International audienceMany researches for the abatement of aqueous pharmaceutical pollutants in water by Advanced Oxidation Processes (AOPs), including electrical discharge plasmas, have been performed in the last decade. In the present study, non-thermal plasma coupled to catalyst was used for the degradation of paracetamol in water. The plasma was produced in a reactor consisting in a multiple needle-to-plate DBD discharge configuration, while catalyst is a metal oxide based catalyst. In order to investigate the influence of the oxide nature, various home-made catalysts (iron or manganese-based), prepared by wet impregnating method, were tested. Comparisons of the results with or without catalyst on the paracetamol degradation and the physico-chemistry of the treated liquids were done, and they showed that the iron-based catalyst presented better results in terms of conversion and mineralization. Concretely, coupling this catalyst to non-thermal plasma, after 30 min of treatment, the paracetamol conversion is 78 % with 45 % mineralization, against 51% and 3% respectively with plasma alone. The paracetamol degradation as a function of the treatment duration was investigated with this catalyst

Aubry, Olivier

Hong, Dunpin

Norsic, Caroline

Rabat, Hervé

English

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HAL Id: hal-01980069
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Combination of non-thermal plasma and hetergeneous
catalysis for paracetamol degradation in water
Caroline Norsic, Hervé Rabat, Olivier Aubry, Dunpin Hong
To cite this version:
Caroline Norsic, Hervé Rabat, Olivier Aubry, Dunpin Hong. Combination of non-thermal plasma
and hetergeneous catalysis for paracetamol degradation in water. International Symposium on Non-
Thermal/Thermal Plasma Pollution Control Technology & Sustainable Energy, ISNTPT-11, Jul 2018,
Montegegrotto Terme, Italy. ￿hal-01980069￿
Combination of non-thermal plasma and heterogeneous catalysis for 
paracetamol degradation in water  
 
C. Norsic1, H. Rabat1, O. Aubry1, D. Hong1 
 
1 GREMI UMR7344, 14 rue d'Issoudun 45067 Orléans, France  
caroline.norsic@univ-orleans.fr 
 
Abstract. Many researches for the abatement of aqueous pharmaceutical pollutants in water by 
Advanced Oxidation Processes (AOPs), including electrical discharge plasmas, have been performed in 
the last decade. In the present study, non-thermal plasma coupled to catalyst was used for the degradation 
of paracetamol in water. The plasma was produced in a reactor consisting in a multiple needle-to-plate 
DBD discharge configuration, while catalyst is a metal oxide based catalyst. In order to investigate the 
influence of the oxide nature, various home-made catalysts (iron or manganese -based), prepared by wet 
impregnating method, were tested. Comparisons of the results with or without catalyst on the 
paracetamol degradation and the physico-chemistry of the treated liquids were done, and they showed 
that the iron-based catalyst presented better results in terms of conversion and mineralization. 
Concretely, coupling this catalyst to non-thermal plasma, after 30 min of treatment, the paracetamol 
conversion is 78 % with 45 % mineralization, against 51% and 3% respectively with plasma alone. The 
paracetamol degradation as a function of the treatment duration was investigated with this catalyst. 
 
 
1. Introduction 
Due to an important humans’ drug consumption, many pharmaceutical compounds are present 
at low concentration in surface water and ground water, while various studies reported the 
presence of drug residues in drinking water even after treatment [1-2]. Water pollution with the 
pharmaceutical compounds is considered as a serious environmental problem since these 
chemicals have harmful effects on aquatic ecosystems and negative impacts on human health. 
In order to remedy this issue, Advanced Oxidation Processes (AOPs) have been developed [2-
3], since these processes such as the Fenton process, peroxone, UV oxidation, and Non-Thermal 
Atmospheric pressure Plasma (NTAP) generate many oxidizing species (O•, O3, OH•, H2O2…), 
very reactive with pollutants. The degradation of pharmaceutical compounds by NTAP was 
studied during the last decade [4-6] by using discharges in the gas phase in contact with the 
liquid or directly in the liquid (electrohydraulic discharges). Note that Electrohydraulic 
discharges have low energy efficiency for water decontamination [7-8]. 
In this paper, the experiments carried out with a plasma reactor consisting in a multiple needle-
to-plate discharge DBD configuration are presented. The discharges are generated at the tip of 
the needles above liquid. With the aim of improving energy efficiency in plasma degradation 
process, catalyst was added in the liquid.  
In literatures, various types of catalyst were studied combined with plasma. Carbon materials 
have been widely used due to their important adsorption efficiency and their catalytic property 
in the oxidizing environment [9-10]. Photocatalysts like TiO2 were also frequently studied with 
the plasma for the decomposition of organic pollutants in liquid media [11-12]. Ferrous salts 
were also often added in plasma system because these salts catalytically transform formed H2O2 
into hydroxyl radicals via Fenton reactions [13-14]. Like the classic Fenton catalysts (with 
ferrous salts), the heterogeneous Fenton-like catalysts can be used with plasma to convert H2O2 
into reactive species, but few results have been reported to date. However, the heterogeneous 
Fenton-like catalysts can have several advantages over the homogeneous. It can easily be 
recycled or regenerated, and contrary to the homogeneous catalyst, the solid catalyst is easy to 
handle. The Fenton-like catalysts are frequently iron oxides based catalysts, but Fe in Fe oxides 
structures can be replaced by other cations like Co, Mn, Cr, Cu… [15]. These transition metal 
oxides are also well known to be very effective for ozone decomposition. It seems thus really 
interesting to combine non thermal plasma, which produces ozone, with a heterogeneous 
Fenton-like catalyst. Indeed, this catalyst can convert both, formed H2O2 into hydroxyl radicals, 
but also ozone into oxygenated radicals. 
In the present study, various oxide based catalysts (Al2O3/GF, Fe2O3/Al2O3/GF and 
MnO2/Al2O3/GF) were tested in combination with the plasma for paracetamol degradation in 
water. These oxides were supported on Glass Fibers fabric (GF). The results are presented in 
terms of paracetamol conversion and mineralization. Comparisons of the results with or without 
catalysts and the physico-chemistry of the treated liquids were realized. The paracetamol 
degradation as a function of the treatment duration was also investigated. 
 
2. Experimental 
2.1 Experimental setup 
The used NTAP reactor is showed in Figure 1 and was described in previous papers [5, 16]. It 
is a DBD reactor with a multiple needles-to-plate configuration inside a vessel made of PVC 
where the working gas can be controlled. The working gas (air) was introduced through the 
needles with a total flow rate of 100 sccm. High voltage is applied to 12 needles. The grounded 
electrode is a copper film deposited on a dielectric epoxy plate. The liquid to be treated is above 
this dielectric and under the needle-electrodes. The distance between the tip of the needles and 
the surface of the liquid was 5 mm. The volume of liquid to be treated was 40 mL. The liquid 
was a solution of pure water containing paracetamol with an initial concentration of 25 mg.L-1. 
The catalyst was placed in the liquid to be treated above the dielectric. 
The discharges were generated thanks a High Voltage (HV) square waveform with a frequency 
of 500 Hz using a HV amplifier (Trek® 20/20C) driven by a function generator (TG4001 TTI®). 
Electrical measurements were realized by means of high-voltage (PE20 KV Lecroy®) probes 
connected to an oscilloscope (DPO 3054 Tektronic®). The dissipated power was determined 
using the so-called Lissajous method requiring the adding of a convenient capacitor in the 
discharge circuit.  
 
Fig. 1 Scheme of the multiple needle-to-plate reactor 
2.2 Catalyst preparation 
Glass Fiber fabric (GF) (Diall 135 g/m²) used as support had a circular shape of 110 mm in 
diameter. GF were then calcined to 400°C during 4 hours to remove the binder. A washcoat of 
alumina (Aluminum oxide nanopowder, 13 nm primary particle size from Aldrich®) was 
realized on calcinated GF to create a bearing layer for the active phase. The washcoat was 
prepared with 5 g of alumina, 0,7 mL of nitric acid and 20 mL of ultra-pure water [17]. The 
mixture was stirred during 12 hours at room temperature by means of a magnetic rod. Glass 
fibers were immersed a few second in the washcoat solution, dried during 2 hours in a drying 
oven at 100°C, and then calcined under air at 400°C during 4h (2°C/min) to eliminate nitric 
acid and residual water. After these steps, supported catalyst Al2O3/GF was obtained. 
Metal oxide catalysts of Fe2O3/Al2O3/GF and MnO2/Al2O3/GF were synthesized following the 
incipient wetness method. Al2O3/GF were impregnated with an aqueous solution of iron (III) 
nitrate nonahydrate (Aldrich®) or manganese (II) nitrate aqueous (Strem Chemicals®, 50-52%) 
with a metal oxide loading of 10 wt.%. The obtained solid was then dried overnight at 100°C 
and after calcined under air, during 4h at 300 °C for manganese and 400 °C for iron oxide. 
2.3 Analytical methods 
The paracetamol concentration was quantified using an UV-Visible absorption 
spectrophotometer (Cary 60 UV-Vis Agilent Technologies®) and the Beer Lambert equation 
from the absorption peak of paracetamol at the wavelength of 244 nm. The concentrations of 
the formed NO3
- and H2O2 were estimated using a photometer MultiDirect from Lovibond
®. 
pH and conductivity were measured with a Accumet XL600 (Fisher Scientific®). A TOC-L 
(SHIMADZU®) was used to determine the Total Carbon (TC), Inorganic Carbon (IC) and by 
subtracting the Total Organic Carbon (TOC) in the solution before and after treatment. With 
TOC, it is possible to calculate the mineralization rate (degradation of the organic compounds 
in the liquid to CO2).  
3. Results and Discussion 
3.1 Influence of the oxide nature 
The effects of different oxides coupled with plasma were evaluated in terms of paracetamol 
conversion and mineralization rates. The conversion and mineralization rates were calculated 
with the following equations (1) and (2), respectively. C0, Ct are the concentrations of 
paracetamol and TOC0, TOCt the concentrations of organic carbon in the solution, at the 
beginning (t = 0) and at the end of the treatment (t).  
𝑐𝑜𝑛𝑣𝑒𝑟𝑠𝑖𝑜𝑛 (%) =
𝐶0 − 𝐶𝑡
𝐶0
× 100 (1) 
𝑚𝑖𝑛𝑒𝑟𝑎𝑙𝑖𝑧𝑎𝑡𝑖𝑜𝑛 (%) =
𝑇𝑂𝐶0 − 𝑇𝑂𝐶𝑡
𝑇𝑂𝐶0
× 100 (2) 
According to the results shown in Fig. 2, we observed an increase of the paracetamol conversion 
and mineralization with all the tested oxides coupled with plasma. The beneficial effects of the 
catalysts are as follow for conversion and mineralization: 
MnO2/Al2O3/GF < Al2O3/GF < Fe2O3/Al2O3/GF 
 
Fig. 2  Paracetamol conversion and mineralization rates after treatment with plasma alone and with plasma 
coupled with different oxide based catalysts (U = ± 5,6 kV, treatment time : 30 min, gas : 100 sccm air ) 
The least important improvement is obtained with MnO2 oxide. MnO2 is well known for ozone 
decomposition [18], but the formed ozone in gas phase can have difficulties to reach MnO2 
surface because it has a very low solubility in water and there is a competition between water 
and ozone adsorption on the active sites of MnO2. Moreover, it seems that this oxide does not 
allow to improve H2O2 conversion (Table 1). H2O2 concentrations are similar after treatment 
with plasma alone and with plasma + MnO2/Al2O3/GF. The Al2O3/GF catalyst, in turn, seems 
act like a Fenton Catalyst (FC), an improvement of the H2O2 conversion was observed (Table 
0
10
20
30
40
50
60
70
80
90
100
plasma alone plasma +
Al2O3/GF
plasma +
MnO2/Al2O3/GF
plasma +
Fe2O3/Al2O3/GF
%
Conversion rate Mineralization rate
1) and thus conversion and mineralization rates significantly increase. With the 
Fe2O3/Al2O3/GF catalyst, the best results were observed. This catalyst seems really efficient to 
form hydroxyl radicals, according to the equation (3), which quickly react with the pollutant or 
by-products.  
FC + H2O2  FC+ + OH• + OH- (3) 
According to the results shown in Table 1, we observed a slight decrease of the pH after each 
treatment due to the formation of nitrates and carboxylic acids (observed by HRMS analysis). 
With catalysts, more nitrates were still formed compared to plasma alone. Indeed, with catalysts 
more reactive species are formed, thereby improving the paracetamol conversion and 
mineralization rates but also the formation of nitrates. The conductivity of the solution is also 
very important after treatment with catalysts.  
Table 1 Concentration of NO3-, H2O2, pH and conductivity before and after the different treatment (U = ± 5,6 kV, treatment 
time t : 30 min, gas : 100 sccm air) 
 [NO3-]t mg.L-1 [H2O2]t mg.L-1 pH0  pHt λ0  λt  µS.cm-1 
Plasma alone 25 3 6.5  5 18  37 
Plasma + Al2O3/GF 56 <1 8.5  8.2 75  227 
Plasma + MnO2/Al2O3/GF 62 3 8  6.5 63  192 
Plasma + Fe2O3/Al2O3/GF 56 <1 9  8 70  196 
In the following section, a study of the paracetamol degradation as a function of treatment 
duration was presented with Fe2O3/Al2O3/GF catalyst. This catalyst was chosen because it 
showed better results coupled to plasma than other catalysts. 
3.2 Study of the paracetamol degradation as a function of the treatment time 
In this part, the paracetamol conversion and mineralization rates were determined as a function 
of the treatment duration. The non-thermal plasma was combined with the Fe2O3/Al2O3/GF 
catalyst for this study and the results were compared with those obtained by plasma alone. 
Better results were obtained with the presence of the catalyst. After 1h of treatment, a total 
conversion of the paracetamol and a mineralization rate of 84 % were obtained with catalyst 
(Figure 3).  
The energy yield was also calculated according to the equation (3). C0, Ct (g.L
-1) are the 
concentrations of pollutant in the solution at the beginning and at the end of the time interval 
Δt (h), V is the volume of the treated solution (L) ant P the consumed power (kW). 
EY (g.kWh-1)= 
(𝐶0−𝐶𝑡)×𝑉
𝛥𝑡×𝑃
 (3) 
An improvement of the energy yield was observed in presence of the catalyst (Figure 3a) during 
the paracetamol treatment. For 45 and 60 min of treatment, the gap between plasma alone and 
plasma + catalyst is however lower. Indeed, the more the treatment time increases, the less it 
remains of paracetamol to be treated. But more by-products were oxidized as can be seen with 
the rate of mineralization (Figure 3b). From 45 min of treatment, the mineralization rate 
increases. HRMS analysis confirm these results. By-products with important molar mass were 
observed after treatment by plasma alone, but with catalyst lighter by-products were observed, 
and for 45 and 60 min of treatment you can see there's not much left in there. 
  
Fig. 3 Paracetamol degradation for different treatment duration with and without catalyst, (a) Conversion rates 
and energy yields, (b)Mineralization rates (Catalyst : Fe2O3/Al2O3/GF, U = ± 5,6 kV, gas : 100 sccm air) 
4. Conclusion 
In this study, non-thermal plasma coupled to catalysis was used for the degradation of 
paracetamol. Various heterogeneous catalysts were developed and tested. Until now, the 
coupling of plasma and heterogeneous catalyst was studied little. But according to this study, 
the combination of non-thermal plasma and heterogeneous catalysis shows a great interest. 
Indeed, the degradation of the paracetamol was highly improved with their presences, and the 
conversion, mineralization rates but also energy yield were improved greatly. The best results 
in terms of conversion and mineralization were achieved with the iron-based catalyst 
(Fe2O3/Al2O3/GF). Coupling with this catalyst to non-thermal plasma, the paracetamol 
conversion is 100% with 84% mineralization after 60 min of treatment, against 64% and 4% 
respectively with plasma alone (without catalyst).  
 
Acknowledgments 
We gratefully acknowledge the financial support provided to the PIVOTS project by the Région 
Centre – Val de Loire. 
 
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Combination of non-thermal plasma and hetergeneous catalysis for paracetamol degradation in water

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Combination of non-thermal plasma and hetergeneous catalysis for paracetamol degradation in water

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