Study and Modeling of Methylorange degradation with the Fenton Reaction

Transcription

1 Study and Modeling of Methylorange degradation with the Fenton Reaction ORLANDO GARCÍA-ROJAS*, CLAUDIA GÓMEZ-QUINTERO*, MIGUEL RÍOS-BOLÍVAR*, ABEL ROMERO **, ANTONIO RODRÍGUEZ ** * Departamento de Sistemas de Control Facultad de Ingeniería Universidad de Los Andes, Mérida VENEZUELA ** Laboratorio de Bioquímica Adaptativa Facultad de Medicina Universidad de Los Andes, Mérida VENEZUELA orlandog@ula.ve, claudiag@ula.ve, riosm@ula.ve, abelula@ula.ve, anrod@ula.ve Abstract: - Wastewater from textile industries is not satisfactorily depolluted by conventional wastewater treatments because of their refractory composition. The use of Advanced Oxidation Processes (AOPs) has shown to be very effective to degrade this type of wastewater. Fenton's reaction is one of the AOPs commonly applied for removing of refractory dyes. Due to the complex mechanism of Fenton s reaction, very few theoretical models representing the process kinetics have been developed. This paper proposes a theoretical model for the degradation of Methylorange (MO) by Fenton reagent, which involves the initial concentrations of the reagents (hydrogen peroxide and ferrous sulfate) and approximates experimental data in the steady state. Also, a study is conducted on the variables affecting the process (i.e. temperature, ph, reagents and MO concentrations) to set appropriate operational conditions to carry out the reaction efficiently. Key-Words: - Fenton Reaction, Methylorange, Degradation, Wastewater Treatment, Modeling, Arrhenius Law. 1 Introduction Textile industries are very harmful to the environment due to the nature of their discharged wastewater, which is mainly composed by refractory dyes. Such organic material cannot be eliminated by applying conventional wastewater treatment methods. Thus, the use of more recently developed methods known as Advanced Oxidation Processes (AOPs) is imposed, since they have shown to be a highly effective alternative to remove non-biodegradable organic material in refractory wastewater [1]. One of these advanced oxidation processes is known as Fenton process or Fenton reagent. This procedure removes organic dyes by generating hydroxyl radicals, a strong oxidant, from the reaction between hydrogen peroxide (H O ) and ferrous salts under acidic conditions. The Fenton process is even more effective than ozone oxidation, being capable of degrading a larger amount of pollutants [1,]. Fenton reagent has been widely studied over years. Although this process was discovered a century ago, the reaction mechanism is still under intense and controversial discussion since it involves a complex set of reactions, including cross-reactions between hydrogen peroxide, hydroxyl radicals, ferrous and ferric ions, and other substances. In fact, if the effect of organic compounds is completely ignored, whose intermediate products are virtually impossible to measure, main dynamics are still ruled by about ten chemical reactions [3,4]. Therefore, the task of obtaining a mathematical model describing the main dynamics, even for any specific pollutant, is a hard one to deal with. Kang et al. [5], for example, studied the kinetic degradation of mono-chlorophenols with Fenton reagent, identifying at least twenty eight different reactions. Rivas et al. [6] found about twenty reactions in their study of the oxidation of p- hydroxybenzoic acid with Fenton reagent. The degradation of azo dyes has also been of interest in latter researches. Azo dyes represent about 70% of pigments used in the textile industry [7]. About 10-15% of the synthetic dyes used in the industry are lost in rivers and other water sources during processing operations [8]. Methylorange (MO) is one of the azo dyes frequently found in textile wastewater and is a nasty substance because of its high level of color and toxicity, both having severe ecological impacts [9]. There are no online measurement instruments to obtain dyes concentrations during the degradation process. Hence, efforts have been made on ISBN:

2 understanding the degradation dynamics and the relationship between the process variables, and on indirect regulation schemes based on online measurements such as Oxide Reduction Potential (ORP), ph and temperature, which do not incorporate the dye concentration explicitly. Different strategies to eliminate this kind of pollutant have been proposed. Zambrano [10] and Dumitru et al. [8] have found some operational conditions to remove MO with the Fenton reaction on aqueous solutions. Villanueva et al. [9] have studied both the MO and acid-yellow 36 through electrochemical oxidation. Zhang et al. [11] have proposed a method to degrade the MO by combining ultrasound and ozonation. Also, Sun et al. [1] have studied the process kinetics and the effects of system parameters in the decolorization of the azo dye Orange G by Fenton oxidation. Yu et al. [13] have built a Fenton dosage control strategy for removing color from textile wastewater, by using artificial neural networks models. The object of this paper is to propose a theoretical model for the Methylorange degradation by Fenton reagent, involving the initial concentrations of the reagents (hydrogen peroxide and ferrous sulfate), based on specific operational conditions for a laboratory-scale reactor located at the Laboratory of Adaptive Biochemistry, Faculty of Medicine of the Universidad de Los Andes, Mérida, Venezuela. The influence of the main process variables (i.e. temperature, ph, initial concentrations of reagents and MO) are studied through experimentation to determine their values or criteria ranges ensuring the model validity. This paper is organized as follows. Firstly, we review in section the characteristics and kinetic study for the Fenton reaction and MO degradation. Also, some results shown in previous studies on the influence of parameters variation on the Fenton reaction are reviewed in section 3. Then, the equipment, experimental procedures and analytical methods used to conduct the experiments are described in section 4. In section 5, both the influence of parameters variation on process efficiency is verified through experimentation and appropriate operational conditions are determined. Section 6 is dedicated to obtaining a dynamic model for MO degradation and verifying it through experimentation in a laboratoryscale reactor. Finally, a conclusion is presented in Section 7. Problem Formulation Chemical reactions can be described by first order differential equations depending on a rate constant and reactants concentrations. The reaction order and the value of the rate constant have to be determined experimentally. The degradation of MO concentration can be described as: d[ MO] α = k[ MO] (1) dt where α corresponds to the order of the reaction and k is the rate constant. This reaction rate constant is temperature dependent and follows the Arrhenius law:, () with A, the pre-exponential factor, and E a, the activation energy of the reaction, which are considered to be temperature-independent, and R is the gas constant. On the other hand, Dumitru et al. [8] have proposed a set of reactions to explain the MO degradation mechanism in aqueous solutions in the presence of Fenton reagent: (3) (4) (5) (6) (7) (8) (9) (10) (11) where P are all the possible species of radicals obtained during the decolorization process and P F is the final product of the reactions. As a part of the results, in [8] it has been found that the MO degradation dynamics follow the relationship: with: Fe + H O Fe + OH + OH + k k + OH Fe Fe 3 OH OH + H O OOH + H O k k4 + + Fe OOH Fe O H + + k5 OH NM P H O k6 P + H O OH + P F k7 P P P + + k8 OH OOH O H O + k9 OH OH H O k k k 5 1 g = kisi (1), (13) k S = k [ Fe ] + k [ H O ] + k [ OOH ] + k [ OH ] i i d[ MO] = k dt k( T ) = A exp g [Fe + E a R T ][H O ][ MO] α (14) ISBN:

3 The parameter α is the reaction order, while [Fe + ] and [ H O ] are the initial concentrations of reagents. In this case, it is straightforward to study the effect of + the initial values [ H O ] and [Fe ] on the MO degradation. As the rate constant is experimentally obtained and the initial concentrations of reagents are known, the constant k g can be easily calculated by equaling equation (1) to (1). Then, equation (1) represents a continuous dynamic model of the MO degradation in time. 3 Process parameters influence The Fenton reaction efficiency depends on several process variables, i.e. ph, temperature, initial reagents concentrations. In this section, the influence of each variable is discussed and appropriate operational values are given for the case of study. 3.1 Initial ph influence The ph is a fundamental variable in wastewater treatment processes. The Fenton reaction, in particular, is effective only in acidic conditions. For high ph values (ph > 5), the reaction dynamics are limited because of the precipitation of ferrous compounds. For very low ph values (ph < ), the ion FeOOH + is generated starting to react with hydrogen peroxide and consuming hydroxyl radicals. Dumitru et al. [8] has studied the Fenton reaction at ph=3.5. Luo et al. [15] propose the ph must be kept between and 4. More specifically, they have shown for their case of study that the optimal ph for the Fenton reaction must be at.5. Nevertheless, Yu et al. [13] have noted that, after dosing the Fenton reagents, the ph behavior exhibits small variations around the initial value of ph. Hence, for processes with similar operational characteristics, it is not necessary to regulate this variable. 3. Temperature influence The Fenton reaction is dependent of the process temperature. As temperature increases, the rate constant increases as well and, consequently, the process dynamics become faster. At a higher temperature, the generation of hydroxyl radicals by the decomposition of the hydrogen peroxide is faster, reacting with the dye and degrading it during a shorter period of time. At atmospheric pressure, the recommended operational temperature interval is from 5 to 45 C. For temperatures over 50 C, the reaction efficiency decays because of an accelerated self-decomposition of hydrogen peroxide into oxygen and water [3,10]. Typically, the Fenton reaction is very fast, due to the high reaction rate constant of the hydroxyl radicals (between 10 7 and L.m -1.s -1 ) [14]. Thus, in order to assure a good performance of the process, the temperature must be regulated at a desired value from the beginning of the reaction. 3.3 Initial H O concentration influence Hydrogen peroxide is the principal reagent of the Fenton process. The absence or very low concentration of H O inhibits the generation of hydroxyl radicals. As the concentration of H O increases, more hydroxyl radicals are generated and the efficiency of the reaction is improved. However, there is a bound to this behavior. For H O concentrations higher than a certain value, the free hydroxyl radicals would stimulate the selfdegradation of the H O, which is an undesirable reaction mechanism [16]. A value for this bound has to be obtained by experimentation. 3.4 Ferrous sulfate concentration influence Ferrous sulfate is the catalyst in the Fenton reaction. Its concentration affects the generation rate of hydroxyl radicals. There is no evidence of the formation of hydroxyl radicals in its absence. As ferrous compound concentration increases the reaction rate increases to reach a certain bound. For concentrations higher than this value, the excess of ferrous particles favors several undesirable secondary reactions. One of those reactions stimulates the formation of Fe(OH) 3, which may precipitate, consuming the ferrous ions and decreasing the reaction efficiency [16]. As for the hydrogen peroxide, a value for this bound on ferrous ions concentration has to be obtained by experimentation and it will depend on the wastewater characteristics. However, there is an optimal relationship between the initial values of [H O ] and [Fe + ], as Chang et al. [14] have shown. A [Fe + ]/[H O ] ratio equals to seems to be the most effective when the hydroxyl radicals generation is considered. 3.5 Initial MO concentration influence The MO concentration is the main process variable but it cannot be measured online. However, the initial MO concentration can be estimated through an offline measurement of the absorbance. In batch operation, it is very useful to know the best reagents/dye ratio to determine the appropriate reagents dosage for any initial MO concentration. It is clear that if the MO concentration in the wastewater ISBN:

4 to be treated increases the Fenton reagents doses should be increased. However, the existence of a bound for the Fenton reagents dosage is also suspected in this case. It means that for a specific MO concentration in the wastewater, there must be an appropriate [MO]:[H O ]:[Fe + ] relationship to assure a good color removal efficiency in a short period of time. In this case of study, a [MO]:[H O ]:[Fe + ] ratio has to be obtained by experimental procedures. 4 Materials and Methods Materials used for experimentation and the procedure followed to achieve the Fenton reaction, including the instrumentation utilized, are described in this section. 4.1 Reagents and Reactants Substances used for experimentation are listed in Table 1. Methylorange was the pollutant to be removed from the aqueous solution, whilst both hydrogen peroxide and ferrous sulfate heptahydrate were the reagents employed to produce hydroxyl radicals. Sulfuric acid and sodium hydroxide were used to adjust wastewater ph. The quinhydrone and ph buffer were used to calibrate ORP and ph sensors, respectively. 4. Experimental reactor and equipment Experiments were carried out on a laboratory scale reactor with an operational volume of 18 liters. Stirring in the reaction tank was achieved by liquid reflux, by using both an electrovalve and a pump, working at a flow rate of 4 L/min. Heating was provided by a thermal resistor of 500W of power, placed into a quartz pipe; and temperature was regulated by using a heat exchanger. Reagents and reactants were supplied into the reactor by using dosing peristaltic pumps (Buchler instruments). The industrial sensors CZ and CZ (Cole Parmer, USA) were utilized for ph and ORP measurements, respectively, which were connected to preamplifiers CZ (Cole Parmer, USA). Temperature was measured by using a thermistor placed in the reactor. All sensors were connected to a data acquisition card DAQ USB-6008 (National Instruments), through a Universal Serial Bus (USB), as shown in Figure 1. Software LabVIEW 8.1 (National Instruments) was used for data acquisition, working at 1 sample/sec speed. Substance Table 1. Reagents and Reactants Formula Physical state Concentration Molecular Weight (g/mol) Methylorange C 14H 14N 3NaO 3S Solid - 37,00 Hydrogen Peroxide Ferrous Sulfate Heptahydrate H O Liquid 35% (p/p) 34,010 FeSO 47H O Solid - 78,0 Sulfuric Acid H SO 4 Liquid 1,0 mol/l 98,000 Sodium Hydroxide NaOH Solid 0,564 mol/l 40,000 Quinhydrone C 1H 10O 4 Solid - 18,00 ph Buffer - Liquid ph=4 ph=7-4.3 Experimental procedure and analytical methods In general, the procedure carried out in each experiment consists of the following steps: firstly, wastewater with MO is transferred into the reaction tank and the stirring system is activated to achieve a homogenous solution. Then, the thermal resistor is switched on to increase temperature to the desired level. After reaching the desired temperature, H SO 4 is added to adjust the solution ph level. Finally, reagents are added to start the Fenton reaction. Samples of 1 ml were taken each minute to be analyzed by a UV/VIS Spectrophotometer, Lambda 3B (Perkin Elmer) at 465 nm wavelength [Zambrano, 009] and, thus, to obtain the solution absorbance. The ORP is commonly used for tracking and control of wastewater processes. This variable is highly related to the concentration of oxidants and reducers present in a solution, which provides information about the activity level of hydroxyl radicals in the reaction. However, an explicit relationship with the Fenton process variables is not available so far. Both ORP and ph values in the reactor were monitored simultaneously on-line through experimental sampling at a period of 1 sample/sec. 4.4 Calibrating the MO concentration through the absorbance measurement Absorbance (Abs) is the measured variable indicating the fraction of light absorbed by a sample. By using the Lambert-Beer law, a proportional relationship can be obtained between the dissolved pollutant absorbance and the MO concentration. However, the Lambert-Beer law s validity is assured for diluted solutions with absorbance values lower than 1. ISBN:

5 5 Verification of parameters influence on the process In order to verify the influence of main process variables on the Color Removal Efficiency (CRE), variations of the initial values of ph, temperature, reagents concentrations and MO concentration were performed separately, for aqueous solutions of MO. Fig. 1. Laboratory-scale reactor schematic diagram. In order to obtain that relationship, six measurements of absorbance were undertaken at different MO concentrations, and the same wavelength. Figure depicts the resulting calibration curve for the MO concentration. By applying a correlation, the following relation was obtained 5.1 Effects of ph variations Luo et al. [15] have shown that the polluted solution must be acidic (ph < 7) in order to carry out the Fenton reaction. To verify the effect of ph in the process efficiency, a set of four experiments were conducted at initial values of ph of.,.5, 3.0 and 3.5, for aqueous solutions of MO, all of them with the same initial concentrations: [MO]=50 mg.l -1, [H O ]=100 mg.l -1 and [Fe + ]=14.7 mg.l -1. Process temperature was kept constant at 35 C (Figure 3). Abs MO = (15) [ ] =, r with r being the correlation factor. Thus, the percentage of Color Removal Efficiency (CRE(%)) can be computed by with [ MO] 0 [ MO] [ ] CRE (%) = (16) MO 0 the initial MO concentration. Fig. Calibration curve for the MO Concentration Fig. 3. Color removal efficiency at different initial ph values. The best MO degradation was obtained at ph=.5, for which hydroxyl radicals reactivity is higher than for the rest of experiments. From minute, the degradation percentage exceeds 95% and for minute 10 it has achieved 99.43%. Values of ph lower to.5 deteriorate the transitory behavior of the process. For higher ph values, the transient results show a satisfactory MO removal but not as fast as at ph=.5. In all the cases, MO removal was better than 95%. 5. Effects of temperature variations As the rate constant value increases when the temperature increases, the speed of MO degradation has to improve. A set of four experiences were carried out at different temperatures: 5, 35, 45 and 55 C, for aqueous solutions of MO, at initial ph=.5 and initial concentrations: [MO]=50 mg.l -1, [H O ]=100 mg.l -1 and [Fe + ]=14.7 mg.l -1 (Figure 4). ISBN:

6 For all the experiments, the MO removal was higher than 95%. The fastest dynamic is exhibited by the experience conducted at 55 C (during the first minute) and the slowest one corresponds to the experiment carried out at 5 C. Nevertheless, any of these experiences does not achieve the best color removal percentage (obtained at 35 C). The energetic costs associated to higher operational process temperatures can be significant. Therefore, for the case of study, the appropriate operational temperature condition is around 35 C. Fig. 4. Color removal efficiency at different process temperatures. 5.3 Effects of initial reagent concentration variations Chang et al. [14] have proposed an optimal ratio [Fe + ]/[H O ]=0,147 to generate hydroxyl radicals in the Fenton reaction. This ratio was verified experimentally, at 35 C, with initial ph = 3.0, initial [MO] = 50 mg.l -1, [Fe + ] = 14.7 mg.l -1, varying the reagents ratio as follows: [Fe + ]/[H O ] at , and ; for [H O ]= 75 mg.l -1, 100 mg.l -1, 150 mg.l -1 and 00 mg.l -1, respectively (Figure 5) mg.l -1 and [H O ] = 100 mg.l -1 ([Fe + ]/[H O ] = 0.147) requires a lower reagent dosage than the other two. In this sense, the ratio is optimal as it generates enough hydroxyl radical minimizing the reagents doses. 5.4 Effects of initial MO concentration variations To verify the best [reagents]/[dye] ratio, 4 experiences were conducted at 35 C, initial ph =.5, [Fe + ]/[H O ] ratio = 0.147,, initial [MO] = 50 mg.l - 1, for [H O ] = 50 mg.l -1, 100 mg.l -1, 150 mg.l -1 and 00 mg.l -1 ([H O ]/[MO] = 1,, 3 and 4, respectively). The curves obtained from experimental data are shown in figure 6. For [H O ]/[MO] =, 3 and 4 the experimental results are similar after minutes. The color removal for the experiment at [H O ]/[MO] = 1 is very poor during the first 6 minutes, while the rest of the experiments has already reached the 97%. To assure fast process dynamics and to minimize reagents dosage, the appropriate [H O ]/[MO] ratio is. So, it can be concluded that the best [MO]:[H O ]:[Fe + ] ratio is given by : [MO]:[H O ]:[Fe + ] 1 : : (16) The relation (16) was verified for other different experiments obtaining, for all the cases, MO degradation values higher than 95% after 3 minutes of reaction. Fig. 6. Color removal efficiency at different initial [H O ]/[MO] ratios ([Fe + ]/[H O ] = 0.147). Fig. 5. Color removal efficiency at different [Fe + ]/[H O ] ratios. From figure 5, it can be noticed that experiences with [Fe + ]/[H O ] = 0.147, and exhibit similar results. However, the experience for [Fe + ] = 6 MO Degradation Model 6.1 Reaction order determination The reaction order was obtained by applying the integral method by undertaking experiments at ISBN:

7 [MO]=50 mg / l, [H O ]=100 mg / l, [Fe + ]=14,7 mg / l, at a temperature 35 C and ph=3 for 5 minutes. Thus, the resulting reaction order was α=, with the correlation factor r = (Fig. 7). 7 Conclusion A theoretical model for the degradation of Methylorange (MO) by Fenton reagent, involving the initial concentrations of the reagents (hydrogen peroxide and ferrous sulfate), has been obtained. Also, a study was conducted on the variables affecting the process (i.e. temperature, ph, reagents and MO concentrations) to set appropriate operational conditions to carry out the Fenton reaction efficiently. Fig. 7. Second order kinetic correlation 6. The reaction rate constant determination The reaction rate constant was obtained by applying the Arrhenius law. To this end, a set of experiments were carried out at different temperatures (5 C, 35 C, 45 C y 55 C) with ph=,5, [MO]=50 mg / l, [H O ]=100 mg / l and [Fe + ]=14.7 mg / l. From equation () and the Arrhenius picture the following parameters were obtained Thus, the MO degradation kinetic results d [ MO] dt = T e MO [ ] (17) (18) (19) Finally, by equating (1) and (19), the constant k g is obtained and thus, the MO degradation model results [ MO] [ ][ ][ ] d 4 T + = e Fe H O MO dt KJ E a = 48,603 mol 4, l A = mg min (0) A comparison between theoretical and practical values was carried out through a correlation, and by undertaking an experiment with the following conditions: 35 C, ph=.50, [NM]=50 mg / l, [H O ]=00 mg / l and [Fe + ]=9.4 mg / l (Fig. 8). It can be noticed that similar responses are obtained by both set of values. Fig. 8. Comparison between practical and theoretical values References [1] Behnajady, M. A., Modirshahla, N., & Ghanbary, F. A kinetic model for the decolorization of C.I. Acid Yellow 3 by Fenton process. Journal of Hazardous Materials, 148, 007, pp [] Heredia, J., Torregrosa, J., Dominguez, J., & Peres, J. Kinetic model for phenolic compound oxidation by Fenton's reagent. Chemosphere, 45, 001, pp [3] Rodríguez, M. Fenton and UV-vis based advanced oxidation processes in wastewater treatment: Degradation, mineralization and biodegrability enhancement. Trabajo para optar al título de Doctor en Ingeniería Química, Universidad de Barcelona, Barcelona, España, 003. [4] Syafiie, S., Tadeo, F., Martínez, E., & Alvarez, T. Model-Free control based on reinforcement learning for a wastewater treatment problem. Applied Soft Computing Journal, 10(18), 009, pp [5] Kang, S. F., Liao, C. H., and Chen, M. C. Preoxidation and coagulation of textile wastewater by the Fenton process. Chemosphere, 46, 00, pp [6] Rivas, F., Beltrán, F., Frades, J., & Buxeda, P. Oxidation of P-Hydroxybenzoic acid by Fenton s reagent. Elsevier Science, 35(), 001, pp ISBN:

8 [7] Tantak, N. & Chaudhari, S. Degradation of azo dyes by sequential Fenton s oxidation and aerobic biological treatment. Journal of Hazardous Materials, B136, 006, pp [8] Dumitru, M., Samide, A., Preda, M., & Moanta, A. Kinetic Study of Methylorange Oxidation Process from Aqueous Solution. Revista de Chimie, 60(9), 009, pp [9] Villanueva, M., Hernández, A., Peralta, H., Quiroz, M., & Bandala, E. Congreso Regional QFB 008. Degradación del Amarillo Ácido 36 y Naranja de Metilo mediante electrogeneración de ion ferrato [Fe(IV)] en medio acido. San Nicolás de los Garza, México, Abril de 008. [10] Zambrano, B. Estudio Cinético y Comparación del Desempeño de los Filtros UKF y EKF en la Decoloración del Naranja de Metilo mediante la Reacción de Fenton. Trabajo de grado para optar el título de Ingeniero Químico, Escuela de Ing. Química, Universidad de Los Andes, Mérida, Venezuela, 009. [11] Zhang, H., Duan, L. & Zhang, D. Decolorization of methyl orange by ozonation in combination with ultrasonic irradiation. J. of Hazard Materials, 138 (1), 006, pp [1] Sun, S.P., Li, S.J., Sun, J.H., Shi, S.H., Fan, M.H. & Zhou, Q. Decolorization of an azo dye Orange G in aqueous solution by Fenton oxidation process: effect of system parameters and kinetic study. J. of Hazard Materials, 161(- 3), 009, pp [13]Yu, R.F., Chen H., Cheng, W & Hsieh P. Dosage Control of the Fenton Process for Color Removal of Textile Wastewater Applying ORP Monitoring and Artificial Neural Networks. Journal of Env. Engineering, 5, 009, pp [14] Chang, C.-Y., Hsieh, Y.-H., Cheng, K.-Y., Hsieh, L.-L., Cheng, T.-C., & Yao, K.-S. (008). Effect of ph on Fenton Process using estimation of hydroxyl radical with salicylic acid as trapping reagent. Water Science & Technology, 58(4) [15] Luo, W., Abbas, W., Zhu, L., Deng, K., & Tang, H. (008). Rapid quantitative determination of hydrogen peroxide by oxidation decolorization of methyl orange using a Fenton reaction system. Elsevier Science. [16] Blanco, J. (009). Degradación de un efluente textil real mediante procesos Fenton y Foto- Fenton. Tesis de Maestría en Ingeniería Ambiental. Universidad Politécnica de Cataluña. Barcelona, España. ISBN: