The CDI (Capacitive deionization) is one of the desalination technologies that use a carbon material electrode with large surface area and excellent electrical conductivity. Recently, research on a MCDI (Membrane Capacitive deionization) process, which is a combination of an ion-exchange membrane, has been actively conducted. In this study, we tried to find out the water quality of treated water and the concentration characteristics of concentrated water through TDS analysis by MCDI conventional and circulation process. In producing treated water, there was no significant difference in adsorption efficiency between MCDI conventional and circulation process. It was confirmed that both processes adsobed more than 96 %. However, the MCDI conventional process showed a low yield of 50 %, whereas the MCDI circulation process showed a high yield of 97.6 %. It's because, the wasted water was reused at desorption. In the case of the TDS concentration using MCDI circulation process, as the cycle progressed, the TDS concentration was concentrated up to 1,300 mg/L, but the rate gradually decreased. It is believed that this is because the volume of the concentrated water tank is limited, and the amount of soluble ions gradually decreases. As a result of analyzing the wasted water at MCDI circulation process through Ion Chromatography, it was confirmed that the concentration of all ions were concentrated. However, there was no significant difference in the types and proportions of analyzed ions. It is judged that the types and concentration of ions do not have a significant effect on adsorption and desorption in the MCDI circulation process.

본 연구에서는 오염된 점토 내 Cs을 제거하기 위하여, 계면활성제의 소수성 알킬사슬의 길이에 따른 Cs의 탈착특성을 연구 하였다. 양이온성 계면활성제로 Alkyl trimethyl ammonium bromide를 사용하였고, 소수성 알킬사슬은 octyl-, dodecyl-, cetyl- 으로 변화시켰다. 소수성 알킬사슬이 길어질수록 montmorillonite 내 계면활성제의 흡착량이 증가하였고, 계면활성제의 층간 흡착으로 층간거리가 증가하는 것으로 나타났다. Cs의 탈착률도 알킬사슬의 길이가 증가함에 따라 향상되었고 cetyl 그룹을 갖는 양이온성 계면활성제는 최대 99±2.9%의 Cs 제거율을 나타냈다.

The adsorption/desorption characteristics of toluene vapors filled with activated carbon(AC) were studied. Adsorption performance of AC was investigated according to flow rate, moisture content, and other factors. The breakthrough time was shortened as the flow rate and moisture content increased. The AC loaded with toluene was regenerated by programmed heating and pressure. AC was regenerated well, as the conditions of heating temperature(80oC) and pressure(100 torr) were appropriate. Toluene is more easily removed at low temperature than through thermal desorption methods. The test of AC regeneration was carried out three times.

Desorption reaction characteristics of the used activated carbons collected from manufacture of rubber and plastics products in Shiwha/Banwal industrial complex were investigated. Desorption reactions were analyzed based on the data obtained from a thermogravimetric analyzer. Activation energies and reaction orders for desorption reaction characteristics of the used activated carbons were estimated by employing the Friedman method and the Freeman-Carroll method. It was found that the activation energies were 24.7∼41.3 kJ/㏖ in the Friedman method and 13.9∼24.4 kJ/㏖ in the Freeman-carroll method, and reaction orders were 0.3∼1.4.

Desorption characteristics of waste activated carbons collected from chemicals manufacturing industries in Shiwha/Banwal industrial complex were investigated. Activated carbons were decomposed in a thermogravimetric analyzer (TGA) at 513K with heating rate of 10 ℃/min under nitrogen atmosphere. Activation energies and reaction orders for desorption, from the waste activated carbon were estimated by employing Friedman method and Freeman-Carroll method. It was found that the reaction orders of desorption in waste activated carbons were 0.27-1.69, and activation energies were 15.2-45.7 kJ/mol in Friedman method and 13.7-17.1 kJ/mol in Freeman-Carroll method.

In this study, the removal characteristics of reduced sulfur compounds (RSC) were investigated against activated carbon (AC) by means of electric cooling and thermal desorption. To this end, three types of AC materials were selected and tested against gaseous RSC standards prepared at 50 ppb concentration. Each of these AC materials designated with its own target odorant compounds was tested for the removal rate of RSC by comparing their quantities between prior to and after passing the adsorption tube. All the analysis of RSC was made by Gas Chromatography (GC)/Pulsed Flame Photometric Detector (PFPD) combined with Air Server (AS)/Thermal Desorber (TD). The rate of RSC removal was quantified as a function of RSC loading time (Exp. 1) and of RSC flow rate into TD (Exp. 2). The results of Exp. 1 showed that the adsorption of RSC increased with RSC loading time (from as little as 1 to 20 min). In Exp. 2, the adsorption of RSC also increased in relation to RSC flow rate (10 to 100 mL/min). The removal rate of RSC was also distinguished by chemical properties such as the compounds of low molecular weights (H₂S and CH₃SH) vs. high ones (DMS and DMDS).

In order to accurately analyze trace-level, reduced sulfur compounds (RSC) in ambient air, one needs to rely on the thermal desorption technique (TD) to atone for the limited sensitivity of direct gas chromatography (GC) analysis. In this study, the relative performance of GC/PFPD system combined with TD unit was evaluated to help accurately determine RSC based on the comparative analysis of two types of calibration approaches. Hence, calibration results of RSCs were compared by controlling sample transfer system (air server (AS) and TD unit) between the two contrasting calibration approaches such as: incremental-loading of a given standard with the fixed standard concentration (FSC) vs. supply of standards made at multiple concentration points at the fixed standard volume (FSV). The results of our study indicate that RSC calibration is affected fairly sensitively by sample loading conditions of the AS/TD system. It is hence necessary to delicately control the TD operation conditions for the accurate quantification of RSCs, when GC/PFPD system with TD is employed for RSC analysis.

중수로 원전내 여러 계통으로 부터 발생된 폐수지내에는 핵종이 다량 함유되어 있으며, Class A 및 C 폐기물로 분류되는 폐수지의 적정 처리 기술 개발을 위한 기초연구를 수행하였다. IRN-150 혼상 이온교환수지를 이용하여 비방사성 이온과 양이온의 흡착 특성 및 탈차용액을 이용한 이온의 제거 특성을 고찰하였다. IRN-150 수지의 이온의 흡착능은 이론값에 근접한 11 mg-C/g-IRN-150을 나타내었고, 양이온의 흡착 친화도를 단일성분 및 복합성분 시스템을 이용하여 분석하였다. 여러 가지 탈착용액을 이용한 폐수지로부터 이온의 제거 특성을 평가한 결과, 핵종을 전량 효과적으로 제거하기 위해서는 보다도 용액이 유리한 것으로 나타났다.

Volatile organic compounds (VOCs) are considered as one of the main air pollutants, and legislation has already been introduced in many countries to reduce their emissions. In addition to the main emission sources, such as petroleum industries, there are also many local sources, such as painting, printing and laundering etc., which emit low concentrations of VOC. A modified adsorption system (MAS) has been suggested for the control low concentrations and high flow rate streams of VOC. The MAS was based on adsorption, followed by the treatment of concentrated VOC, such as incineration (catalytic or thermal) or recovery. In this paper, the results of the adsorption/desorption of toluene (target VOC) over several adsorbents (activated carbon, hydrophobic zeolites and mesoporous materials) were reviewed for the selection of a good VOC adsorbent for the MAS. From the results, zeolite HY, with a FAU structure, was selected as the most potential adsorbent for the MAS.

아미드옥심기와 복합재료 섬유흡착제를 제조하였고 해수로부터 우라늄이온의 분리 특성을 조사하였다. 흡착량은 흡착시간이 증가함에 따라 증가하였고 An:TEGMA:DVB의 몰비가 1:0.1:0.003인 수지가 pH 8 부근에서 최대 흡착능을 나타내었다. 또한 흡착량은 CFA에 첨가한 흡착제의 양이 증가함에 따라 증가하였으며 1시간 까지 선형적으로 증가하였고, 25˚C에서 최대흡착량을 나타내었다. 한편 Ca, Mg 이온은 흡-탈착 cycle이 반복될수록 증가하였으며 그양은 각각 0.3, 0.9mmole/g-Ads로 우라늄 이온의 그것보다 매우 낮았다. 흡착된 우라늄 이온의 탈착은 흡착제의 종류에 관계없이 약 30분 이내에 거의 100% 탈착되었다.

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 order to establish the design parameters of adsorption for arsenic compounds with hydrotalcite including chlorine ion, the basic properties of adsorption and desorption as well as the oxidation of As (Ⅲ) were examined in batch tests. The maximum adsorption capacities of arsenite and arsenate were 6.2 ㎎-As(Ⅲ)/g and 103 ㎎-As (Ⅴ)/g, respectively. Although 80.4% of maximum desorption was shown in 20% NaOH solution, 5∼10% of NaOH was recommended considering operating benefits, where the proper condition of the desorption was in the range of 73% to 80%. The most suitable desorption condition was in the combination of NaCl (10∼20%) and NaOH (5∼10%). Within 2 minutes, As (Ⅲ) was easily oxidized to As (Ⅴ) with 0.0001 N KMnO4, where the maximum oxidization ratio was shown to 98.9%.

This study provides an experimental result of thermal mercury reduction and condensation characteristics for inventing a mercury recovery technology from the waste sludge which contains high concentration of mercury. Thermal treatment was conducted in the temperature range of up to 900oC from 600oC with different residence time using a waste sludge from domestic industrial facility. Properties of powder material condensed after thermal treatment were analyzed to assess the effectiveness of thermal processing. Leaching characteristics of bottom ash and condensed powder material were analyzed by Korean Standard Leaching Test method (KSLT). Cold vapor atomic absorption spectroscopy (CVAAS) Hg analyzer was used for the analysis of mercury content in solid and liquid samples. We found that mercury contents was concentrated compared with waste sludge. However, the mercury concentration of leached solution from the condensed powder material was very low. The chemical characteristics of condensed powder material was estimated using experimental analysis and literature survey. In order to recover purified elemental mercury, the further researches of refining experiments would be required.

Adsorption and desorption characteristics of the representative 10 kinds components consisting of gasoline vapor on activated carbon were investigated at the temperature range of -30℃∼25℃. The breakthrough curves of each vapors obtained by the Thomas model were well described the breakthrough experimental results of this study. The breakthrough times of each vapors were correlated with the molecular weight, density, and vapor pressure. The breakthrough times had greater correlation with boiling point than molecular weight and density. The slope of the breakthrough curve was a proportional relationship with the rate constant (k) of Thomas model expression. The higher the slope of the breakthrough curve, the rate constant was larger. The biggest slope vapor had the smallest adsorption capacity (qe). Adsorption and desorption characteristics of mixed vapor similar to the gasoline vapor were studied at room temperature (25℃). The mixed vapor consisting of 9 components; group A (pentane, hexene, hexane), group B (benzene, toluene), group C (octane, ethylbenzene, xylene, nonane) was examined. Group A was not nearly adsorbed because of substitution by group C, and the desorption capacity of group A was smaller than group C. The adsorbed substances were confirmed to be Group C.