There are two primary sludge drying methods such as the direct heating microwave method and the indirect heating steam one. In this study, the drying treatment facility at sewage treatment plant A applied both of these drying methods. The research aimed to investigate the optimal operation approach for the drying facility, considering the input sludge and the moisture content data after the drying process. Moisture content and removal rate data were executed at the research facility from January 2016 to December 2018. First, the microwave, a direct heating drying method, performed intensive drying only on the outer surface of the sludge by directly applying heat to the sludge using far infrared rays, so effective sludge drying was not achieved. On the other hand, the steam method of the indirect heating method used steam from a gas boiler to maximize the utilization of the heat transfer area and reduce energy of the dryer, resulting in an effective sludge drying efficiency. The sludge moisture content brought into the sludge drying facility was about 80%, but the moisture content of the sludge that went through the drying facility was less than 10% of the design standard. Therefore, the steam method of the indirect heating method is more effective than the microwave method of the previous direct heating method and is more effective for maintenance It has proven that it is an efficient method of operating construction facilities.

In this work, we have designed a novel gas inlet structure for efficient usage of growth and doping precursors. Our previous gas injection configuration is that the gas is mixed to one pipe first, then divided into two pipes, and finally entered the chamber symmetrically above the substrate without a jet nozzle. The distance between gas inlet and substrate is about 14.75 cm. Our new design is to add a new tube in the center of the susceptor, and the distance between the new tube and substrate is about 0.5 cm. In this new design, different gas injection configurations have been planned such that the gas flow in the reactor aids the transport of reaction species toward the sample surface, expecting the utilization efficiency of the precursors being improved in this method. Experiments have shown that a high doping efficiency and fast growth could be achieved concurrently in diamond growth when methane and diborane come from this new inlet, demonstrating a successful implementation of the design to a diamond microwave plasma chemical vapor deposition system. Compared to our previous gas injection configuration, the growth rate increases by 15-fold and the boron concentration increases by ~ 10 times. COMSOL simulation has shown that surface reaction and precursor supply both have a change in determining the growth rate and doping concentration. The current results could be further applied to other dopants for solving the low doping efficiency problems in ultra-wide-band-gap semiconductor materials.

특정작물의 연작재배가 만연한 국내 경작지 중, 특히 인삼재배지는 인삼뿌리썩음병균, 시설재배지는 선충에 의한 연작피해가 매우 심각하며, 주로 화학·생물학 약제로 방제하지만 효과가 낮고 토양오염과 약제저항성 등의 부작용을 유발하고 있음. 모든 살아 있는 병해충은 고온에 저항성이 없는 장점에 착안하여 마이크로파(915MHz) 전력밀도 균일화 응용으로 경작지 토양 30cm 이상 깊이까지 100℃ 이상 침투 가열하는 마이크로파 방제장치 및 방제기술을 개발하여 토양 속에 존재하는 선충, 개미, 인삼뿌리썩음병균에 적용한 결과, 선충은 60℃, 개미는 50℃에서 완전사멸 되었으며, 인삼뿌리썩음병균은 80℃에서 연작 가능한 수치까지 떨어지는 방제 효과를 나타 냄에 따라 농약을 대체하는 방제기술로 평가된다.

The optimization of deacetylation process parameters for producing chitosan from isolated chitin shrimp shell waste was investigated using response surface methodology with central composite design (RSM-CCD). Three independent variables viz, NaOH concentration (X1), radiation power (X2), and reaction time (X3) were examined to determine their respective effects on the degree of deacetylation (DD). The DD of chitosan was also calculated using the baseline approach of the Fourier Transform Infrared (FTIR) spectra of the yields. RSM-CCD analysis showed that the optimal chitosan DD value of 96.45 % was obtained at an optimized condition of 63.41 % (w/v) NaOH concentration, 227.28 W radiation power, and 3.34 min deacetylation reaction. The DD was strongly controlled by NaOH concentration, irradiation power, and reaction duration. The coefficients of correlation were 0.257, 0.680, and 0.390, respectively. Because the procedure used microwave radiation absorption, radiation power had a substantial correlation of 0.600~0.800 compared to the two low variables, which were 0.200~0.400. This independently predicted robust quadratic model interaction has been validated for predicting the DD of chitin.

Ion exchange resins are commonly employed in the treatment of liquid radioactive waste generated in nuclear power plants (NPP). The ion exchange resin used in NPP is a mixed-bed ion exchange resin known as IRN-150, which is of nuclear grade. This resin is a mixture of cation exchange resin and anion exchange resin. The cation exchange resin removes cationic radionuclides such as Cs and Co, while anion exchange resin handles anions (e.g., H14CO3 -), effectively purifying the liquid waste. Spent ion exchange resins (spent resin) containing C-14 are classified as low and intermediate level radioactive waste, and their radioactivity needs to be reduced as it exceeds the disposal limit regulated by law. Therefore, the microwave technology for the removal of C-14 from spent resin has been investigated. Previous studies have successfully developed a method for the effective removal of C-14 during the resin treatment process. However, it was observed that, in this process, functional groups in the resin were also removed, resulting in the generation of off-gases containing trimethylamine. These off-gases can dissolve in water from process, increasing its pH, which can subsequently hinder the recovery of C-14. In this study, we investigated the high-purity recovery of C-14 by adjusting the moisture content within the reactor following microwave treatment. Mock spent resins, consisting of 100 g of resin with HCO3 - ion-exchanged and 0, 25, or 50 g of deionized water, were subjected to microwave treatment for 40 or 60 minutes. Subsequently, the C-14 desorption efficiency of the mock spent resins was evaluated using an acid stripping process with H3PO4 solution. The functional group status of the mock spent resins was analyzed using 15N NMR spectroscopy. The results showed that the mock spent resins exhibited efficient C-14 recovery without significant functional group degradation. The highest C-14 desorption efficiency was achieved when 25 g of deionized water was used during microwave treatment.

In NPP (nuclear power plant), boric acid is used as a neutron absorbent. So radioactive boric acid waste are generated from various waste streams such as discharge or leakage of reactor coolant water, floor drains, drainage of equipment for operation or maintenance, reactor letdown flows and etc. Depending on KHNP, 20,015 drum (200 L drum) of concentrated boric acid waste were stored in KOREA NPP until 2019. In previous study, our group suggested the waste upcycling process synthesizing B4C neutron absorber using boric acid waste and activated carbon waste to innovatively reduce radioactive wastes. Radioactive activated carbon waste was utilized in off gas treatment system of NPP to capture nuclide such as I-131, C-14 and H-3. Activated carbon waste is treated as low-level radioactive waste and pre-treatment system for removing nuclide from the activated carbon waste is needed to use B4C up-cycling process. In this study, microwave treatment system is suggested to treat the activated carbon waste. Activated carbon waste was exposed to microwave for a few minutes and temperature of the waste was dramatically increased over 400°C. Nuclide in the activated carbon waste were selectively removed from the waste without massive production of secondary off gas waste.

Characteristics and useful effects for human health of antioxidant carbon nanodots contained in microwave-assisted Opuntia humifusa extract (MA-OHE(CD)) were investigated in this work. MA-OHE(CD) was characterized using transmission electron microscopy, dynamic light scattering analysis, X-ray diffraction, UV–vis spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform-infrared spectroscopy. Besides, total phenolic content and antioxidant activity of MA-OHE(CD) were measured. It was revealed that the MA-OHE(CD) increases aquaporin-3 expression in human epidermal keratinocytes cell with hydrophilic characteristics. Moreover, the bio-active compound extraction efficacy and antioxidant activity of microwave-assisted extraction were great when compared to maceration.

Sulfur and nitrogen co-doped carbon dots (NSCDs) were quickly synthesized by the microwave-assisted method from triammonium citrate and thiourea. NSCDs showed a quantum yield of 11.5% with excitation and emission bands at 355 and 432 nm, respectively. Also, a fluorescence quenching was observed in the presence of Pb(II) ions, and the as-synthesized CDs were used as a sensitive probe for detecting Pb(II) in water and food samples. The results showed the optimal conditions for Pb(II) determination were CDs concentration of 0.02 mg mL− 1 at pH 6.0–7.0 and an incubation time of 20 min. The relative fluorescence intensity of NSCDs was proportional to Pb(II) concentrations in the range of 0.029–2.40 and 2.40–14.4 μmol L− 1 with a correlation coefficient (R2) of 0.998 and 0.955, respectively, and a detection limit of 9.2 × 10– 3 μmol L− 1. Responses were highly repeatable, with a standard deviation below 3.5%. The suggested method demonstrates the potential of a green, fast, and low-cost approach for Pb(II) determination in water, tea, and rice samples with satisfying results.

The effects of Ni2+ substitution for Mg2+-sites on the microwave dielectric properties of (Mg1-xNix)(Ti0.95(Mg1/3 Ta2/3)0.05)O3 (0.01 ≤ x ≤ 0.05) (MNTMT) ceramics were investigated. MNTMT ceramics were prepared by conventional solid-state reaction. When the MgO / TiO2 ratio was changed from 1.00 to 1.02, MgTi2O5 was detected as a secondary phase along with the MgTiO3 main phase in the MNTMT specimens sintered at 1,400 °C for 4h. For the MNTMT specimens with MgO / TiO2 = 1.07 sintered at 1,400 °C for 4h, a single phase of MgTiO3 with an ilmenite structure was obtained from the entire range of compositions. The relative density of all the specimens sintered at 1,400 °C for 4h was higher than 95 %. The quality factor (Qf) of the sintered specimens depended strongly on the degree of covalency of the specimens, and the sintered specimens with x = 0.01 showed the maximum Qf value of 489,400 GHz. The dielectric constant (K) decreased with increasing Ni2+ content because Ni2+ had a lower dielectric polarizability (1.23Å3) than Mg2+ (1.32Å3). As Ni2+ content increased, the temperature coefficient of resonant frequency (TCF) improved, from -55.56 to -21.85 ppm/°C, due to the increase in tolerance factor (t) and the lower dielectric constant (K)

본 실험은 마이크로웨이브 처리가 상추 유묘의 생육 변화와 이차대사산물 함량의 변화를 알아보고자 수행되었다. 파종 후 3주째 상추 유묘에 2.45GHz 주파수와 200W의 마이크로 웨이브를 0, 4, 8 및 12초 동안 처리하고, 4주간 식물공장에서 재배한 후 생육 및 성분 분석을 수행하였다. 지하부와 지상부 의 생체중과 건물중, 엽면적, 엽장 및 엽수는 마이크로웨이브 처리시간이 증가할수록 감소하였다. 4초 처리구와 비교하여 12초 처리구에서 chlorophyll a, chlorophyll b 및 총 carotenoids 의 함량이 증가되었으며 총 페놀 함량은 감소하였다. 무처리 구와 비교하여 8초 처리구에서 총 플라보노이드 함량이 감소 하였다. 이러한 결과들은 산화적 스트레스에 의해 이차대사 산물 함량이 변화된 것으로 사료된다. 총 플라보노이드 함량 을 제외한 이차대사산물 함량은 각 처리구에서 무처리구와 비 교하여 유의한 차이가 없었지만, 각 처리구 사이의 유의한 차 이는 200W와 2.45GHz의 마이크로웨이브 처리가 4주 후 상 추의 이차대사산물 함량에 영향을 줄 수 있다는 것을 시사한다.

Evaporative emission generated through the fuel supply system of a gasoline automobile is prevented into the atmosphere through an activated carbon canister system. In this study, the oxygen functional group of activated carbon was controlled using a simple gas phase treatment to improve evaporative emission reduction performance, and the adsorption/desorption performance of evaporative emissions was evaluated according to microwave heating conditions. Microwave heating was used to remove the oxygen functional group of the activated carbon efficiently. Microwave heating was found to remove oxygen functional groups in a short treatment time (1–7 min). Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope–energy-dispersive X-ray spectroscopy were employed to investigate modifying the oxygen functional group of the activated carbon. Using N2/ 77K adsorption/desorption isotherm, the textural properties of the activated carbon according to microwave heating conditions were examined. The Brunauer–Emmett–Teller (BET) equation was used to calculate the specific surface area of the activated carbon, and the Dubinin–Radushkevich (DR) equation was used to calculate the micropore volume of activated carbon. Microwave heating effectively increased the butane working capacity, which is the neat adsorption capacity of activated carbon, from 7.12 g/100 ml to a maximum of 8.04 g/100 ml.

Mixed-bed ion exchange resin consist of anion exchange resin and cation exchange resin is used to treat liquid radioactive waste in nuclear power plants. C-14 from heavy water reactors (HWR) is adsorbed on the anion exchange resin and is considered intermediate-level radioactive waste. The total amount of radioactivity of C-14 in spent ion exchange resin exceeds the activity limits for the disposal facility. Therefore, it is necessary to reduce the radioactivity through pre-treatment. There are thermal and non-thermal methods for the treatment of spent ion exchange resin. However, destructive methods have the problem of emitting off-gas containing radionuclides. To solve this challenge, various methods have been developed such as acid stripping, PLO process, activity stripping, thermal treatment and others. In this study, spent ion exchange resin (spent resin) was treated using microwave. The reaction characteristics of the resin to microwave were used to selectively remove the C-14 on the functional groups. Simulated spent anion exchange resin and spent resin from Wolseong NPP were treated with the microwave method, and the desorption rate was over 95%. An integrated process system of 1 kg/batch was built to produce operating data. After the operation of the process, characterization and evaluation of post-treatment for condensate water and adsorbent used in the process were performed. When the process system was applied to treat simulated spent resin and real spent resin, both showed a desorption rated of more than 97%. It means that the C-14 was successfully removed from the radioactive spent resin.

Carbon nanodots (CNDs) are 0D quasi-spherical nanoparticles that are less than 10 nm in size. CNDs that possess surface functional groups such as hydroxyl, amino, and carboxyl groups have been demonstrated to scavenge free radicals efficiently and effectively, resulting in them being beneficial for cosmetic and cosmeceutical applications. In this study, we successfully prepared novel CNDs, namely black VC, using vitamin C (VC) as a promising precursor. Black VC was prepared by a facile one-step method based on short-time microwave irradiation. The properties of black VC were characterized by transmission electron microscopy (TEM) analysis, X-ray diffraction (XRD), high-resolution X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and UV–vis spectrophotometry. Radical scavenging, cell viability, and anti-pollution activity assays were also conducted to demonstrate the functionalities of black VC. The developed black VC exhibited lower cytotoxicity and better antioxidant, metal chelating ability, and anti-pollution activities than its precursor. These results provide a new approach for developing advanced antioxidants for innovative cosmetic formulations using a simple microwave treatment method. However, black VC retained some problems of its precursor in the form of low stability, which is likely to be a challenge for its cosmeceutical application.

Carbon dots (CDs) with tunable fluorescence emissions have been developed from a wide range of small organic molecules with various bottom-up syntheses. However, most of them were prepared under high temperatures and high pressures with long reaction times and tedious purification processes. In addition, previously reported carbon dots frequently displayed excitation-dependent emissions, which restrict their further applications. Herein, we present a simple and rapid microwaveassisted solvothermal synthesis of multicolour carbon dots with excitation-independent emissions. In ethylene glycol, the green (G)-CDs emitting at 537 nm with a quantum efficiency (QY) of 15% were obtained by using a single precursor of phloroglucinol, and blue (B)- and yellow (Y)-CDs emitting at 436 nm and 557 nm with QYs of 55% and 28% were derived with additives of o- and m-phenylenediamine, respectively. Analyses of their chemical structures and optical processes suggest that highly polymeric carbon dots were uniformly formed from the small molecules and their fluorescences were predominantly originated from rapid direct recombination. Furthermore, emissions at different wavelengths were mainly attributed to different degrees of oxidation (13.9%, 15.2% and 16.4% oxygen in B-, G- and Y-CDs, respectively) and different proportions of pyrrolic nitrogen (10.4% and 1.40% in B- and Y-CDs, respectively). To demonstrate the application feasibility, the obtained carbon dots were utilized for ion detection and anti-counterfeiting. Based on static quenching of the carbon dots’ fluorescence, micro amounts of ferric ion in water samples were detected selectively and reproducibly. Moreover, the anti-counterfeiting pattern constructed by the carbon dots emitted fluorescence under ultraviolet illumination, but concealed perfectly under daylight. This achievement is of great potential for developing multicolour carbon dots of high qualities.

해수면온도는 해양-대기의 현상을 이해하고 기후변화를 예측하기 위해 사용되는 중요한 변수이다. 마이크로파 영역의 인공위성 원격탐사는 구름과 강수와 같은 기상현상 위성 관측 측기의 경로에 존재하더라도 해수면온도 획득을 가능하게 한다. 따라서 마이크로파 해수면온도의 높은 활용도를 고려하면 위성 해수면온도를 정확도를 지속적으로 검증 하고 오차 특성을 분석할 필요가 있다. 본 연구에서는 2014년 3월부터 2021년 12월까지 약 8년 동안 Global Precipitation Measurement (GPM)/GPM Microwave Imager (GMI) 마이크로파 해수면온도의 정확도를 표층 뜰개 부이 수온 자료를 사용하여 검증하였다. GMI 해수면온도는 실측 해수면온도에 비해 0.09 K의 편차와 0.97 K의 평균 제곱근 오차를 보였 고, 이는 기존 연구 결과에 비해 다소 높게 나타났다. 이외에도 GMI 해수면 온도의 오차 특성은 위도, 연안과의 거리, 해상풍 및 수증기량과 같은 환경적 요인과 관련성이 있다. 오차는 육지에서 300 km 이내의 거리에서 해안 지역에 가까 운 지역과 고위도 지역에서 증가하는 경향이 있다. 또한 낮에는 약한 풍속(<6 m s−1 ), 밤에는 강한 풍속(>10 m s−1 ) 범위 에서 상대적으로 높은 오차가 나타났다. 대기 수증기는 30 mm 미만의 매우 낮은 범위 또는 60 mm보다 큰 매우 높은 범위에서 높은 해수면온도 차이에 기여했다. 이러한 오차들은 저수온에서 GMI 자료의 정확도가 떨어지는 기존 연구와 일치하며, 연안으로부터의 거리, 풍속, 수증기량에 의한 오차의 경우 육지와 해양의 방사율 차이 및 바람에 의한 해수 면 거칠기 변화, 수증기의 마이크로파 대기 흡수에서 기인하는 것으로 추정된다. 이는 한반도 주변해에서 마이크로파 위성 계산 SST를 보다 광범위하게 활용하기 위해서는 GMI 해수면온도 오차의 특성에 대한 이해가 필요함을 시사한다.

In preparation of porous carbon materials microwave oven brightening is one of the warming modes used ever. The various procedures that take place in microwave combustion process include carbonization, incitation, and recovery and thus carbon is defined. This paper compares ideal conditions of traditional warming methods, as well as their implementation potential, losses, and specifications. This porous carbon with heat treatment possesses various properties and they are well suited for energy applications which require constrained space such as hydrogen storage in solid-state and supercapacitors. The enhanced properties are chemical and thermal stability, ready availability, low framework density and ease of processability. The recent trend in class of porous carbons is Activated Carbons that are employed traditionally as adsorbents or catalyst supporters but currently, they found potent applications in fabricating for hydrogen storage materials and supercapacitors. These activated carbons are much enhanced form in class of porous carbon materials and they possess the capability to enable hydrogen economy, where the energy carrier is hydrogen. Therefore, the utility of activated carbons as a source for energy storage experiences a rapid growth at current trend and they possess significant advances. This investigation is based on detailed cost development data and electrical imperativeness applications.

This work reported the electrochemical and photoelectrochemical (PEC) properties of a new photoelectrode based on hematite Co-Fe2O3@NiO, a photoactive semiconductor, was prepared using a process involving a combination of the co-precipitation and microwave-assisted synthesis of Fe2O3, Co-Fe2O3 and Co-Fe2O3@NiO, respectively. The obtained products were characterized by X-Ray powder Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray analysis (EDX), Ultraviolet–Visible (UV–vis) analysis, Fourier Transform Infrared spectroscopy (FT-IR). X-ray diffraction (XRD) pattern of the sample determined the crystal structure of α-Fe2O3 nanoparticles. The SEM image shows spherical nanoparticles. FTIR spectrospy spectrum confirmed the phase purity and chemical bond for the sample. Optical studies show a variation of band gap from 2.118 to 2.07 eV. The electrochemical and photoelectrochemical (PEC) performance of the films were examined by cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The electrochemical oxidation of water achieved by Cobalt-doped Fe2O3@ GCE modified electrode exhibited the current density of 21 mA/g at 0.5 V vs. SCE for 5 at% of Co and reveals enhanced specific capacitance of 352.11 F/g. The catalytic performance of urea oxidation was measured by cyclic voltammetry on Co-Fe2O3@NiO nanoparticles modified glassy carbon electrode (GCE) in alkaline medium. The electrode Co-Fe2O3@NiO without annealing showed a peak current density of 1.59 mA/cm2 at 0.1 M urea in 1.0 M NaOH, which was 3.6 fold higher than that of Co-Fe2O3@NiO with annealing. In another part, this work reported the photoelectrochemical (PEC) properties of photoanode prepared by spin coating. The highest photocurrent 0.042 mA/cm2 at 0.5 V Vs SCE was obtained for 5% Co-Fe2O3@NiO while the photocatalytic oxidation of urea.