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Combined calcination (700 °C) and extraction was applied for aluminum recovery from alum sludge (AS) for phosphorus removal. Calcined AS had higher aluminum and lower COD content than the intact and dried AS. Both acid and alkali extraction recovered more than 90% of the aluminum in the intact and the pretreated AS. Alkali extract of the AS had less heavy metals and COD contents than the acid extract. Response surface methodology (RSM) of Box–Behnken Design (BBD) was applied to find the optimal condition for phosphorus removal with the recovered aluminum solutions. The aluminum solutions showed that the highest phosphorus removal efficiency was more than 98% at the optimal condition (pH 6.4 and Al/P molar ratio higher than 2) with the extract from the calcined AS. FTIR and XRD analyses confirmed that the recovered precipitate contained AlPO4 and Al(OH)3.

Herein, we present a hierarchical structure consisting of an expanded interlayer, which comprises MoS2 dispersed onto and diffused into nitrogen-doped carbon nanotubes (MoS2-CNTPPys), as an electro...

This work investigated the removal of toluene using cyclic adsorption/oxidation operation in a fixed-bed dielectric barrier discharge (DBD) plasma-catalytic reactor containing Pd/ZSM-5 catalyst. The modification of ZSM-5 with Pd catalyst (2 wt %) substantially improved the adsorption capability for toluene. The catalyst adsorbing toluene was readily regenerated during the plasma-catalytic oxidation step. The synergistic effect of the catalyst promoted the toluene oxidation process as well as improved the selectivity towards CO2. As a method of reducing the energy in generating plasma, two cases (when the ground electrode was exposed to the external air and when the ground electrode was immersed in insulating oil) were compared. No micro-discharge occurred outside the ground electrode surface after oil jacketing, which prevented NOx and ozone from forming, improved energy efficiency, and promoted CO2 selectivity to 91%. The energy consumption with the oil insulation was 14.5 J/L, while that without it was 58.0 J/L. The catalyst was characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).

An essential key to enhancing the specific capacity and cyclic stability of transition metal oxide materials is the hybridization of carbon compounds by binder-free methods for supercapacitors. Carbonaceous compounds shorten the electron-ion diffusion pathways due to their high active surface area and conductivity. Herein, we focus on improving the specific energy, stability, and conductivity of the electrode by the incorporation of nanosized carbon material. The integration of nano carbons from viable eco-friendly glucose with CoMoO4 enhanced the experimental specific capacity of the electrode. The self-grown CoMoO4 on a nickel foam (CMO-NF) was confirmed as the best approach after extensive optimization process by the feasible hydrothermal (HT) method. The amount of carbon deposited and the structural morphology on the fabricated CoMoO4-glucose-derived carbon (CMO-GC) electrode was varied by adjusting the concentration of glucose by the viable HT technique. Notably, the hybrid CMO-GC-2 achieved a maximum specific capacity of 851.85 C g−1 at 1 A g−1, and it is relatively higher than that of CMO-NF (301.4 C g−1). The asymmetric supercapacitor device (CMO-GC-2//AC) demonstrated excellent energy density (36.86 W h kg−1 for 152.84 W kg−1), power density (3209.35 W kg−1 for 11.19 W h kg−1), and extensive capacity retention of 87% for up to 5000 cycles. The high performance is related to the synergetic effect of EDLC and the redox reaction, with nano-architecture and well-defined morphology of the electrode material.

This work involved an investigation of the plasma-catalytic process, which consists of two steps: repeated cycles of adsorption to concentrate the ethylene and plasma catalysis to decompose the adsorbed ethylene. Investigations showed that the Pd/ZSM-5 catalytic adsorbent, which is prepared by an ion-exchange method, was found to be capable of efficiently adsorbing highly volatile ethylene, even under the humid conditions prevalent in agricultural facilities. The conditions under which the catalyst was prepared with the aid of ion exchange also greatly influenced the adsorption performance. The appropriate ion-exchange conditions were found to be room temperature, no pH adjustment, and the use of PdCl2 as the precursor, and the optimal Pd content was in the range of 0.268˜0.361 wt%. The dynamical adsorption and plasma-catalyzed oxidation of ethylene was carried out in a packed-bed plasma reactor with Pd/ZSM-5 pellets. The adsorbed ethylene could be completely oxidized to carbon dioxide during the plasma-catalyzed step. The effect of ethylene removal on the storage stability of agricultural products was examined using kiwi fruit and broccoli. These experiments demonstrated that ethylene removal could substantially enhance the storage stability of these products.

The effective removal of dilute ethylene in a novel honeycomb plasma reactor was investigated using a honeycomb catalyst (Pd/ZSM-5/monolith) sandwiched between two-perforated electrodes operating at ambient temperature. Herein, the dependence of catalyst performance on the binder fraction, catalyst preparation method, and catalyst loading was examined. Ethylene removal was carried out by a process comprising cycles of 30-min adsorption conjugated with 15-min plasma-catalytic oxidation. Interestingly, the performance of the cyclic process was superior to continuous plasma-catalytic oxidation and thermally activated catalyst in terms of energy conservation, i.e., ~36 compared to ~105 and ~300 J/L, respectively. Hence, the novel cyclic process can be considered advanced-oxidation technology that features room-temperature oxidation, offers low energy consumption, negligible hazardous by-products emissions such as NOx and O3. Moreover, the process operated under described conditions: low-pressure drop, ambient atmosphere, a mechanically stable system, and a simple reactor configuration, suggesting the practical applicability of this plasma process.

Three-dimensional (3D) metal phosphides are promising superior electrode components for supercapacitors. In this study, 3D porous nickel phosphide nanoarrays are successfully enrooted on the surface of nickel foam (Ni2P/NF) by low-temperature hydrothermal treatment. Subsequently, a nanocarbon was embedded over Ni2P@NF by efficient utilization of the environmental pollutant ethylene gas via a dielectric barrier discharge plasma reactor. This nanocarbon was deposited on porous Ni2P/NF nanoarrays (Ni2P-C/NF) as a positive electrode sandwiched with peanut shell-derived porous activated carbon (PNS-AC) as a negative electrode for the fabrication of a hybrid supercapacitor device. The hybrid supercapacitor device (Ni2P-C/NF//PNS-AC) delivers an enormous amount of areal and gravimetric capacities values at a 1 A g–1 current density of 318.8 μAh cm–2 and 106.2 mAh g–1, respectively. Moreover, the hybrid supercapacitor device achieved outstanding energy and power density with excellent cyclic durability (90.1%) ev...

The conditions for the deposition of stable superhydrophobic coatings on glass substrates using a dielectric barrier discharge plasma jet with tetramethylsilane (TMS) and 3-aminopropyl(diethoxy)methylsilane (APDMES) as precursors were investigated. The coatings, which were formed under different plasma conditions, were characterized by various methods including atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, static water contact angle (WCA) and sliding angle measurement, and a scratch test. The results presented that superhydrophobic and mechanically stable plasma coatings could be obtained by optimizing the treatment time, applied voltage, gas flow rate into the plasma chamber, and APDMES/TMS ratio. The results indicated that the use of TMS on its own as the coating precursor led to the formation of unstable coatings. However, the mechanical stability increased significantly when APDMES and TMS were used in combination. As a result, a durable coating layer with a WCA of 163° and sliding angle of 3° was achieved for an APDMES/TMS ratio of 1.7.

Deposition of superhydrophobic coatings on glass substrates from hexamethyldisiloxane (HMDSO) precursor using an argon plasma jet at a relatively low power frequency (11.5 kHz) was studied. The coating hydrophobicity was first found to be strongly dependent on the gaseous shield. Nitrogen (N2) rather than inert gases (argon, Ar, and helium, He) had an excellent shielding effect against the interference of ambient air on the plasma jet. The evolution of water contact angle (WCA) of the prepared coating was investigated upon the variations of the operating parameters, such as N2/Ar ratio, HMDSO concentration, deposition time and nozzle-to-substrate distance. Generally, the measured WCA gradually increased with increasing the values of these parameters and then leveled off at some specific values, except for the nozzle-to-substrate distance. The wettability of glass was completely switched from hydrophilicity to superhydrophobicity with the WCA reaching 168° and the sliding angle of about 3° at optimum conditions. The surface morphology analyses by scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the prepared coating had a very high surface roughness and micro-nano structure, which intensely promoted the water repellence property. The chemical examination by X-ray photoelectron spectroscopy (XPS) clearly showed the shielding effect on the surface chemical composition of the coating. N2 shield preserved a high carbon content (in CH3 groups) from the precursor, while minimizing the incorporation of oxygen into the coating surface. Also, it was found that O (from O and OH radicals) has replaced C to form silica-like coating in case of without shielding gas or with Ar and He shields.

Non-thermal plasma is getting more popular in industrial applications, mainly treatment of material surfaces. Hydrophobic coatings often suffer mechanical instability and do not function well after abrasion/scratching. In this study, non-thermal plasma jet generated at atmospheric pressure in ambient condition was applied to the hydrophobic treatment of glass surface using two precursors. Tetramethylsilane (TMS) was used to promote hydrophobicity and (3-Aminopropyl)triethoxysilane (APTES) was used to get durable mechanical strength of the coating although it is hydrophilic in character. An alternating current (AC) high voltage (operating frequency: 11.5 kHz) was used to generate plasma jet for producing a coating layer onto the soda-lime glass sample. Water contact angle of 139° and a stable mechanical strength were achieved at an optimal TMS/APTES ratio of 4.8. The coating thickness, strength and water contact angle were varied by changing treatment time, applied voltage, and carrier gas (argon) flow rate. The coating layer were characterized by atomic-force microscopy (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), water contact angle (WCA), scratch test and UV/visible spectroscopy.

Reverse electrodialysis (RED), based on non-precious electrodes, was applied to disinfect domestic aquaculture wastewater. It was found that treatment could be achieved either by an anodic reaction of electro-generated sodium hypochlorite (NaClO) or via a cathodic reaction of electro-generated hydrogen peroxide (H2O2). Without circulation, the disinfection rate was sub-optimal and depended on the anodic and cathodic reactions, reaching 82 ± 5% at the anode (0.3–2.9 mg/L of chlorineDPD, pH 3.2 ± 0.4) and 59 ± 7% at the cathode (2.9–8.7 mg/L of H2O2, pH 10.7 ± 0.3). In contrast, a high removal efficiency of ≥99 ± 1% was obtained when anodic and cathodic solutions were circulated due to the synergetic effect between HClO and H2O2 (0.1–2.1 mg/L of chlorineDPD, 3.9–4.9 mg/L of H2O2, pH 7.8 ± 0.2). Both operating modes resulted in a stable power production of 6 ± 0.5 W/m2. These results support the view that RED can offer a cost-effective and energy-efficient option for disinfecting aquaculture wastewater.

A practical-scale sandwich-type honeycomb catalyst reactor incorporating non-thermal plasma was developed for the high-throughput removal of isopropanol (IPA) from air. The Pd/γ-Al2O3/honeycomb catalyst was fabricated by coating a cordierite monolith with γ-alumina powder on which to support the palladium (Pd). The supported catalyst showed good activity and the combination of the honeycomb structure with plasma produced a uniform plasma inside the catalyst chamber. The influence of different parameters, including the energy density (SIE), humidity, initial concentration, and flow rate, on the plasma characteristics and IPA removal efficiency was investigated. The results showed that the SIE has the strongest effect on the IPA removal efficiency. The efficiency of IPA removal was 94.5% and the CO2 selectivity was 85% for an SIE of 180 J/L. Using optical emission spectroscopy, we found that the increased formation of atomic oxygen and reactive species plays an essential role in the oxidation of IPA by plasma catalysis. The main byproducts were identified by GC-MS, which indicated that acetone is the major liquid product. A plausible reaction mechanism for the plasma-catalytic oxidation of IPA is proposed based on the intermediates and byproducts.

Nonthermal plasma combined with a practical-scale honeycomb catalyst of 5.0 cm in height and 9.3 cm in diameter was investigated for the removal of toluene. The creation of plasma in the honeycomb catalyst greatly depended on the humidity of the feed gas and the presence of metals on the honeycomb surface. Compared to the bare ceramic honeycomb, the metal-loaded one gave higher toluene removal efficiency because the decomposition of toluene by the plasma-generated reactive species occurred not only homogeneously in the gas phase but also heterogeneously on the catalyst surface. The present plasma-catalytic reactor was able to successfully remove about 80% of dilute toluene (15 ppm in air) at a large flow rate of 60 L/min with a specific energy input of 58 J/L. The honeycomb-based plasma-catalytic reactor system is promising for practical applications since it can overcome such problems as high-pressure drop and difficulty in scale-up encountered in packed-bed reactors.

The development of polymer-based devices has attracted much attention due to their miniaturization, flexibility, lightweight and sustainable power sources with high efficiency in the field of wearable/portable electronics, and energy system. In this work, we proposed a polyvinylidene fluoride (PVDF)-based composite matrix for both energy harvesting and energy storage applications. The physicochemical characterizations, such as X-ray diffraction, laser Raman, and field-emission scanning electron microscopy (FE-SEM) analyses, were performed for the electrospun PVDF/sodium niobate and PVDF/reduced graphene oxide composite film. The electrospun PVDF/sodium niobate nanofibrous mat has been utilized for the energy harvester which shows an open circuit voltage of 40 V (peak to peak) at an applied compressive force of 40 N. The PVDF/reduced graphene oxide composite film acts as the electrode for the symmetric supercapacitor (SSC) device fabrication and investigated for their supercapacitive properties. Finally, the self-charging system has been assembled using PVDF/sodium niobate (energy harvester), and PVDF/reduced graphene oxide SSC (energy storage) and the self-charging capability is investigated. The proposed self-charging system can create a pathway for the all-polymer based composite high-performance self-charging system.

Plasma polymerisation of hexamethyldisiloxane (HMDSO) and (3-aminopropyl)triethoxysilane (APTES) was attempted to form a robust hydrophobic coating film on glass surface. Although HMDSO is a common...

This work investigated the decomposition of dilute N2O from gas streams with various oxygen contents by using a plasma-catalytic process over metal oxide catalysts supported on γ-Al2O3. Among the metals explored (Ru, Co, Cu, V, etc.), Ru was found to be the best catalyst for the decomposition of N2O in a plasma-catalytic reactor, and most of the experiments were conducted with alumina-supported Ru. The effects of applied voltage, reaction temperature, O2 content, gas flow rate and initial N2O content on the decomposition efficiency and byproducts formation were examined. Compared to the catalyst-alone case, the presence of plasma enhanced the decomposition efficiency by 30–50%, depending on the operating condition. The increase in the oxygen content from 0 to 20% largely decreased the catalytic decomposition efficiency, whereas in the presence of plasma N2O could be successfully decomposed even at 20% O2 content. The decomposition efficiency was not a strong function of the initial N2O concentration in the range of 225–1800 ppm, exhibiting pseudo first-order reaction kinetics. Without O2, there were negligible byproducts, but in the presence of O2, NO and NO2 were formed mainly due to the plasma-induced reactions between background molecules such as N2 and O2. The results obtained in this work showed the feasibility of plasma-catalytic process for the abatement of N2O.

The challenge that needs to be overcome regarding the removal of nitrogen oxides (NOx) and soot from exhaust gases is the low activity of the selective catalytic reduction of NOx at temperatures fluctuating from 150 to 350 &deg, C. The primary goal of this work was to enhance the conversion of NOx and soot simulant by employing a Ag/&alpha, Al2O3 catalyst coupled with dielectric barrier discharge plasma. The results demonstrated that the use of a plasma-catalyst process at low operating temperatures increased the removal of both NOx and naphthalene (soot simulant). Moreover, the soot simulant functioned as a reducing agent for NOx removal, but with low NOx conversion. The high efficiency of NOx removal required the addition of hydrocarbon fuel. In summary, the combined use of the catalyst and plasma (specific input energy, SIE &ge, 60 J/L) solved the poor removal of NOx and soot at low operating temperatures or during temperature fluctuations in the range of 150&ndash, 350 &deg, C. Specifically, highly efficient naphthalene removal was achieved with low-temperature adsorption on the catalyst followed by the complete decomposition by the plasma-catalyst at 350 &deg, C and SIE of 90 J/L.

Dry reforming of propane (DRP) with CO2 was examined over iron–ceria spinel (FeCe2O4) that was synthesized on mesoporous alumina foam by the sol–gel method. The FeCe2O4/Al-F catalyst exhibited significant catalytic activity for the DRP with propane and CO2 conversions of 93% and 76%, respectively. Moreover, the redox behavior of the spinel was found to greatly reduce the deposition of carbon, which could be attributed to the oxidation of surface carbon to CO via the interaction with FeCe2O4 lattice oxygen. The FeCe2O4/Al-F catalyst with good catalytic activity, long-term stability and coke resistance may be a promising candidate for the DRP.

In this work, sustainably synthesized metal-organic framework (MOFs) MIL-100 (Fe) nanoparticles were incorporated into polysulfone (PSF) matrix to fabricate a novel PSF/MIL-100 (Fe) composite membrane. Compared to the pristine PSF membrane (M0), incorporation of the hydrophilic MIL-100 (Fe) nanoparticles significantly altered the membrane morphology, hydrophilicity (water contact angle reduced to 64.2° ± 1.2 from 84.6° ± 1), work of adhesion (WA), wetting energy (WE), porosity, and pore size. Furthermore, loading 0.5 wt% of MIL-100 (Fe) particles into the PSF matrix (M0.5) was found to deliver the uppermost performance relative to the membranes with other loadings. Those above mentioned, M0.5 membrane comprise superior pure water flux (10.3 times higher than M0) with more than 99% rejection efficiency of methylene blue (MB) and excellent anti-fouling performances for MB dye, microplastics (MPs) + MB dye solutions. Furthermore, the M0.5 membrane sustained an outstanding performance at various concentrations of MB dye, MPs, and a range of transmembrane pressures (TMPs). In addition, the membrane exhibited moderate salt rejection efficiency and reusability for as many as six cycles of MB dye rejection without compromising the permeability and anti-fouling performances. Overall, the fabricated PSF/MIL-100 (Fe) composite membrane proposed an efficient route to separate the contaminants from textile wastewater.

The purification of hazardous textile dyeing wastewater has exhibited many challenges because it consists of a complex mixture, including dyestuff, additives, and salts. It is necessary to fabricate membranes with enhanced permeability, fouling resistance, stability, and superior dyes and salts removal from wastewater. Incorporating a highly water stable metal-organic framework (MOFs) into membranes would meet the requirements for the efficient purification of textile wastewater. In this study, nanofiltration (NF) membranes are fabricated by incorporating MIL-100 (Fe) into the chitosan (CS) through film casting technique. The effect of MIL-100 (Fe) loadings on chitosan characterized by FT-IR, XRD, contact angle measurement, FESEM-EDS, XPS, zeta potential, and surface roughness analysis. The membrane characterization confirmed the enhanced surface roughness, pore size, surface charge, and hydrophilicity. The CS/MIL-100 (Fe) membrane exhibited an improved pure water flux from 5 to 52 L/m2h as well as 99% rejection efficiency for cationic methylene blue (MB) and anionic methyl orange (MO). We obtained the rejection efficiency trend for the MB mixed salts in the order of MgSO4 (Mg2+ - 51.6%, SO42− - 52.5%) > Na2SO4 (Na+ - 26.3%, SO42− - 29.3%) > CaCl2 (Ca2+ - 21.4%, Cl− - 23.8%) > NaCl (Na+ - 16.8%, Cl− - 19.2%). In addition, the CS/MIL-100 (Fe) composite membrane showed excellent rejection efficiency and antifouling performances with high recycling stability. These stunning results evidenced that the CS/MIL-100 (Fe) nanofiltration membrane is a promising candidate for removing toxic pollutants in the textile dyeing wastewater.

This study focused on the removal of styrene using a metal-coated monolith (MCM) catalyst integrated with non-thermal plasma. The MCM catalyst was prepared by depositing a ZSM-5 support impregnated with a combination of three metals (Co, Pd, La) on a practical-scale honeycomb monolith. A comparative study with a commercial metal-coated monolith (CMCM) of the same dimensions was conducted to evaluate the effectiveness of the MCM with respect to styrene removal. The plasma discharge in the monolith was characterized by measuring the voltage and current waveforms and optical emission spectroscopy (OES). The electric power of the plasma discharge largely depended on the metal loading, flow rate, and humidity of the feed gas. The removal efficiency of styrene (inlet concentration: 20 parts per million, volumetric (ppm)) was examined using both plasma catalytic oxidation (PCO) and thermal catalytic oxidation (TCO), to enable the effect of plasma to be clearly assessed. PCO with the MCM catalyst achieved styrene removal efficiency of nearly 100% at a specific energy input (SEI) of 40 J/L, whereas the CMCM catalyst achieved 92% removal for identical SEI. In comparison, TCO with the MCM and CMCM catalysts required high temperatures of 420 °C and 480 °C, respectively, for the complete removal of styrene. In addition, the CO2 selectivity of the MCM catalyst was higher at 83% compared with 75% for the CMCM at SEI of 40 J/L. The optimal silica binder content for the deposition of a robust washcoat layer was found to be approximately 5%.

The abatement of dilute p-xylene (500 ppm) from a contaminated air stream (2 L min−1) by the non-thermal plasma in combination with an ozone decomposing catalyst (pelleted Mn/γ-Al2O3) was investigated. The reactor performance was evaluated in terms of p-xylene conversion, CO x selectivity and ozone emission with and without external heating. Generally, the removal of p-xylene gradually increased with increasing the applied voltage from 16 to 22 kV (peak height). As the catalyst was used (i.e., packed inside the plasma active region), the reactor was able to remove ca. 82% of p-xylene at 22 kV, compared to 54% done by plasma alone. Under the same plasma-catalytic condition, the removal of p-xylene was successfully achieved (ca. 96%) by heating up the reactor to 150 °C. Not only was the conversion improved, but also the mineralization of p-xylene was also enhanced considerably by the mild thermal heating, increasing the CO2 selectivity from ca. 41 to 59%. The ozone emission measurement showed that ozone formed in plasma was readily catalytically decomposed on Mn/γ-Al2O3 at above 16 kV, even without external heating. As revealed by the reactor infrared thermographic images, the plasma-induced surface temperature of the catalyst was far higher than the external heating temperature (i.e., 150 °C), facilitating the catalytic degradation of ozone and reducing the formation of byproducts. Additionally, no organic compounds have been found on the spent catalyst, avoiding the possibility of catalyst deactivation during the course of experiment.

Oxidative stress enhances cellular DNA oxidation and may cause mutations in DNA bases, including 8‑oxoguanine (8‑oxoG). Our recent study reported that exposure of cells to non‑thermal dielectric barrier discharge (DBD) plasma generates reactive oxygen species and damages DNA. The present study investigated the effect of non‑thermal DBD plasma exposure on the formation of 8‑oxoG in HaCaT human keratinocytes. Cells exposed to DBD plasma exhibited increased level of 8‑oxoG. In addition, mRNA and protein expression levels of 8‑oxoguanine glycosylase 1 (OGG1), an 8‑oxoG repair enzyme, were reduced in plasma‑exposed cells. Furthermore, the expression level of nuclear factor erythroid 2‑related factor 2 (Nrf2), a transcription factor that regulates OGG1 gene expression, was reduced following exposure to DBD plasma. Pretreatment of cells with an antioxidant, N‑acetyl cysteine (NAC), prior to plasma exposure suppressed the formation of 8‑oxoG and restored the expression levels of OGG1 and Nrf2. In addition, phosphorylation of protein kinase B (Akt), which regulates the activation of Nrf2, was reduced following plasma exposure. However, phosphorylation was restored by pretreatment with NAC. These findings suggested that non‑thermal DBD plasma exposure generates 8‑oxoG via inhibition of the Akt‑Nrf2‑OGG1 signaling pathway in HaCaT cells.

The current challenges in the usage of liquid electrolyte in energy storage devices are closely correlated with the flexibility and portability of the devices. In this paper, a highly flexible, pouch-type hybrid supercapacitor in liquid electrolyte based on a binderless cobalt hydroxide–cobalt molybdate (CoMoO4@Co(OH)2) core–shell structure (prepared by electrochemical deposition; ECD) sandwiched with honeycomb-like porous carbon derived from laboratory waste tissue paper (prepared by a hydrothermal reaction and carbonization) is presented. Its excellent hierarchical core–shell structure and honeycomb-like porous carbon results in a large electrochemically active surface area, which yields a high areal capacity of 265 μA h cm−2 and excellent specific capacitance of 227 F g−1 in liquid potassium hydroxide (KOH) electrolyte with excellent cyclic stability. An assembled pouch-type hybrid supercapacitor using the prepared core–shell structure as the positive electrode and porous carbon as the negative electrode shows an extended working voltage of 1.5 V in 2 M KOH electrolyte, which stores a maximum energy density of 167.5 μW h cm−2. Interestingly, the fabricated pouch-type supercapacitor shows an excellent flexibility under different bending conditions and exhibits remarkable cyclic stability with >98% capacitance retention even after long cycles. Furthermore, the capability of the device is demonstrated by integrating it with a solar cell to drive the various types of light-emitting diodes (LEDs) and seven segment displays for self-powered applications.

Removal of dilute N2O from gas streams by a cyclic adsorption–decomposition using Ca13X (Ca2+ exchanged 13X) in combination with N2 nonthermal plasma was studied in this work. Zeolite 13X was found to be the best for N2O uptake among tested commercial zeolites including 4A, H-β and 13X. By modifying 13X with Ca2+ cation using ion-exchange method, the N2O adsorption capacity was greatly enhanced from ca. 3.5 × 10−6 to 80 × 10−6 mol g zeolite - 1 due to the stronger interaction of N2O with Ca2+ cation than that with Na+ cation. Ca. 96% of N2O removal efficiency at a SIEeq (equivalent specific input energy) of 1116 J L−1 was obtained under the cyclic operation of 60-min N2O adsorption (initial concentration: 510 ppm, gas flow rate: 0.5 L min−1) over Ca13X followed by 20-min plasma decomposition of adsorbed N2O in stationary N2 atmosphere. In comparison, a similar performance was reached at a relatively high SIE of 1700 J L−1 as the reactor was operated under continuous plasma condition. The time period of plasma step and therefore the energy consumption could be reduced by properly circulating N2 gas in the reactor. Also, SIEeq was found to decrease with increasing the adsorption time, whereby ca. 95% of N2O removal efficiency could be achieved at a SIEeq of 298 J L−1 as the adsorption time was 180 min. The regeneration of N2O-adsorbed Ca13X by N2 plasma was initiated by plasma-induced desorption of adsorbed N2O followed by decomposing the desorbed N2O in plasma gas phase.

The SrNiO3 perovskite catalyst was synthesized by the citrate sol-gel method and supported on &gamma, Al2O3 and Nickel foam, which was used to produce syngas (CO and H2) via dry reforming of propane (DRP). Several techniques characterized the physicochemical properties of the fresh and spent perovskite catalyst. The X-ray diffractograms (XRD) characterization confirmed the formation of the perovskite compound. Before the catalytic activity test, SrNiO3 perovskite catalyst was reduced in the H2 atmosphere. Results indicated that the H2 reduction slightly increased the activity of the SrNiO3 perovskite catalyst. The catalytic activity was examined for the CO2/C3H8 ratio of 3 and reaction temperatures in the range of 550 &deg, C&ndash, 700 &deg, C. The results from the catalytic study achieved 88% conversion of C3H8 and 66% conversion of CO2 with SrNiO3/NiF at 700 &deg, C. Also, syngas with a maximum concentration of 21 vol.% of CO and 29 vol.% of H2 was produced from the DRP. The strong basicity of SrNiO3 perovskite enhanced the CO selectivity, resulting in minimal carbon formation. Post reaction catalyst characterization showed the presence of carbon deposition which could have originated from propane decomposition.

Combined removal of n-heptane and CO using a catalytic reactor coupled with dielectric barrier discharge plasma was investigated over several metal oxide catalysts including bare γ-Al 2 O 3 , Ag 2 O/γ-Al 2 O 3 , MnO/γ-Al 2 O 3 , RuO 2 /γ-Al 2 O 3 and PdO/γ-Al 2 O 3 . In order to effectively utilize the heat generated during plasma discharge for enhancing catalytic reactions, the plasma-catalytic reactor was thermally insulated by covering it with a glass wool jacket. Plasma propagated radially outward from the central high-voltage electrode with gradually increasing the applied voltage, and the temperature decreased with the radial distance due to the decreased plasma intensity, exhibiting a volcanic temperature distribution. The increased reactor temperature could improve the removal of CO and the selectivity toward CO 2 . The results obtained from separate experiments of n-heptane and CO removal showed that the PdO/γ-Al 2 O 3 was the best for the simultaneous removal purpose. The effects of specific input energy ( SIE ), oxygen content, reaction temperature and PdO loading on the simultaneous removal of n-heptane and CO and the formation of byproducts were examined. The removal efficiencies of n-heptane obtained with different catalysts were similar to one another, whereas the removal of CO strongly depended on the type of catalyst. The catalytic activity for the oxidation of CO followed the order: MnO/γ-Al 2 O 3 2 O/γ-Al 2 O 3 2 /γ-Al 2 O 3 2 O 3 . In the present plasma-catalytic hybrid reactor, the mixture of n-heptane and CO was mainly converted into CO 2 , and under an optimized condition, the selectivity toward CO 2 reached 100%.

This work investigated the decomposition of aqueous anatoxin-a originated from cyanobacteria using an underwater dielectric barrier discharge plasma system based on a porous ceramic tube and an alternating current (AC) high voltage. Plasmatic gas generated inside the porous ceramic tube was uniformly dispersed in the form of numerous bubbles into the aqueous solution through the micro-pores of the ceramic tube, which allowed an effective contact between the plasmatic gas and the aqueous anatoxin-a solution. Effect of applied voltage, treatment time and the coexistence of nutrients such as , and glucose on the decomposition of anatoxin-a was examined. Chemical analyses of the plasma-treated anatoxin-a solution using liquid chromatography-mass spectrometry (LC-MS) and ion chromatography (IC) were performed to elucidate the mineralization mechanisms. Increasing the voltage improved the anatoxin-a decomposition efficiency due to the increased discharge power, but the energy required to remove a given amount of anatoxin-a was similar, regardless of the voltage. At an applied voltage of 17.2 kV (oxygen flow rate: ), anatoxin-a at an initial concentration of (volume: 0.5 L) was successfully treated within 3 min. The chemical analyses using LC-MS and IC suggested that the intermediates with molecular weights of 123~161 produced by the attack of plasma-induced reactive species on anatoxin-a molecule were further oxidized to stable compounds such as acetic acid, formic acid and oxalic acid.

Global warming is primarily a problem of excessive carbon dioxide (CO2) in the atmosphere, which acts as a blanket, trapping heat and warming the planet. One of the inevitable reactions during syngas (SNG) production by the dry reforming reaction (DRR) of hydrocarbons is the deposition of carbon over the catalyst which can be eliminated as anthropogenic CO2. This is the main obstacle for SNG production during the DRR, diminishes the performance of the catalysts and enhances the CO2 formation which leads to global warming. In this study, for the first time, we present a novel approach to use the carbon-deposited catalyst formed during the DRR as an effective electrode material for supercapacitor applications. This disposable carbon-deposited catalyst shows ∼22 times higher capacity than the bare catalyst and acts as a positive electrode for asymmetric supercapacitors. The fabricated supercapacitor device works with an extended voltage of 1.6 V and exhibits an excellent electrochemical performance. Moreover, serially connected supercapacitor devices could power up various types of LEDs and UV light sensors.

The aim of this study was to identify the mechanisms through which dielectric-barrier discharge plasma damages human keratinocytes (HaCaT cells) through the induction of oxidative stress. For this purpose, the cells were exposed to surface dielectric-barrier discharge plasma in 70% oxygen and 30% argon. We noted that cell viability was decreased following exposure of the cells to plasma in a time-dependent manner, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The levels of intracellular reactive oxygen species (ROS) were determined using 2′,7′-dichlorodihydro-fluorescein diacetate and dihydroethidium was used to monitor superoxide anion production. Plasma induced the generation of ROS, including superoxide anions, hydrogen peroxide and hydroxyl radicals. N-acetyl cysteine, which is an antioxidant, prevented the decrease in cell viability caused by exposure to plasma. ROS generated by exposure to plasma resulted in damage to various cellular components, including lipid membrane peroxidation, DNA breaks and protein carbonylation, which was detected by measuring the levels of 8-isoprostane and diphenyl-1-pyrenylphosphine assay, comet assay and protein carbonyl formation. These results suggest that plasma exerts cytotoxic effects by causing oxidative stress-induced damage to cellular components.

13X zeolite-supported Ag was employed as the dual-functional adsorbent/catalyst for the plasma-catalytic abatement of dilute ethylene. The adsorbent/catalyst prepared by ion exchange (Ag-EX/13X) exhibited better adsorption capability than the parent 13X and Ag-IM/13X prepared by the impregnation method. The oxidative transformation of the adsorbed ethylene was then performed by using three different reactor configurations such as one-stage (i.e., adsorbent/catalyst in direct contact with plasma), two-stage (i.e., adsorbent/catalyst located downstream of the plasma region), and the combination of the two (hybrid). The oxidation of the adsorbed ethylene to CO2 in the two-stage configuration can be explained by the diffusion of ozone into zeolite micro-pores, which was, however, much slower than in the one-stage and hybrid configurations. When compared at an identical applied voltage of 20 kV (inlet ethylene: 200 ppm; adsorption time: 100 min; plasma oxidation time: 20 min), the mineralization efficiency of the hybrid reactor was greater than the sum of those of one- and two-stage reactors, i.e., 63, 42, and 10%, respectively. Using the hybrid configuration, ozone and other reactive species were more effectively produced, thereby shortening the oxidation time of ethylene and therefore achieving a higher energy efficiency which was evaluated to be ca. 2.4 g (kWh)−1.

Ethylene removal was investigated using a reactor system combining plasma and a catalyst (Pd/ZSM-5). The catalyst could adsorb ethylene effectively even under harsh conditions of 100% humidity and 10,000 ppm CO2. The air in a 1-m3 container, which was prepared to imitate agricultural storage, was circulated through the reactor. The process of ethylene treatment consists of one cycle comprising adsorption, plasma-catalyst oxidation, and desorption, and this cycle is repeated until the ethylene is completely removed. Among the variables such as initial concentration, amount of catalyst, voltage, adsorption time, and flow rate of the circulating gas, the most influential were the flow rate and the catalyst amount. The lower the initial ethylene concentration is, the less time required for complete removal, although the percent removal was not largely affected by the initial concentration. The ethylene removal was improved by injecting 20-ppm ozone into the container once per cycle. In the absence of ozone, using only the plasma-catalytic reactor, it took 20 h for complete removal, whereas all ethylene was removed in about 8 h in the presence of ozone. A mass balance model could provide a good prediction of the temporal variations of ethylene concentration. The long-term storage stability of a Fuji apple in the container was tested for 40 days. A comparison of the control group with the group subjected to ethylene processing revealed that the ethylene concentrations were significantly different from each other, indicating the efficiency of the plasma-catalyst system. After 40 days of storage, the hardness and sugar content were higher in the group from which ethylene was removed than in the control group, and the acidity was higher in the control group. Furthermore, after 40 days, the control group showed a decay rate of 10%, whereas that of the group that underwent ethylene processing was only 1%.

The adsorption and plasma-catalytic oxidation of dilute ethylene were performed in a pin-type corona discharge-coupled Pd/ZSM-5 catalyst. The catalyst has an adsorption capacity of 320.6 &mu, mol gcat-1. The catalyst was found to have two different active sites activated at around 340 and 470 &deg, C for ethylene oxidation. The removal of ethylene in the plasma catalyst was carried out by cyclic operation consisting of repetitive steps: (1) adsorption (60 min) followed by (2) plasma-catalytic oxidation (30 min). For the purpose of comparison, the removal of ethylene in the continuous plasma-catalytic oxidation mode was also examined. The ethylene adsorption performance of the catalyst was improved by the cyclic plasma-catalytic oxidation. With at least 80% of C2H4 in the feed being adsorbed, the cyclic plasma-catalytic oxidation was carried out for the total adsorption time of 8 h, whereas it occurred within 2 h of early adsorption in the case of catalyst alone. There was a slight decrease in catalyst adsorption capability with an increased number of adsorption cycles due to the incomplete release of CO2 during the plasma-catalytic oxidation step. However, the decreased rate of adsorption capacity was negligible, which is less than one percent per cycle. Since the activation temperature of all active sites of Pd/ZSM-5 for ethylene oxidation is 470 &deg, C, the specific input energy requirement by heating the feed gas in order to activate the catalyst is estimated to be 544 J/L. This value is higher than that of the continuous plasma-catalytic oxidation (450 J/L) for at least 86% ethylene conversion. Interestingly, the cyclic adsorption and plasma-catalytic oxidation of ethylene is not only a low-temperature oxidation process but also reduces energy consumption. Specifically, the input energy requirement was 225 J/L, which is half that of the continuous plasma-catalytic oxidation, however, the adsorption efficiency and conversion rate were maintained. To summarize, cyclic plasma treatment is an effective ethylene removal technique in terms of low-temperature oxidation and energy consumption.

A dielectric barrier discharge (DBD) plasma reactor was employed for non-oxidative coupling of methane. The coupling reaction in the DBD plasma bed was conducted near atmospheric pressure and room temperature. In the bed, dielectric materials such as ordered mesoporous silica (KIT-6), sea sand silica, and α-Al2O3 were employed. This non-catalytic reaction system could successfully activate C H bond to produce methyl radicals and light hydrocarbons without additional thermal energy and oxidant molecules. The gap distance between dielectric particles was determined by their sizes, which was experimentally shown. The effects of gap distance were found significant on the conversion and the selectivity. The existence of maximum conversion at a specific gap distance was experimentally observed and could be described successfully by using a newly developed concept of micro-electrodes. Based on the concept, the minimum threshold electric potential difference between the dielectric particles could be successfully estimated, where the conversion was shown to be maximized. Furthermore, it seemed quite possible to control the compositions of ethane, ethylene, and acetylene by properly adjusting the size or the gap distance of particles.

During the storage, agricultural products continue their metabolic processes and physiological responses before harvesting, resulting in quality changes related to afterripening. In particular, ethylene produced from the respiration process of agricultural products acts as a plant hormone that regulates the growth of plants such as seed germination and ripening. The increase in ethylene concentration in the storage facility significantly reduces the commercial value of agricultural products. The negative effects of ethylene include leaf yellowing, change in texture, and russet spotting. Even though there are several technologies available for controlling ethylene, practical applications are scarce. Non-thermal plasma process is a relatively new technology, in which ethylene is removed by a variety of plasma-induced reactive species. The plasma process has several advantages of high response speed and miniaturization of the system, while it has a poor selectivity to carbon dioxide and may generate harmful byproducts. Plasma-catalyst hybrid process has been actively studied as a method to overcome the disadvantages while maintaining the merits of the plasma treatment method. However, it is a great disadvantage to continuously supply electric energy for plasma generation. In this work, plasma/adsorption-catalytic process was investigated, which consists of repeated cycles of adsorption step to concentrate ethylene and plasma-catalyzed decomposition step. Since no electricity is used for the adsorption step, the operating cost can be greatly reduced and the adsorbed ethylene can be completely oxidized by the catalyst. The plasma reactor is filled with a catalytic adsorbent capable of highly concentrating ethylene. In the first step, ethylene is passed through the reactor to adsorb and concentrate ethylene, and in the next step, a high voltage is applied to the plasma reactor to rapidly decompose the previously adsorbed ethylene. The Ag/zeolite (or Pd/zeolite) catalytic adsorbent prepared by ion exchange method was found to be capable of efficiently adsorbing ethylene having high vapor pressure. When the catalytic adsorbent was directly exposed to the plasma discharge, plasma-induced reactive species accelerated the oxidation and increased the carbon dioxide yield in the decomposition step. The proposed ethylene treatment system was able to greatly reduce the ethylene oxidation time and ultimately the energy consumption. In addition, the cyclic treatment consisting of a long-time adsorption step and a short-time oxidation step led to a reduction in toxic by-products such as ozone and nitrogen-containing compounds as compared to typical continuous plasma treatment process.

This work dealt with treatment of ethylene using zeolite-based adsorbents and regeneration of the ethylene-enriched adsorbent by plasma. So as to maximize the adsorption capacity, ethylene adsorption characteristics of various zeolites (ZSM-5, USY, Y, beta, etc.) were first examined, and then Ag, Pd and Ag-Pd were supported on the zeolite exhibiting the largest adsorption capacity by ion exchange method to find out the best metal component. The prepared adsorbent pellets of about 10g were packed in a ceramic tube in which a high voltage electrode was coaxially installed. A copper foil was wound around the outer surface of the ceramic tube, which served as a ground electrode. The feed gas consisted of 79% nitrogen, 21 % oxygen and 200 ppm ethylene. The flow rates of the gases were controlled by mass flow controllers, and the total flow rate was fixed at 2 L min-1. The breakthrough curves obtained with the above mentioned adsorbents showed that Pd supported on ZSM-5 was the best, and further experiments were carried out using only Pd/ZSM-5. The treatment of ethylene with Pd/ZSM-5 and plasma was a repetitive cycle of adsorption and regeneration. First, the gas mixture containing 200 ppm of ethylene was continuously fed into the reactor for 30 min to adsorb ethylene, and plasma was created inside the zeolite-packed bed for 2 min to regenerate the ethylene-enriched adsorbent by plasma-catalytic oxidation. The measurements of the concentration of CO2 produced as a result of plasma-catalytic oxidation indicated that the adsorbed ethylene was completely oxidized within 5 min, depending on the intensity of plasma discharge. Identical results were obtained by repeating the adsorption and oxidation process several times, demonstrating that the cyclic adsorption-oxidation process using the Pd/ZSM-5 adsorbent and plasma can be applied to agricultural storage facilities for ethylene removal.

Non-thermal plasma treatment is an emerging innovative technique with a wide range of biological applications. This study was conducted to investigate the effect of a non-thermal dielectric barrier discharge plasma technique on immature chicken Sertoli cell (SC) viability and the regulatory role of microRNA (miR)-7450. Results showed that plasma treatment increased SC apoptosis in a time- and dose-dependent manner. Plasma-induced SC apoptosis possibly resulted from the excess production of reactive oxygen species via the suppression of antioxidant defense systems and decreased cellular energy metabolism through the inhibition of adenosine triphosphate (ATP) release and respiratory enzyme activity in the mitochondria. In addition, plasma treatment downregulated miR-7450 expression and activated adenosine monophosphate-activated protein kinase α (AMPKα), which further inhibited mammalian target of rapamycin (mTOR) phosphorylation in SCs. A single-stranded synthetic miR-7450 antagomir disrupted mitochondrial membrane potential and decreased ATP level and mTOR phosphorylation by targeting the activation of AMPKα, which resulted in significant increases in SC lethality. A double-stranded synthetic miR-7450 agomir produced opposite effects on these parameters and ameliorated plasma-mediated apoptotic effects on SCs. Our findings suggest that miR-7450 is involved in the regulation of plasma-induced SC apoptosis through the activation of AMPKα and the further inhibition of mTOR signaling pathway.

A double dielectric barrier discharge reactor operated at a low power frequency of 400 Hz and atmospheric pressure was utilized for regulating the wettability of glass surface. The hydrophobic treatment was performed by plasma polymerization of tetramethylsilane (TMS, in argon gas). The obtained results showed that the TMS coatings formed on the glass substrates without oxygen addition were smooth, uniform films with the maximum water contact angle (WCA) of about 106°, which were similar to those obtained by low pressure, high power frequency plasmas reported in the literature. The addition of oxygen into TMS/Ar plasma gas decreased the WCA and induced the formation of SiOSi and/or SiOC linkages, which dominated the existence of Si(CH2)nSi network formed in TMS/Ar (without oxygen) plasma.

The purpose of this study is to explain how plasma improves the performance of selective catalytic reduction (SCR) of nitrogen oxides (NOx) with a hydrocarbon reducing agent. In the plasma-coupled SCR process, NOx reduction was performed with n-heptane as a reducing agent over Ag/γ-Al2O3 as a catalyst. We found that the plasma decomposes n-heptane into several oxygen-containing products such as acetaldehyde, propionaldehyde and butyraldehyde, which are more reactive than the parent molecule n-heptane in the SCR process. Separate sets of experiments using acetaldehyde, propionaldehyde and butyraldehyde, one by one, as a reductant in the absence of plasma, have clearly shown that the presence of these partially oxidized compounds greatly enhanced the NOx conversion. The higher the discharge voltage, the more the amounts of such partially oxidized products. The oxidative species produced by the plasma easily converted NO into NO2, but the increase of the NO2 fraction was found to decrease the NOx conversion. Consequently, it can be concluded that the main role of plasma in the SCR process is to produce partially oxidized compounds (aldehydes), having better reducing power. The catalyst-alone NOx removal efficiency with n-heptane at 250 °C was measured to be less than 8%, but it increased to 99% in the presence of acetaldehyde at the same temperature. The NOx removal efficiency with the aldehyde reducing agent was higher as the number of carbons in the aldehyde was more; for example, the NOx removal efficiencies at 200 °C with butyraldehyde, propionaldehyde and acetaldehyde were measured to be 83.5%, 58.0% and 61.5%, respectively, which were far above the value (3%) obtained with n-heptane.

Ruthenium oxide nano-catalysts supported on mesoporous γ-Al2O3 have been prepared by co-precipitation method and tested for CO oxidation. The effect of polyethylene glycol (PEG) on the properties of the catalyst was studied. Addition of the PEG surfactant acted as a stabilizer and induced a change in the morphology of ruthenium oxide from spherical nanoparticles to one-dimensional nanorods. Total CO conversion was measured as a function of morphology at 175 °C and 200 °C with 1.0 wt.% loading for PEG-stabilized and un-stabilized catalysts, respectively. Conversion routinely increased with temperature but in each case, the PEG-stabilized catalyst exhibited a notably higher catalytic activity as compared to the un-stabilized equivalent. It can be assumed that the increase in the activity is due to the changes in porosity, shape and dispersion of the catalyst engendered by the use of PEG.

The degradation of sulfonamide antibiotics, such as sulfathiazole (STZ), sulfamethazine (SMT) and sulfamethoxazole (SMZ) in water was carried out with a nonthermal dielectric barrier discharge plasma reactor operating under dry air or oxygen. In order to understand the degradation pathways of the antibiotics, the plasma-treated aqueous antibiotic solutions were characterized by various techniques such as UV–visible spectroscopy, ion chromatography, liquid chromatography coupled to a tandem mass spectrometer (LC–MS/MS), pH and electrical conductivity measurements, and total organic carbon analysis. The degradation rates of the antibiotics investigated were found to be higher with pure oxygen than with dry air, and decreased in the order: SMT > STZ > SMZ. As the degradation proceeded, the characteristic absorption peaks gradually decreased and the solution pH and conductivity increased, indicating that the antibiotics were being mineralized. The ion chromatography identified both inorganic (SO42−, NO3− and NH4+) and organic ions (acetate, formate and oxalate) as the stable degradation products. After 60-min plasma treatment with oxygen, the percentage of the S atoms transformed into SO42− was in the range of 66.9–86.4%, depending upon the type of antibiotics, while of the percentage of the N atoms transformed into NH4+ and NO3− was in the range of 15.7–33.2%. The possible degradation pathways of the antibiotics were proposed from the identified intermediate products formed during the degradation, which elucidates that the hydroxylation of the ring structures in the antibiotic molecules initiates the degradation.

Present study deals with the preparation of differently shaped copper oxide nanomaterials (CuO NMs) using simple, reproducible wet chemical and hydrothermal approach. The influence of polyethylene glycol on the morphological control was also studied. The prepared nanomaterials exhibited new types of surface morphologies such as rice grain-like, needle-like and plate-like. The Fourier transform infrared spectra and the X-ray photoelectron spectra of all the samples showed identical chemical functional groups and did not exhibit the presence of any impurities. They exhibited good stability in the aqueous environment with the zeta potential values between −25 and −27 mV. The shape dependent anti-bacterial property of the prepared CuO NMs was evaluated against two Gram-positive bacteria namely Streptococcus iniae and Streptococcus parauberis and two Gram-negative bacteria such as Escherichia coli and Vibrio anguillarum . Among three CuO NMs, the plate-like CuO NMs displayed more powerful antibacterial activity than grain or needle shaped CuO NMs.

A series of experiments using atmospheric-pressure non-thermal plasma coupled with transition metal catalysts were performed to remove ethylene from agricultural storage facilities. The non-thermal plasma was created by dielectric barrier discharge, which was in direct contact with the catalyst pellets. The transition metals such as Ag and V2O5 were supported on γ-Al2O3. The effect of catalyst type, specific input energy (SIE) and oxygen content on the removal of ethylene was examined to understand the behavior of the hybrid plasma-catalytic reactor system. With the other parameters kept constant, the plasma-catalytic activity for the removal of ethylene was in order of V2O5/γ-Al2O3¤Ag/γ-Al2O3¤γ-Al2O3 from high to low. Interestingly, the rate of plasma-catalytic ozone generation was in order of V2O5/γ-Al2O3¤γ-Al2O3¤Ag/γ-Al2O3, implying that the catalyst activation mechanisms by plasma are different for different catalysts. The results obtained by varying the oxygen content indicated that nitrogen-derived reactive species dominated the removal of ethylene under oxygen-lean condition, while ozone and oxygen atoms were mainly involved in the removal under oxygen-rich condition. When the plasma was coupled with V2O5/γ-Al2O3, nearly complete removal of ethylene was achieved at oxygen contents higher than 5% by volume (inlet ethylene: 250 ppm; gas flow rate: 1.0 L min; SIE: ~355 J L).

This work investigated the plasma-catalytic decomposition of isopropyl alcohol (IPA) and the behavior of the byproduct compounds over monolith-supported metal oxide catalysts. Iron oxide (Fe2O3) or copper oxide (CuO) was loaded on a monolithic porous α-Al2O3 support, which was placed inside the coaxial electrodes of plasma reactor. The IPA decomposition efficiency itself hardly depended on the presence and type of metal oxides because the rate of plasma-induced decomposition was so fast, but the behavior of byproduct formation was largely affected by them. The concentrations of the unwanted byproducts, including acetone, formaldehyde, acetaldehyde, methane, carbon monoxide, etc., were in order of Fe2O3/α-Al2O3 < CuO/α-Al2O3 < α-Al2O3 from low to high. Under the condition (flow rate: 1 L min -1 ; IPA concentration: 5,000 ppm; O2 content: 10%; discharge power: 47 W), the selectivity towards CO2 was about 40, 80 and 95% for α-Al2O3, CuO/α-Al2O3 and Fe2O3/α-Al2O3, respectively, indicating that Fe2O3/α-Al2O3 is the most effective for plasma-catalytic oxidation of IPA. Unlike plasma-alone processes in which tar-like products formed from volatile organic compounds are deposited, the present plasma-catalyst hybrid system did not exhibit such a phenomenon, thus retaining the original catalytic activity.

This work investigated the performance of ethylene and butane decomposition in a dielectric barrier discharge (DBD) plasma reactor packed with nanoparticle-coated γ-alumina at 150 °C. The effects of input power and type of metal oxide nanoparticle (TiO 2 and ZrO 2 coated on γ-alumina) on the decomposition efficiency and the distribution of by-products were examined and discussed. The decomposition efficiencies of ethylene and butane obtained with the nanoparticle-coated γ-alumina were higher than those with the bare γ-alumina. The main decomposition by-products were found to be carbon oxides. Nitrogen-containing by-products such as nitrous oxide and nitrogen dioxide were also detected with both ethylene and butane. Besides, some partially oxidized by-products like formaldehyde and acetaldehyde and lower molecular weight by-products like acetylene and methane were identified during the decomposition of ethylene and butane. The formations of such unwanted by-products were completely avoided and high selectivity towards carbon oxides was achieved when the ZrO 2 nanoparticle-coated γ-alumina was used as the packing material. The emission spectra of the DBD plasma showed various oxygen and nitrogen reactive species that are responsible for the decomposition of ethylene and butane.

In the present work, ZrO2nanoparticles loaded on glass wool (GW) were employed for catalytic and plasma-catalytic decomposition of ethylene. Unlike ZrO2 pellets, nanosized ZrO2 was found to exhibit catalytic activity for the decomposition of ethylene. Some carbon-containing by-products like CH4 ,C 2H2, and HCHO were detected under room-temperature operation of the reactor. The formations of such unwanted byproducts were suppressed and the conversion into CO2 was enhanced when the ZrO2 catalyst was combined with non-thermal plasma at high temperatures. The nanosized ZrO2 exhibited a stable decomposition performance during 80-h continuous operation, suggesting that it is able to withstand deactivation without substantial loss in its catalytic activity.

This work investigated the hydrophobic coating of silicate yellow phosphor powder in the form of divalent europium-activated strontium orthosilicate (Sr2SiO4:Eu 2+ ) by using an atmospheric pressure dielectric barrier discharge (DBD) plasma with argon as a carrier and hexamethyldisiloxane (HMDSO), toluene and n-hexane as precursors. After the plasma treatment of the phosphor powder, the lattice structure of orthosilicate was not altered, as confirmed by an X-ray diffractometer. The coated phosphor pow- der was characterized by scanning electron microscopy, fluorescence spectrophotometry and contact angle analysis (CAA). The CAA of the phosphor powder coated with the HMDSO precursor revealed that the water contact angle increased from 21.3° to 139.5° (max. 148.7°) and the glycerol contact angle from 55° to 143.5° (max. 145.3°) as a result of the hydrophobic coating, which indicated that hydrophobic layers were successfully formed on the phosphor powder surfaces. Further surface character- izations were performed by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry, which also evidenced the formation of hydrophobic coating layers. The phosphor coated with HMDSO exhibited a photoluminescence (PL) enhance- ment, but the use of toluene or n-hexane somewhat decreased the PL intensity. The results of this work suggest that the DBD plasma may be a viable method for the preparation of hydrophobic coating layer on phosphor powder.