• Journal of Wetlands Research
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• v.18 no.3
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• pp.244-249
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• 2016

Anaerobic digester supernatant including high concentrations of nitrogen is recycled to water treatment line and make pollutant load increase in municipal wastewater treatment plant(MWTP). To treat nitrogen in anaerobic digester supernatant is suggested the method of MWTP retrofit. In this study, the lab scale reactor was operated about 200 days using supernatant of anaerobic digester. The results could draw operation condition that ammonium nitrogen removal efficiency more than 90% and nitrite conversion efficiency over 70%. Correlation between operation efficiency and operation factors was analyzed based on the operation results. Ammonium nitrogen remove efficiency and nitrite conversion efficiency were related to solid retention time (SRT), ammonium nitrogen load and ammonium nitrogen loading per unit mixed liquer suspended solid (MLSS). Results of this study can be used effective data on nitritation of supernatant of anaerobic digester, and be expected to increase availability of nitritation.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.2
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• pp.20-23
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• 2012

본 연구는 유기성폐기물을 처리하고 그것을 이용하여 고체연료 또는 퇴비를 생산하는 종합시스템에 관한 것이다. 유기성폐기물은 90% 전후의 높은 함수율을 나타내고 있기 때문에 처리에 중점을 두어야 할 부분이 수분 처리 방법이다. 따라서 기존의 처리방법으로는 고액분리하여 처리 후 하천에 방류하는 시스템에 의해 처리되고 있다. 하지만 본 연구에서는 기술개발의 차별화 및 선행기술의 회피 전략을 위해, 유기성폐기물의 수분을 건조시키는 방법으로 미생물이 유기성폐기물의 유기물을 분해하여 발생 되는 $80^{\circ}C$ 이상의 열에너지에 의해 수분을 제거하는 발열반응을 적용하여 수분을 제거하는 무방류시스 템이다. 뿐만 아니라 고체연료의 발열량을 높이기 위해서 무연탄, 코크스, 기름 등의 열량보조제를 첨 가하는 대신에 유기성폐기물을 첨가 한 후 적당한 발열반응 및 건조시켜 고체연료를 제조하는 방법으 로 4,000kcal/kg 이상의 높은 발열량을 얻을 수 있으며 불완전연소 등에 의한 2차 오염을 방지할 수 있는 기술이다. 따라서 친환경 미생물 발열반응에 의해 유기성폐기물을 저렴한 비용으로 액상 및 고상 을 동시에 처리 할 수 있으며, 고체연료를 제조할 수 있는 새로운 신기술이다.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.52-61
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• 2009

In this study, TAPEH (t-amyl peroxy 2-ethyl hexanoate) was selected for the reaction initiator which is a core factor for developing acrylic polyol binder. Tone M100 (caprolactone acrylate), 4HBA (4-hydroxy butyl acrylate), and 2HEMA (2-hydroxy ethyl methacrylate) were used for hydroxy-monomers. To check the applicability of raw materials mentioned above into the binders of 2 components acrylic polyurethane paint and reduce the VOC, the reactivity and film performance by different kinds of aliphatic polyisocyanate hardeners which are already generalized were reviewed. As the Tin-based catalyst has been regulated, the comparison test of reactivity and performance between the conventional catalyst and non-toxic metal catalyst recommended as the alternative was conducted as well. As a result, we were able to obtain the basic data which are necessary for applying 2 components high solid polyurethane paint and also reached a conclusion that it can be applied for developing new paints in terms of high performance, workability and environmental care.

• Clean Technology
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• v.18 no.1
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• pp.38-42
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• 2012

Photonic crystals (PCs) are highly ordered porous materials which have been much attention because of its potential for controlling the light sauces. There are many methods for synthesizing this kind of materials among them we chose the supercritical deposition. With this method the reactants can easily infiltrate into the complex structure. In this paper, supercritical carbon dioxide ($scCO_2$) was used as a reaction medium, which is known as a sustainable solvent due to its nontoxic and noninflammable characteristics. We coated the colloidal template with metal alkoxide by using $scCO_2$ and then obtained macro-porous inverse opals. The reaction was carried out at $40^{\circ}C$ and 80 bar. We synthesized two different inverse opals which called silica and titania inverse opals by use of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TTIP) as a precursor, respectively.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.33-41
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• 2021

Feldspar, along with Quartz, are the most frequently produced minerals in Korea; however, the potential value is estimated to be significantly low because of the scarce research on the development and application of material properties, except for their limited use in manufacturing minerals, glass, and paints. In this study, we analyzed the eco-friendly material and reactivity improvement characteristics of weathered feldspar through activation technique. The joint structural features observed on the surface of the weathered feldspar show that the joint arrangements are irregularly distributed, and the cavities are interconnected. Due to the irregularly connected cavities on the surface of weathered feldspar, the reaction area of the weathered feldspar is increased; hence the weathered feldspar is considered as a highly reactive pozzolan material when combined with cement. As a result of applying the thermal, mechanical, and chemical activation techniques to improve the functionality of the weathered feldspar, the cation exchange capacity, density, and uniaxial compression strength characteristics were improved. It is considered that weathered feldspar by these porous characteristics can be used as an eco-friendly construction material with excellent physical and chemical properties.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.786-791
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• 2016

Spherical graphene balls were fabricated by an aerosol spray drying process after reduced graphene oxide was prepared by the liquid phase reaction using glucose as an environment-friendly reducing agent. Spherical morphology of the as-fabricated particles was observed by FE-SEM analysis. Diffraction patterns of spherical particles were found as graphene by XRD analysis. Sphericity of GB was controlled by the variation of operating temperature, amount of glucose, and addition of $NH_4OH$. Higher sphericity of GB was prepared at higher operating temperature in the presence of $NH_4OH$. As the amount of glucose in the liquid phase reaction increased in the presence of $NH_4OH$, sphericity of GB increased. The highest sphericity of GB was 1.1. GB of higher sphericity showed lower aggregation property than that of lower sphericity. Furthermore, as-prepared GBs were found as a potential electrode material for capacitor.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.357-363
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• 2015

The development of the environment-friendly tire that meets the standard requirements according to tire labeling system can be improved through using highly homogeneous silica immobilized zinc oxide nanoparticles. In this study, a considerable amount of nanoporous silica was essentially added into nano zinc oxide to improve the physiochemical properties of the formed composite. The introduction of nanoporous silica materials in the composite facilitates the improvement of the wear-resistance and increases the elasticity of the tread. Therefore, the introduction of nanoporous silica can replace carbon black as filler in the formation of composites with desirable properties for conventional green tire. Herein, mesoporous silica immobilized zinc oxide nanoparticle with desirable properties for rubber compounds was investigated. Composites with homogeneous dispersion were obtained in the absence of dispersants. The dispersion stability was controlled through varying the molar ratio, ageing time and mixing order of the reactants. A superior dispersion was achieved in the sample obtained using 0.03 mol of zinc precursor as it had the smallest grain size (50.5 nm) and then immobilized in silica aged for 10 days. Moreover, the specific surface area of this sample was the highest ($649m^2/g$).

• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.28-32
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• 2004

The condensation reaction of (benzylene)triphenylphosphoranes with carbonyl compounds in supercritical carbon dioxide was examined. Reactions of (benzylene)phosphoranes (ca. 1 mmol) with several benzaldehydes in a supercritical carbon dioxide (80 $^{\circ}C$, 2,000 psi) containing THF entrainer (5%) in a 24 mL reactor proceed smoothly to yield olefination products in fairly good to excellant yields but slower, compared to reactions in a conventional THF solvent. Generally, phosphoranes that are not substituted with a nitro group show more (Z)-selective reactions with aromatic aldehydes under $scCO_2$ condition than in THF. The reaction of (benzylene)triphenylphosphoranes with 4-t-butylcyclohexanone gave the corresponding olefin compounds with a low conversion under both the supercritical carbon dioxide and the organic THF solvent. Our preliminary study showed the Wittig reaction carries out smoothly in supercritical carbon dioxide medium and also a possibile tunability of this reaction pathway by adding a entrainer. The results would be useful for devising a novel process for the environmentally friendly Wittig reaction.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.710-721
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• 2012

This study is to find out the search of the desirable tree cutting permit system by investigating and analyzing timber logger's consciousness in Korea. A sample group, including 64 officers in 5 Regional Forest Services and 27 National Forest Stations, 161 local government of 322 officers and team leaders with cutting permits, and 308 tree loggers was surveyed. The survey results showed that the ongoing harvest year plan for national, public and private-type forests, which was applied differently, could be integrated as 3.73 points, which was not significant among the groups. A total of 95.1% of the national forest officers stated that the environmentally friendly harvesting system could be improved and that it is exempted from bad broadleaf trees and renewal of forest type (4.14 points). An environmentally friendly harvesting system including the type of forest and location status (slide, soil, etc) is needed (3.87 points). Additionally, the round timber purchased from tree loggers managed in 2009 was about 10.6% of the domestic timber supply ($3,176,000m^3$) and round timber sales were about 50.1%. A total of 72% of the loggers suggested that a environmentally friendly harvesting system is needed (4.11 points). These results show that a new system for harvesting timber is needed to replace the current environmentally unfriendly harvesting system, and that tree loggers should be registered for management.

• Clean Technology
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• v.27 no.4
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• pp.341-349
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• 2021

In combustion facilities, the nitrogen and sulfur in fossil fuels react with oxygen to generate air pollutants such as nitrogen oxides (NO_X) and sulfur oxides (SO_X), which are harmful to the human body and cause environmental pollution. There are regulations worldwide to reduce NO_X and SO_X, and various technologies are being applied to meet these regulations. There are commercialized methods to reduce NO_X and SO_X emissions such as selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and wet flue gas desulfurization (WFGD), but due to the disadvantages of these methods, many studies have been conducted to simultaneously remove NO_X and SO_X. However, even in the NO_X and SO_X simultaneous removal methods, there are problems with wastewater generation due to oxidants and absorbents, costs incurred due to the use of catalysts and electrolysis to activate specific oxidants, and the harmfulness of gas oxidants themselves. Therefore, in this research, microbubbles generated in a high-pressure disperser and reducing agents were used to reduce costs and facilitate wastewater treatment in order to compensate for the shortcomings of the NO_X, SO_X simultaneous treatment method. It was confirmed through image processing and ESR (electron spin resonance) analysis that the disperser generates real microbubbles. NO_X and SO_X removal tests according to temperature were also conducted using only microbubbles. In addition, the removal efficiencies of NO_X and SO_X are about 75% and 99% using a reducing agent and microbubbles to reduce wastewater. When a small amount of oxidizing agent was added to this microbubble system, both NO_X and SO_X removal rates achieved 99% or more. Based on these findings, it is expected that this suggested method will contribute to solving the cost and environmental problems associated with the wet oxidation removal method.