• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.243-249
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• 2005

Esterification of lactic acid with alcohols catalyzed by Amberlyst-type ion exchange resins and sulfuric acid was carried out in a batch reactor with total /or partial recycle of distilled condensates, respectively. The esterification of lactic acid in the total-recycling reactor (n-butanol/lactic acid = 4, $100^{\circ}C$) was promoted by decreasing the residual water and increasing the mole ratio of n-butanol/lactic acid. Also, it was confirmed that methanol with simple structure and tert-butanol with superior substitution reactivity were more effective in increasing the conversion of esterification reaction, compared to ethanol, n-butanol, and iso-butanol. In a partial-recycling reactor (n-butanol/ammonium lactate = 4, $115^{\circ}C$), the conversion of ammonium lactate into butyl lactate with 1.0 wt% Amberyst-type resins was higher in comparison to that with 0.2 mol $H_2SO_4$ (per 1.0 mol ammonium lactate). The esterification was gradually occurred during the initial stage of reaction in the presence of solid catalyst, whereas the initial addition of $H_2SO_4$ did not affect the initial rate of esterification reaction because of ammonium sulfate formation by the neutralizing reaction of ammonium lactate with sulfuric acid.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.103-106
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• 2014

Recycling of bottom ash from municipal solid waste (MSW) incinerator has been strictly limited due to its composition of high level chlorine and other unfavorable substances. The composition of MSW has been, however, changed after the introduction of garbage-bag sales system, extended producer responsibility (EPR) policy and the prohibition of direct landfill of food waste. Recent waste shows reduced moisture and chlorine content, increased calorific value due to the separation of food waste, incombustible materials and PVC. The main purpose of this study is to investigate the trend of composition changes of MSW incinerator bottom ash and to compare the analytical results with those before the separation system was introduced. CaO content of bottom ash, one of the major component of cement clinker, increased from 26.7% in 2001 to 34.0% in 2006. The chlorine content showed a dramatic decrease from 1.84% in 2001 to 0.00655% in 2006, which is closely compatible with that of the fly ash of coal-utilizing thermal power plants, which is mainly due to the changes of MSW composition. It is eventually considered that there is a possibility of utilizing the incinerator bottom ash as a raw material of cement clinker feed substances.

• Korean journal of food and cookery science
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• v.19 no.5
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• pp.609-615
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• 2003

In the Kimchi manufacturing industry, the process of brining baechu produces a vast amount of high salinity waste water. To study if this brine can be recycled, the quality characteristics of Kimchi salted by waste brine(F), which was used five times successively, was compared with those salted using water after recycling filtration through sand (F1) and activated carbon (F2) columns. No significant difference in the salinity and soluble solid contents, during fermentation at 10 was observed among the samples, but the salinity and soluble solid contents of the F-sample were slightly higher than in the control. The F1 and control Kimchi showed similar pHs and titratable acidities, while the F-Kimchi had a lower pH and a higher acidity during fermentation. The numbers of total viable cells were highest in the F, and lowest in the F2-Kimchi, while the counts of lactic acid bacteria were lowest in the F-Kimchi. The sensory tests for appearance, odor, taste and overall acceptance showed that the F-Kimchi was the least desirable, the F2-Kimchi had lower sour odor and taste, and a higher toughness, than the others. The F1- and control Kimchi had similar sensory grades for appearance, odor, and tastes, and there were no significant difference in the overall acceptance, showing the possibility of recycling wastewaters as brine for the production of baechu Kimchi.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5376-5383
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• 2011

The objective of this study is the development of carbon-recycle technology, that converts carbon dioxide captured from flue gas to carbon monoxide or carbon for reuse in industrial fields. It is difficult to decompose $CO_2$ because $CO_2$ is very stable molecule. And then metal oxide was used as an activation agent or catalyst for the decomposition of $CO_2$ at low temperature. Metal oxides, which converts $CO_2$ to CO or C, were prepared using Ni-ferrite by solid state method and hydrothermal synthesis in this study. TPR/TPO and TGA were used as an analysis method to analyze the decomposition characteristics of $CO_2$. As the results, the reduction area of $H_2$ was high value at 15 wt% of NiO and the decomposition area of $CO_2$ was superior capacity at 5 wt% of NiO. However, TGA data showed contrary results that reduction area of $H_2$ was 28.47wt% and oxidation area by $CO_2$ was 26.95wt% at 2.5 wt% of NiO, one of the Ni-ferrite powders synthesized using solid state method. $CO_2$ decomposition efficiency was 94.66% and it is excellent results in comparison with previous studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5357-5364
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• 2011

The objective of this study is development of carbon recycle technology which convert carbon dioxide captured from flue gas to carbon monoxide or carbon and reuse in industrial fields. Since carbon dioxide is very stable and difficult to decompose, metal oxide was used as activation agent for the decomposition of carbon dioxide at low temperature. Metal oxides which convert $CO_2$ to CO or carbon were prepared using Ba-ferrite by solid and hydrothermal synthesis. TPR/TPO and TGA were used in this study. The results of TPR by H2 and TPO by $CO_2$ showed that Ba-ferrite powders synthesized by hydrothermal method were better than those by solid method. TGA showed contrary results that reduction of Ba-ferrite powders synthesized using solid method by $H_2$ was 21.96 wt%, oxidation by $CO_2$ was 21.24 wt% and 96.72 wt% of $CO_2$ decomposition efficiency showing excellent oxidation-reduction characteristics at $500^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.27-33
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• 2016

Phenolic resin has excellent heat resistance and good mechanical properties as a thermosetting resin. However, its thermosetting characteristics cause it to produce a non-recyclable waste in the form of sprue and runner which is discarded and represents up to 15~20% of the overall products. Forty thousand tons of phenolic resin sprue and runner are disposed of (annually). The (annual) cost of such domestic waste disposal is calculated to be 20 billion won. In this study, discarded phenol resin scraps were pulverized and treated by silanes to improve their interfacial adhesion with HDPE. The sizes of the pulverized pulverulent bodies and fine particles were (100um~1000um) and (1~100um), respectively. The pulverized phenol resin was treated with 3-(methacryloyloxy) propyltrimethoxysilane and vinyltrimethoxy silane and the changes in its characteristics were evaluated. The thermal properties were evaluated by DSC and HDT. The mechanical properties were assessed by a notched Izod impact strength tester. When the silane treated phenol resin was added, the heat distortion temperature of HDPE increased from $77^{\circ}C$ to $96^{\circ}C$ and its crystallinity and crystallization temperature also increased. Finally, its impact strength and tensile strength increased by 20% and 50%, respectively, in comparison with the non-treated phenol resin.

• Resources Recycling
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• v.25 no.6
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• pp.13-22
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• 2016

This study is aimed at compare and evaluate the environmental impact of End-of-Life Vehicle(ELV) on the eco-friendly technology dismantling and recycling system, using Life Cycle Assessment (LCA) method. In this study, it was analyzed for the environmental impacts of raw materials, disassemble process, recycle parts separation and waste treatment into the process of ELV treatment by greenhouse gas and resource consumption, etc. Through this study, the indoor rail type dismantling technology were recycling rate applied on the alternate system was increased by approximately 8%. As a result, it was 3 to 88% by improving the environmental impact category. In addition, the added benefit of approximately 8 - 62% in pre-market occurred through the recycling rate, improve parts reuse rate of ELV. Through the results of this study, legal compliance, improved reuse and recycling ratio, used parts market reach, enable exports has identified the need for the effort that the dissemination and diffusion of eco-friendly technology.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.1-7
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• 2020

As of 2018, Steel slag was generated approximately 24.23 million tons. Howeve, except blast furnace slag, steel slag is a typical by-product which does not have a clearly defined purpose in recycling. Thus, countries around the world are putting great efforts into developing a purpose for the recycling of steel slag. The vast habitat foundation of marine life has been destroyed due to recent reckless marine development and environment pollution, resulting in intensification of the decline of marine resources, and a solution to this issue is imperative. In order to propose a method to recycle large amounts of by-product slag into a material that can serve as an alternative to natural aggregate, the engineering properties and applicability for each mixing factor of environment friendly porous concrete as a material for the composition of seawater purification were in this study. Regarding the nutrient elution properties, it was clear that the nutrients continuously flowed out up to an immersion time by 8 months in natural seawater; the nitrogenous fertilizer displayed excellent elution properties in this regard.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.223-228
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• 2021

The final disposal method for asbestos building materials is to be landfilled at a designated waste landfill in accordance with the Waste Management Act. However, it is difficult to secure a domestic designated waste landfill site to landfill the entire amount of asbestos waste, which is expected to emit more than 400,000 ton/year by 2044. In this study, a detoxification treatment was performed on a ceiling tex with a density of 1.0 to 1.2g/cm³ containing 3 to 7% of chrysotile, and it was used as a reinforcing fiber for extruded panels. It was confirmed that asbestos components were detoxified through the reaction process using 30% oxalic acid and carbon dioxide, and it was recognized that these detoxifying properties were maintained even after extrusion molding. However, it was found that milling to a fiber size of less than 1mm for complete detoxification of asbestos resulted in a decrease in reinforcing performance. Therefore, in the case of using detoxified asbestos fibers in the extrusion molding process, it is considered desirable to add fibers with a length of 5mm or more to improve the reinforcing performance.

• Resources Recycling
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• v.27 no.6
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• pp.23-29
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• 2018

Recently rapid economic growth and technological development have led to an increase in the generation of waste electrical and electronic equipment (WEEE). As the amount of electric and electronic waste generated increases, the importance of processing waste printed circuit boards (PCB) is also increasing. Various studies have been conducted to recycle various valuable metals contained in a waste PCB in an environmentally friendly and economical manner. To get anode slime containing Ag and Au, Anode copper prepared from PCB scraps was used by means of electro-refining. Ag and Au recovery was conducted by leaching, direct reduction, and ion exchange method. In the case of silver, the anode slime was leached at 3 M $HNO_3$, 100 g/L, $70^{\circ}C$, and Ag was recovered by precipitation, alkali dissolution, and reduction method. In the case of gold, the nitrate leaching residues of the anode slime was leached at 25% aqua regia, 200 g/L, $70^{\circ}C$, and Au was recovered by pH adjustment, ion exchange resin adsorption, desorption and reduction method. The purity of the obtained Au and Ag were confirmed to be 99.99%.