4TH International Congress on Technology - Engineering & SCIENCE - Kuala Lumpur - Malaysia (2017-08-05)

Investigation Of The Photocatalytic Activity Variation Of The Coated Mwcnts With Zno Nanoparticles

In the recent decades, the pollution of water is a major problem in the worldwide. It can be due to the disposal of the industrial sewage to the water systems. The wastewater of the different industrials such as textile industry involves hazardous materials. The presence of these kinds of materials in the water systems is minatory for human ecology and aquatic organisms [1, 2]. Among the different techniques, the photocatalytic oxidation of the organic pollutants is common and applicable. In this technique, different kinds of semiconductors such as ZnO, SnO2 and TiO2 have been great deal of interest [3-5]. The mechanism of the photocatalytic oxidation is based on the transmittance of electron from valence band to the conduction band. Therefore, irradiation of the light source such as UV leads to the transition of electrons and generation of electron-hole pairs which are the main propellant of pollutants decomposition [6]. The photocatalytic performance of the photocatalysts can restrict due to the fast recombination of the generated electron-hole pairs. Up to now, the researchers reported the different methods for overcome to this problem. Some of these techniques contain decoration the surface of semiconductors with noble metals such as Au and Ag [7, 8], enhancement of surface area and decorating the semiconductors on the outer surface of materials with high aspect ratio [9, 10] and loading the semiconductors with higher band-gap on the outer surface of the studied photocatalysts [1, 4]. The variation of photodecomposition of methyl orange (MO) as pollutant using decorated MWCNTs by pH has never been studied up to now. Therefore, in the current study, we investigate the photodecomposition of methyl orange at different acidic conditions. For this purpose, the modified MWCNTs with ZnO nanoparticles is applied as photocatalysts. The experimental results show that the decomposition of the pollutant enhances with respect to the UV irradiation time. Meanwhile, the results of the pH study (Fig. 1) reveals that the maximum removal efficiency of methyl orange obtains at pH=4. In addition, the sequence of the photodecomposition of methyl orange is as pH=4>pH=10>pH=7. The statistical analysis of the removal efficiency of methyl orange is carried out using design of experiment (DOE). The obtained results of DOE (Table 1) confirm that the statistical model that proposed using DOE, can predict the removal efficiency of methyl orange with accuracy up to 98%. The investigation of the different levels of the pH using Duncan’s multiple range test at 5% (Fig. 2) reveals that there is a significant difference among three levels of studied pH.
Keywords: MWCNTs, decoration, ZnO nanoparticles, photodecomposition, methyl orange
Sedigheh Abbasi , Maryam Hasanpour, Mehri-Saddat Ekrami-Kakhki