Dual-frequency (20/40 kHz) ultrasonic assisted photocatalysis for degradation of methylene blue effluent: Synergistic effect and kinetic study
Highlights
► Dual-ultrasonic assisted photocatalysis (DUAP) was employed to degrade methylene blue (MB) solution. ► The synergistic effect of DUAP was intensified to exist obviously. ► MB degradation under DUAP process obeys first-order kinetics. ► Increasing ultrasonic power density facilitates the increase of the apparent rate constant.
Introduction
Advanced oxidation processes (AOP), such as UV light/H2O2, UV/ozone and UV/TiO2, have recently emerged as a promising technique to degrade organic dyes in the textile effluent due to its strong oxidizing power, non-toxic, and low cost [1], [2], [3], [4], [5], [6], [7]. However, it is difficult to completely mineralize the opaque or translucent wastewater by photocatalysis because of the low penetrating ability of light. In addition, it is confronted with the usual problems such as the aggregation of catalyst particles during photocatalysis, and sonochemical formation of stable H2O2 in the presence of low levels of pollutants [8].
One strategy to solve these problems is the degradation of dye effluent by coupling ultrasonic field with photocatalysis. The penetrating ability of ultrasound is very strong even for the opaque wastewater medium and its penetrating depth can ordinarily attain 15–20 cm [9], [10]. Ultrasonic activation also contributes dye degradation via de-aggregating catalyst particles and acceleration of the splitting of H2O2 produced by both photocatalysis and sonolysis to form more OH and OOH free radicals [6], [11], [12], [13], [14], [15], [16].
Reports on the combination of ultrasonic irradiations with photocatalysis are available by examining the influencing factors including irradiation time, ultrasonic arrangement and ultrasonic power density [2], [11], [12], [13], [17], [18], [19], [20].
On the other hand, the dual-frequency or multiple frequency ultrasonic processes have wide applications in the intensification of metal leaching process [21], sonolysis of organic pollutants [22], [23], [24], [25] and combination with enzyme processing [26], etc. The corresponding results indicate that the dual-frequency ultrasonic process is more effective in the terms of improvement of the leaching or degradation efficiency, shortening of the processing time, etc. compared to the single frequency ultrasonic process. The single-frequency ultrasonic assisted photocatalysis process (SUAP) for the degradation of organic effluents has been reported in recent years. However, very little attention has been focused on the combination of dual-frequency ultrasound with photocatalysis for the treatment of industrial effluents.
The present work was aimed at investigating the synergistic effect and evaluating kinetic parameters of the DUAP process. The degradation efficiency of the DUAP process was compared to that of the SUAP process and the photocatalysis process (UV/TiO2). In addition, the intermediate products were analyzed by UV–Vis spectra and the free radical scavenging experiment.
Section snippets
Materials
Methylene blue (MB, AR, Tianjin Kaiyuan Reagent Corporation, China) were used as model organic pollutants. Degussa P-25 TiO2 (Nippon Aerosil) was used in all experiments as a standard photocatalyst.
Other chemicals were obtained as analytical reagents and used without further purification.
Experimental setup and process
The reactor consisted of a pyrex beaker and a temperature controllable water bath with a working volume of 3 L. The pyrex beaker containing 1 L MB solution of 10 mg L−1 was suspended in the water bath where its
Comparison of different degradation process and kinetic analysis
The investigation of MB degradation kinetics in aqueous solution under conditions of UV/TiO2, US/UV/TiO2 (ultrasonic frequency: 20 or 40 kHz) and dual-US/UV/TiO2 are given in Fig. 2. The power dissipation level for US/UV/TiO2 (20 kHz) and US/UV/TiO2 (40 kHz) is herein 100 W L−1. The power dissipation level of dual-US/UV/TiO2 is 200 W L−1.
After 18 min treatment, the removal ratios of MB are, respectively 24.8%, 53.9% and 62.2% under conditions of UV/TiO2, US (20 kHz)/UV/TiO2 and US (40 kHz)/UV/TiO2, while
Conclusion
The DUAP process was employed to the degradation of MB solution. MB solution with an initial concentration of 10 mg L−1 can be degraded rapidly to 98.4% in 18 min under conditions of dual frequencies of 20/40 kHz, orthogonal position, P25 photocatalyst of 80 mg L−1 and 298 K. Compared to the SUAP process, the synergistic effect of the DUAP process was intensified obviously by calculation of the synergy index (2.36).
MB degradation in the DUAP process obeys first-order kinetics. Based on the results of
Acknowledgements
The authors would like to express their gratitude to Jishou university for their financial support of this Project (No: jsdxkyzz201008). The work was also partially supported by the key science and technology financing projects of ministry of education (No. 211124) and the natural science foundation of Hunan province, China (No. 11JJ3053).
References (32)
- et al.
Study on UV-LED/TiO2 process for degradation of Rhodamine B dye
Chem. Eng. J.
(2011) - et al.
Intensification of sonophotocatalytic degradation of p-nitrophenol at pilot scale capacity
Ultrason. Sonochem.
(2011) - et al.
Ti-containing mesoporous silica for methylene blue photodegradation
Appl. Catal. A: Gen.
(2011) Production of electricity and hydrogen by photocatalytic degradation of organic wastes in a photoelectrochemical cell the concept of the photofuelcell: a review of a re-emerging research field
J. Hazard. Mater.
(2011)- et al.
Adsorption and photocatalytic degradation of methylene blue over TiO2 films on carbon fiber prepared by atomic layer deposition
J. Mol. Catal. A: Chem.
(2011) - et al.
Visible light induced sonophotocatalytic degradation of reactive red dye 198 using dye sensitized TiO2
Ultrason. Sonochem.
(2007) - et al.
On the origin of sonoluminescence and sonochemistry
Ultrasonics
(1990) - et al.
Sonocatalytic degradation of methyl orange in the presence of TiO2 catalysts and catalytic activity comparison of rutile and anatase
Ultrason. Sonochem.
(2005) - et al.
Advanced oxidation processes (AOPs) involving ultrasound for waste water treatment: a review with emphasis on cost estimation
Ultrason. Sonochem.
(2010) - et al.
Ultrasound assisted photocatalytic degradation of diclofenac in an aqueous environment
Chemosphere
(2010)
Synergistic effect of hydrogen peroxide production and sonochemiluminescence under dual frequency ultrasound irradiation
Ultrason. Sonochem.
Photocatalysis-enhanced electrosorption process for degradation of high-concentration dye wastewater on TiO2/carbon aerogel
Chem. Eng. J.
Mechanism of heterogeneous catalytic ozonation of nitrobenzene in aqueous solution with modified ceramic honeycomb
Appl. Catal. B: Environ.
Synergistic effects of high-frequency ultrasound on photocatalytic degradation of aldehydes and their intermediates using TiO2 suspension in water
Ultrason. Sonochem.
Sonophotocatalytic degradation of 4-chlorophenol using Bi2O3/TiZrO4 as a visible light responsive photocatalyst
Ultrason. Sonochem.
Intensification of leaching process by dual-frequency ultrasound
Ultrason. Sonochem.
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