Kinetic Modeling of Photocatalytic Degradation of an Azo Dye Using Nano-TiO 2 /Polyester

Abstract

Photocatalytic degradation of Reactive Orange 16 (RO16) was investigated using immobilized TiO₂ nanoparticles on polyester support in exposure of UV irradiation in recirculated tubular photoreactors. Utilization of the polyester as a support has several advantages, such as low price, remarkable surface area, flexibility, and durability. Moreover, the prepared TiO₂/polyester was successfully applied for the photocatalytic degradation of RO16 in aqueous media for several times without any discernible diminution in its activity. Applied TiO₂ nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Experimental results indicate that the degradation rate of RO16 follows pseudo-first-order kinetics. With nonlinear regression, a model was developed for prediction of pseudo-first-order rate constants (k_app) as a function of operational parameters, including temperature (295–328K), flow rate (5–15 L·min⁻¹), and initial concentration of RO16 (5–25 mg·L⁻¹) as \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes {10} {9} {7} {6} \begin{document} $$k_{\rm app} = 2.20 ( \exp { [- 7427 / \rm RT} ]) ( FR ) ^{0.5034} [ {0.112 / (1 + 0.112 [ \rm RO16 ] _0} )] .$$ \end{document} Calculated data from the model are in good agreement with the experimental results. Electrical energies per order (E_EO) were estimated from the calculated and experimental data show that E_EO depends on the operational parameters, considerably. To monitor the mineralization of RO16, chemical oxygen demand (COD) measurements were carried out during the UV/TiO₂ process. COD measurement results indicated that all organic substances were completely mineralized after 5 h of UV irradiation.

Introduction

Lack of usable water sources is one of the most significant global problems; on the other hand, release of various industrial effluents such as textile wastewaters to the environment is a serious threat to the ecology since they are highly colorful and have considerable chemical oxygen demand (COD) (Malato et al., 2009). Azo dyes are utilized more than other ones in textile industries (50%–70%) and have at least one −N=N− chromophore. Sizable amounts of dyes (up to 20%) are lost during the dyeing process. Based on studies, azo dyes and degradation byproducts of them such as aromatic amines, which are generated during different treatment processes, are carcinogenic (Golka et al., 2004; Ho et al., 2010; Mahyar et al., 2011). Therefore, treatment of them is essential from an environmental point of view.

Among wastewater treatment techniques such as precipitation, coagulation, electrocoagulation, adsorption, and filtration, the UV/TiO₂ process, which is classified as one of the advanced oxidation processes (AOPs), has some advantages in comparison with them: (1) complete mineralization of pollutants, (2) producing no secondary (solid) contamination, and (3) low operational cost; moreover, it can be used for the destruction of nonbiodegradable organic contaminants (Gaya and Abdullah, 2008; Aquino et al., 2010; Mahyar et al., 2010). In all AOPs, oxidizing species are generated such as hydroxyl radicals (OH^•) and hydroperoxide radicals ( \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes {10} {9} {7} {6} \begin{document} $$\rm HO_2^{ \bullet}$$ \end{document} ) to degrade the pollutants. Semiconductors like TiO₂ can absorb photons with proper energies, and after photoexitations, electron-hole pairs are generated in conduction and valence bands of TiO₂, respectively. Then, if they do not recombine to produce heat, they will take part in the reactions with electron acceptors and donors, the reactions that can produce highly reactive radical species, generally hydroxyl radicals, which can oxidize organic pollutants and their degradation intermediates unselectively. Furthermore, pollutants can be oxidized directly by the holes too (Fujishima et al., 2000; Gaya and Abdullah, 2008).

From a practical point of view, TiO₂ nanoparticles can be utilized for the photocatalytic treatment of wastewater in two forms of aqueous suspensions or immobilized on inert and stable supports, in batch, semibatch, or continuous systems (Dijkstra et al., 2001a, 2001b; Behnajady et al., 2008; Benotti et al., 2009). Immobilized TiO₂ nanoparticles have some privileges in comparison with suspended ones such as (1) no need for separation of them at the end of the process and (2) the satisfactory penetration of UV light through the solution; moreover, the immobilized TiO₂ nanoparticles on various supports like glass, sand, polyethylene, and nonwoven paper can be used repeatedly without losing their activity (Matthews, 1991; Aguedach et al., 2005; Zhiyonga et al., 2007; Khataee et al., 2011). Various benefits of the polyester, including low price, remarkable surface area, flexibility, and durability, make it a suitable candidate to use as a support in photocatalytic degradation process. The polyester support with immobilized TiO₂ nanoparticles on it was used in the gaseous phase for the degradation of methanol under UV irradiation (Mejía et al., 2010). However, to the best of our knowledge, application of a TiO₂/polyester for the destruction of organic contaminants in aqueous media has not been reported.

The aim of the present study was to apply the immobilized TiO₂ nanoparticles on the polyester support for photocatalytic degradation of Reactive Orange 16 (RO16) under UV irradiation and then to develop a kinetic model for prediction of apparent pseudo-first-order rate constant (k_app) of RO16 degradation as a function of different operational parameters, including temperature, flow rate (FR), and initial concentration of RO16. Eventually, the obtained model can be utilized to evaluate the required electrical energies per order (E_EO) for the UV/TiO₂ process at various operational conditions.

Materials and Methods

Materials

All the chemicals used for preparation of TiO₂/polyester phtocatalyst and COD measurements were of analytical grade from Merck and used without further purification. The polyester support and RO16 (color index number=17,757, molecular formula=C₂₀H₁₇N₃Na₂O₁₁S₃, Mw=617.5 and λ_max=494 nm), were purchased from Arian Bushehr Co. (Iran) and Alvan Sabet Co. (Iran), respectively.

Preparation of TiO₂/polyester

The TiO₂ nanoparticles were prepared by the thermal hydrolysis method using TiCl₄ as a titanium precursor (Pourata et al., 2009). First, the desired amount of TiCl₄ was dissolved in double-distilled water in an ice bath to reach 3 M concentration. Next, the obtained solution was added dropwise to a 0.05 M (NH₄)₂SO₄ solution up to 0.5 M and stirred vigorously for an hour at 80°C. Afterward, the pH of the solution was adjusted in 7 by adding NH₄OH (2.5 M) to obtain TiO₂ precipitation. After that, the obtained white precipitate was filtered, washed with double-distilled water, and dried at room temperature, and finally calcined at 400°C for 2 h.

Poly-methyl methacrylate was synthesized by polymerization of methyl methacrylate monomers using benzoyl peroxide as an initiator (Ahmad et al., 2007). Briefly, 20 mL of MMA was inserted into a 250-mL three-necked round-bottom flask; after that, the solution of 0.15 g of benzoyl peroxide in 100 mL of water was added to the solution. Next, 0.5 g of polyvinyl alcohol and 5 g of di-sodium hydrogen phosphate were added and the solution was stirred for 1 h at 80°C. The reaction was accomplished under nitrogen atmosphere. Upon completion of the reaction, the solution was filtered, washed, and finally dried at 100°C for 24 h under vacuum condition to yield PMMA solid material.

To immobilize the prepared TiO₂ nanoparticles on polyester support, the obtained polymer was dissolved in toluene (20% w/w), and then TiO₂ nanoparticles were suspended in the solution (15 g·L⁻¹). Thereafter, the polyester support was submerged into the suspension for 15 min, and lastly the obtained TiO₂/polyester was dried at room temperature, and washed with double-distilled water.

Characterization of TiO₂ nanoparticles

TiO₂ nanoparticles were characterized by XRD, TEM, and SEM. The crystalline structure and the average crystallite size of TiO₂ nanoparticles were investigated by XRD (Philips X'PERT MPD). From Fig. 1a, the nanocrystalline anatase structure of TiO₂ was confirmed by a main peak at 2θ=25.28°; moreover, the mean crystallite size of the photocatalyst was determined by the Scherrer formula (Mahyar and Amani-Ghadim, 2011) as 6.7 nm. Also, the grain size of TiO₂ nanoparticles was investigated by the TEM (Philips CM 100). Figure 1b shows that the majority of TiO₂ nanoparticles sizes are between 6 and 8 nm, which is consistent with the XRD result. The morphology of the immobilized TiO₂ nanoparticles on the polyester support was investigated by a Zeiss LEO 1455 VP-SEM. Figure 2a–c proves that the TiO₂ nanoparticles were well-immobilized on the polyester support.

FIG. 1.

(a) X-ray diffraction pattern; (b) transmission electron microscopy image of the applied TiO₂ nanoparticles.

FIG. 2.

Experimental procedure

The experimental setup for the UV/TiO₂ process consisted of two similar photoreactors, which were joined to each other with the rubber tubing. The photoreactor had a Pyrex reactor (outer diameter=55 mm and inner diameter=50 mm) with a high-pressure mercury lamp (15 W, UV-C, manufactured by Osram) surrounded by a quartz tube (outer diameter=32 mm and inner diameter=30 mm) at the center of it. For measuring UV light intensity, the UV lamp was centered in a quartz tube and the light intensity of 0.9 mW·cm⁻² was measured by a UV-Lux-IR meter (Leybold Co.) at the distance of 18 mm, which was equal to the distance between the outer surface of the quartz tube and the inner surface of the pyrex photoreactor. Each of the photoreactors was covered with the metallic cover to protect the laboratory from the harmful UV irradiation. The TiO₂/polyester (with the height of 440 mm) was wrapped around the inner wall of the reactors. In each experiment, 2 L of RO16 solution with a known initial concentration was circulated in the semibatch system by a diaphragm pump (Max pressure=125 p.s.i.; WaterSafe). To adjust the FR, a liquid flow meter (LZB-4; Guanshan) was used. A heater was used to maintain the reaction temperature at a constant value within ±0.5°C. The solution was blended by a magnet stirrer to keep the solution homogenous. The UV lamps and the pump were switched on at the beginning of each experiment. At different reaction intervals, the absorbance was measured at λ_max=494 nm by a UV-vis spectrophotometer (DR-5000; Hach-Lange) and was related to the concentration by the calibration plot based on the Beer-Lambert's law. The degradation efficiency was defined as the percent ratio of the dye concentration at a definite reaction time relative to that at the beginning of the experiment.

COD measurements were implemented based on the open reflux method (APHA, 2005).

Results and Discussion

Kinetic model development and evaluation

Before kinetic modeling, it is essential to know the photocatalytic degradation kinetics of RO16 at different operational conditions. Therefore, the decolorization plots of RO16 in different operational conditions during the UV/TiO₂ process were presented in Fig. 3a–c. Based on pseudo-first-order kinetic supposition [Eq. (1)], the plots of ln ([RO16]/[RO16]₀) against irradiation time (t), where [RO16]₀ and [RO16] are initial and at time t concentrations of RO16, were obtained. In all graphs, straight lines with correlation coefficients of more than 0.99 proved the suggested kinetics, and the apparent rate constants were calculated from the slope of the plots.

FIG. 3.

The effect of (a) temperature, (b) FR, and (c) initial concentration of dye on decolorization of RO16 through the UV/TiO₂ process ([RO16]_o=15 mg L⁻¹, T=295 K, and FR=10 L h⁻¹). RO16, Reactive Orange 16; FR, flow rate.

\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*}- \frac { d [ \rm RO16 ] } { dt } = k_ { \rm app } [ \rm RO16 ] \tag { 1 } \end{align*} \end{document}

A correlation between k_app and the process temperature (T) can be expressed by the Arrhenius equation [Eq. (2)]: \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*}- \ln k_ { \rm app } = - \ln A + \frac { E_ { \rm a } } { R } \left( \frac { 1 } { T } \right) \tag { 2 } \end{align*} \end{document}

Figure 4 shows that the reaction rate increases as the temperature rises. Although thermal energy is not adequate for activation of TiO₂ particles, various studies indicate that increase in process temperature from 20°C up to 80°C promotes the photocatalytic degradation of pollutants (Chong et al., 2010). As a consequence, in this study, the operational temperature was chosen in the range of 22°C to 55°C, which is in accordance with the optimum process temperature for the photocatalytic degradation. Although the amount of adsorption decreases with an increase in the reaction temperature, the photocatalytic reaction competes more effectively with an electron-hole recombination, and thus the photocatalytic reaction rate enhances, which is consistent with the Arrhenius plot (Fig. 4) (Daneshvar et al., 2004; Malato et al., 2009; Chong et al., 2010). From the slope of the Arrhenius plot, the activation energy for the photocatalytic degradation of RO16 was determined as 7.43 kJ·mol⁻¹ in the temperature range of 295K to 328K, which is consistent with other studies that the activation energies were measured between 5.5 and 8.24 kJ·mol⁻¹ (Daneshvar et al., 2004).

FIG. 4.

Arrhenius plot for photocatalytic degradation of RO16 ([RO16]₀=15 mg·L⁻¹ and FR=10 L·h⁻¹).

As can be observed from Fig. 5, k_app can be correlated to the FR in the range of 5–15 L·h⁻¹ with a power law-type empirical equation [Eq. (3)]: \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*}k_{\rm app} = 0.0044 \ ( \rm FR ) ^{0.5034} \tag{3}\end{align*} \end{document}

Figure 5 reveals that the reaction rate enhances with increasing of the FR because of greater mass coefficient, which was caused by more turbulence in the photoreactors. In addition, when external resistance occurs against mass transfer especially at low FRs, the reaction rate promotes with enhancement of the circulating flow rates (Mozia et al., 2007; Laoufi et al., 2008).

FIG. 5.

Plot of k_app versus FR ([RO16]₀=15 mg·L⁻¹ and T=295K).

A correlation between k_app and intial concentration of RO16 can be concluded [Eq. (4)] from the modified Langmuir-Hinshelwood equation (Daneshvar et al., 2004): \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*}k_ { \rm app } = \frac { k_ { \rm obs } K_ { \rm R } } { 1 + K_ { \rm R } [ \rm RO16 ] _0 } \tag { 4 } \end{align*} \end{document}

Reaction rate constant (k_obs) of the photocatalytic degradation reaction and adsorption rate constant (K_R) of RO16 in the concentration range of 5–25 mg·L⁻¹ were estimated from the plot of 1/k_app against [RO16]_o (Fig. 6) as 0.340 mg·(L·min)⁻¹ and 0.112 L·mg⁻¹, respectively. Also, Fig. 6 demonstrates that the reaction rate decreases with increasing of initial concentration of RO16. This trend can be explained by constant produced amount of hydroxyl radicals and active sites on TiO₂ surface at the same operational conditions, which are not sufficient for the degradation of more RO16 dyes and their degradation intermediates; on the other hand, the solution becomes more impermeable for UV irradiation with increasing of RO16 concentration due to the inner filtration effect of RO16 molecules (Fathinia et al., 2010).

FIG. 6.

Modified Langmuir plot (T=295K and FR=10 L·h⁻¹)

With the aim of above results a model can be developed for predicting k_app as a function of temperature, FR, and initial concentration of RO16 as following [Eq. (5)]: \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*}k_ { \rm app } = k^ { \prime } \bigg( \exp \frac { - E_ { \rm a } } { RT } \bigg) (\hbox { FR } ) ^n \bigg( \frac { K_ { \rm R } } { 1 + K_ { \rm R } [ \rm RO16 ] _0 } \bigg) \tag { 5 } \end{align*} \end{document}

E_a, n, and K_R were estimated by nonlinear regression analysis with polymath 5.1, and then with known values of T, FR, and [RO16]₀, k′ can be calculated as 2.20. By substituting estimated values in Equation (5), the following equation was obtained: \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*}k_ { \rm app } = 2.20 \bigg( \exp \frac { - 7427 } { RT } \bigg) ( { \rm FR } ) ^ { 0.5034 } \bigg( \frac { 0.112 } { 1 + 0.112 [ { \rm RO } 16 ] _0 } \bigg) \tag { 6 } \end{align*} \end{document}

The above equation can determine k_app theoretically in the various ranges of operational conditions. Figure 7 compares experimental and theoretical k_app for degradation of RO16 at several operational conditions. It can be concluded that the experimental data are consistent with predicted data by the model properly in the wide ranges of operational parameters (Table 1).

FIG. 7.

Comparison between the experimental and calculated apparent pseudo-first-order rate constants of the UV/TiO₂ process. For experimental details refer to Table 1.

Table 1.

Experimental and Calculated E_EO at Different Operational Conditions for the Photocatalytic Degradation of RO16

			E_EO (kW·h·m⁻³·order⁻¹)
[RO16]₀ (mg·L⁻¹)	Flow rate (L·h⁻¹)	Temperature (K)	Experimental	Calculated
5	7.5	295	27.170	27.323
5	10	295	24.202	23.639
10	10	295	30.476	32.125
10	10	311	27.560	27.490
10	15	295	26.301	26.194
15	5	295	57.598	57.567
15	7.5	295	48.000	46.939
15	10	295	40.851	40.610
15	10	301	38.919	38.232
15	10	312	34.909	34.433
15	10	320	32.360	32.055
15	10	323	31.475	31.234
15	10	328	30.001	29.945
15	12.5	295	36.226	36.296
15	15	295	33.488	33.113
20	7.5	295	60.000	56.747
20	7.5	311	47.213	48.560
20	10	295	48.403	49.096
20	12.5	295	44.308	43.880
25	10	295	57.601	57.582
25	10	303	54.857	53.157

RO16, Reactive Orange 16; E_EO, electrical energy per order.

Electrical energy determination

Since the electric energy consumption in AOPs includes a significant part of the operating costs, evaluation of it can be performed by the E_EO for the first-order–kinetics regime, which was observed in this study too. E_EO was accepted by IUPAC and is defined as the required amount of electric energy (kW·h) to eliminate 90% of a pollutant in one liter of contaminated water; E_EO can be measured as following [Eq. (7)] (Behnajady et al., 2009): \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*} { \rm E } _ { \rm EO } = \frac { 38.4 P_ { \rm el } } { V k_ { \rm app } } \tag { 7 } \end{align*} \end{document}

where P_el and V are the sum of the input power (kW) from UV lamps to the UV/TiO₂ system and the volume of solution (L), respectively. The experimental and predicted E_EO values are summarized in Table 1; it can be concluded that the kinetic model can be used successfully for prediction of E_EO values at different operational conditions.

Photocatalytic mineralization of RO16

The mineralization of RO16 was monitored by COD decrease during the process with 20 mg·L⁻¹ of RO16 aqueous solution at FR and temperature of 12.5 L·h⁻¹ and 295K, respectively. Based on the open reflux method, the results demonstrated that COD was removed completely after 5 h of irradiation (Fig. 8).

FIG. 8.

COD removal of RO16 aqueous solution during the UV/TiO₂ process ([RO16]₀=15 mg·L⁻¹, T=295K, and FR=10 L·h⁻¹). COD, chemical oxygen demand.

Conclusions

The TiO₂/polyester was used for photocatalytic degradation of RO16 repeatedly without losing its efficiency. The apparent pseudo-first-order rate constant is affected by operational parameters; it decreases with increasing the initial concentration of RO16 and increases with the enhancement of FR and temperature. With nonlinear regression a model was developed for prediction of k_app at the different operational conditions as following: \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland,xspace}\usepackage{amsmath,amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6} \begin{document} \begin{align*}k_{\rm app} = 2.20 \bigg( \exp {\frac {- 7427} {RT}} \bigg) ( {\rm FR} ) ^{0.5034} \bigg(\frac {0.112} {1 + 0.112 [ {\rm RO}16 ] _0} \bigg) \tag { 8 } \end{align*} \end{document}

E_EO was evaluated based on the experimental and theoretical k_app,which were calculated from the model. The results indicated that the model can properly predict the values of k_app at various operational conditions. The results of COD measurements demonstrated that this process can be used for complete mineralization of RO16.

Footnotes

Acknowledgments

The authors sincerely appreciate Water and Wastewater Company of East Azerbaijan and Iranian Nano Technology Initiative Council for financial and other support. We are also grateful to Mrs. Movahed for COD measurements and Mr. Monokchian for his help in running the setup.

Author Disclosure Statement

No competing financial interests exist.

References

Aguedach

, Brosillon

, Morvan

, Lhadi

E.K.

2005. Influence of ionic strength in the adsorption and during photocatalysis of reactive black 5 azo dye on TiO₂ coated on non woven paper with SiO₂ as a binder. Appl. Catal. B Environ., 57:55.

Ahmad

, Ahmad

, Agnihotry

S. A.

2007. Synthesis and characterization of in situ prepared poly (methyl methacrylate) nanocomposites. Bull. Mater. Sci., 30:31.

American Public Health Association (APHA). 2005. Standard Methods for the Examination of Water and Wastewater, 1 21st. Washington: American Public Health Association, 5220 B.

Aquino

S.F.

, Lacerda

C.A.

, Ribeiro

D.R.

2010. Use of ferrites encapsulated with titanium dioxide for photodegradation of azo dyes and color removal of textile effluents. Environ. Eng. Sci., 27:1049.

Behnajady

M.A.

, Modirshahla

, Mirzamohammady

, Vahid

, Behnajady

2008. Increasing photoactivity of titanium dioxide immobilized on glass plate with optimization of heat attachment method parameters. J. Hazard. Mater., 160:508.

Behnajady

M.A.

, Vahid

, Modirshahla

, Shokri

2009. Evaluation of electrical energy per order (E_EO) with kinetic modeling on the removal of Malachite Green by US/UV/H₂O₂ process. Desalination, 249:99.

Benotti

M.J.

, Stanford

B.D.

, Wert

E.C.

, Snyder

S.A.

2009. Evaluation of a photocatalytic reactor membrane pilot system of pharmaceuticals and endocrine disrupting compounds from water. Water Res., 43:1513.

Chong

M.N.

, Jin

, Cow

C.W.K.

, Saint

2010. Recent developments in photocatalytic water treatment technology: A review. Water Res., 44:2997.

Daneshvar

, Rabbani

, Modirshahla

, Behnajady

M.A.

2004. Kinetic modeling of photocatalytic degradation of Acid Red 27 in UV/TiO₂ process. J. Photochem. Photobiol. A Chem., 168:39.

10.

Dijkstra

M.F.J.

, Buwalda

, de Jong

A.W.F.

, Michorius

, M.Winkelman

J.G.

, Beenackers

A.A.C.M.

2001a. Experimental comparison of three reactor designs for photocatalytic water purication. Chem. Eng. Sci., 56:547.

11.

Dijkstra

M.F.J.

, Michorius

, Buwalda

, Panneman

H. J.

, Winkelman

J.G.M.

, Beenackers

A.A.C.M.

2001b. Comparison of the efficiency of immobilized and suspended systems in photocatalytic degradation. Catal. Today, 66:487.

12.

Fathinia

, Khataee

A.R.

, Zarei

, Aber

2010. Comparative photocatalytic degradation of two dyes on immobilized TiO₂ nanoparticles: effect of dye molecular structure and response surface approach. J. Mol. Catal. A: Chem., 333:73.

13.

Fujishima

, Rao

T.N.

, Tryk

D.A.

2000. Titanium dioxide photocatalysis. J. Photochem. Photobiol. C Photochem. Rev., 1:1.

14.

Gaya

U.I.

, Abdullah

A.H.

2008. Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide: a review of fundamentals, progress and problems. J. Photochem. Photobiol. C: Photochem. Rev., 9:1.

15.

Golka

, Kopps

, Myslak

Z.W.

2004. Carcinogenicity of azo colorants: influence of solubility and bioavailability. Toxicol. Lett., 151:203.

16.

C.H.

, Huang

Y. J.

, Huang

Y. H.

2010. Degradation of azo dye reactive black B using an immobilized iron oxide in a batch photo-fluidized bed reactor. Environ. Eng. Sci., 27:1043.

17.

Khataee

A.R.

, Zarei

, Fathinia

, Khobnasab Jafari

2011. Photocatalytic degradation of an anthraquinone dye on immobilized TiO₂ nanoparticles in a rectangular reactor: destruction pathway and response surface approach. Desalination, 268:126.

18.

Laoufi

N.A.

, Tassalit

, Bentahar

2008. The degradation of phenol in water solution by TiO₂ photocatalysis in a helical reactor. Global Nest J., 10:404.

19.

Mahyar

, Amani-Ghadim

A.R.

2011. Influence of solvent type on the characteristics and photocatalytic activity of TiO₂ nanoparticles prepared by the sol-gel method. Micro Nano Lett., 6:244.

20.

Mahyar

, Behnajady

M.A.

, Modirshahla

2010. Characterization and photocatalytic activity of SiO₂-TiO₂ mixed oxide nanoparticles prepared by sol-gel method. Indian J. Chem. Sec. A, 49:1593.

21.

Mahyar

, Behnajady

M.A.

, Modirshahla

2011. Enhanced photocatalytic degradation of C.I. Basic Violet 2 using TiO₂-SiO₂ composite nanoparticles. Photochem. Photobiol., 87:795.

22.

Malato

, Fernández-Ibánez

, Maldonado

M.I.

, Blanco

, Gernjak

2009. Decontamination and disinfection of water by solar photocatalysis: recent overview and trends. Catal. Today, 147:1.

23.

Matthews

R.W.

1991. Photooxidative degradation of coloured organics in water using supported catalysts. TiO₂ on sand. Water Res., 25:1169.

24.

Mejía

M.I.

, Marín

J.M.

, Restrepo

, Rios

L.A.

, Pulgarĺn

, Kiwi

2010. Preparation, testing and performance of a TiO₂/polyester photocatalyst for the degradation of gaseous methanol. Appl. Catal. B Environ., 94:166.

25.

Mozia

, Tomaszewska

, Morawski

A.W.

2007. Photodegradation of azo dye Acid Red 18 in a quartz labyrinth flow reactor with immobilized TiO₂ bed. Dyes Pigments, 75:60.

26.

Pourata

, Khataee

A.R.

, Aber

, Daneshvar

2009. Removal of the herbicide bentazon from contaminated water in the presence of synthesized nanocrystalline TiO₂ powders under irradiation of UV-C light. Desalination, 249:301.

27.

Zhiyonga

, Mielczarskib

, Laubc

, Buffatc

, Klehmd

, Albersd

, Lee

, Kulike

, Kiwi-Minskera

, Renkena

, Kiwia

2007. Preparation, stabilization and characterization of TiO₂ on thin polyethylene films (LDPE). Photocatalytic applications. Water Res., 41:862.

Kinetic Modeling of Photocatalytic Degradation of an Azo Dye Using Nano-TiO 2 /Polyester

Abstract

Abstract

Introduction

Materials and Methods

Materials

Preparation of TiO2/polyester

Characterization of TiO2 nanoparticles

Experimental procedure

Results and Discussion

Kinetic model development and evaluation

Electrical energy determination

Photocatalytic mineralization of RO16

Conclusions

Footnotes

Acknowledgments

Author Disclosure Statement

References

Preparation of TiO₂/polyester

Characterization of TiO₂ nanoparticles