Development of SnO2: Ag Nanoparticle as an Affordable Catalyst for the Degradation of Gentian Violet Dye

Abstract

An effective visible catalyst (SnO2:Ag) was successfully synthesized using co-precipitation method for the decomposition of the dye Gentian Violet (GV). In addition to XRD, SEM and UV – Visible analysis, a variety of other physicochemical measurements were used to validate the as-prepared SnO2:Ag nanoparticles. The phase identification of prepared sample is characterized by X – ray powder diffraction (XRD), which confirms the tetragonal rutile structure. The surface morphology is examined using a scanning electron microscope (SEM) and the optical absorption and the band gap value are calculated using the UV-visible spectrum. These results confirm the synthesis of nanoparticles by successive steps. A nanoparticles was demonstrated to be a superior catalyst for the degradation of GV dye when exposed to UV light. The photocatalytic activity studies are discussed using SnO2:Ag nanoparticles. The degradation efficiency of the nanoparticle is 96 % towards the degradation of the GV dye.

Introduction

I. INTRODUCTION

Now a day, the increase of industrial activities has intensified problems in environmental pollution and the deterioration of several ecosystems with the accumulation of pollutants, especially dyes. Effluents containing various dyes are discharged from various industrial processes. According to World Health Organization (WHO) the metals of the most immediate concern are effluents from various textile industries (cationic, anionic and neutral dyes), organic acids, heavy metals. Dyes may be found in wastewater discharges from the manufacture of pigments dyes and textile operations. The waste generated by the textile industry not only poses a threat to human health, but also poses a threat to the environment, so appropriate remedial technologies are needed [1–3]. In particular, organic dyes are highly stable and easily identifiable compounds in water, which can cause life-threatening problems. Therefore, various technologies such as adsorption, membrane filtration, chemical oxidation, biological digestion, electrochemical oxidation and advanced oxidation process (AOP) are widely used to remove organic pollutants in water. Compared with other methods, the AOP-based semiconductor photocatalytic decomposition process has been proven to be efficient and environmentally friendly. Among the most promising approaches, semiconductor-based photocatalysts have been recognized for their economic, environmentally friendly, and well-organized nature. In addition, semiconductor based photodegradation processes have attracted curiosity due to their harmlessness, effectiveness, and stability [[4, 5]. There are numerous metal oxide semiconductor materials in various shapes and structures that have proven effective in the degradation of organic dyes, including ZnO, TiO2, CuO, and MgO. Compared to TiO2, ZnO has a broad direct band gap (3.37 eV), high binding energy for excitation (60 meV), and excellent electrical, mechanical, and optical and photocatalytic properties. Ag doped with metal oxides can significantly improve the photocatalytic activity.

According to experimental calculations, SnO2 is significant n-type semiconductors with a broad energy band gap (3.6 eV) among the metal oxides (ZnO, TiO2, WO3, CeO3 and so on). It has a wide range of uses in gas sensors, optoelectronic devices, dye base solar cells, secondary lithium batteries, and catalysts due to its optical transparency in the visible area. The Sol-gel and microwave procedures, evaporative breakdown of solution [6], template-assisted growth [7], wet chemical synthesis [8], and gas-phase reaction [9, 10] are only a few of the many techniques used to create silver doped SnO2 nanoparticles. For the synthesis of silver doped SnO2 nanoparticles, we chose the chemical co-precipitation approach over the others because it allows us to easily regulate the structural and surface characteristics of the nanoparticles.

Transparent conducting oxides such as SnO2 have a great technological potential related to the ideal combination of electrical and optical properties. Since they have found many applications in technology, the SnO2-based systems are extensively studied. Particularly, for gas sensing materials the sensitivity is strongly dependent upon the crystallite size and shape, inasmuch as this property is influenced by the surface to volume ratio in SnO2:Ag systems [11].

A. Experimental Details

Synthesis of Ag doped SnO2

Nanoparticle samples of SnO2: Ag were prepared by Co-precipitation method. The starting    materials    are    Tin    Chloride SnCl2/AgCl2 and     Sodium     hydroxide (NaOH). We dissolved 1M of SnCl2in 100 ml   H2O   under   heating   and   continuous stirring   of   30 minutes.  Then, various concentrations (x=1 and 3%)  of silver nitrate [AgNO3] were used  for  preparing the doped samples. Then sodium hydroxide (0.5  mol)  was  dissolved  in  100 ml  of  distilled  water  and  added  drop  wise to the stirring solution of Tin chloride and the  mixture  was  stirred  using  magnetic Stirrer for 2  hours. The precipitate was filtered and annealed at 80° C. The dried sample was also calcined at 550° C.

II. RESULT AND DISCUSSSIONS

A. Structural Properties 

Pure and Ag doped SnO2 nanoparticles

Figure 1 revealed the crystal structure and phase of the SnO2 and SnO2:Ag were recorded by XRD analysis. The peaks at 2θ values at 26.1º, 33.2º, 37.4º and 51.2º can be associated with (110), (101), (200) and (211) respectively. Peaks can be ascribed to tetragonal rutile structure.

The above figures shows the SEM images of Ag doped SnO2 with different concentration of 1wt% and 3wt% respectively. The Pure SnO2 shows the tetragonal shape. This tetragonal shape is changed to spherical for various doping concentration of Ag (1 wt% and 3 wt%). This indicates that the Ag doping into SnO2 can change the surface character of the primary nanoparticles, which was deduced to be from the effects of the diffusion of Ag+ into the SnO2 lattice, and the formation of Ag-O-Sn bond on the surface of the doped samples were confirmed [15, 16].

D. Applications of Nanomaterials

Photocatalytic activity                             

It is important from mechanistic and application point of view to study the dependence of substrate concentration on the photocatalytic degradation rate. Photocatalytic activity studies confirmed that when increase the dose of the catalyst with increase the percentage of removal (%R) and Ag-doped nanoparticles enhanced the rate of degradation of Gentian Violet (GV) dyes. In the absence of catalyst, pure SnO2 which has the lower efficiency (0.1g in 58% and 0.5g in 65% removal of dye). In the presence of catalyst, Percentage removal of dyes increased with the increased with increase in contact time and dose of catalyst. Amount of dyes adsorbed increases with the decrease in particle size of catalyst. This results shows that the efficiency of catalyst increases upto 96.00 % for the removal of GV dye [17-21].

III. ACKNOWLEDGEMENTS

The authors thank the Management and Principal of ANJA College, Sivakasi, for providing facilities and encouragement. The authors also thank the TNSCST, Chennai, for financial assistance under Student Project scheme.

Conclusion

A novel SnO2 nanomaterial are well dispersed on Ag nanoparticle was demonstrated by a fruitful coprecipitation method. As prepared nanoparticle was characterized thoroughly by adopting various analytical techniques. This nanoparticle could be used as economically very feasible catalyst alternative to other commercially available catalyst for the cost effective treatment of effluents, especially for the removal of industrial dyes in general and Gentian Violet in particular using co-precipitation method. The XRD pattern of the Ag doped SnO2 nanoparticles were indexed to the tetragonal structure with average crystallite sizes in the range 45 -38 nm. The UV- Visible spectral studies concluded that the optical band gap of the Ag doped SnO2 were found to be 3.27 eV, 3.39 eV and 3.49eV. The SEM images revealed that the Pure SnO2 shows the tetragonal shape. This tetragonal shape is changed to spherical for various doping concentration of Ag. Photocatalytic activity studies confirmed that when increase the dose of the catalyst with increase the percentage of removal (%R) and Ag-doped nanoparticles enhanced the rate of degradation of dyes.

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Copyright

Copyright © 2023 A. Mubeenabanu, A. Bismibanu, T. Veemaraj. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.