director, NIT Durgapur for providing laboratory facilities with reagents and instrumentation. Our special thanks to the department of MME for providing FESEM, XRD data and the Department of Chemistry for FTIR, spectrophotometric data. The financial support from the Department of Science and Technology under the SERB (N-PDF) sponsored project (No. PDF/2017/000390), Government of India, is gratefully acknowledged.

CONFLICT OF INTEREST

The authors declare that they have no conflict of interest.

REFERENCES

REFERENCES
Ali
R.
Abu Bakar
W. A. W.
Mislan
S. S.
Sharifuddin
M. A.
2010
Photodegradation of n-methyldiethanolamine over ZnO/SnO2 coupled photocatalysts
.
Transactions C: Chemistry & Chemical Engineering
17
(
2
),
24
130
.
Bhattacharjee
A.
Ahmaruzzaman
M.
Sinha
T.
2015
A novel approach for the synthesis of SnO nanoparticles and its application as a catalyst in the reduction and photodegradation of organic compounds
.
Spectrochimica Acta Part A, Molecular & Biomolecular Spectroscopy
136
,
751
760
.
Chakraborty
S.
Dutta
S.
Saha
R.
Moi
S. C.
Sukul
D.
Panja
S. S.
2017
Efficacy of a photo-catalyst towards the degradation of a pharmaceutical compound, 4-aminopyridine by application of response surface methodology
.
Desalination & Water Treatment
76
,
389
397
.
Elango
G.
Kumaran
S. M.
Kumar
S. S.
Muthuraja
S.
Roopan
S. M.
2015
Green synthesis of SnO2 nanoparticles and its photocatalytic activity of phenolsulfonphthalein dye
.
Spectrochimica Acta Part A: Molecular & Biomolecular Spectroscopy
145
,
176
180
.
Hao
Y.
Jiaqiang
X.
2010
Preparation, characterization and photocatalytic activity of nanometer SnO2
.
International Journal of Chemical Engineering & Applications
1
(
3
),
241
246
.
Hara
K.
Zhao
Z. G.
Cui
Y.
Miyauchi
M.
Miyashita
M.
Mori
S.
2011
Nanocrystalline electrodes based on nanoporous-walled WO3 nanotubes for organic-dye-sensitized
.
American Chemical Society
27
,
12730
12736
.
Huy
T. H.
Phat
B. D.
Thi
C. M.
Viet
P. V.
2018
High photocatalytic removal of NO gas over SnO2 nanoparticles under solar light
.
Environmental Chemistry Letters
17
,
527
531
.
Kim
S. P.
Choi
M. Y.
Choi
H. C.
2016
Photocatalytic activity of SnO2 nanoparticles in methylene blue degradation
.
Material Research Bulletin
74
,
85
89
.
Li
F.
Chen
L.
Chen
Z.
Xu
J.
Zhu
J.
Xin
X.
2002
Two-step solid-state synthesis of tin oxide and its gas-sensing property
.
Materials Chemistry & Physics
73
(
2
),
335
338
.
Lin
C. F.
Wu
C. H.
Onn
Z. N.
2008
Degradation of 4-chlorophenol in TiO2, WO3, SnO2, TiO2/WO3 and TiO2/SnO2 systems
.
Journal of Hazardous Materials
15
,
1033
1039
.
Lin
Y. M.
Nagarale
R. K.
Klavetter
K. C.
Heller
A.
Mullins
C. B.
2012
SnO2 and TiO2-supported-SnO2 lithium battery anodes with improved electrochemical performance
.
Journal of Material Chemistry
22
,
11134
11139
.
Ljubas
D.
Cizmic
M.
Vrbat
K.
Stipanicev
D.
Repec
S.
Curkovic
L.
Babic
S.
2018
Albendazole degradation possibilities by UV-based advanced oxidation processes
.
International Journal of Photoenergy
. Article ID 6181747.
Nadaf
L. I.
Venkatesh
K. S.
2016
Synthesis and characterization of Tin oxide nanoparticles by Co-precipitation method
.
IOSR Journal of Applied Chemistry
9
,
01
04
.
Patil
G. E.
Kajale
D. D.
Gaikwad
V. B.
Jain
G. H.
2012
Preparation and characterization of SnO2 nanoparticles by hydrothermal route
.
International Nano Letters
2
,
17
.
Prakasha
K.
Senthil
K. P.
Pandiarajb
S.
Saravanakumara
K.
Karuthapandian
S.
2016
Controllable synthesis of SnO2 photocatalyst with superior photocatalytic activity for the degradation of methylene blue dye solution
.
Journal of Experimental NanoScience
11
(
14
),
113
1155
.
Regmi
C.
Joshi
B.
Ray
S. K.
Gyawali
G.
Pandey
R. P.
2018
Understanding mechanism of photocatalytic microbial decontamination of environmental wastewater
.
Frontiers in Chemistry
6
,
33
.
Saleh
T. A.
Gupta
V. K.
2012
Column with CNT/magnesium oxide composite for lead (II) removal from water
.
Environmental Science & Pollution Research
19
,
1224
1228
.
Soltani
N.
Saion
E.
Hussein
M. Z.
Erfani
M.
Abedini
A.
Bahmanrokh
G.
Navasery
M.
Vaziri
P.
2012
Visible light-induced degradation of methylene blue in the presence of photocatalytic ZnS and CdS nanoparticles
.
International Journal of Molecular Science
13
,
12242
12258
.
Srivastava
N.
Mukhopadhyay
M.
2014
Biosynthesis of SnO2 nanoparticles using bacterium Erwinia herbicola and their photocatalytic activity for degradation of dyes
.
Industrial & Engineering Chemical Research
53
(
36
),
13971
13979
.
Taib
H.
Sorrell
C. C.
2007
Preparation of tin oxide
.
Journal of the Australian Ceramic Society
43
,
56
61
.
Tripathy
S. K.
Mishra
A.
Jha
S. K.
Wahab
R.
Al-Khedhairy
A. A.
2013
Microwave assisted hydrothermal synthesis of mesoporous SnO2 nanoparticles for ethanol sensing and degradation
.
Journal of Materials Science: Materials Electronics
24
,
2082
2090
.
Viet
P. V.
Thi
C.
Hieu
L. V.
2016
The high photocatalytic activity of SnO2 nanoparticles synthesized by hydrothermal method
.
Journal of Nanomaterials
8
, Article ID 4231046.