• Journal of Soil and Groundwater Environment
• /
• v.27 no.1
• /
• pp.17-24
• /
• 2022

This work examined the effect of mixing transition metal-based additives [FeCl₃, Fe-containing paper mill sludge (PMS), CoCl₂·H₂O, ZrO₂, and α-Fe₂O₃] on the thermochemical conversion of coffee waste (CW) in carbon dioxide-assisted pyrolysis process. Compared to the generation amounts of syngas (0.7 mole% H₂ & 3.0 mole% CO) at 700℃ from single pyrolysis of CW, co-pyrolysis in the presence of Fe- or Zr-based additives resulted in the enhanced production of syngas, with the measured concentrations of H₂ and CO ranging 1.1-3.4 mole% and 4.6-13.2 mole% at the same temperature, respectively. In addition, α-Fe₂O₃ biochar possessed the adsorption capacity of As(V) (19.3 mg g^-1) comparable to that of ZrO₂-biochar (21.2 mg g^-1). In conclusion, solid-type Fe-based additive can be highly considered as an efficient catalyst to simultaneously produce syngas (H₂ & CO) as fuel energy resource and metal-biochar as sorbent.

• Korean Chemical Engineering Research
• /
• v.55 no.3
• /
• pp.419-425
• /
• 2017

In this study, the performance characteristics of the K-based sorbents (KEP-CO2P2, KEPCO RI, Korea) has been studied in relation with the heat exchanger structure and shape in a mixing zone of the carbonator in the bench-scale dry $CO_2$ capture process. Two types of heat exchangers (different structure and shape) were used in the carbonator as CASE 1 and CASE 2, in which the experiment has been continuously performed under the same operating conditions. During the continuous operation, working temperature of carbonator was 75 to $80^{\circ}C$, that of regenerator was 190 to $200^{\circ}C$, and $CO_2$ inlet concentration of the feed gas was 12 to 14 vol%. Especially, to compare the dynamic sorption capacity of sorbents, the differential pressure of the mixing zone in the carbonator was maintained around 400 to 500 mm $H_2O$. Also, solid samples from the carbonator and the regenerator were collected and weight variation of those samples was evaluated by TGA. The $CO_2$ removal efficiency and the dynamic sorption capacity were 64.3% and 2.40 wt%, respectively for CASE 1 while they were 81.0% and 4.66 wt%, respectively for CASE 2. Also, the dynamic sorption capacity of the sorbent in CASE 1 and CASE 2 was 2.51 wt% and 4.89 wt%, respectively, based on the weight loss of the TGA measurement results. Therefore, It was concluded that there could be a difference in the performance characteristics of the same sorbents according to the structure and type of heat exchanger inserted in the carbonator under the same operating conditions.

• Journal of Energy Engineering
• /
• v.14 no.3 s.43
• /
• pp.203-211
• /
• 2005

To investigate the effects of the number of multiple-cycles and $SO_2$ concentration on $CO_2$ absorption characteristics by means of limestone, $CO_2$ capture capacity has been measured in a bubbling fluidized bed reactor (0.1m 1.D., 1.17m high). Danyang limestone was used as a $CO_2$ sorbent and the number of cycles $(\~10th\;cycle)$ and $SO_2$ concentrations (0, 2000, 4000 ppm) were considered as variables. The measured $CO_2$ capture capacity decreased as the number of cycles increased and it showed $50\%$ or initial value after 10 cycles. Moreover, $CO_2$ rapture capacity decreased with 501 concentrations. For three different $SO_2$ concentrations, the total CaO utilization was almost the same but $SO_2$ capture capacity increased and $CO_2$ capture capacity decreased as $SO_2$ concentration increased. These results suggest that $SO_2$ capture reaction is predominant over $CO_2$ capture reaction in the simultaneous $CO_2/SO_2$ capture conditions.

• Korean Chemical Engineering Research
• /
• v.50 no.4
• /
• pp.646-653
• /
• 2012

We studied the economic evaluations on Korea Institute of Energy Research (KIER)'s $CO_2$ capture process using dry sorbents, and compared the results with those of comparable technologies. Capital and operating costs of the $CO_2$ capture system for 500 MW coal fired power plant were estimated to determine the economic feasibility. LCOE (Levelized Cost of Energy) and $CO_2$ capture cost appeared 32.46$/MWh and 28.15$/ton$CO_2$, respectively. The internal rate of return (IRR), the net present values (NPV), and the payback period (PBP), were calculated by assuming several variables. As the result of calculation, IRR of KIER's $CO_2$ capture system was 15%, NPV was calculated 6,631,000$, and PBP was 5.93 years at $50/t$CO_2$ of CER price. Consequently, this process can compete with other comparative processes using dry sorbents.

• Journal of Environmental Health Sciences
• /
• v.30 no.5 s.81
• /
• pp.395-401
• /
• 2004

In this study, lots of methods have been studing to utilize energy and decrease contaminated effluents. There has been great progress on IGCC (Integrated gasification combined cycle) to reduce thermal energy losses. The following results have been conducted from desulfurization experiments using waste shell to remove $H_{2}S$. Unreacted core model ior desulfuriration rate prediction of sorbent was indicated. These were linear relationship between time and conversion. So co-current diffusion resistance was conducted reaction rate controlling step. The sulfidation rate is likely to be controlled primarily by countercurrent diffusion through the product layer of calcium sulfide(CaS) formed. Maximum desulfurization capacity was observed at 0.631 mm for lime, oyster and hard-shelled mussel. The kinetics of the sorption of $H_{2}S$ by CaO is sensitive to the reaction temperature and particle size at $800^{\circ}C$, and the reaction rate of oyster was faster than the calcined limestone at $700^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.73.2-73.2
• /
• 2011

석탄 합성가스 중에는 $H_2S$, HCl, $NH_3$와 같은 불순물이 포함되어 있다. 이러한 가스들은 오염가스 배출과 관련한 환경기준 준수와 터빈과 같은 설비의 보호를 위해 제거되어야 한다. 석탄 합성가스 중 HCl 농도는 탄종에 따라 다르기는 하지만 많게는 1000 ppmv 수준까지 존재한다. 합성가스를 이용하여 발전을 하는 경우 가스터빈 보호를 위해 HCl은 <3 ppmv 이하로 정제되어야 하고, 합성가스를 연료전지에 사용하고자 하는 경우에는 HCl을 <0.5 ppmv 수준까지, 화학원료로 사용하고자 하는 경우에는 <10 ppbv 수준까지 정제하여야 한다. 또한 HCl은 고온 탈황공정에 사용되는 흡수제의 활성에도 장기적으로 부정적인 영향을 주기 때문에 고온에서 HCl을 정제할 수 있는 흡수제가 필요하다. 본 연구에서는 알칼리금속을 활성물질로 사용하여 분무건조법으로 제조한 HCl 흡수제에 대해 물성 및 HCl과의 반응성을 살펴보았다. $300-500^{\circ}C$ 영역에서 K-계 및 Na-계 흡수제에 대해 고정층반응기에서 HCl 가스를 함유한 모사 합성가스를 이용하여 상압 조건에서 Cl 흡수능을 측정한 결과 15wt% 이상의 흡수능을 나타내었으며 반응온도가 높을수록 흡수능이 증가함을 알 수 있었다. XRD 분석을 통하여 Cl은 K 및 Na와 반응하여 KCl과 NaCl을 형성하면서 흡수됨을 알 수 있었다. 20 bar 조건에서 실험한 결과에서도 동일한 경향의 반응성을 나타내었으며 반응온도가 낮을수록 흡수능은 감소하지만 Cl을 더 낮은 농도로 정제할 수 있었다. 본 실험에 사용된 Na 및 K계 흡수제는 모두 연소 후 배가스 중 $CO_2$를 제거하기 위한 흡수제로 사용되는 고체 흡수제이다. 석탄화력발전소 배가스에 연계되어 $CO_2$ 회수실험에 사용되었던 사용 후 $CO_2$ 흡수제에 대해 HCl 흡수 실험을 수행한 결과에서도 우수한 HCl 제거 성능을 보여 주었다. 이로부터, 폐 $CO_2$ 흡수제의 HCl 흡수제로서의 활용가능성을 확인 하였다.

• Proceedings of the SCSK Conference
• /
• 2003.09b
• /
• pp.12-25
• /
• 2003

L-camitine ($\beta$ -hydroxy-${\gamma}$ -trimethyl-ammoniumbutyric acid) is a small water-soluble molecule important in mammalian fat metabolism. It is essential for the normal oxidation of fatty acids by the mitochondria, and is involved in the trans-esterification and excretion of acyl-CoA esters. In this paper, to investigate the relationship between aging and L-camitine, we investigated the effects of in vitro MMP inhibition and activity and expression of UVA-induced MMP 1 in human skin fibroblasts. Fluorometric assays of the proteolytic activities of MMP-l were performed using fluorescent collagen substrates. ELISA (enzyme linked immuno sorbent assay), gelatin-substrate zymography, and RT-PCR ELISA techniques were used for the effects of L-camitine on MMP expression and activity, MMP mRNA expression in UVA irradiated fibroblast. L-camitine inhibited the activities of MMP-l in a dose-dependent manner and the $IC_{50}$/ values calculated from semi-log plots were 2.45mM, and L-carnitine showed strong inhibition on MMP-2 (gelatinase) activity in UVA irradiated fibroblast by zymography. Also, UVA induced MMP expression was reduced 40% by treated with L-carnitine, and MMP-l mRNA expression was reduced dose-dependent manner. Therefore L-carnitine was able to significantly inhibition the MMP activity, regulation of MMP expression in protein and mRNA level. All these results suggest that L-carnitine may be useful as new anti-aging cofactor for protection against UVA induced MMP expression and activity.

• Korean Chemical Engineering Research
• /
• v.53 no.3
• /
• pp.333-338
• /
• 2015

In this study, we investigated carbonation-regeneration and agglomeration characteristics of dry sorbents. Experiment has been proceeded in the batch-type reactor, which is made of quartz: 0.05 m of I.D and 0.8 m in height. The sorbents that is collected at the cyclone of the carbonation reactor of continuous process were used in this study. The reactivity was studied at the various concentrations of water vapor, $N_2$ and $CO_2$ in the fluidizing gas at regeneration reaction. As a result, the reactivity increased as the regeneration temperature increased, the reactivity decreased as the concentration of water vapor increased. The absorption capacity showed the highest value in case of using $N_2$ 100% as regeneration gas. And decreased in order of $H_2O+N_2$, $CO_2$ 100% and $H_2O+CO_2$. The agglomeration characteristics were investigated according to the particle sizes and concentrations of water vapor at carbonation reaction. As a result, the particle with smaller size and higher concentration of water vapor showed the higher agglomeration characteristic.

• Nuclear Engineering and Technology
• /
• v.54 no.11
• /
• pp.4013-4021
• /
• 2022

A kind of zirconium phosphate mesoporous coordination polymer Zr-EDTMPA was successfully synthesized and characterized using XRD, FTIR, TGA, EA, SEM-EDS, and N₂ sorption-desorption measurements. The prepared Zr-EDTMPA was first employed for the removal of Co(II) from an aqueous solution, and the effects of pH, contact time, temperature, initial Co(II) concentration, reusability, and sorption mechanism were systematically investigated. The results showed that the Zr-EDTMPA is a zirconium phosphate complex formed by the coordination of EDTMPA to Zr in a molar ratio of 1:1. The sorption of Co(II) by Zr-EDTMPA was a pH-dependent, spontaneous and endothermic process, which was better fitted to the pseudo-second-order kinetic model and Langmuir isotherm model. The Zr-EDTMPA was demonstrated to have excellent reusability and presented a high sorption capacity of 73.0 mg·g^-1 for Co(II) at pH 8.0. The sorption mechanism was mainly attributed to the strong coordination between cobalt and the untapped hydroxyl functional groups on Zr-EDTMPA, which was confirmed by XPS spectra. Therefore, as a candidate sorbent with high sorption capacity and excellent reusability, Zr-EDTMPA has a great potential for the removal of Co(II) from aqueous solutions.

• Transactions of the Korean hydrogen and new energy society
• /
• v.15 no.2
• /
• pp.108-118
• /
• 2004

To find out rational design and synthetic strategies toward efficient hydrogen storage materials, molecular modeling and quantum mechanical studies have been carried out on the MOFs(Metal-Organic Frameworks) having various organic linkers and nanocube frameworks. The calculation results about the free volume ratio, surface area, and electron density variation of the frameworks indicated that the capacity of the hydrogen storage of MOFs was largely dependent on the specific surface area and electron localization around benzene ring rather than the free volume of MOFs. The prediction of the modeling study could be supported by the hydrogen adsorption experiments using IRMOF-1 and -3, which showed more enhanced hydrogen storage capacities of IRMOF-3 compared with the IRMOF-1's at both experimental conditions, 77K, ∠ $H_2$ 1 atm and ambient temperature, ∠ $H_2$ 35 atm.