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Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

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Use of Fenton’s Reagent for Pollutants Removal in 

Pharmaceutical Effluent 

 

By 

E.I. Madukasi and O.B.Tojuola 

 

 

 

Abstract 

Effluent from a pharmaceutical factory producing a single chemical product was treated on a 

bench scale with advance oxidation process (H2O2 & Fe2+). The effluent was as a result of the 

factory treatment of the pharmaceutical wastewater by UASB (up flow anaerobic sludge bed) 

and a SBR (sequencing batch reactor) process. The chromatechemical oxygen demand 

(CODcr) range of the discharged effluent was between 8000-10,000mg/L with some residual 

recalcitrant compounds. The residual recalcitrant compounds which were measured by gas 

chromatography mass spectrometry (GC-MS) mainly consisted of alcohols, phenols and 

nitrogenous and sulfur compounds. The experimental variables studied include dosages of Fe2+, 

H2O2 and mixing speed. The result showed that the oxidation by Fenton’s reagent was best 

when concentration of iron (II) sulfate and hydrogen peroxide were [Fe2+]=1.093mmol/L; 

[H2O2] = 2.5mmol/L at pH = 3.0 for 30min at 80rpm; followed by conditioning with lime (1%) 

to pH = 8.0 where coagulation by iron hydroxide took place over 20min. Under these optimal 

operating conditions, the maximum removal efficiency for CODcr, Color and the aromatic 

compounds were 56%, 95% and 90% respectively. 

Keywords: Fenton reagent; pharmaceutical effluent; hydrogen peroxide; ferrous salt; effluent 

treatment; chemical treatment 

 

 

Introduction 

The process of toxicity reduction in pharmaceutical wastewater is of paramount 

importance due to known fact that substances synthesized in pharmaceutical 

industry are either toxic inhibitory compound or structurally complex organic 

chemicals that are resistant to biological degradation and consequent 

accumulation in the environment as well as possible carcinogenic and 



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mutagenic effect (Jia et al, 2015; Ronak & Shweta, 2015; Balcioglu & Otker, 

2003). This makes conventional treatment methods inadequate for the 

treatment of pharmaceutical wastewater. One of the possible methods for their 

degradation and removal is chemical oxidation, especially advanced oxidation 

processes (AOPs) using for example O3/H2O2 (peroxone); O3/H2O2/UV; 

O3/UV; H2O2/UV; Tio2/UV and Fenton reactions. These processes involve the 

in-situ formation of highly reactive hydroxyl radicals (•OH), which react 

quickly and non-selectively with almost all organic pollutants (Vrushali & 

Gawande, 2015; Tijani et al., 2016; Sanchis et al., 2013). One of the most 

important advance oxidation processes used to generate hydroxyl radicals 

employs the Fe2+/H2O2 system where the catalyst (ferrous ions) is dissolved in 

water, thus being known as Fenton process (Yuan et al., 2013). Fenton’s 

reaction is one of the most effective methods of oxidation of organic pollutants 

that are oxidatively degraded by hydroxyl radicals generated from H2O2 in the 

presence of Fe3+ as a catalyst (Hartmann et al., 2010; Maezono et al., 2011). 

Fe2+ + H2O2 ------------> fe3+ + OH + OH• equation1.  

When ferrous salts are used, the hydroxyl radical is produced immediately by 

the rapid reaction between ferrous ion and H2O2 (equqtion1). Fe3+ can also be 

used to decompose H2O2 and to produce oxidative radicals in the Fenton-like 

process. With Ferric salts, the hydroxyl radical is produced in a two-stage 

process with the slow reaction between ferric ion and H2O2 (equation2) 

followed by the rapid reaction between the produced ferrous ion and additional 

hydrogen peroxide [Kiwi et al.,1993]. Fe3+ + H2O2------------> fe2+ +HO2
• + H+ 

equation 2.  

In most applications, it does not matter whether fe2+ or fe3+ ions are used to 

catalyze the reaction, although some authors (Pera-Titus et al., 2004; Walling 

& Amarnath, 1982) suggested that if low doses of Fenton’s reagent are used 

ferrous ions may be preferable. The efficiency of Fenton’s process depends on 

H2O2 and fe2+ concentrations and the pH of the reaction. According to some 

previous researcher’s report, pH value should range from 3 to 5 

(Mohammadine et al., 2014; Navalon et al., 2010 and Maezono et al., 2011).  

Fenton reagent was found to be very effective in treating various industrial 

wastewater components, including aromatic & aliphatic compounds 

(Barbusinski & Filipek, 2001), a wide variety of dyes (Hsueh et al., 2005) as 

well as many other substances, including pesticides (Barbusïñki & Filpek., 

2001). In this work, we present the oxidative treatment of pharmaceutical 

effluent that contained some recalcitrant compounds by Fenton reaction, using 

COD as determinand for the parameter only. This is because the 

pharmaceutical effluent will be subjected to critical biological treatment but 

effort was geared towards understanding the behavior of the effluent in a 

chemical treatment method hence the use of a single and most suitable 



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parameter for efficiency determination. 

 

Material & Methods 

Wastewater: 

The pharmaceutical effluent is from a medium scale drug manufacturing plant 

situated in Ota near Lagos State Nigeria. The presence of toxic compounds in 

wastewater was both due to the factory product as well as chemicals used in 

sterilizing the manufacturing equipment. The intermittent cleaning and 

disinfecting of the tanks used in the production as well as domestic utilization 

of the tap water make up the wastewater coming out of the plant. The plant 

manufacturing line is operated as batch reactor. All the characteristics of the 

wastewater (Table1) were measured according to procedures described in 

standard methods (AWWA, 1995) 

Table1: Pharmaceutical Effluent Chemical Characterization 

PARAMETERS MEAN VALUE 

pH 

BOD5 (mg L-1) 

COD (mg L-1) 

Suspended solids (mg L-1) 

Total solids (mg L-1) 

Fats and Oils (mg L-1) 

Detergents (mg L-1) 

Odour 

4,3 ± 0,3 

1370 ± 260 

8030 ± 800 

65 ± 10 

1400 ± 400 

45 ± 25 

100 ± 50 

Noticeable, peculiar, savoury 

 

Experimental procedure: 

The following parameters of Fenton’s reaction were examined and optimized; 

hydrogen peroxide and ferrous concentration, [fe2+]: [H2O2] ratio, and initial 

pH of the reaction. A liter of wastewater was added into one liter Erlenmeyer 

flask which served as the reactor, acidified with H2SO4 (Fenton reaction is 

effective at acidic pH range). Since the initial pH of the wastewater is above 

5.0, the sample was acidified to the desired value in the pH range of 2.5 –4.0. 

After which various doses of 30% H2O2 and solid FeSO4.7H2O were added, the 

mixture was vigorously stirred for 1hour at 80rpm (oxidation process), then pH 

was adjusted to 8.0 with 1% lime and coagulated at 30rpm for 20min. it was 

allowed to sediment and chemical oxygen demand (COD) and residual H2O2 

were determined in the clear solution. COD tests were made after total removal 

of residual H2O2. The residual H2O2 can increase the COD value since it acts as 

a reductant, especially in the chromate based analysis of COD determination. 

Talinli and Anderson (1992) investigated the reducing effect of H2O2 on 



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K2Cr2O7 and they showed linear relationship between concentration of H2O2 

and COD. 

 

Residual H2O2 removal 

This was achieved by raising the pH of the solution (pH=10.5) at high 

temperature (45) in the presence of fe3+ with stirring at 65rpm and was sit 

overnight (Walling & Amarnath, 1982; Krzysztof Barbusinski, 2009). 

 

Analytical methods 

Aromatic and aliphatic compounds were analyzed by Infrared spectrometer 

(FTIR spectrometer) and confirmed with gas chromatography – mass 

spectrometry (GC– MS) as shown in fig1. The trace element analyses were 

carried out with inductive coupled plasma (optimal emission spectrometer, 

optima 5300DV). COD (closed reflux, trimetric method). Concentration of 

residual H2O2 was analyzed by the KMnO4 method. 

 

Fig.1: GC Chromatogram of the pharmaceutical Effluent 

 

Statistical Analysis  

Data are presented as mean ± SD of triplicate determinations and descriptive 

statistics was conducted using Microsoft Excel (2016). 

 

Result and Discussion 

Effect of Fe2+ concentration. 

It was shown that as the concentration of Fe2+ increased, the COD removal 

increased until a point where further addition of iron becomes inefficient. The 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

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feature of an optimal dose range for the iron catalyst is characteristics of 

Fenton reagent although the range varies for different wastewater. Typical 

ranges are [Fe2+]:[H2O2 ] = 5– 25 (Pere-Titus et al., 2004). Figure2 shows the 

effect of iron dosage on COD removal using different initial H2O2 

concentrations. The result showed that the efficiency of Fenton reaction 

depends on the concentration of fe2+ as occurs in the classical Fenton reagent 

process. (Rajesh & Raman, 2013) have demonstrated that the COD removal is 

nearly the same using either fe2+ or fe3+ in the degradation of a textile 

wastewater by the Fenton process. The maximum COD removal achieved in 

this study was between 40 – 56% depending on the hydrogen peroxide dosage. 

 

FIG. 2:: Effect of Fe2+ Concentration variation 

H2O2 @ 1.6M; pH = 2.5; Mixing speed = 100rpm @ 30min 

 

Effect of temperature and pH 

An initial experiment was carried out at room temperature and at 50oC, to show 

the effect of temperature on COD removal efficiency but no significant 

differences were observed in the treatment efficiency for the tested 

temperatures (data not shown). Thus all further work was carried out at room 

temperature. Research findings indicate that the temperature of the wastewater 

almost does not affect the efficiency of COD removal in Fenton’s oxidation 

(Peral et al., 2002; Casero et al., 1997), although the redox reaction can be 

accelerated by rising the temperature as expected. The time required for the 

oxidation to be completed at room temperature was about 15–20 times longer 

than at 50oC which required several minutes (data not shown). When tested 

with initial pH range of 2.5 – 4.5, no significant differences in the treatment 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

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efficiency were observed although pH 3.5 showed slightly better results. This 

finding is in adherence with the recent research reports that suggest that the 

optimum pH for Fenton oxidation is between 3–5 and that it is independent of 

the nature of the wastewater. (Tambosi et al., 2006; Hsueh et al., 2005) all 

observed that pH affects significantly the degradation of organics by Fenton 

reaction and acidic condition is required to produce sufficient hydroxyl radicals 

by the decomposition of hydrogen peroxide catalyzed by ferrous ions. In a 

recent study, (Zhang et al., 2005) reported the optimum pH as 2.5 for the 

treatment of landfill leachate by Fenton’s oxidation. 

 

Effect of H2O2 concentration 

The degradation rate of organics in wastewater increases as the concentration 

of H2O2 increases until a critical H2O2 concentration is achieved (Huseh, et al., 

2005). Above this critical concentration, the degradation rate of organic 

compounds decreases as a result of the scavenging effect, according to 

equation3 H2O2 + OH• ------------> HO2 
• + H2O (3) Fig.3 clearly shows that as 

the concentration of H2O2 increases, there was an increase in the COD removal 

efficiency up to the optimum concentration of 15ml/L. Above this amount of 

H2O2, there was decrease in the efficiency removal. 

 

Conclusion 

The Fenton process could be applied to pharmaceutical effluent. The COD 

removal efficiency using oxidation was greatly affected by the initial pH of the 

solution. The most efficient reaction was observed at a pH of 3.0 and the 

optimum coagulation pH range to maximize the COD removal efficiency was 

between 6.0 – 8.0. For a pharmaceutical wastewater with a COD range of 8000 

– 10000mg/L, average COD removal efficiency was highest when the ratio of 

H2O2/Fe2+ was about 150–250. At 0.3M H2O2 and 0.012M the optimum COD 

removal efficiency of 65% was achieved. Fenton reagent could be used to treat 

pharmaceutical wastewater that contains some constituents that are extremely 

toxic to biological processes hence viewed as biocides. Fenton’s reaction 

proves to be an efficient treatment technology when biological treatment is not 

feasible. 

 

 

 



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Acknowledgements 

The authors wish to acknowledge the technical support given by FIIRO and 

COOU respectively. 

 

 

REFERENCES  

Alpha Standard Methods for the Examination of Water and Wastewater, 18th 

edn. American Public Health Association Washington, DC, 1992.  

Balcioglu, A. and Otker,M.(2003). Treatment of pharmaceutical wastewater 

containing antibiotics by O3 and O3/H2O2 processes, Chemosphere 50: 

85–95. 

Barbusïñki, K. and Filpek, K. (2001). Use of Fenton’s Reagent for Removal of 

pesticides from Industrial Wastewater. Polish Journal of Environmental 

Studies. 10(4): 207 – 212. 

Barbusinski, K. (2009). Fenton Reaction-Controversy concerning the 

chemistry, Journal of society of ecological chemistry and engineering, 

16(3):348-358. 

Casero, D., Sicilia, S. R, and Perez, D. B. (1997). Chemical degradation of 

aromatic amines by Fenton’s reagent, Water Res.31: 1985 - 1995. 

Hsueh,C. L; Huang, Y.H., Wang, C.C. and Chen, C.Y. (2005). Degradation of 

azo dyes using low iron concentration of Fenton and Fenton-like system, 

Chemosphere, 58: 1409-1414. 

Huicen, Z., Weimin, G., Zhemin, S., Qingli,T., Wenchao, J. and Lijuan, J. 

(2015). QSAR models for degradation of organic pollutants in ozonation 

process under acidic condition. Chemosphere 119:.65-71. 

Jimoh. O., Tijani, O.,  Fatoba, O., Omotola, O., Babajide, L. and Petrik, 

F.(2016). Pharmaceuticals, endocrine disruptors, personal care products, 

nanomaterials and perfluorinated pollutants. A review. Environmental 

chemistry letters. 14(1):27-49. 

Kiwi, J., Dulgarin, C., Peringer, P. and Gratzel, M. (1993). Beneficial effects of 

homogenous photofenton pretreatment up on the biodegradation of 

anthraquinone sulfonate in wastewater treatment. Appl. Catal. B. 

Environmental. .3: 85-88. 

https://pubag.nal.usda.gov/?q=%22Jimoh+O.+Tijani%22&search_field=author
https://pubag.nal.usda.gov/?q=%22Ojo+O.+Fatoba%22&search_field=author
https://pubag.nal.usda.gov/?q=%22Omotola+O.+Babajide%22&search_field=author
https://pubag.nal.usda.gov/?q=%22Leslie+F.+Petrik%22&search_field=author


Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

14 
 

Maezono, T., Tokumura, M., Sekine M., and Kawase, Y. (2011). Hydroxyl 

radical concentration profile in photo-Fenton oxidation process: 

Generation and consumption of hydroxyl radicals during the 

discoloration of azo-dye Orange II. Chemosphere 82(10):1422-1430. 

Marin, S.,  Ramos, A. J.,  Cano-Sancho, G., and Sanchis, V. (2013). 

Mycotoxins: Occurrence, toicology and exposure assessment (Review). 

Food and Chemical Toxicology 60: 218–237. 

Mohammadine, E. H., Abdelmajid, Regti., Rachid, Laamari., Rachid, 

Mamouni. and Nabil, Saffaj. (2014). Use of Fenton reagent as advance 

oxidative process for removing textile dyes from aqueous solutions. 

Journal of Material and Environmental Science 5(3): 667-674. 

Navalon, S., Alvaro, M. and Garcia, H. (2010). Heterogeneous Fenton catalysts 

based on clays, silicas and zeolites. Applied Catalysis B: Environmental. 

99(1-2):1-26.  

Pere-Titus, M., Garcia-Molina, V., Banos, M. A., GimeneZ, J., Esplugas, S. 

(2004). Degradation of chlorophenols by means of advanced oxidation 

process: a general review, Applied Catalysis B: Environmental, 47: 219-

256. 

Pérez, M.,  Torrades, F., Doménech, X. and Peral, J. (2002). Fenton and photo-

Fenton oxidation of textile effluents, Water Res. 36: 2703–2710.  

Rajesh, N., and Raman, S. (2013). Treatment of Pharmaceutical Sludge by 

Fenton Oxidation Process. International Journal of Chemical 

Engineering and Applications. 4(6): 359-364. 

Ronak, S., Shweta, V. (2015). Fenton’s Reagent for the Treatment of 

Pharmaceutical Industry Wastewater. International Journal of Science 

and Research. 4(7): 3093-3095. 

Talinli, I. Anderson, G. K. (1992). Interference of hydrogen peroxide on the 

standard COD test. Wat. Res. 26: 107- 110. 

Tambosi, J.L., Domenico, M., Schirmer, W.N., Jose, H.J., Moreira-Reaina, 

F.P.M (2006). Pre-oxidation and coagulation on pper & pulp wastewater 

by fenton-like process. J. Chem. Tech and Biotech. 81(8): 1426-1432. 

Vrushali, P. and Sagar, G. (2015). .An overview of the Fenton Process for 

Industrial Wastewater. Journal of Mechanical and Civil Engineering. 

21:127-136. 

Walling, C., Amarnath, K. (1982). Oxidation of mandelic acid by Fenton’s 

reagent. J. Am. Chem. Soc. 104: 1185-1189. 



Global Online Journal of Academic Research (GOJAR), Vol. 2, No. 2 Mar-Apr 2023 

 

 

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Zhang, H., Choi, H. J. and Huang, C. P. (2005) Optimization of Fenton process 

for the treatment of landfill leachate, J. Hazard. Mater. 125: 66-174. 

 

 

 

Author Information: Dr Edith Ifeoma Madukasi is a lecturer in the 

Department of Environmental Management, Faculty of Environmental 

Sciences, Chukwuemeka Odumegwu Ojukwu University, Uli, Anambra 

State, Nigeria. Email: madify2002@gmail.com 
 

 

O.B.Tojuola works at the Federal Institute of Industrial Research, Oshodi, 

Lagos, Nigeria. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


