• 한국물환경학회지
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• 제22권6호
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• pp.1130-1136
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• 2006

This work elucidates the effects of pretreatment of the sewage sludge from wastewater treatment plant by microwave irradiation on elutriated acid fermentation. These experiments typically fell into two process; pretreatment as microwave irradiation and elutriated acid fermentation for hydrolysis and acidification as main process of primary sludge. The results of maximum solubilization rate of B, D primary and secondary sludge were 0.042, 0.086 and 0.15 gSCODprod./gICODin and the optimum irradiation time of microwave on 2,450 MHz and 900 W were 5 min. for primary sludge and 7 min. for secondary sludge. From batch tests on elutriated acid fermentation that was used the pretreated primary sludge as microwave, the optimum pH and HRT (hydraulic retention time) were 7 and 5 days at $35^{\circ}C$ condition.

• 대한환경공학회지
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• 제27권7호
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• pp.732-738
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• 2005

본 연구는 슬러지의 효율적인 처리를 위하여 슬러지의 탈수 및 건조 효율에 미치는 마이크로파의 영향을 실험하여 마이크로파의 적정 처리 조건을 제시하는데 목적이 있다. 마이크로파를 이용하여 슬러지의 탈수 효율을 향상시키기 위해서는 슬러지 부피에 따른 적정 마이크로파의 조사시간의 결정이 매우 중요하며, 적정 시간 동안 마이크로파 처리된 농축슬러지의 경우 모세흡입시간이 52.3초에서 30.8초로 저감되어 탈수성이 상당히 향상되었고, 마이크로파에 의해 개량된 농축슬러지의 압력여과 후 함수율은 81.4%로 나타났다. 또한 마이크로파와 전기로의 탈수슬러지 건조 특성을 평가한 결과, 슬러지의 함수율을 55% 이하로 건조시키는데 마이크로파 가열 방식은 3분이 소요된 반면, 전기로를 이용하여 $105^{\circ}C$에서 건조한 경우에는 40분이 소요되었고, $170^{\circ}C$에서 건조한 경우는 20분이 소요되었으며, $300^{\circ}C$에서 건조한 경우는 9분이 소요되었다. 따라서 마이크로파를 이용하여 슬러지를 건조할 경우, 기존 가열 방식보다 훨씬 효율적으로 슬러지에서 수분을 제거할 수 있음을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.1957-1964
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• 2011

Various reaction conditions uding temperature, time and type and concentration of templates have been changed in order to facilely synthesize, especially with microwave (MW) heating, SAPO-34 molecular sieves. SAPO-34 molecular sieve can be synthesized rapidly with microwave irradiation from a gel containing tetraethylammonium hydroxide (TEAOH) as a template. However, other several templating molecules lead to SAPO-5 molecular sieve under microwave irradiation even though SAPO-34 is obtained by conventional electric synthesis from the same reactant gels. Moreover, SAPO-34 can be obtained more easily by increasing the TEAOH or silica concentration or by increasing the reaction temperature. SAPO-34 can be obtained within 5 min in a selected condition (high temperature of 210 $^{\circ}C$) with microwave heating, which may lead to a continuous production of the important material. SAPO-34 synthesized by microwave irradiation is homogeneous and small in size and shows acidity and a stable performance in the dehydration of methanol and 2-butanol to olefins, suggesting potential applications in acid catalysis.

• Journal of Electrochemical Science and Technology
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• 제13권3호
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• pp.390-397
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• 2022

The use of microwaves as the energy source for synthesis and sintering of ceramics offers substantial advantages compared to conventional gas-fired and electric resistance furnaces. Benefits include much shorter processing times and reaching the sintering temperature more quickly, resulting in superior final product quality. Most oxide ceramics poorly interact with microwave irradiation at low temperatures; thus, a more complex setup including a susceptor is needed, which makes the whole process very complicated. This investigation pursued a new approach, which enabled us to use microwave irradiation directly in poorly coupled oxides. In many solid-state electrochemical devices, the support is either metal or can be reduced to metal. Metal powders in the support can act as an internal susceptor and heat the entire cell. Then sufficient interaction of microwave irradiation and ceramic material can occur as the sample temperature increases. This microwave heating and exothermic reaction of oxidation of the support can sinter the ceramic very efficiently without any external susceptor. In this study, yttria stabilized zirconia (YSZ) and a Ni-YSZ cermet support were used as an example. The cermet was used as the support, and a YSZ electrolyte was coated and sintered directly using microwave irradiation without the use of any susceptor. The results were compared to a similar cell prepared using a conventional electric furnace. The leakage test and full cell power measurement results revealed a fully leak-free electrolyte. Scanning electron microscopy and density measurements show that microwave sintered samples have lower open porosity in the electrode support than conventional heat treatment. This technique offers an efficient way to directly use microwave irradiation to sinter thin film ceramics without a susceptor.

• 한국염색가공학회지
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• 제10권4호
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• pp.7-14
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• 1998

Microwaves are high frequency radiation capable of generating very rapid, uniform and efficient heating of textile material. Microwave heated dyeing of polyester fabric was tried with different solvent systems, irradiation time and dye concentration. Microwave fixation methods were used with 100% water,30% urea, EG and DMF, respectively, pad-baths in which the padded fabrics were exposed over a heated or boiling water bath to maintain sufficient moisture content during irradiation. In order to ascertain the relation between the dyeing property of polyester fabric and the microwave irradiation condition caused by microwave heating, the K/S values and fastness properties of dyed fabrics such as light, washing and sublimation fastness were measured.

• 한국환경과학회지
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• 제17권5호
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• pp.493-500
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• 2008

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 $g_{toluene}/g_{ACB}$. Desorption efficiency of toluene increased as higher microwave output was applied.

• Current Research on Agriculture and Life Sciences
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• 제32권3호
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• pp.131-134
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• 2014

The thermal death kinetics of the Black timber bark beetle, Xylosandrus germanus, was investigated to develop a heat treatment for control of infested wood packing materials used to export goods. To determine the feasibility of microwave irradiation as an alternative control method, laboratory experiments irradiating wooden blocks of Douglas fir ($200{\times}200{\times}250mm$), which were artificially infested with adults, with 2.45 GHz of microwave energy. All (100%) Ambrosia beetle adults were killed by both hot water treatments and microwave irradiation at $52^{\circ}C$ and $58^{\circ}C$, respectively. Probit analyses estimated the internal wood temperature required to produce Probit (0.99) efficacy to be $64.7^{\circ}C$ (95% CI $62.4-69.9^{\circ}C$) at one minute after microwave treatment.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.174-178
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• 2013

A highly reliable dealkylation protocol of alkyl aryl ethers, whose alkyl groups are longer than methyl group, has been developed. We report that various ethyl, n-propyl, and benzyl aryl ethers are successfully cleaved using an ionic liquid, 1-n-butyl-3-methylimidazolium bromide, [bmim][Br], under microwave irradiation. Despite many characteristics such as lower cost and less toxicity of the alkylating agents, and greater hydrophobicity of the products, longer alkyl ethers have been significantly less exploited than methyl ethers, probably due to more difficulty in the deprotection step. Since it has the same advantages as the demethylation method developed by this group including mild conditions, short reaction time, and small use of the ionic liquids, the dealkylation protocol can greatly encourage the broader use of longer alkyl groups in the protection of phenolic groups. As with our previous study of demethylation using [bmim][Br], the microwave irradiation is crucial for the deprotection of longer alkyl aryl ethers. Unlike the conventional heating, which causes either low conversion or decomposition, the microwave irradiation seems to more effectively provide energy to cleave the ether bonds and therefore suppresses the undesired reactions.

• 한국물환경학회지
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• 제23권4호
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• pp.498-503
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• 2007

The performance of elutriated acid fermentation to evaluate the effects of microwave irradiation and pH control as pretreatment was investigated. The MW pH 7 reactor which was used the pretreated primary sludge as microwave irradiation was operated at pH 7 and $35^{\circ}C$. The EAF pH 9 reactor was operated at pH 9 and $35^{\circ}C$ without pretreatment. The SCOD and VFAs production rate were 0.17 gSeOD/gVSrem. and 0.27 gVFAs as COD/gVSrem. in MW pH 7 reactor, 0.16 gSCOD/gVSrem. and 0.24 gVFAs as COD/gVSrem. in EAF pH 9 reactor, respectively. VS and Volume reduction were 54% and 48% in MW pH 7 reactor, 54.6% and 36% in EAF pH 9 reactor, respectively. A comparison of the microwave irradiation and controlled pH in elutriated acid fermentation showed that the former is more efficient in SCOD and VFAs production and it rises to slightly higher reduction in the volume of the sludge. In addition, E. coli. was not detected in the wasting sludge of MW pH 7 reactor. Based on the results, microwave irradiation appeared to be one of the viable options for generating class A sludge. According to the batch tests, sequencing batch test which was used the pretreated primary sludge as microwave was performed at pH 7 and $35^{\circ}C$, SCOD production was 0.16 gSCOD/gVSrem., VS reduction and volume reduction were 64% and 63%, respectively.

• 한국식품영양과학회지
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• 제28권4호
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• pp.954-957
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• 1999

The changes in L ascorbic acid content by processing treatments; gamma irradiation, heating and microwave were investigated using high performance liquid chromatography. The content of L ascorbic acid in standard solutions and citrus fruits decreased from 27.4 to 44.9% and from 6.9 to 21.9%, re spectively, by gamma irradiation doses in the range of 1 to 10 kGy. By heating treatments, L ascorbic acids in standard solutions and citrus fruits were destroyed 22.5 to 36.8% and 4.5 to 18.1%, respectively. By microwave treatment, L ascorbic acid content also decreased from 23.1 to 47.4% and from 6.5 to 22.6%, respectively.