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Phenol is toxic to human and persistent in the environment. Traditional treatment methods have the disadvantages of long treatment time, large amount of agents, and secondary pollution. In this study, a novel gas-liquid two-phase dielectric barrier discharge reactor was designed to remove phenol in aqueous solution. The effects of operating conditi...
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In this study the content of phenol and 2,4-DCP (2,4-dichlorophenol) in synthetic wastewater was decomposed using the excitation technique of a mixture of waste liquid and air in a cold plasma Dielectric Barrier Discharge (DBD) reactor. The purpose of this study was to study the degradation process of organic compounds of phenol and 2,4-DCP liquid...
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... Considering the high reaction rate constant between phenol and hydroxyl radical (10 9 M − 1 S − 1 ) and the oxidizing potential of hydroxyl radical, which is the highest among oxidants after fluorine, the role of tert-butyl alcohol (TBA) as an effective deactivator of OH• in this combined system was investigated (Zhang et al., 2018). TBA competes with phenol for the available hydroxyl radicals and thus reduces the rate of phenol decomposition (Liu and Jiang, 2005). ...
... The results showed that the removal efficiency reaches 15% in 20 min and then it does not increase. This result clearly confirms that OH• is the main active species in the degradation of phenol by DBD (Zhang et al., 2018). The results of another study conducted by Hu et al. in 2021 to remove the antibiotic pefloxacin with DBDP showed that the removal percentage of this antibiotic decreases by increasing the concentration of TBA as an OH radical scavenger. ...
In this study, a non-thermal dielectric barrier discharge-Fenton/photo-Fenton process was investigated to remove phenol from synthetic wastewater. The changes and optimal values of influencing parameters, including treatment time, iron concentration, phenol initial concentration, and pH, were investigated based on the central composite design (CCD) method. The presence of 0.4 mmol/L of iron in the phenol solution with a concentration of 100 mg/L increased the removal efficiency and pseudo-first-order kinetic constant compared to dielectric barrier discharge cold plasma (DBDP) alone from 0.0824 min 1 and 56.8% to 0.2078 min 1 and 86.83%, respectively. The phenol removal efficiency was reduced to 52.9%, 45.6%, and 31.8% by adding tert-butylalcohol (TBA) with concentrations of 50, 100, and 200 mg/l, respectively. After 12 min of DBDP irradiation, the pH of the sample decreased from 5.95 to 3.42, and the temperature of the sample increased from 19.3 to 37.2 degrees Celsius. The chemical oxygen demand (COD) of the sample containing 100 mg/L phenol under plasma-Fenton/photo-Fenton irradiation decreased from 241 mg/L to 161 mg/L. Phenol removal efficiency after 10 min of treatment in the presence of 0.4 mmol/L of iron with the reactor volume of 50 mL was 87%, but the efficiency decreased to 76%, 47%, and 9% by increasing the volume to 100, 200, and 400 mL, respectively. Reducing the power led to a decrease in the removal efficiency from 56.8% for 100 W power to 10.8% for 40 W. The energy efficiency for 50% removal by DBDP and plasma-Fenton/photo-Fenton systems was 5.86 × 10 3 kWh/mg and 1.27 × 10 3 kWh/mg, respectively.
... Zhang et al. studied the phenol degradation by coaxial DBD plasma at an applied voltage of 17.6 kV, and removal efficiency of 63.9% was observed with an exposure time of 30 min. However, adding H 2 O 2 (10 mM) to coaxial DBD enhanced the degradation and observed 95.5% removal efficiency [17]. In another study, Hafeez et al. studied the degradation of reactive black-5 by a corona-DBD plasma reactor at an applied voltage of 5 kV. ...
The study describes developing an energy-efficient and scalable alternative to conventional non-thermal plasma systems by integrating surface dielectric barrier discharge (SDBD) and UV-C radiation sources. The unprecedented enhancement in the mineralisation rate of an azo dye (brilliant red 5B) by the hybrid reactor (photo-SDBD) is demonstrated thoroughly as a function of dye concentrations, pH, and background salts. The photo-SDBD is 1.25 - 4.9 times more energy efficient than SDBD under similar experimental conditions. The photo-SDBD could overcome the problems such as the recombination of hydroxyl radicals and scavenging of radicals by salts (NaCl, Na2SO4, Na2CO3) observed in conventional non-thermal plasma systems. The TOC and HR-MS analysis establish the complete mineralisation potential and chemical mineralisation pathway. Besides, the phytotoxicity of the treated water is tested and demonstrated its utility as a liquid fertiliser for enhanced germination of mung bean seeds. The optical emission spectroscopy measurements were performed to estimate the plasma's electron temperature (1.6 ± 0.2 eV) and density (1021/m3). The emission line ratio (I763.5/I738.3) approach is used to compare the influence of UV-C on plasma parameters in the SDBD reactor. The study opens a new pathway for developing energy-efficient and scalable plasma-assisted mineralisation of complex and emerging organic pollutants.
... Katayama et al. used argon/neon-liquid DBD to decompose aqueous persistent organic substances and determined that the produced OH groups played a very important role in the decomposition of acetic acid [37]. Zhang et al. developed a gas-liquid DBD reactor to remove phenol in an aqueous solution and verified that OH was the main active species in phenol removed [38]. Yang et al. applied gas-liquid DBD to remove NO x and found the treatment effectiveness was much better than traditional gas-phase DBD [39]. ...
A discharge in contact with water in atmospheric air and argon (Ar) was presented. The electrical and optical characteristics were experimentally investigated and compared in different voltage ranges. The waveforms of voltage and current revealed this discharge didn't happen symmetrically in each period due to the asymmetric geometry of the reactor. The OH intensity obtained by Optical Emission Spectrometer (OES), discharge power P and transfer charge Q analyzed by the Lissajous method, and rotational temperature Tr and vibrational temperature Tv fitted by LIFBASE software based on OH spectra were bigger in Ar–H2O dielectric barrier discharge (DBD) than in air-H2O at 11 and 12 kV, except only Tv of Ar–H2O DBD was a little bit smaller than that of air-H2O DBD at 12 kV. Tr and Tv indicated these two gas-H2O DBDs were non thermal-equilibrium discharges. This experimental work is helpful in comprehensively understanding the discharge manner of gas-liquid at electrical, physical, and chemical aspects.
... Besides the substitution of reactor type from the straight type with 25 mm length to the helical type with 2.0 m length can improve the contact area between gas-liquid water and applied discharge plasma, it seems that this substitution also can provide the longer residence time of bubble motion in the slug-flow reactor system from 3 s to 3 min. This aspect is one of important factors in terms of applying high voltage discharge plasma to provoke the discharge plasma reactivity in gasliquid water system [37][38][39]. Figure 4 displays the conversions of CBB and MB dye compounds after treatment by high voltage discharge plasma with various gas phases in the straight and helical types of slug-flow reactor system. As informed before, besides CBB was known as a prominent synthetic dye and widely applied in various industrial applications, this dye compound is recognized to be an organic pollutant in wastewater when this organic pollutant released into the water environment directly without some treatment. ...
... The influence of pH affects the reactivity of the compound since chlorophenol is dissociating compound. In addition, the effect of the pH value will have an impact on the production of hydroxyl and ozone radicals [5]. ...
Liquid waste containing 2-chlorophenol compound has high toxicity, carcinogenic, and poor degradation properties, leading to bioaccumulation in the environment. It also considered as a primary chemical feedstock in the manufacture and widely used in various industry. Conventional methods such as chlorination, adsorption, liquid-liquid extraction, steam distillation, photocatalytic are inefficient and expensive. Plasma technology with a non-thermal dielectric barrier discharge (DBD) plasma reactor can efficiently degrade chlorophenol compounds without producing side effects. Various active species produced in the reactor are electrons and radical compounds •OH, O 3 , H 2 O 2 . This study aims to evaluate the degradation performance of DBD plasma reactors, namely the percentage of degradation, degradation concentrations of 2-chlorophenol, and chemical oxygen demand (COD). Variations were made with pH 4 and 10, while the fixed variables were waste flow rate 50 mL/min, air flow rate 2.5 L/min, and plasmatron voltage 19kV. It was found that degradation process of 2-chlorophenol with DBD reactor in pH 4 and 10 achieve 70.96% and 79.41%, respectively.
... Many studies of AOP systems used phenol as an indicator substance [11,23,[52][53][54][55][56][57][58]. This aromatic substance can be degraded by both radical mechanisms and direct reaction with O3 [54,55]. ...
... Phenol was used to study the effect of discharge conditions in the electric field on the amount of degradation. The results of Tang et al. [56] and Zhang et al. [23] showed higher removal of phenol at rising voltage level due to the correlation of the input energy accelerating free electrons and the number of active species produced. Also secondary physical effects such as ultraviolet light (UV) emission and shock waves might be stronger during the discharge process at higher applied voltages, further enhancing radical formation [23]. ...
... The results of Tang et al. [56] and Zhang et al. [23] showed higher removal of phenol at rising voltage level due to the correlation of the input energy accelerating free electrons and the number of active species produced. Also secondary physical effects such as ultraviolet light (UV) emission and shock waves might be stronger during the discharge process at higher applied voltages, further enhancing radical formation [23]. Additionally, increasing repetition rates of the HV pulses seem to promote the degradation, which was attributed to rising energy input in the electrode system intensifying the electric field and the oxidizing agent formation [57]. ...
In this study, a lab-scale plant was designed to treat water in continuous flow condition using non-thermal plasma technology. The core was an electrode system with connected high-voltage (HV) pulse generator. Its potentials and limitations were investigated in different experimental series with regard to the high-voltage settings, additions of oxygen-based species, different volume flow rates, and various physical-chemical properties of the process water such as conductivity, pH value, and temperature. Indigo carmine, para-Chlorobenzoic acid, and phenol were chosen as reference substances. The best HV settings was found for the voltage amplitude Û = 30 kV, the pulse repetition rate f = 0.4–0.6 kHz, and the pulse duration tb = 500 ns with an energy yield for 50% degradation G50, which is of 41.8 g∙kWh−1 for indigo carmine, 0.32 g∙kWh−1 for para-Chlorobenzoic acid, and 1.04 g∙kWh−1 for phenol. By adding 1 × 10−3 mol∙L−1 of oxygen, a 50% increase in degradation was achieved for para-Chlorobenzoic acid. Conductivity is the key parameter for degradation efficiency with a negative exponential dependence. The most important species for degradation are hydroxyl radicals (c ≈ 1.4 × 10−8 mol∙L−1) and solvated electrons (c ≈ 1.4 × 10−8 mol∙L−1). The results show that the technology could be upgraded from the small-scale experiments described in the literature to a pilot plant level and has the potential to be used on a large scale for different applications.
... Dielectric Barrier Discharge (DBD) is one of the cold plasma technologies that has received enormous attention for the removal of organic pollutants in recent years. The use of DBD technology for wastewater degradation has been studied before, including Zhang that conducted a study on degradation of 2,4-dichlorophenol in aqueous solution by DBD with effects of plasma-working gases, degradation pathways and toxicity assessment [4] and Zhang, H that conducted a study on effects of discharge spacing, pH, conductivity for phenol degradation by DBD [5] further chemical reactions. As compared to other treatment methods, DBD produces a stable, uniform, and diffuse discharge. ...
Pheolic compounds, including phenol and DCP (2,4-Dichlorophenol), are one of the most toxic compounds commonly found in chemical, pharmaceutical, textile, and petrochemical industrial wastes. This compound has been considered a great potential risk for the environment and human health. Previous studies have shown that it can be removed from industrial wastes by several biological and physical-chemical methods such as chemical adsorption and oxidation techniques, however, these methods are still considered to possess distinctive disadvantages. This is the first study to employ the use of a prototype of cold plasma Dielectric Barrier Discharge (DBD) reactor, with a coaxial configuration. The purpose of this study was to investigate the degradation process of phenolic compounds, obtained from synthetic wastewater into a simpler compound. The performance of the DBD plasma reactor and the effects of various parameters, such as air flow rates 2 – 2.5 L/min and water flow rates 50 – 100 mL/min, combination with ozonation, and the presence of iron in treated wastewater have been investigated. The results showed the DBD plasma reactor was successfully removed phenol as a water pollutant, achieving 98% efficiency with a combination of ozonation.
... The increase in thermal effect accelerated the migration rate of ammonia nitrogen and phenol molecules to the zeolite surface and improved the adsorption efficiency of zeolite. As the discharge voltage increased, the amount of active groups, such as H 2 O 2 and O 3 , in the reaction solution increased, and the energy and quantity of high-energy electrons were greatly improved [24,25].Therefore, as the applied voltage increased, the ammonia nitrogen and phenol removal efficiencies improved. Fig. 6 shows that the removal rate of ammonia nitrogen (100 mg/L) or phenol (20 mg/L) wastewater increased with discharge frequency. ...
In this work, dielectric barrier discharge (DBD) coupled with Fe-based zeolite catalyst was used to treat ammonia
nitrogen and phenol wastewater. This experiment mainly investigated the effects of discharge voltage, discharge
frequency, zeolite dosage, initial solution concentration and pH on ammonia nitrogen or phenol removal. Results
showed that the removal rate of ammonia nitrogen increased with increased discharge voltage, discharge fre�quency, zeolite dosage, and initial pH and decreased with increased initial ammonia nitrogen concentration. The
best removal rate of ammonia nitrogen reached 75.11%, which was higher than removal rates of the solutions
treated with zeolite adsorption alone (10.93%) and DBD discharge alone (9.67%). However, the removal rate of
phenol increased with discharge voltage, discharge frequency, and zeolite dosage and decreased with increased
initial phenol concentration and initial solution pH. After 20 min of reaction, the removal rate of phenol reached
56.67%, which was higher than the removal rates of the solutions treated with zeolite adsorption alone (20.61%)
and DBD discharge alone (3.54%).Therefore, a DBD-coupled metal zeolite catalyst system has a good treatment
effect on inorganic and organic wastewater. In addition, DBD-coupled Fe-based zeolite catalyst was used to
simultaneously treat mixed ammonia nitrogen and phenol wastewater. The degradation process and mechanism
of mixed ammonia nitrogen and phenol wastewater in the system were studied to reflect the synergistic effect of
the system.
Specialized chemicals are used for intensifying food production, including boosting meat and crop yields. Among the applied formulations, antibiotics and pesticides pose a severe threat to the natural balance of the ecosystem, as they either contribute to the development of multidrug resistance among pathogens or exhibit ecotoxic and mutagenic actions of a persistent character. Recently, cold atmospheric pressure plasmas (CAPPs) have emerged as promising technologies for degradation of these organic pollutants. CAPP-based technologies show eco-friendliness and potency for the removal of organic pollutants of diverse chemical formulas and different modes of action. For this reason, various types of CAPP-based systems are presented in this review and assessed in terms of their constructions, types of discharges, operating parameters, and efficiencies in the degradation of antibiotics and persistent organic pollutants. Additionally, the key role of reactive oxygen and nitrogen species (RONS) is highlighted. Moreover, optimization of the CAPP operating parameters seems crucial to effectively remove contaminants. Finally, the CAPP-related paths and technologies are further considered in terms of biological and environmental effects associated with the treatments, including changes in antibacterial properties and toxicity of the exposed solutions, as well as the potential of the CAPP-based strategies for limiting the spread of multidrug resistance.
