Different Methods, Sol-Gel and Autoclave, Applied on the Ceramic Materials to Obtain Better Photo Catalysis

Dikra Bouras^1*, Regis Barillé² and Abla Mecif^1
*Correspondence: Dikra Bouras, Laboratory of Active Components and Materials, Larbi Ben M’Hidi University, Oum El-Bouaghi 04000, Algeria, Email:

Keywords

Ceramic • Autoclave • Sol-Gel • Cu:ZnO • Degradation rates.

Introduction

In recent years, the world has experienced a large population growth and a number of huge modern industries. These factors contributed significantly to increasing the percentage of waste disposed of each day. Most of this waste, one way or another, begins or ends in the valleys and rivers which leads to a terrible increased pollution. To remedy this, we resorted to ceramic as a raw material for the purification of water [1,2]. The choice of this raw material was motivated by the fact that the ceramic is available significantly in nature and Algeria in particular. The zone of Jebel Debbagh, located in Guelma east of Algeria, is among the richest areas in kaolinitic clay of different types. For our study, we chose one of the types of the named DD3 kaolinitic clay.

Numerous studies were discussed regarding the purification using the most popular material which is zinc oxide by adding several elements to increase the degree of improvement [3,4], but in our work we made the reverse. A content of 38% ZrO₂ is added to DD3 kaolinitic clay and treated at 1300°C for 2h. This step is performed for only a composite of mullite and zircon with a rate of suitable porosity (33%) [5,6].

The copper and zinc are two oxides may improve the properties of the catalyst, non-toxic, semiconductors and give it a good morphology; what has been shown in several applications [7-10].

Materials and Methods

Preparation of solution

The synthesis of ZnO is obtained from zinc acetate dihydrate of molar mass 219.49 g/mol. 3.51 g of the latter was dissolved in 40 ml of absolute ethanol to obtain a solution with a molar concentration of 0.4 mol/l. For the Cu doping, 0.21 g (corresponding to wt 6%) of copper acetate (molar mass 181.63 g/mol) are added to the same solution prepared above. 2 ml of MEA catalyst was added to each solution to stabilize it and the resulting product was mixed with a magnetic stirrer for 2 hours at a temperature of 60ºC.

X-Ray diffraction

The structural analysis of the ceramic substrates obtained from DD3+ZrO₂ with active thin layers are carried out by XRD. The patterns recorded on all the samples are shown in Figure 1. From this figure, we show that the obtained results are the essential phases of ceramics: Mullite (JCPDS 15–0776), cristobalite (JCPDS 01–0424) for DD3-clay based substrates and Zircon (JCPDS 06–0266) and Zirconia (JCPDS 37–1484) for DD3 +ZrO₂-clay based substrates. For Sol-gel method the CuO peaks are masked by those more intense of zircon (Figure 1A). The characterization by X-ray diffraction when the thin film has been deposited by Autoclave method shows the most intense peaks corresponding to zinc and copper oxide phases (Figure 1B).

Scanning Electron Microscopy

Figure 2 displays the SEM images of Cu doped ZnO thin films grown on the DD3+ZrO₂ substrates. These images confirm the morphology differences between the two methods application. For the substrate deposed with Sol-gel method the flower-like growth dominates and the roughness is more important, offering a wider active surface area (Figure 2A). Whereas for the substrate deposed with Autoclave method has almost a spherical shape and covers the surfaces of ceramics (Figure 2B).

Photocatalytic performance

This study is carried out by analyzing the degradation of OII, obtained from the absorbance spectra evolution shown in Figure 3. These spectra are typical of those of aqueous solutions of OII, with a maximum absorbance at 484 nm. When Cu:ZnO is deposited on the latter substrates DD3+38% ZrO₂, the photocatalytic effect appears clearly (Figures 3A-3C). The degradation rate increases to 80.06% for the 7 hours exposure time (Figure 3B) with Sol-gel method. After the same time of UV exposure and the same substrates, 90.5% degradation of OII was obtained for Autoclave method (Figure 3C).

Discussion and Conclusions

The objective of this work is the study of the effect of different preparation methods on the photocatalytic activity of Orange II (O-II) under UV-visible:

• The shape of the sample surface is influenced by the doping.

• The addition of 6% Cu doped ZnO layer on the ceramic substrates increases the surface energy which results the formation of flowerslike by sol-gel method and spherical-like particles by Autoclave method.

• The absorption of the samples prepared by "Autoclave" is much better than those prepared by "Sol-gel".

References

1. Seabra MP, RR Pires and JA Labrincha. "Ceramic tiles for photodegradation of Orange II solutions." Chem Eng J. 171(2011): 692-702.
2. Marto J, P São Marcos, T Trindade and JA Labrincha, et al. "Photocatalytic decolouration of Orange II by ZnO active layers screen-printed on ceramic tiles." J Hazard Mater. 163(2009): 36-42.
3. Ma Jianfeng, Kai Wang, Liangyin Li and Tianli Zhang, et al. "Visible-light photocatalytic decolorization of Orange II on Cu2O/ZnO nanocomposites." Ceram Int. 41(2015): 2050-2056.
4. Siuleiman Shahin, Nina Kaneva, Assya Bojinova and Karolina Papazova, et al. "Photodegradation of Orange II by ZnO and TiO2 powders and nanowire ZnO and ZnO/TiO2 thin films." Colloids Surf A Physicochem Eng Asp 460(2014): 408-413.
5. Bouras D, A Mecif, A Mahdjoub and A Harabi, et al. "Photocatalytic degradation of orange II by active layers of cu-doped ZnO deposited on porous ceramic Substrates." J Ovonic Res. 13(2017): 271-281.
6. Bouras D, A Mecif, R Barillé and A Harabi, et al. "Cu:ZnO deposited on porous ceramic substrates by a simple thermal method for photocatalytic application." Ceram Int. 44(2018): 21546-21555.
7. Zaman Saima. "Synthesis of ZnO, CuO and their composite nanostructures for optoelectronics, sensing and catalytic applications." PhD diss, Linköping University Electronic Press, 2012.
8. Kanade KG, BB Kale, Jin-Ook Baeg and Sang Mi Lee, et al. "Self-assembled aligned Cu doped ZnO nanoparticles for photocatalytic hydrogen production under visible light irradiation." Mater Chem Phys. 102(2007): 98-104.
9. Liu Bin and Hua Chun Zeng. "Fabrication of ZnO “dandelions” via a modified Kirkendall process."               J Am Chem Soc. 126(2004): 16744-16746.
10. Rautaray Debabrata, SR Sainkar and Murali Sastry. "SrCO3 crystals of ribbonlike morphology grown within thermally evaporated sodium bis-2-ethylhexylsulfosuccinate thin films." Langmuir 19 (2003): 888-892.