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.

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.

본 연구에서는 파장의 위상차를 변화시켜 균일한 살균을 유도할 수 있고 저전력으로 효과를 높일 수 있는 QRD(quadratic residue diffusor) 마이크로파를 이용하여 챔버 내부의 위치에 따른 온도변화를 측정하여 효율성과 균등성을 분석한 결과는 다음과 같다. 챔버 내부의 수직 35cm, 중앙 위치에서는 7kW 조사시 가장 효율이 높게 나타났고, 좌우측 위치에서는 5kW에서 효율성이 높았다. 그리고 마그네트론 No. 1, 2, 3에서 3kW로 하였을 때, Bar의 위치에 따른 온도 균등성은 1Bar와 2Bar의 위치에서는 거의 비슷하게 나타났다. 마그네트론 No. 3, 4, 5의 3kW로 하였을 경우에는 3Bar에서 온도가 약 10~ 20% 정도 높게 나타났고 마그네트론 용량을 5, 7, 9kW로 하였을 때, 조사 시간에 대한 평균 온도는 Bar의 위치에 무관하게 거의 유사한 형태로 증가하였다. 반면에 챔버의 적정 내용적에 대한 효율성은 조사용량에 반드시 비례하지는 않았다. 마그네트론 3kW를 60, 120, 180초 동안 조사하였을 경우 마그네트론 조사 위치에 따라 구석 부분에서 약 5~10oC 더 높게 상승하였고 수평면의 위치별 온도 분포는 비교적 균일하였으며 부분적으로 구 석부분에서 약간 더 온도가 상승하는 경향이 있었다. 마그네트론 5, 7, 9kW 조사에서는 Bar의 위치와 상관없이 전반적으로 온도가 비교적 균일하게 상승하고 있었다.

Graphene oxide has been synthesized by microwave-assisted exfoliation of graphite oxide prepared by modified Hummers method. Graphite was oxidized in a solution of H2O2 and KMnO4 at 65~80˚C, followed by 10 % H2O2 solution treatment at 80~90˚C. The graphite oxide was exfoliated under microwave irradiation of 1 kW and was reduced to graphene effectively by hydrazine hydrate (H4N2·H2O) treatment. The exfoliation of graphene oxide was significantly affected by the microwave irradiation on (heating)/off (cooling) period. An on/off period of 10 s/20 s resulted in much more effective exfoliation than that of 5 s/10 s with the same total treatment time of 10 min. This can be explained by the higher exfoliation temperature of 10 s/20 s. Repetition of the graphite oxidation and exfoliation processes also enhanced the exfoliation of graphene oxide. The thickness of the final graphene products was estimated to be several layers. The D band peaks of the Raman spectra of the final graphene products were quite low, suggesting a high crystal quality.

This study aimed to determine adhered mortar content of recycled aggregate (RA) using microwave irradiation (700W)and mixed solution of hydrochloric acid (HCl) and hydrogen peroxide (H2O2). The optimum condition was first to soakRA in tap water for 30 min and then RA was soaked in mixed solution of 30% HCl and 15% H2O2 (HCl:H2O2=1:2) for 70-90min after 15-min microwave irradiation. The mortar of RA in the condition was completely removed within2.3 hrs. Reaction rate (k) with the condition was −0.6408hr−1, which was about 190 times faster than that with HCl only(k=−0.0034hr−1).

This study aimed to completely remove adhered mortar from recycled aggregate (RA) using microwave irradiation (700 W) and mixed solution of hydrochloric acid (HCl) and hydrogen peroxide (H2O2). The optimum condition was first to soak RA in tap water for 30 min and then RA was soaked in mixed solution of 30% HCl and 15% H2O2 (HCl : H2O2 = 1 : 2) for 70-90 min after 15-min microwave irradiation. Therefore, the mortar of RA in the condition was completely removed within 2.3 hrs. Reaction rate (k) with the condition was –0.6408 hr-1, which was about 190 times faster than that with HCl only (k = -0.0032 hr-1).

Silicon carbide with aluminium oxide was used to remove the sulphur hexafluoride (SF6) gas using microwave irradiation. The destruction and removal efficiencies (DREs) of SF6 were studies as a function of various decomposition temperatures and microwave powers. The decomposition of SF6 gas was analyzed using GC-TCD. XRD (X-ray powder diffraction) and XRF (X-ray Fluorescence Spectrometer) were used to characterize the properties of aluminum oxide. DREs of SF6 were increased as the microwave powers were increased. Additive aluminium oxide on SiC increased the removal efficiencies and decreased the decomposition temperature. The XRD results show that the γ-Al2O3 was transformed to α-Al2O3 during SF6 decomposition by microwave irradiation. It was found that the best material to control SF6 was SiC with Al2O3 30 wt% in consideration of microwave energy consumption and SF6 decomposition rate.

In this study, the characteristics of granular activated carbon (GAC) supported metal was investigated in an area influenced by flame discharge and temperature variation during irradiating microwave. The modified GAC was formulated by impregnating metal hydroxides of nickel (Ni/GAC), barium (Ba/GAC), copper (Cu/GAC), zinc (Zn/GAC), cobalt (Co/GAC) and lanthanum (La/GAC). Ba/GAC was selected as it showed lack of spark discharge and temperature increasing aspects. Comparison of adsorption and desorption amount of GAC and Ba/GAC showed that adsorption and desorption rate of the GAC were higher than those of Ba/GAC. The results show that the presence of barium can decrease adsorption/desorption rate because of plugging pore of GAC. Toluene regeneration rate of Ba/GAC was better than that of GAC due to barium loading. Finally, GAC with barium can be controled a rapid increasing temperature and spark discharge, increased the regeneration rate of toluene during desorption by irradiating microwave.

This paper describes the adsorption/desorpton efficiency of a modified activated carbon by irradiated microwave to treat toluene. By employing microwave energy, the regeneration time was considerably shortened compared with conventional thermal heating regeneration. New adsorbent called ACB(Activated Carbon-Bentonite) was prepared from powder activated carbon with mixing bentonite as a binder. Specific surface area, average pore size and total pore volume of ACB were calculated from the nitrogen adsorption/desorption isotherm. The surface of ACB was characterized with scanning electron microscope(SEM). The results showed that the specific surface area, total pore volume, average pore size of ABC was not influenced by regenerating cycle with microwave irradiation. Toluene was adsorbed onto ACB which desorbed by MW irradiation. Absorption capacity of ACB was 0.117 gtoluene/ gACB. Desorption efficiency of toluene increased as higher microwave output was applied.

The purposes of this paper were to monitor the temperature rising courses and spark discharge of the modified granular activated carbon (GAC) by microwave (MW) irradiation and to evaluate absorption of benzene. The GAC coated on SiO2, boron, talc, ferrite was named as the modified GAC. Thermal and spark discharge measurement of virgin GAC and modifed GAC has been carried out using a MW device operating at 2450 MHz under various energy conditions. The results of this paper as follows. First, the modified GAC is more efficient than the virgin GAC in temperature control. Temperature gradient of the modified GAC is more lower than that of virgin GAC. The temperature gradient of GAC was observed in the following order : virgin GAC, Mn-Zn ferrite/GAC, Ni-Zn ferrite,/GAC, SiO2/GAC, Boron/GAC, Talc/GAC. Second, the spark discharge of the modified GAC was diminished, compared with that of virgin GAC. Because of its excellent electrical insulating properties, the coating material prevents the spark discharge. Finally, the benzene adsorption capacity of the modified GAC decreased due to diminishing of adsorption site by the coating material. Considering the temperature gradient and spark discharge of GAC, the GAC coated SiO2 would be appropriate absorbent under irradiation of MW.

Adsorption characteristics of benzene by zeolite were investigated using irradiating microwave. Experimental apparatus was applied to a U-type fix-bed column equipped with microwave system. Zeolite, itself, seems to be inappropriated to remove benzene because of a hygroscopic property. Microwave irradiation to zeolite, however, brings about decreasing H2O adsorption and increasing benzene adsorption. This causes that the dipole material such as H2O was vibrated and heated by irradiation of microwave and desorbed from zeolite. And then, benzene starts to be absorbed by zeolite. In this study, the results showed that the selective adsorption of benzene was occurred by the microwave irradiation and the adsorption capacity of benzene was increased by increasing microwave energy. As a results, it was found that the zeolite could be used to adsorb benzene with microwave and this method make it feasible simultaneously to adsorb and desorb benzene.