Non-thermal Plasma Technology Research Articles

Decomposition of VOCs using serial surface dielectric barrier discharge reactors

ABSTRACT Decomposition of two typical volatile organic compounds (VOCs): toluene and methyl ethyl ketone (MEK), was investigated by introducing the complete energy yield (i.e. amount of VOCs totally converted to CO and CO2 for every 1 kWh of electrical usage) and specific energy density (SED) for the non-thermal plasma technology. Three dielectric barrier discharge reactors of which SED range was 55 J/L to 283 J/L at a flow rate of 1 L/min were connected in a 3-reactor arranged in series using interconnecting tubes in the inlets and outlets. As a result of the serial reactor design, the energy efficiency of the system improved, and in particular, 7% of increase was found in at the same level of energy consumption. The mixed phase of VOCs (toluene and MEK) showed MEK as a limiting species in this study. As the inlet concentration rose from 20 to 100 ppmv, both energy yield and complete energy yield increased from 0.8 to 9.2 g/kWh and from 0.8 to 2.3 g/kWh, respectively.

Non-Thermal Plasma Coupled with Catalyst for the Degradation of Water Pollutants: A Review

Non-thermal plasma is one of the most promising technologies used for the degradation of hazardous pollutants in wastewater. Recent studies evidenced that various operating parameters influence the yield of the Non-Thermal Plasma (NTP)-based processes. In particular, the presence of a catalyst, suitably placed in the NTP reactor, induces a significant increase in process performance with respect to NTP alone. For this purpose, several researchers have studied the ability of NTP coupled to catalysts for the removal of different kind of pollutants in aqueous solution. It is clear that it is still complicated to define an optimal condition that can be suitable for all types of contaminants as well as for the various types of catalysts used in this context. However, it was highlighted that the operational parameters play a fundamental role. However, it is often difficult to understand the effect that plasma can induce on the catalyst and on the production of the oxidizing species most responsible for the degradation of contaminants. For this reason, the aim of this review is to summarize catalytic formulations coupled with non-thermal plasma technology for water pollutants removal. In particular, the reactor configuration to be adopted when NTP was coupled with a catalyst was presented, as well as the position of the catalyst in the reactor and the role of the main oxidizing species. Furthermore, in this review, a comparison in terms of degradation and mineralization efficiency was made for the different cases studied.

Gas-phase isopropanol degradation by nonthermal plasma combined with Mn-Cu/-Al2O3.

In this study, the dielectric barrier discharge (DBD) induced by nonthermal plasma (NTP) technology was used for isopropanol (IPA) degradation. IPA, intermediate, final product, and ozone concentrations were analyzed using GC-MS, carbon dioxide detector, and ozone detector. The experimental flow rate and concentration were fixed to 1 L/min and 1200 ppm ± 10%, respectively. Different reaction procedures were proposed for self-made metal catalyst combined with a plasma system (plasma alone and γ-Al2O3 combined with plasma, Cu (5 wt%)/γ-Al2O3 combined with plasma, Mn (3 wt%)-Cu (5 wt%)/γ-Al2O3 combined with plasma). In addition, the effect of the carrier gas oxygen content (0%, 20%, and 100%) on IPA conversion and intermediate and carbon dioxide selectivity was also investigated. The results revealed that the Mn (F)-Cu/γ-Al2O3 combined with plasma exhibited more efficient IPA conversion. In the 100% oxygen environment, the IPA conversion rate increased from 79.32 to 99.99%, and carbon dioxide selectivity increased from 3.82 to 50.23%. IPA was completely converted after 60 min of plasma treatment with the acetone selectivity, carbon dioxide selectivity, and tail ozone concentration of 26.71% ± 1.27%, 50.23% ± 0.56%, and 1761 ± 11 ppm, respectively. This study proved that the current single planar DBD configuration is an effective advanced treatment technology for the decomposition of VOCs.

Degradation of cefixime antibiotic in water by atmospheric plasma bubbles: Performance, degradation pathways and toxicity evaluation

• Underwater plasma bubbles were used to degrade cefixime in water. • Complete cefixime degradation with high-energy yield of 1.5 g/kWh. • Degradation of cefixime was conducted by reactive species, especially short-lived OH radicals. • Degradation pathways of cefixime were proposed by intermediates identified by LCMS. • Plasma treatment leads to the loss of antibacterial activity and cytotoxicity of cefixime. Excessive use and indiscriminate discharge of antibiotics inevitably lead to their accumulation in the environment, posing significant ecological and physiological risks. Non-thermal plasma (NTP) is receiving increasing attention as a sustainable technology for the efficient breakdown of these antibiotics as well as other contaminants. However, implementation of NTP technology still faces several hurdles, particularly the maximization of the reactive plasma effects and the practical scaling approaches. In this study, we generated NTP inside forming bubbles with enlarged gas-liquid interfacial areas for efficient delivery of reactive plasma species to target cefixime antibiotic molecules in aqueous solution. The degradation of cefixime was largely dependent on the different number of microholes, air flow rate, discharge power, plasma exposure time and solution properties. Results show that a high-performance degradation was achieved in the 10-microhole reactor with an energy yield of 1.5 g/kWh, after 30 min of plasma treatment. Based on LC-MS analysis, an NTP-initiated cefixime degradation pathway was proposed. Cytotoxicity studies demonstrated that the antibiotic activity of cefixime was effectively and wholly deactivated by the plasma process, and that no toxic effects of the 30 min-treated water were observed toward human cell lines. Furthermore, considering that air was employed as the inducer gas, which results in the formation of reactive nitrogen species in the water, the treated water was able to enhance seedling growth, further contributing to the societal and economic benefits of this plasma-based antibiotic degradation strategy.

Material extrusion additively manufactured alumina monolithic structures to improve the efficiency of plasma-catalytic oxidation of toluene

Abstract Non-thermal plasma (NTP) technology is one of the strategies with the most potential for the degradation of volatile organic compounds. Exploring the combination of plasma and catalysts in one system is of considerable significance to improve energy efficiency and decrease harmful by-products. The current geometrical design of monolithic catalysts is not optimal due to the limitations of traditional manufacturing processes. Here, the use of material extrusion additive manufacturing, followed by debinding and sintering to construct alumina monolithic catalysts with two-dimensional channels is suggested. A new feedstock material was adapted to the additive manufacturing process, and Al2O3 structures with unique axial and radial channels coated with Mn-Co nanospheres were successfully prepared for the plasma-catalytic degradation of toluene. The monoliths with radial and axial channels considerably increased energy efficiency with a minor increase in by-products. This work demonstrates the advantages of using additive manufacturing and provides a general strategy for the design and fabrication of monolithic catalysts with two-dimensional channel structures for heterogeneous catalysis.

Applications of nonthermal plasma technology on safety and quality of dried food ingredients.

Cold plasma technology is an efficient, environmental-friendly, economic and noninvasive technology; and in recent years these advantages placed this novel technology at the centre of diverse studies for food industry applications. Dried food ingredients including spices, herbs, powders and seeds are an important part of the human diet; and the growing demands of consumers for higher quality and safe food products have led to increased research into alternative decontamination methods. Numerous studies have investigated the effect of nonthermal plasma on dried food ingredients for food safety and quality purposes. This review provides critical review on potential of cold plasma for disinfection of dried food surfaces (spices, herbs and seeds), improvement of functional and rheological properties of dried ingredients (powders, proteins and starches). The review further highlights the benefits of plasma treatment for enhancement of seeds performance and germination yield which could be applied in agricultural sector in near future. Different studies applying plasma technology for control of pathogens and spoilage micro-organisms and modification of food quality and germination of dried food products followed by benefits and current challenges are presented. However, more systemic research needs to be addressed for successful adoption of this technology in food industry.

A Review about the Recent Advances in Selected NonThermal Plasma Assisted Solid-Gas Phase Chemical Processes.

Plasma science has attracted the interest of researchers in various disciplines since the 1990s. This continuously evolving field has spawned investigations into several applications, including industrial sterilization, pollution control, polymer science, food safety and biomedicine. nonthermal plasma (NTP) can promote the occurrence of chemical reactions in a lower operating temperature range, condition in which, in a conventional process, a catalyst is generally not active. The aim, when using NTP, is to selectively transfer electrical energy to the electrons, generating free radicals through collisions and promoting the desired chemical changes without spending energy in heating the system. Therefore, NTP can be used in various fields, such as NOx removal from exhaust gases, soot removal from diesel engine exhaust, volatile organic compound (VOC) decomposition, industrial applications, such as ammonia production or methanation reaction (Sabatier reaction). The combination of NTP technology with catalysts is a promising option to improve selectivity and efficiency in some chemical processes. In this review, recent advances in selected nonthermal plasma assisted solid–gas processes are introduced, and the attention was mainly focused on the use of the dielectric barrier discharge (DBD) reactors.

Removal of bromoamine acid in dye wastewater by gas-liquid plasma: The role of ozone and hydroxyl radical

As a widely used anthraquinone dye intermediate, bromoamine acid (BAA) exists extensively in dye wastewater. In this study, the gas-liquid discharge non-thermal plasma technology was employed to degrade BAA. Efficient removal was achieved by the system within 15 min treatment. Besides, the effects of input power, working gas flow rate and solution pH value on BAA removal efficiency were investigated. BAA removal rate increased with higher input power and lower pH value, while too high or too low working gas flow rate could lead to the decrease of BAA removal. The existence of BAA caused significant decline of aqueous ozone concentration while enhanced the production of H2O2, indicating that the aqueous ozone participated in BAA degradation. The contributions of main active species were investigated. H2O2 and UV produced by discharges showed little effects on BAA degradation individually, however led to synergistic effect by producing OH. Over 60 % removal of BAA was attributed to OH oxidation, while direct molecular ozone contributed around 20 % degradation. The second-order rate constants of BAA reacting with ozone and OH were determined to be 1.22 × 103 M−1 s−1 and 4.06 × 109 M−1 s−1, respectively. A kinetic model was established to predict BAA degradation. 12 degradation intermediates were detected by HPLC-Q-ToF-MS, GC–MS and HPLC-UV. The degradation was mainly caused by hydroxylation, bond cleavage and addition of OH on double bonds.

Evaluating the Performance of a Lab-Scale Water Treatment Plant Using Non-Thermal Plasma Technology

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.

Continuous Generation of HgCl2 by Dielectric Barrier Discharge Nonthermal Plasma. Part II: Influences of the Cl Source

This study is the first investigation on the effects of the Cl source on Hg0 oxidation by dielectric barrier discharge (DBD) nonthermal plasma technology in a self-developed DBD reactor under atmos...

Real diesel engine exhaust emission control: indirect non-thermal plasma and comparison to direct plasma for NOX, THC, CO, and CO2.

Recently, diesel engine exhaust emission control by non-thermal plasma (NTP) technology has been shown to be promising. However, carbon and soot deposition on the inner surface of the NTP reactor for direct plasma processing decreased the efficiency of the plasma process throughout the experiments. In the present work, the feasibility of indirect plasma processing was investigated as an innovative and novel method compared to direct plasma processing. Air was directed through an NTP at an applied voltage of VP-P = 7kV and a flow rate of 1-4L/min, and then, it was combined with engine exhaust gas at a flow rate of 5L/min. In this case, the maximum conversion of NOX was 64.9% at 4L/min. However, for direct plasma processing at 5L/min, NO conversion was 58%, which proves that the indirect NTP process can decrease NOX concentration effectively. The maximum conversion for unburned hydrocarbon (UHC), carbon monoxide (CO) and carbon dioxide (CO2) was obtained as 2%, 4% and 0.7% at 4, 2 and 3L/min in indirect plasma processing; While their remove rate for direct plasma processing was 16.3%, -0.5% and 13.2%, respectively.

Oil extraction from spent coffee grounds assisted by non-thermal plasma

Coffee is one of the most popular beverages in the world and around 50% of the processed coffee beans becomes waste as spent coffee grounds (SCG). These SCG contain up to 20% of oil, which can be recovered and used in many different processes, such as biodiesel production, cosmetics and pharmaceuticals. The extracted oil contains large amounts of antioxidants, anti-inflammatory agents and immunomodulators, in addition to fatty acids that have excellent emollient and moisturizing properties. It is therefore of interest to improve the oil extraction technique, to enhance the efficiency, reduce the extraction time and improve the quality of the oil extracted. Thus, in this study, a new technique for SCG oil extraction, using a non-thermal plasma technology as a pre-extraction procedure prior to Soxhlet extraction, was investigated, aiming to improve the extraction efficiency and oil quality. For comparison purposes, experiments were also carried out using an ultrasound pre-extraction procedure prior to Soxhlet extraction. It was observed that the use of pre-extraction with the plasma more than double the extraction yield compared with the Soxhlet extraction alone. Also, it increased the yield by around 30% compared with the use of ultrasound as the pre-extraction procedure. Analysis of the oil extracted by GC–MS showed that the quality of the oil composition was maintained. Also shows an increase in the antioxidant potential, which can prevent the harmful effects of ultraviolet (UV) radiation on the skin, due to their antioxidant, anti-inflammatory and immunomodulatory properties. The SEM images showed significant changes in the walls of the polyhedral cells of the spent coffee grounds after non-thermal plasma pre-treatment.

Enhanced azo dye removal in aqueous solution by H2O2 assisted non-thermal plasma technology

Abstract The focus of the present study is to assess the performances of H 2 O 2 assisted non-thermal plasma (NTP) technology for the degradation of the Acid Orange 7 textile azo dye in aqueous solution. The reactor configuration used during the experiments was the “dielectric barrier discharge” (DBD). The comparison between DBD (only non-thermal plasma) and H 2 O 2 /DBD system (in the presence of H 2 O 2 in the solution) was also performed. The experimental tests were carried out using 100 mL of aqueous solution with an initial Acid Orange 7 concentration equal to 10 mg/L, in the presence of oxygen as process gas in the DBD reactor operating with 20 kV of applied voltage. The results demonstrated that in presence of only oxygen in the DBD reactor, a discoloration and simultaneous mineralization of about 60% was obtained after only 2.5 min, while the addition of H 2 O 2 enhanced the dye degradation rate, obtaining in the same a discoloration and simultaneous mineralization of about 80%. The higher degradation rate achieved by adding H 2 O 2 could be attributed to the presence of higher amounts of hydroxyl radicals in DBD reactor. A deeply study on the influence of the main macroscopic parameters such as O 2 flow rate, H 2 O 2 and Acid Orange 7 initial concentration has been assessed in order to find the optimal operating conditions for the H 2 O 2 /DBD system. The kinetic evaluation and the energy yield study were performed under specific experimental condition. If compared with traditional AOPs, the results obtained with the H 2 O 2 /DBD system, showed that this technology is faster and extremely efficient and consequently very promising for the removal of Acid Orange 7 azo dye in aqueous solutions.

Plasma-catalytic conversion of CO2 to CO over binary metal oxide catalysts at low temperatures

Non-thermal plasma (NTP) technology is gaining increasing interest for CO2 conversion due to its potential to convert inert and stable CO2 to value-added fuels and chemicals at ambient conditions. Combining catalysts with plasma can enhance conversion and energy efficiency simultaneously, overcoming the trade-off barrier commonly present in plasma processes. This work reports the influence of various ceria-promoted iron oxide catalysts on the decomposition of CO2 to carbon monoxide and oxygen in a packed bed, dielectric barrier discharge (DBD) reactor at low temperatures and ambient pressure. As ceria is an expensive rare earth metal, its combination with a cheap, abundant metal such as iron can make the process far more economical. The optimum CO2 conversion (24.5%) and energy efficiency (13.6%) were achieved using γ-Al2O3 supported 5Fe5Ce, almost twice the conversion attained using 10Fe (13.3%). Catalysts were characterized using N2 adsorption, X-ray diffraction (XRD), Raman spectroscopy, H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) analysis. A solid solution formed from the mixture of iron oxide and ceria. A critical concentration of iron oxide is required to increase the number of oxygen vacancy sites in the solid solution. The synergy between Fe and Ce, and thus the oxygen vacancy sites, can also be optimized via the synthesis method. A reaction mechanism has been proposed for CO2 conversion at the catalyst surfaces.

Hydrogen production via catalytic pulsed plasma conversion of methane: Effect of Ni–K2O/Al2O3 loading, applied voltage, and argon flow rate

Despite industrial application of methane as an energy source and raw material for chemical manufacturing, it is a potent heat absorber and a strong greenhouse gas. Evidently reduction of methane emission especially in the natural gas sector is essential. Methane to hydrogen conversion through non-thermal plasma technologies has received increasing attention. In this paper, catalytic methane conversion into hydrogen is experimentally studied via nano-second pulsed DBD plasma reactor. The effect of carrier gas flow, applied voltage, and commercial Ni–K2O/Al2O3 catalyst loading on methane conversion, hydrogen production, hydrogen selectivity, discharge power, and energy efficiency are studied. The results showed that in the plasma alone system, the highest methane conversion and hydrogen production occurs at argon flow rate of 70 mL/min. Increase in the applied voltage increases the methane conversion and hydrogen production while it decreases the energy efficiency. Presence of 1 g Ni–K2O/Al2O3 catalyst shifts the optimum voltage for methane conversion and hydrogen production to 8 kV, reduces the required power, and increases the energy efficiency of the process. Finally in the catalytic plasma mode the optimum process condition occurs at the argon flow rate of 70 mL/min, applied voltage of 8 kV, and catalyst loading of 6 g. Compared with the optimum condition in the absence of catalyst, presence of 6 g Ni–K2O/Al2O3 catalyst increased the methane conversion, hydrogen production, hydrogen selectivity and energy efficiency by 15.7, 22.5, 7.1, and 40% respectively.

Effect of plasma-activated water, used as a disinfectant, on the hatch rate of dormant cysts of the Artemia salina

Various disinfectants have been used to sterilize fish eggs, breeding water, and aquaculture facilities. These disinfectants exert a considerable negative effect on the environment when used in large amounts and, thus, are a public-health concern. In this study, eco-friendly plasma-activated water (PAW) was produced using non-thermal plasma technology and used as a disinfectant in an aquaculture experiment using the cysts of the Artemia salina. We used bacterial strains (Vibrio alginolyticus rm-8420, Vibrio harveyi SFC-BS, Vibrio parahaemolyticus CRS 09–17, and Edwardsiella tarda ATCC 15947) as opportunistic pathogens. The PAW rapidly reduced the number of these bacteria in cyst samples for up to 3 h after treatment, and thereafter, there was no reduction in bacterial counts. The effect was the highest in brine shrimp cyst samples inoculated with V. harveyi and treated with PAW; a similar trend was observed for the other three strains. In addition, the hatch rate of A. salina cysts infected with V. harveyi was reduced, which was recovered after PAW treatment. The cysts in the group treated with bacteria and seawater (VhS) showed a 17.6% reduction in the hatch rate relative to the control group treated with seawater, but the group inoculated with bacteria and treated with PAW showed a significant increase in the hatch rate relative to the VhS group. The results suggest that PAW can be used as an alternative disinfectant in aquaculture to sterilize fish eggs.

Nonthermal Plasma Induces the Viable-but-Nonculturable State in Staphylococcus aureus via Metabolic Suppression and the Oxidative Stress Response.

As a novel nonthermal technology, nonthermal plasma (NTP) has attracted a lot of attention. However, it could induce microorganisms into a viable but nonculturable (VBNC) state, posing a potential risk to food safety and public health. In this study, the molecular mechanisms of VBNC Staphylococcus aureus induced by NTP were investigated. With the use of a propidium monoazide quantitative PCR (PMA-qPCR) technique combined with a plate count method, we confirmed that 8.1 to 24.3 kJ NTP induced S. aureus into a VBNC state at a level of 7.4 to 7.6 log10 CFU/ml. The transcriptomic analysis was conducted and revealed that most energy-dependent physiological activities (e.g., metabolism) were arrested in VBNC S. aureus, while the oxidative stress response-related genes (katA, dps, msrB, msrA, and trxA) were significantly upregulated. In addition, this study showed that the ATP depletion by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) pretreatment could accelerate the formation of VBNC S. aureus The NTP-generated oxidative stress triggers the staphylococcal oxidative stress response, which consumes part of cellular energy (e.g., ATP). The energy allocation is therefore changed, and the energy assigned for other energy-dependent physiological activities (cell growth and division, etc.) is reduced, subsequently forcing S. aureus into a VBNC state. Therefore, the alterations of energy allocation should be some of the major contributors to the induction of VBNC S. aureus with NTP exposure. This study provides valuable knowledge for controlling the formation of VBNC S. aureus during NTP treatment.IMPORTANCE In recent years, nonthermal plasma (NTP) technology has received a lot of attention as a promising alternative to thermal pasteurization in the food industry. However, little is known about the microbial stress response toward NTP, which could be a potential risk to food safety and impede the development of NTP. A viable but nonculturable (VBNC) state is one of the most common survival strategies employed by microorganisms against external stress. This study investigated the mechanisms of the formation of VBNC Staphylococcus aureus by NTP in a more comprehensive and systematic aspect than had been done before. Our work confirmed that the NTP-generated oxidative stress induced changes in energy allocation as a driving force for the formation of VBNC S. aureus This study could provide better knowledge for controlling the occurrence of VBNC S. aureus induced by NTP, which could lead to more rational design and ensure the development of safe foods.

Reaction kinetic study of nonthermal plasma continuous degradation of acetone in a closed-loop reactor

Nonthermal plasma (NTP) degradation has been shown to be a promising method for volatile organic compounds (VOCs) removal from air. However, there have been few studies on the degradation of indoor VOCs using NTP, and even less on their reaction kinetics. In this study, NTP degradation of acetone, a representative of oxygenated VOCs, in a closed-loop reactor operating in recirculation mode was investigated. Acetone and organic by-products were characterized in real-time by proton transfer reaction time-of-flight mass spectrometry. The results showed that approximately 85.7% of the acetone degraded within 7.5 h with dielectric barrier discharge treatment at 4.3 W. Methanol, acetaldehyde, formic acid, and acetic acid were observed to be the main organic byproducts with concentrations time-dependent on the order of ppb/ppm. The concentrations of the inorganic by-products O3 and NO2 are also time-dependent and can decrease to nearly 0 after a sufficient degradation time. Based on the concentration measurement in real-time, several rate laws were used to fit the concentration variations of acetone and the organic by-products, and it was observed that they strictly followed the simple kinetic reaction rate laws: acetone followed the first-order rate law, and formic acid formation followed the one-half-order rate law, etc. This study provides a good example of characterizing NTP removal of VOCs in airtight spaces and has important theoretical and practical significance in designing a better NTP device, predicting NTP degradation reaction rate, and accelerating the practical application of NTP technology for indoor air treatment.

Ionic Wind Drying for Leaves of Andrographis Paniculata Bush Plant

Ionic wind drying or High Electric Field Drying is a convective drying technique. It is a non-thermal plasma technology that can effectively remove product moisture whilst retaining heat-sensitive. The purpose of this study was to determine the physical characterization of the dried Andrographis paniculate leaves. The ionic wind is generated using high voltage DC 4 kV is applied on the pin-three rings concentric electrode by the distance between the 4 mm electrodes. Drying time is 5 to 35 minutes at 5 minute intervals. The results showed that the bitter leaf experienced a reduction in mass during drying and obtained values of the drying rate of 11 x 10 -3 db/min, shrinkage of 10.5% and energy efficiency of 2086 kJ/gram at 30 minutes. Keywords: Ion wind drying, Drying rate. Shrinkage, Andrographis paniculate leaves DOI : 10.7176/APTA/83-04 Publication date: February 29 th 2020

1,2,4-trichlorobenzene decomposition using non-thermal plasma technology

Non-thermal plasma (NTP) is regarded as a potential application for environmental pollution control due to its ability to remove pollutants. As a major precursor of dioxins, the influence of the parameters of 1,2,4-trichlorobenzene (TCB) decomposition using NTP technology was investigated through a series of experiments, including voltage, frequency, water content, initial concentration, flow rate, and oxygen content. The experimental results show that the energy injected into the NTP system has a positive correlation to voltage and frequency. Oxygen has the greatest influence on TCB decomposition. The optimal reaction condition was at 15 kV, 1000 Hz, an initial concentration of 20 mg m−3, a flow rate of 2 l min−1, H2O at 4%, and O2 at 0%. Under this condition, the TCB removal efficiency could reach 92%. According to the generated product backstepping, the hydroxyl radical (·OH) plays an important role in TCB decomposition due to its strong oxidation, which participates in the dechlorination and oxidation reactions as free radicals, and the possible decomposition pathway of TCB by NTP is inferred from the identified by-products. It is of great significance to investigate the influence of the parameters of TCB decomposition using NTP technology in order to provide references for industrial application.