This study was carried out to synthesis the zeolite using the bituminous coal fly ash emitted from power plant that occurs several environmental problems. In spite of fly ash has contained high content of SiO2 and Al2O3, it disposed mainly landfill. If the effective methods to recover the SiO2 and Al2O3 were developed, the fly ash could be utilized valuable raw materials. In this study, fly ash was used as raw material to synthesize the zeolite by pressurized hydrothermal reaction. Also, experimental parameters included temperature(70~110℃, and pressure(140~200 psi) of crystallization were investigated. The more crystallization pressure was increased, the more Zeolite 4A was synthesized at 70 and 90℃. Zeolite 4A of metastable phase tend to be transformed into sodalite of stable phase at 110℃.

A zeolite material (ZCH) was synthesized from coal fly ash in an HD thermal power plant using a fusion/hydrothermal method. ZCH with high crystallinity could be synthesized at the NaOH/CFA ratio of 0.9. Ion-exchanged ZCH adsorbents for ammonia removal were prepared by ion-exchanging various cation (Cu2+, Co2+, Fe3+, and Mn2+) on the ZCH. They were used to evaluate the ammonia adsorption breakthrough curves and adsorption capacities. The ammonia adsorption capacities of the ZCH and ion-exchanged ZCHs were high in the order of Mn-ZCH > Cu-ZCH ≅ Co-ZCH > Fe-ZCH > ZCH according to NH3-TPD measurements. Mn-ZCH ion-exchanged with Mn has more Brønsted acid sites than other adsorbents. The ion-exchanged Cu2+, Co2+, Fe3+, or Mn2+ ions uniformly distributed on the surface or in the pores of the ZCH, and the number of acidic sites increased on the alumina sites to form the crystal structure of zeolite material. Therefore, when the ion-exchanged ZCH was used, the adsorption capacity for ammonia gas increased.

A zeolite material with a Si/Al molar ratio of 1.2 was synthesized by changing the NaOH/CFA ratio of coal fly ash (CFA) via a fusion/hydrothermal reaction in the HD thermal power plant. The change in the crystal structure of the zeolite was confirmed using XRD and SEM, and the ammonia adsorption capacities of the synthesized zeolitic materials and a commercial zeolite (Na-A zeolite) were analyzed via an ammonia temperature-programmed desorption (NH3-TPD) process. The SEM and XRD results revealed out the zeolitic materials from the coal fly ash maintained a hexagonal Linde-type crystal structure similar to that of Na-A zeolite, but the crystallinity of the synthesized zeolitic material was reduced due to impurities. The NH3 adsorption capacity, determined from the NH3-TPD analysis of was 1.122 mmol/g of the synthesized zeolitic material, which was lower than the NH3 adsorption capacity of the Na-A zeolite.

Zeolitic material, Z-Y3, was synthesized from coal fly ash (CFA) under low-alkaline conditions (NaOH/CFA ratio = 0.3 and NaOH solution concentrations of 0.0, 0.5, and 1.0 M) using a fusion/hydrothermal method. The adsorption capacities of the fabricated Z-Y3 samples for Cs and Sr ions and the desorption capacity of Na ions were evaluated. The XRD patterns of the Z-Y3 sample fabricated using a 1.0 M NaOH solution (Z-Y3 (1.0 M)) indicated the successful synthesis of a zeolitic material, because the diffraction peaks of Z-Y3 coincided with those of the Na-A zeolite in the 2θ range of 7.18-34.18. Moreover, the SEM images revealed that morphology of the Z-Y3 (1.0 M) sample, which presented zeolitic materials characteristics, consisted of sharp-edged cubes. The adsorption isotherms of Cs and Sr ions on all the fabricated Z-Y3 samples were described using the Langmuir model, and the maximum adsorption capacities of Cs and Sr were calculated to be 0.14-0.94 mmol/g and 0.19-0.78 mmol/g, respectively. The desorption of Na ions from the Cs and Sr ions adsorbed Z-Y3 samples followed the Langmuir desorption model. The maximum desorption capacities of Na ions from the Cs and Sr ions adsorbed Z-Y3 (1.0 M) samples were 1.28 and 1.49 mmol/g, respectively.

A zeolitic material (Z-Y2) was synthesized from Coal Fly Ash (CFA) using a fusion/hydrothermal method under low-alkali condition (NaOH/CFA = 0.6). The adsorption performance of the prepared zeolite was evaluated by monitoring its removal efficiencies for Sr and Cs ions, which are well-known as significant radionuclides in liquid radioactive waste. The XRD (X-ray diffraction) patterns of the synthesized Z-Y2 indicated that a Na-A type zeolite was formed from raw coal fly ash. The SEM (scanning electron microscope) images also showed that a cubic crystal structure of size 1~3㎼ was formed on its surface. In the adsorption kinetic analysis, the adsorption of Sr and Cs ions on Z-Y2 fitted the pseudo-second-order kinetic model well, instead of the pseudo-first-order kinetic model. The second-order kinetic rate constant (k2) was determined to be 0.0614 g/mmol·min for Sr and 1.8172 g/mmol·min for Cs. The adsorption equilibria of Sr and Cs ions on Z-Y2 were fitted successfully by Langmuir model. The maximum adsorption capacity (qm) of Sr and Cs was calculated as 1.6846 mmol/g and 1.2055 mmol/g, respectively. The maximum desorption capacity (qdm) of the Na ions estimated via the Langmuir desorption model was 2.4196 mmol/g for Sr and 2.1870 mmol/g for Cs. The molar ratio of the desorption/adsorption capacity (qdm/qm) was determined to be 1.44 for Na/Sr and 1.81 for Na/Cs, indicating that the amounts of desorbed Na ions and adsorbed Sr and Cs ions did not yield an equimolar ratio when using Z-Y2.

In this study, zeolitic materials at Na2CO3/CFA ratio of 0.6 1.8 were synthesized from coal fly ash from a thermal power plant using a fusion/hydrothermal method. The zeolitic materials were found to have cubic crystals structure and X-ray diffraction (XRD) peaks of Na-A zeolite by XRD and SEM analysis. When the zeolitic materials were synthesized from the coal fly ash, the XRD peaks of the zeolitic materials at Na2CO3/CFA ratios of 0.9-1.8 had the same location as the XRD peaks of commercial Na-A zeolite. The XRD peaks of the Na-A zeolite (Na12Al12Si12O4827.4H2O) were confirmed in the 2θ in the range of 7.18-34.18. However, it was also confirmed that peaks of CaCO3, an impurity inhibiting synthesis of Na-A zeolite from CaO and Na2CO3 in the coal fly ash, occurred in the XRD peaks of the zeolitic materials at Na2CO3/CFA ratio of 1.5-1.8. The crystallinities of the zeolitic materials tended to increase gradually within the Na2CO3/CFA ratio range of 0.6-1.8.

In this study, zeolite (Z-C1) was synthesized using a fusion/hydrothermal method from coal fly ash. The morphological structures of Z-C1 were confirmed to be highly crystalline with a cubic crystal structure. Exchange capacities of Ca2+ and Mg2+ ions in a single and a mixed solution reached equilibrium within 120 min. The exchange kinetics of these ions were well predicted by the pseudo-second-order rate equation. The exchange isotherms of the Ca2+ and Mg2+ ions matched the Langmuir isotherm better than the Freundlich isotherm. The maximum cation exchange capacities (qm) obtained by the Langmuir isotherm model were 2.11 mmol/g (84.52 mg/L) and 1.13 mmol/g (27.39 mg/L) for the Ca2+ and Mg2+ ions, respectively.

This study investigated both leaching of heavy metals and ecological toxicity when coal bottom ash (CBA) generated by power plants has been used to reduce both erosion and turbidity of surface runoff at construction sites. The Korean leaching test (KLT) method, sequential extraction method, and acute toxicity test using Daphnia magna were performed to evaluate the environmental impacts and the ecological risks of CBA. According to the results of the KLT method of CBA, trace amounts of Cu were leached at limit of quantitation whereas metal leaching was not monitored for other heavy metals. Through the sequential extraction method of CBA, the relatively high leaching potential was found for As and Pb due to greater fraction of exchangeable (F1) and bound to carbonates (F2), and reasonable probability of leaching under the reducing/anaerobic environment was expected for Cu due to high faction of bound to Fe?Mn oxides (F3). However, significantly low probability of leaching was expected for Cd, Cr, Ni, and Zn with grater fractions of bound to organic matter (F4) and residual (F5). Additionally, total amount of heavy metals in CBA was lower than criteria for soil pollution concerns, and were similar or slightly lower levels than the ‘15 National soil average concentration excluding Cr6+. Finally, acute toxicity test using Daphnia magna display no impact for mobilization and lethality in either the prefiltration or post-filtration experiment, indicating that the ecological toxicity was insignificant with zero values of toxic unit. Consequently, no environmental impacts or ecological toxicity are expected when CBA generated by power plants has been used to reduce both erosion and turbidity of surface runoff at construction sites.

기후변화의 원인으로는 온실가스의 과량 배출이 문제화 되는 현 시점에서 온실가스 중 가장 많은 양을 차지하는 이산화탄소의 경우 기후변화에 미치는 영향이 다른 종류의 온실가스보다 크다는 것은 널리 알려진 사실이다. 여러 분야의 산업과 인간 활동에서 발생하는 이산화탄소를 KOH 흡수제를 통해 흡수된 CO2양을 측정하고 발전소 탈황 공정에서 발생하는 ASH를 첨가하여 반응시켜 생성된 CaCO3를 다른 유용한 물질로 전환하여 자원화하고 재사용하는 것이다. 본 연구에서는 KOH 흡수제 농도에 따른 CO2 흡수량 측정과 KOH 흡수제와 흡수첨가제(piperazine)을 함께 넣고 흡수된 CO2양을 측정하였다. 또한, CO2 loading curve 이용하여 CO2 흡수량을 계산하였으며, 화력발전소의 탈황공정에서 발생하는 ASH와 CO2가 흡수된 KOH를 수용액과 반응시켜 생성된 시간당 CaCO3의 양을 측정하고 분석기기 XRD(X-Ray Diffraction)와 SEM(Scanning Electron Microscope)을 사용하여 결정 구조와 표면 구조를 분석하였다.

화력발전소 전기집진기에서 포집되는 FA(Fly ash)는 재활용률이 높으나 화력발전소 노에 떨어지는 BA(Bottom ash)는 FA에 비해 매우 낮은 편이다. 또한 FA에 대한 연구는 활발하게 진행되고 있는 반면 BA에 대해서는 매우 저조하다. 한편 지속적으로 건축 공사 수요가 있지만 건축 재료를 과거처럼 용이하게 그리고 저렴하게 공급 받기는 더욱 어려워지고 있는 실정이므로 BA를 건축 재료로 활용할 수 있게 하는 연구는 매우 유용할 것으로 판단된다. 따라서 본 연구에서는 재활용률이 저조하여 처리에 부담이 되었던 BA를 최대한 재활용할 수 있도록 건축 재료로 연구 개발하여 BA 재활용률을 높일 뿐만 아니라 BA 처리의 부담을 줄이고, 또한 저렴한 건축 재료를 용이하게 다량 확보할 수 있도록 화력발전소에서 발생한 BA가 건축 재료로 갖고 있는 다양한 특성에 대하여 연구하였다. 화력발전소에서 발생한 BA를 건축 재료로의 특성에 대하여 연구를 진행한 결과 타 재료에 비해 경량성과 단열성이 매우 우수함은 물론 원적외선 방사률 등도 비교적 우수하게 나타났다.

기후변화에 따른 신재생에너지 사용에 대한 사회적 요구가 증가되고 있지만, 아직까지 우리나라는 전력생산의 약 40%를 석탄화력발전에 의존하고 있는 실정이다. 이에 따른 석탄재 발생량은 지난 10년간 약 2배 정도 증가하여 2015년 한해에만 약 900만톤의 석탄재가 발생하였다. 이렇게 발생된 석탄재 중 비산재는 주요성분이 Al2O3, SiO2, Fe2O3의 광물 (>95%)로 구성되어 있어, 양회용 건설재료로 많이 쓰이고 있다. 하지만, 아직까지 연간 약 200만톤의 석탄재가 매립되고 있는 실정이여서 이와관련된 여러 가지 환경오염문제들이 발생하고 있다. 본 연구에서는 국내화력발전소에서 수집한 석탄재를 이용하여 주요성분인 Al와 Si를 추출하여, 기존의 보고된 제올라이트 합성방법을 수정하여 새롭고 다양한 제올라이트로 합성하는 기술을 개발하였다. 또한, 합성된 제올라이트를 서포터로 하는 촉매를 개발하여 수내에 환경오염물질의 효과적인 제거가 가능한지 여부를 평가하였다. 본 연구의 결과들은 향후 지속적으로 발생되는 석탄재의 환경정화소재화 기술을 통해서 다양한 오염물질 분해에 적용할 수 있는 가능성을 보여준다.

In this study, zeolite (Z-C2) was synthesized using a fusion/hydrothermal method on coal fly ash (FA) discharged from a thermal power plant in the Ulsan area and then analyzed via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The Z-C2 was characterized in terms of mineralogical composition and morphological analysis. The XRD results showed that its peaks had the characteristics of Na-A zeolite in the range of 2θ of 7.18~34.18. The SEM images confirmed that the Na-A zeolite crystals had a chamfered-edge crystal structure almost identical to that of the commercial zeolite. The adsorption kinetics of Cu, Co, Mn and Zn ions by Z-C2 were described better by the pseudo-second-order kinetic model more than by the pseudo-first-order kinetic model. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model did. The maximum adsorption capacities of Cu, Co, Mn and Zn ions obtained from the Langmuir model were in the following order : Cu (94.7 mg/g) > Co (77.7 mg/g) > Mn (57.6 mg/g) > Zn (51.1 mg/g). These adsorption capacities are regarded as excellent compared to those of commercial zeolite.

The aim in this study was to remove Cl−, which can be problematic in the recycling of bottom ash, by identifying the optimum operating conditions for a soil electrolysis apparatus with spiral paddles and to use these as the base data in removing contaminants from various polluted soils using electrolysis. Unprocessed bottom ash collected from the openair storage yard at thermoelectric power plant H in Gyeong sang nam - do Province was used as the experimental material. The experimental methodology was to identify the optimum operating conditions to remove Cl− contained in the bottom ash using the following variables: use or not of spiral paddles, application or not of electrolysis, change of concentration of the electrolyte solution, electrolysis application time, and the voltage level during electrolysis. From the results, the highest removal efficiency of 91.4% was shown under the following conditions: use of the spiral paddles, use of 0.3% NaOH electrolyte solution, 20 min of electrolysis; and a voltage level of 5 V during electrolysis. It is evident that application of the soil electrolysis apparatus for removal of Cl− from bottom ash could be valuableas base data for purification of polluted soils in the future.

A Controlled Low-Strength Materials (CLSM) is suitable for mine backfilling because it does not require compaction owing to it high fluidity and can be installed quickly. Therefore, a CLSM utilizing CO2-solidified Circulating Fluidzed Bed Combustion (CFBC) coal ash was developed and it’s properties were investigated, since. CO2-solidification of CFBC coal ash can inhibit exudation of heavy metals. The chemical composition and specific surface area of Pulverized coal Combustion fly ash and CFBC fly ash were analyzed. The water ratio, compressive strength and length change ratio of CLSM were confirmed. The water ratios differed with the specific surface area of the CLSM. It was confirmed that the porosity of CLSM affected its compressive strength and length change ratio.

In order to investigate the adsorption characteristics for Sr ion using the Na-X zeolite synthesized from coal fly ash, batch tests and response surface analyses were carried out. The adsorption kinetic data for Sr ions, using Na-X zeolite, fitted well with the pseudo-second-order model. The uptake of Sr ions followed the Langmuir isotherm model, with a maximum adsorption capacity of 196.46 mg/g. Thermodynamic studies were conducted at different reaction temperatures, with the results indicating that Sr ion adsorption by Na-X zeolite was an endothermic (ΔHo>0) and spontaneous (ΔGo<0) process. Using the response surface methodology of the Box-Behnken method, initial Sr ion concentration (X1), initial temperature (X2), and initial pH (X3) were selected as the independent variables, while the adsorption of Sr ions by Na-X zeolite was selected as the dependent variable. The experimental data fitted well with a second-order polynomial equation by multiple regression analysis. The value of the determination coefficient (R2=0.9937) and the adjusted determination coefficient (adjusted R2=0.9823) was close to 1, indicating high significance of the model. Statistical results showed the order of Sr removal based on experimental factors to be initial pH > initial concentration > temperature.

In this research, in order to improvement the performance of the two-component mixed aggregate mixed with fine granite fine aggregate and seawater, the examination of the effect of reject ash on the cement mortar according to the change of substitution rate was done. As a result, it was found that the effect of improving the compressive strength is more effective when the rejection ash is replaced by 5% in the mixed aggregate than in the case of using the high quality aggregate.

This study evaluates the adsorption properties of Sr ions in an aqueous solution of the synthetic zeolite (Z-Y1) prepared using coal fly ash generated from a thermal power plant. In order to investigate the adsorption characteristics, the effects of various parameters such as the initial concentrations of Sr ion, contact time, and solution pH were investigated in a batch mode. The Langmuir and Redlich-Peterson model fitted the adsorption isotherm data better than the Freundlich model. The maximum adsorption capacity of Sr ions, as determined the Langmuir model, was 181.68 mg/g. It was found that by varying the Sr ion concentration, pH, and temperature, the pseudo-second-order kinetic model describes the adsorption kinetics of the Sr ion better than the pseudo-first-order kinetic model. The calculated thermodynamic parameters of ΔH0 and ΔG0 showed that the adsorption of Sr ions on Z-Y1 was occurred through a spontaneous and an endothermic reaction. We found that the adsorption of Sr ions by Z-Y1 was more affected by pH than by temperature and Sr ion concentration.

In this research, in order to improvement the performance of the two-component mixed aggregate mixed with fine granite fine aggregate and seawater, the examination of the effect of reject ash on the cement mortar according to the change of substitution rate was done. As a result, it was found that the effect of improving the compressive strength is more effective when the rejection ash is replaced by 5% in the mixed aggregate than in the case of using the high quality aggregate.

Zeolite (FZ) prepared using coal fly ash from an Ulsan industrial complex was immobilized with polysulfone (PS) to fabricate PS-FZ beads. The prepared PS-FZ beads were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The optimum ratio for preparing PS-FZ beads was 1 g of PS to 2 g of FZ. The removal efficiencies of Sr and Cu ions by the PS-FZ beads increased as the solution pH increased and nearly reached a plateau at pH 4. A pseudo-second-order model morel fit the adsorption kinetics of both ions by the PS-FZ beads better than a pseudo-first-order model. The Langmuir isotherm model fit the equilibrium data well. The maximum adsorption capacities calculated from the Langmuir isotherm model were 46.73 mg/g and 62.54 mg/g for the Sr and Cu ions, respectively. Additionally, the values of thermodynamic parameters such as free energy (ΔG˚), enthalpy (ΔH˚) and entropy (ΔS˚) were determined. The results implied that the prepared PS-FZ beads could be interesting an alternative material for Sr and Cu ion removal.

Zeolite (FZ), prepared from fly ash, was immobilized with polyacrylonitrile (PAN) to fabricate PAN/FZ beads. The prepared PAN/FZ beads were characterized by scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The optimum ratio to prepare PAN/FZ beads was 0.3 g of PAN to 0.3 g of FZ. The diameter of the prepared PAN/FZ beads was about 3 mm. Sr and Cu ion adsorption experiments were conducted with PAN/FZ beads. A pseudo-second-order model fit the kinetic data for Sr and Cu ion adsorption by PAN/FZ beads well. The equilibrium data fitted well with the Langmuir isotherm model, and the maximum adsorption capacities were 96.5 mg/g and 74.6 mg/g for the Sr and Cu ions, respectively. Additionally, the values of thermodynamic parameters such as Gibbs free energy (ΔGo), enthalpy (ΔHo) and entropy (ΔSo) were determined. The positive values of ΔHo revealed the endothermic nature of the adsorption process and the negative values of ΔGo were indicative of the spontaneity of the adsorption process.