Scholarly article on topic 'Performances Evaluation of Photo-Fenton Process and Sonolysis for the Treatment of Penicillin G Formulation Effluent'

Performances Evaluation of Photo-Fenton Process and Sonolysis for the Treatment of Penicillin G Formulation Effluent Academic research paper on "Chemical sciences"

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{"Advanced oxidation" / "Penicillin G" / Photo-Fenton / Sonolysis / Pharmaceuticals}

Abstract of research paper on Chemical sciences, author of scientific article — M. Sadegh Saghafinia, S. Mehdi Emadian, M. Vossoughi

Abstract Penicillin G is an active pharmaceutical ingredient of great importance in health sectors. Meanwhile, because of its huge quantity production and resistance to biodegradability, this antibiotic is ubiquitously presented in aquatic environment. In this study, the degradation of effluent wastewater from Penicillin G production plant by Photo- Fenton process and Ultrasound process (Sonolysis) was investigated, the effects of different process variables in both methods were evaluated and at last the degradation of Pen-G by these two processes in the optimum conditions was compared. Pen-G concentration and Chemical Oxygen Demand (COD) were selected as the environmental parameters to follow the performance of Photo-Fenton process and Sonolysis. Optimum condition of Photo-Fenton process is in H2O2/Fe2+ molar ratio 20 (20mM H2O2 and 1mM Fe2+) and pH 3.5 and for Sonolysis (35 KHz) is in pH 3. Complete degradation of Pen-G occurred in 30 and 70min for Photo-Fenton process and Sonolysis, respectively. Based on the results, Photo-Fenton process is more efficient in terms of both COD degradation and Pen-G removal than Sonolysis (35 KHz).

Academic research paper on topic "Performances Evaluation of Photo-Fenton Process and Sonolysis for the Treatment of Penicillin G Formulation Effluent"

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Procedía EnvironmentalSciences 8 (2011) 202-208

Procedía

Environmental Sciences

ICESB 2011: 25-26 November 2011, Maldives

Performances Evaluation of Photo-Fenton Process and Sonolysis for the Treatment of Penicillin G Formulation

Effluent

M. Sadegh Saghafiniaa'*, S. Mehdi Emadiana, M. Vossoughia

aDepartment of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran

Abstract

Penicillin G is an active pharmaceutical ingredient of great importance in health sectors. Meanwhile, because of its huge quantity production and resistance to biodegradability, this antibiotic is ubiquitously presented in aquatic environment.

In this study, the degradation of effluent wastewater from Penicillin G production plant by Photo-Fenton process and Ultrasound process (Sonolysis) was investigated, the effects of different process variables in both methods were evaluated and at last the degradation of Pen-G by these two processes in the optimum conditions was compared. Pen-G concentration and Chemical Oxygen Demand (COD) were selected as the environmental parameters to follow the performance of Photo-Fenton process and Sonolysis. Optimum condition of Photo-Fenton process is in H2O2/Fe2+ molar ratio 20 (20 mM H2O2 and 1 mM Fe2+) and pH 3.5 and for Sonolysis (35 KHz) is in pH 3. Complete degradation of Pen-G occurred in 30 and 70 min for Photo-Fenton process and Sonolysis, respectively. Based on the results, Photo-Fenton process is more efficient in terms of both COD degradation and Pen-G removal than Sonolysis (35 KHz).

© 2011 PublishedbyElsevierLtd. Selection and/or peer-review underresponsibility of the Asia-Pacific Chemical, Biological & Environmental Engineering Society (APCBEES)

Keywords: Advanced oxidation; Penicillin G; Photo-Fenton; Sonolysis; Pharmaceuticals

CorrocporCirg author. Tel.: +98 2122641736; fax: +98 2122614717. E-mail address: caCogh.caghafiria@gmail.eom (M.SaCegh Saghafinia).

1878-0296 © 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Asia-Pacific Chemical, Biological &

Environmental Engineering Society (APCBEES)

doi:10.1016/j.proenv.2011.10.033

1. Introduction

Antibiotics are an important group of pharmaceuticals. Recently, there has been a growing interest in the fate of antibiotics in municipal sewage and surface waters due to the variety of residues that have been found in the aquatic environment [1]. Antibiotics are known as nonbiodegradable substances that potentially survive sewage treatment.

Penicillin G (Pen-G) (pKa = 2.75) was the first antibiotic isolated and had been used for the treatment of various infectious diseases [2]. It belongs to the lactam class of antibiotics; contain a lactam ring. Widely appearing bacteria resistance for this molecule has been a serious concern for clinicians and environmentalists, because of its large production, worldwide [3].

Numerous treatments have been developed to degrade the residual of Pen-G in industrial effluent. Advanced Oxidation Processes (AOPs) are of great interest for the treatment of contaminated surface and for destruction of toxic and biorefractory organic pollutants found in industrial wastewater. AOPs rely on the generation of very reactive oxidizing agents, e.g. free radicals such as the hydroxyl radical OOH). Hydroxyl radical can initiate oxidative degradation reactions of refractory synthetic and natural organic compounds and is capable of converting them ultimately to CO2 and H2O owing to their high oxidation potential. AOPs have already been successfully applied for the treatment of industrial effluents containing toxic and/or recalcitrant (difficult to degrade) organic pollutants [4].

There are several oxidative processes involving iron compounds and hydrogen peroxide (H2O2) to provide alternative ways of •OH generation. In the Photo-Fenton process, additional reactions occur in the presence of light that produce hydroxyl radicals or increase the production rate of hydroxyl radicals, thus increasing the efficiency of the process. Direct photolysis of H2O2 produces •OH, however, because of the fact that H2O2 only weakly absorbs solar radiation, •OH formation by this process is very slow. H2O2, though, can serve as a •OH source via pathways involving iron salts or oxides [5]. The reaction of H2O2 occurs with ferric (Fe3+) and ferrous (Fe2+) iron in acidic aqueous solutions which are among the most common homogeneous systems and potential sources of hydroxyl radicals' generation (Eq.1). Iron-catalyzed H2O2 decomposition known as the Fenton's reaction provides an alternative way of oxidizing recalcitrant and/or toxic organic compounds present in most industrial wastewaters [6].

Fo2+ + H2O2 (Eq.l(

Fo3+ + OH- + OH' k= 63M-1 s-1

The hydroxyl radical (•OH) formed can react with and initiate the oxidation of organic pollutants (shown as R) in acidic aqueous solutions (Eq.2) [7]:

•OH + RH ^ R' + H2O, k= 117 Co 1111M-1 s-1 (Eq. 2(

Ultrasound process (Sonolysis) is another process of AOP to degrade the refractory organic matters in industrial wastewater. Some important advantages of the Sonolysis are that it does not require addition of oxidants or catalysts and that it does not generate additional waste. The Sonolysis is also not restricted by toxicity or low biodegradability of contaminants [8]. The chemical effect of ultrasound is caused by the phenomenon of cavitations. Acoustic cavitations are the formation, growth and implosive collapse of small bubbles in a liquid blasted with sound [9].

The collapse of these bubbles leads to surprisingly high local temperatures and pressures. Two reaction mechanisms have mainly been proposed to explain sonochemical degradation of organic compounds in aqueous solutions. The first mechanism is pyrolysis in the cavitation bubbles. The second mechanism is the generation of hydroxyl radicals in the cavitation bubbles due to thermolysis of water. These radicals can subsequently oxidize the organic compounds in the interfacial region [10].

Considering the above mentioned facts, the aim of this study was to present experimental results for

the degradation of an effluent containing the antibiotic Pen-G by two methods; namely, the Photo-Fenton process and Sonolysis. Pen-G was selected as the organic index pollutant because of its high consumption rate and its poor biodegradability. The specific objective of this study was to examine and optimize the operating conditions of Photo-Fenton process (H2O2/Fe2+ molar ratio, pH and irradiation time) and of Sonolysis (pH, irradiation time) on degradation for Pen-G. Subsequently the degradation of Pen-G by these two processes in the optimum conditions was compared.

2. Material and Methods

2.1. hyetaitto Wastewater

Antibiotics aqueous solutions were prepared by dissolving pure Pen-G (Solubility in water: 100 g/l; molecular weight of Penicillin G potassium salt, C16H17KN2O4S = 372.48 g/mol) in distilled water. Pure Pen-G was supplied by Shifa PharMed Group of Industries Co., Tehran, Iran. Structure of used KPen-G is shown in Fig.1. The concentrations of aqueous solution were in rang of exited wastewater concentrations of Pen-G from production site in Shifa PharMed Group of Industries Co. and were kept in 4C.

According to the report of Shifa Pharmed Group of Industries Co., minimum and maximum concentrations of Pen-G at the existed wastewater of production site are 50 and 200 ppm, respectively. To observe the effect of initial antibiotics concentrations, experiments were conducted by varying the initial concentration of Pen-G as 50, 100, 150 and 200 ppm for each process in aqueous solution. The corresponding COD were 300, 680, 800 and 940 mg/L, respectively.

Hydrogen peroxide (30%, W/W), ferrous sulphate heptahydrate (FeSO4-7H2O), sodium hydroxide (NaOH) and sulphuric acid (H2SO4) that used for pH adjustment in Photo-Fenton process were all purchased from Merck Co., Germany. All stock and buffer solutions were prepared with distilled water.

2.2. Analytical methods

Antibiotics concentration was determined by HPLC (Knauer, Smartline model) equipped with micro-vacuum degasser. Pump's flow rate was 1ml/ min. UV detector (2600) was at wavelength 220 nm. The detection column was KROMASIL, L1 (10cm*4.6mm* 5^m). The column temperature was set at 50C. Mobile phase was buffer solution (0.01M KH2PO4 in ultra purified water), Methanol 60:40. Fig.1 (a) shows the HPLC chromatograph for Pen-G.

Soluble Chemical Oxygen Demand (SCOD) was measured immediately after filtration through 0.2^m filter papers by closed reflux colorimetric method [11]. Because all samples contained hydrogen peroxide, to reduce interference in COD measurement and to stop the reaction at suitable time, pH was increased to 6-7 to decompose hydrogen peroxide to oxygen and water. The pH-value was measured with a pH-meter (model: 691 pH meter, made by Metrohm Herisau, Switzerland).

Fig. 1: (a) HPLC chromatography and structure of Pen-G; (b) Effect of H2O2/Fe2+ molar ratio on Pen-G removal in Photo-Fenton reaction

2.3. Experimental Setup

This study was performed in two stages; first stage was optimization in terms of Pen-G removal (H2O2/Fe2+ molar ratio, pH and irradiation time optimization for Photo-Fenton, pH and irradiation time for Sonolysis). Subsequently for the second stage, degradation of antibiotics for Photo-Fenton process and Sonolysis were compared in the terms of Pen-G removal and COD degradation. Batch experiments were conducted in 100 ml Pyrex reactor with 50 ml of the antibiotics aqueous solution.

2.3.1. Photo-Fenton process

For each batch the required amount of FeSO4-7H2O was added and mixed homogeneously. Thereafter, pH of aqueous solution was adjusted with NaOH and H2SO4 (0.1M). Then required amount of H2O2 was added to the mixture. The time at which H2O2 was added considered the beginning of the experiment. The source of UV-Light was an UV-Lamp with nominal power of 125W, emitting radiations at wave length ~254nm. The reaction solutions were vigorously mixed by means of a shaker at 120 rpm.

2.3.2. Sonolysis

To make the study more feasible and minimize the cost of treatment operations, all of experiments were conducted with a 35 KHz sonicator (BANDELIN Electconic, type RK 514H, process power 860 W). The temperature in reactor was maintained at room temperature. The pH of the solution was adjusted to desired value by adding the appropriate phosphate buffer (1M).

3. Results and Discussion

3.1. PhoCo-Fo/Co/ Process

3.1.1. Effect of H2O2/Fe2+ molar ratio

To optimize H2O2/Fe2+ molar ratio, experiments were conducted at pH 3.5 with constant H2O2 concentration (20 mM) and varying Fe2+ concentration in range of 0.2 - 4 mM. Therefore the corresponding H2O2/Fe2+ molar ratio were in range of 5-100. The initial concentration of Pen-G was 200 ppm (the highest concentration of Pen-G in wastewater of Shifa PharMed Industrial Group Co.). Fig.1 (b)

shows the effect of H2O2/Fe molar ratio on Pen-G removal. After 50 min irradiation Pen-G removal percent was 57.14, 66.28, 81.28, 77.14 and 81.43 at H2O2/Fe2+ molar ratio 100, 50, 20, 10 and 6.6, respectively. The results show increase in Pen-G removal with decrease in H2O2/Fe2+ molar ratio up to 20 mM. More H2O2/Fe2+ molar ratio decreasing did not improve Pen-G removal. This may owing to the fact that hydroxide radical reacted with metal ions directly at high concentration of Fe2+ as Eq.3;

Fe2+ +OH ^ Fe3+ +OH- (Eq. 3)

Hence, 20 was chosen as optimal H2O2/Fe2+ molar ratio with H2O2 and Fe2+ concentrations at 20 mM and 1 mM, respectively.

3.1.2. Effect of pH and reaction time on Photo Fenton-reaction

According to the overall reaction for Photo-Fenton's oxidation, which is given in Eq.4 [12], the pH value has to be in acidic rang to generate maximum amount of hydroxide radicals.

2Fe2+ +H2O2 +2H+ 2Fe3+ +2H2O (Eq.4)

Thus, experiments were conducted by varying the pH between 2 and 4. Initial Pen-G concentration was 200 ppm in aqueous solution. The other operating condition was H2O2/Fe2+ molar ratio20 mM. Fig.2 (a) shows the effect of pH on Pen-G removal. After 50 minutes irradiation, Pen-G removal percent was 67.14, 81, 81.28 and 78.57 at pH 2, 3, 3.5 and 4, respectively. The results from this study demonstrated that the optimal pH for treatment of antibiotics aqueous solution by Photo-Fenton reaction was 3.5.

To determine the best reaction time for Photo-Fenton reaction, experiments were conducted by analyzing the concentration of Pen-G in different reaction periods. Fig.2 (b) shows Pen-G removal in different reaction times. The results demonstrate that Pen-G removal was increased by increasing reaction time (up to 30 min). However, future extension of the treatment time to 40 and 50 minutes did not significantly improve Pen-G removal (P<0.05). These results agree well with that reported by I. Arslan-Alaton et al. [13]. Hence effective reaction time was fixed as 30 minutes.

100 81 81.29 78 57

67.14 m

I I I I

3 3.5 pH Values

Fig.2: (a) Effect of pH variations on Pen-G removal in Photo-Fenton reaction; (b) Effects of reaction time variations Pen-G removal in Photo-Fenton reaction (H2O2/Fe2+ molar ratio=20 and pH=3.5)

3.2. hrerlysts Prronss

3.2.1. Effect of pH and reaction time

It has been shown that pH can play an important role in sonochemical degradation of chemicals [14]. Hence this parameter was optimized in the term of Pen-G removal. The initial concentration of Pen-G was 200 ppm. Degradation experiments were executed at four pH values (3, 5, 7 and 10). Fig.3 (a) shows

the effect of pH on Pen-G removal. After 120 min irradiation, removal efficiency at pH=3 was significantly higher than other pH values (P<0.05). It is estimated that Pen-G itself is more instable in acidic solution and could get involved in oxidation reaction easier [15]. The small increase in removal efficiency at pH=10 can be attributed to the electrophilic nature of hydroxyl radical.

To determine the effective reaction time for Pen-G removal in Sonolysis process, experiments were sampled in different times which are shown in Fig.5 (b). The initial concentration of Pen-G was 200 ppm and pH was fixed to 3. As the results exhibit, the reaction was almost completed after 70 minutes. Therefore, affective reaction time was fixed to 70 minutes.

100 80 66.68 60 40 20 0

DD. Do

1 ■ 1

pH Values

Fig.3: (a) Effect of pH value variations on Pen-G removal in Sonolysis process; (b) Effect of reaction time variations on Pen-G removal in Sonolysis process

3.3. Effect of initial antibiotics concentration in the optimized condition

Fig. 4 shows the effect of initial antibiotics concentration on Pen-G removal percentage and COD degradation percentage. It is obvious that Pen-G concentration does not have any significant effect on its removal in Sonolysis process, while it is a gentle increase in removal percentage by increase in Pen-G concentration in Photo-Fenton method. This may because of greater amount of H2O2 that was presented in the medium of Photo-Fenton process [16]. Fig.7 shows decrease in COD degradation by increase of Pen-G concentration. This decrease is obvious in Sonolysis, However, it is not significant in Photo-Fenton process (P=0.05). Ultimately, Photo-Fenton process was much more efficient in terms of both COD degradation and Pen-G removal (P=0.05). Undoubtedly, frequency of sonicator (35 KHz) which is not the optimum frequency for cavitation Phenomenon had great impact on the result of this study.

100 50

■"If 11 h|

50 100 150 2C Peri-G coriceritratori {ppm)

Photo-Fenton ■ Sonolysis (a)

{LI Q-

Peri-G coriceritratori {ppm)

Pholo-Fcnlon ■ Sonolysis

Fig.4: Effect of initial (a) COD and (b) Pen-G concentration variations on performance of Photo-Fenton and Sonolysis processes (Photo-Fenton process H2O2/Fe2+ =20, pH=3.5 and irradiation time= 30min; Sonolysis process pH=3 and irradiation time= 70min)

4. Conclusions

Photo-Fenton process and Sonolysis are both effective in Pen-G removal and COD degradation. Optimum condition of Photo-Fenton process is in H2O2/Fe2+ molar ratio 20(20 mM H2O2 and 1 mM Fe2+) and pH 3.5. In optimized condition the reaction reach to the highest degradation in 30 minutes. Optimum condition of Sonolysis (35 KHz) is in pH 3. In optimized condition the reaction reach to the highest degradation in 70 minutes. Initial concentration of Pen-G in both methods has direct proportion with Pen-G removal, whereas has inverse proportion with COD degradation. Photo-Fenton process is more efficient in terms of both COD degradation and Pen-G removal than Sonolysis with 35 KHz frequency.

Acknowledgements

The authors gratefully acknowledge Biochemistry and Environment Center of Sharif University of Technology and Shifa PharMed Industrial Group Co. for providing facilities for this research.

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