Magnetite and inorganic sludge were mainly composed of Fe2O4 and Fe2O3, respectively. Initial specific surface areas of magnetite and inorganic sludge were 130 m2/g and 31.7 m2/g. CO2 decomposition rate for inorganic sludge was increased with temperature. Maximum CO2 decomposition rates were shown 89% for magnetite at 350℃ and 84% for inorganic sludge at 500℃. Specific surface area for magnetite was not varied significantly after CO2 decomposition. However, specific surface area for inorganic sludge was greatly decreased from initial 130 m2/g to approximately 50~60 m2/g after reaction. Therefore, it was estimated that magnetite could be used for CO2decomposition for a long time and inorganic sludge should be wasted after CO2 decomposition reaction.

This research was conducted to estimate the characteristics of carbon dioxide decomposition using an inorganic sludge. The inorganic sludge was composed of high amount (66.8%) of Fe2O3. Hydrogen could be reduced with 0.247, 0.433, 0.644, and 0.749 at 350, 400, 450, and 500℃, respectively. The carbon dioxide decomposition rates at 250, 300, 350, 400, 450, and 500℃ were 32, 52, 35, 62, 75, and 84%, respectively. High temperature led to high reduction of hydrogen and better decomposition of carbon dioxide. The specific surface area of the sludge after hydrogen reduction was higher than that after carbon dioxide decomposition. The specific surface area of the sludge was more decreased with increasing of temperature.

This research was performed to evaluate heavy metal leaching characteristics of the sludge from paper mill process with sintering temperature. Heavy metal leaching of the sludge was characterized with Korean Leaching Test and Toxicity Characteristic Leaching Procedure. The test sludge was composed of 70.72% of moisture, 9.5% of volatile solids and 9.76% of fixed solids. As a result of XRF analysis, Fe was the highest inorganic element in approximately 83%, which implies the recycling possibility of the sludge in reuse of Fenton chemicals and artificial lightweight aggregate. Leaching of heavy metals from sintered sludge was lower than the dry ones. However, there was no significant difference in leaching characteristics between the sludges sintered at 350℃ and 650℃. Zn and Fe were leached more greatly in TCLP and KLT methods respectively.

The hydrogen embrittlement susceptibility of high strength TRIP/TWIP steels with the tensile strength of 600Mpa to 900Mpa grade was investigated using cathodically hydrogen charged specimens. TWIP steels with full austenite structure show a lower hydrogen content than do TRIP steels. The uniform distribution of strong traps throughout the matrix in the form of austenite is considered beneficial to reduce the hydrogen embrittlement susceptibility of TWIP steels. Moreover, an austenite structure with very fine deformation twins formed during straining could also improve the ductility and reduce notch sensitivity. In Ubend and deep drawing cup tests, TWIP steels show a good resistance to hydrogen embrittlement compared with TRIP steels.

Adsorption is one of the most efficient method for the separation of low level carbon dioxide. In order to enhance the adsorption capacity, a few additives such as alkali hydroxides were combined with the zeolitic sorbents. As a result of the experimental examination by applying the CO2 flow of 3000 ppm, the composite sorbent showed the improved quality to a certain degree and the added binder was also found to contribute to better adsorption.

Anaerobic reductive dehalogenation of perchloroethene (PCE) was studied with lactate as the electron donor in a continuously stirred tank reactor (CSTR) inoculated with a mixed culture previously shown to dehalogenate vinyl chloride (VC). cis-1,2- dichloroethene (cDCE) was the dominant intermediate at relatively long cell retention times (〉56 days) and the electron acceptor to electron donor molar ratio (PCE:lactate) of 1:2. cDCE was transformed to VC completely at the PCE to lactate molar ratio of 1:4, and the final products of PCE dehalogenation were VC (80%) and ethene (20%). VC dehalogenation was inhibited by cDCE dehalogenation. Propionate produced from the fermentation of lactate might be used as electron donor for the dehalogenation. Batch experiments were performed to evaluate the effects of increased hydrogen, VC, and trichloroethene (TCE) on VC dehalogenation which is the rate-limiting step in PCE dehalogenation The addition of TCE increased the VC dehalogenaiton rate more than an increase in the H2 concentration, which suggests that the introduction of TCE induces the production of an enzyme that can comtabolize VC.

The present paper deals with gaseous carbon dioxide separation by a commercial adsorbent: X-type zeolite. Experimental work was carried out at an ambient condition focusing on how well meeting to the national guideline. A few types of reactor and material were examined, and practical capability was found in a granular bed type reactor with the flow of 2.5 CMM. An optimum design of reactor and adsorbent could provide the required concentration, less than 2500 ppm, for the continuous operation up to 10 hours. More work including automatic regeneration is now underworking.

Many researchers have been focused on polymer electrolyte membrane (PEM) to improve performance of a fuel cell. Sulfonpolyimide with hydrocarbon was synthesized from ODA (4,4-diaminodiphenyl ether), ODADS (4,4-diaminodiphenyl ether-2,2-disulfonic acid), NTDA (1,4,5,8-naphthalenetetracarboxylicdianhydride) and CSA (chlorosulfonic acid). In order to estimate the feasibility as a fuel cell, the performance of sulfonpolyimide was analyzed through a swelling degree, IEC (ion exchange capacity), ion conductivity and TEM (transmission electron microscope). As the results of this performance test, swelling degree, IEC and ion conductivity were 37%, 0.06 meq/g and 0.08 S/cm respectively, when the CSA concentration was 0.4 M. It was thought that sulfonpolyimide could be used as a fuel cell through improvement of electrolyte membrane.

This study was conducted to evaluate the biofiltration treatment characteristic for benzene vapor gas. Compost and calcium silicate porous material were used as biofilter fillers. Gas velocity and empty bed retention time were 15 m/hr and 4 min, respectively. Benzene gas removal efficiency of P-Bio (calcium silicate porous material with inoculation) was the highest and maintained in over 98%. After shock input of benzene gas, the removal efficiency of P-Bio biofilter was recovered within 2 days, while 5 days were taken in CP-Bio (compost + calcium silicate porous material mixture with inoculation) and CP (compost + calcium silicate porous material mixture without inoculation) biofilters. The removal efficiency of P-Bio biofilter was near 100% in the loading rate of 〈85g/m3(filling material)/hr, It was shown that the maximum elimination capacities of P-Bio, CP-Bio, and CP biofilters were 95, 69, and 66 g/m3(filling material)/hr, respectively. Microbial number of P-Bio, which the number was the lowest at start-up, was 3 orders increased on operational day 48. CO2 was generated greatly in order of P-Bio, CP-Bio, and CP biofilters.

This study was performed to evaluate characteristic of acid mine drainages (AMD) from abandoned mines in Kangwon-Do. Youngdong abandoned mine, and Soo and Hambaek abandoned mines in Hamtae were selected for this study. Average pHs of the mine drainages were 3-6.5, and those of Youngdong and Hambaek drainages were very acidic as 3-4. SO4-2 of Youngdong and Hambaek drainages were over 1,600 mg/L, which higher than average value (845 mg/L) of acid mine drainages in nationwide. Cu, Mn, and As concentrations of the drainages were lower than ‘Pollutant Discharge Permission'. Fe concentrations of Youngdong and Hambaek drainages were approximately 96 mg/L, which were two times higher than average value in nationwide. From correlation analysis using SPSS, significant correlation was not discovered between 'contaminants' analyzed in three acid mine drainages.

LiMn2O4 catalyst for CO2 decomposition was synthesized by oxidation method for 30 min at 600℃ in an electric furnace under air condition using manganese(II) nitrate (Mn(NO3)2·6H2O), Lithium nitrate (LiNO3) and Urea (CO(NH2)2). The synthesized catalyst was reduced by H2 at various temperatures for 3 hr. The reduction degree of the reduced catalysts were measured using the TGA. And then CO2 decomposition rate was measured using the reduced catalysts. Phase-transitions of the catalysts were observed after CO2 decomposition reaction at an optimal decomposition temperature. As the result of X-ray powder diffraction analysis, the synthesized catalyst was confirmed that the catalyst has the spinel structure, and also confirmed that when it was reduced by H2, the phase of LiMn2O4 catalyst was transformed into Li2MnO3 and Li1-2δMn2-δO4-3δ-δ' of tetragonal spinel phase. After CO2 decomposition reaction, it was confirmed that the peak of LiMn2O4 of spinel phase. The optimal reduction temperature of the catalyst with H2 was confirmed to be 450℃(maximum weight-increasing ratio 9.47%) in the case of LiMn2O4 through the TGA analysis. Decomposition rate(%) using the LiMn2O4 catalyst showed the 67%. The crystal structure of the synthesized LiMn2O4 observed with a scanning electron microscope(SEM) shows cubic form. After reduction, LiMn2O4 catalyst became condensed each other to form interface. It was confirmed that after CO2 decomposition, crystal structure of LiMn2O4 catalyst showed that its particle grew up more than that of reduction. Phase-transition by reduction and CO2 decomposition ; Li2MnO3 and Li1-2δMn2-δO4-3δ-δ' of tetragonal spinel phase at the first time of CO2 decomposition appear like the same as the above contents. Phase-transition at 2~5 time ; Li2MnO3 and Li1-2δMn2-δO4-3δ-δ' of tetragonal spinel phase by reduction and LiMn2O4 of spinel phase after CO2 decomposition appear like the same as the first time case. The result of the TGA analysis by catalyst reduction ; The first time, weight of reduced catalyst increased by 9.47%, for 2~5 times, weight of reduced catalyst increased by average 2.3% But, in any time, there is little difference in the decomposition ratio of CO2. That is to say, at the first time, it showed 67% in CO2 decomposition rate and after 5 times reaction of CO2 decomposition, it showed 67% nearly the same as the first time.

The spinel Fe3O4 powders were synthesized using 0.2 M-FeSO4·7H2O and 0.5 M-NaOH by oxidation in air and the spinel LiMn2O4 powders were synthesized at 480 ℃ for 12 h in air by a sol-gel method using manganese acetate and lithium hydroxide as starting materials. The synthesized LiMn2O4 powders were mixed at portion of 5, 10, 15 and 20 wt% of Fe3O4 powders using a ball-mill. The mixed catalysts were dried at room temperature for 24 hrs. The mixed catalysts were reduced by hydrogen gas at 350 ℃ for 2 h. The carbon dioxide decomposition rates of the mixed catalysts were 90% in all the mixed catalysts but the decomposition rate of carbon dioxide was increased with adding LiMn2O4 powders to Fe3O4 powders.

전자산업의 발달로 printed circuit board (PCB)와 같은 구리를 함유한 부품의 수요는 증가하고 있으며, 이를 제조 및 가공하는 과정에서 염산 및 질산과 같은 강한 산이 사용되며, 이 때 발생되는 폐산은 많은 양의 구리를 함유한 채 폐기처분된다. PCB 제조 기기의 구리 석막을 제거하기 위하여 사용되는 세척용 질산은 사용 후, 구리를 3~8% 수준으로 함유하고 있으며, 현재 발생되는 폐질산은 가성소다(NaOH)나 소석회(Ca(OH)2)를 이용하여 중화한 후 처리되고 있는 실정이다. 본 연구에서는 폐산 내 존재하는 구리를 탄산구리(CuCO3) 형태로 침전시키기 위하여 소다회(Na2CO3) 및 소석회(Ca(OH)2)를 이용하여 구리를 중화･침전시켜 회수하고, 이를 재자원화하기 위한 금속소재(금속 구리, 산화구리 등)로 제조하는 것을 목적으로 한다. 폐질산으로부터 탄산구리(CuCO3)를 회수하기 위한 반응인자로 사용 약품의 혼합비, 사용량, 침전 pH, 반응 온도를 달리하여 구리의 회수율을 최적화하였다. 또한, 회수된 탄산구리를 고온에서 산화시켜, X-ray diffraction(XRD)을 통한 결정성을 확인하고, 탄산구리를 폐염산에 용해시켜, 철 치환반응을 통한 금속구리를 제조하였다. 구리를 5% 함유한 폐질산으로부터 99.8% 이상 구리를 회수한 최적 조건은 소다회:소석회 혼합비 1:2에서, 혼합약품 사용량 300 g/kg, 침전 pH 6.5, 반응온도 70℃로 도출되었다. 또한, XRD 분석을 통한 고온산화조건은 1,100℃에서 산화구리(CuO) 전환률 99.9%를 나타냈으며, 폐염산에 용해시켜, 철 치환반응을 통해 제조된 금속구리의 구리 순도는 99.8%로 나타났다. 본 연구를 통하여 현재 중화처리 후, 매립되는 구리 자원의 재활용 방안을 도출하였으며, 이를 사업화하기 위하여 추가적 연구가 필요할 것으로 예상된다.