Modification of the surface of raw activated carbon using chemical solvents can significantly improve the adsorption performance of activated carbon. Triethylenetetramine is one of the most important chemical solvents used to modify raw activated carbon for formaldehyde removal indoor. We conducted the liquid impregnation experiments at different initial concentrations, temperatures, adsorbent dosage and time ranges to fully investigate the adsorption of triethylenetetramine on the surface of raw activated carbon for modification. We found that the Langmuir isotherm model and pseudo-first-order kinetic model fit quite well with the experimental data and the R2 are 0.9883 and 0.9954, respectively. The theoretical maximum adsorption capacity is 166.67 mg/g. The change in Gibbs free energy (ΔG0), enthalpy change (ΔH0) and entropy change (ΔS0) were also calculated to study the direction and driving force of the liquid adsorption process. In order to understand the adsorption process at the molecular level, a new activated carbon model based on the actual physical and chemical properties of activated carbon was carefully established in the Materials Studio to simulate the liquid-phase adsorption. The pore structure, elemental composition, functional group content, density, pore volume, and porosity of the activated carbon model converge close to the actual activated carbon and the adsorption isotherms obtained from the simulation agree well with the experimental results. The results show that the adsorption of triethylenetetramine on activated carbon is a spontaneous, endothermic and monolayer physical adsorption process.

The mobility of radionuclides in the subsurface environment is governed by a interaction of radioactivity characteristics and geochemical conditions with adsorption reactions playing a critical role. This study investigates the characteristics and mechanisms of radionuclides adsorption on site media in viewpoint of nuclear safety, particularly focusing on the potential effect of seawater infiltration in coastal site near nuclear power plant. Seawater intrusion alters the chemistry in groundwater, including parameters such as pH, redox potential, and ionic strength, thereby affecting the behavior of radionuclides. To assess the safety of site near nuclear power plant and the environmental implications of nuclide leakage, this research conducted various experiments to evaluate the behavior of radionuclides in the subsurface environment. High distribution coefficients (50-2,500 ml/g) were observed at 10 mg/L Co, with montmorillonite > hydrobiotite > illite > kaolinite. It decreased with competing cations (Ca2+) and was found to decrease significantly by 90% with a decrease in pH to 4. It is believed that the adsorption capacity of cationic radionuclides decreases significantly as the clay mineral surface becomes less negatively charged. For Cs, the distribution coefficient (180-560 ml/g) was higher for montmorillonite > hydrobiotite > illite > kaolinite. Compared to Co, it was found to be less influenced by pH and more influenced by competing cations. For Sr, the distribution coefficient (100-380 ml/g) was higher in the order of hydrobiotite > montmorillonite > illite > kaolinite. Compared to Cs, it was found to be less affected by pH and also less affected by the effect of competing cations compared to Cs. Seawater samples from Gampo and Uljin site near Nuclear Power Plant in Korea were analyzed to determine their chemical composition, which was subsequently used in adsorption experiments. Additionally, the seawater-infiltrated groundwater was synthesized in laboratory according to previous literature. The study focused on the adsorption and behavior of three key radionuclides such as cesium, strontium, and cobalt onto four low permeability media (clay minerals) such as kaolinite, illite, hydrobiotite, and montmorillonite known for their high adsorption capacity at a site of nuclear power plant. At concentrations of 5 and 10 mg/L, the adsorption coefficients followed the order of cobalt > cesium > strontium for each radionuclide. Notably, the distribution coefficient (Kd) values exhibited higher values in seawater-infiltrated groundwater environments compared to seawater with relatively high ionic strength. Cobalt exhibited a substantial adsorption coefficient, with a marked decrease in Kd values in seawater conditions due to elevated ionic strength. In contrast, cesium displayed less dependency on seawater compared to other radionuclides, suggesting distinct adsorption mechanisms, possibly involving fractured edge sites (FES) in clay. Strontium exhibited a significant reduction in adsorption in seawater compared to groundwater in all Kd sorption experiments. The adsorption data of cobalt, cesium, and strontium on clay minerals in contact with seawater and seawater-infiltrated solutions offer valuable insights for assessing radioactive contamination of groundwater beneath coastal site near nuclear power plant sites. This research provides a foundation for enhancing the safety assessment protocols of nuclear power plant sites, considering the potential effects of seawater infiltration on radionuclide behavior in the subsurface environment.

After the Fukushima accident in 2011, relevant concerns regarding the contamination of the natural environment rose abruptly. For example, water contaminated by radionuclides such as Cs and Sr may directly flow into the ocean and threaten the marine ecosystem. In this respect, costeffective and efficient decontamination techniques need to be developed and verified to remediate the contaminated water. Prussian blue (PB) is known as a representative material that can adsorb Cs by ion-trapping and is widely used for medical purposes. However, there is a limitation that PB itself is non-separable and highly mobile in aqueous system, so it needs a fixture, such as bentonite, to be collected after the adsorption. Furthermore, while the performance of PB toward Cs is relatively well known, its behavior toward Sr has rarely been reported. The object of this study is to investigate the sorption characteristics of Cs and Sr onto PB-functionalized bentonite at various conditions. The adsorbent employed in the present work was prepared by mixing bentonite, FeCl3, and K4[Fe(CN)6] at room temperature for 24 hours in the aqueous solution. The concentrations of FeCl3 and K4[Fe(CN)6] were set to a range of 5-200 % compared to the cation exchange capacity of bentonite. After that, the PB-functionalized bentonite was sieved with a mesh size of 63 μm and then reacted with the Cs and Sr solution at various liquid-to-solid (L/S) ratios of 2-10 g/L for up to 500 minutes. Moreover, synthetic seawater containing additional Cs and Sr was reacted with PBfunctionalized bentonite to characterize the ion selectivity of PB. After the completion of the adsorption experiment, a part of the adsorbent was separated and desorption of Cs and Sr with 2 M of nitric acid was performed. For the quantification of aqueous Cs and Sr concentrations, ICP-MS was employed after the filtration with a pore size of 0.45 μm. The result obtained in this study revealed a high sorption affinity of Cs and Sr onto PBfunctionalized bentonite. The analysis results also presented that the sorption reactions of Cs and Sr reached their steady state within 10 minutes of reaction time. Furthermore, the ion selectivity toward Cs and Sr was verified through sorption test with synthetic seawater. According to the high sorption affinity and selectivity, the PB-functionalized bentonite synthesized through this study is expected to be widely used for remediating the Cs- and Sr-contaminated groundwater and seawater, particularly in nuclear waste-relevant industries.

Perfluorooctanoic acid(PFOA) was one of widely used per- and poly substances(PFAS) in the industrial field and its concentration in the surface and groundwater was found with relatively high concentration compared to other PFAS. Since various processes have been introduced to remove the PFOA, adsorption using GAC is well known as a useful and effective process in water and wastewater treatment. Surface modification for GAC was carried out using Cu and Fe to enhance the adsorption capacity and four different adsorbents, such as GAC-Cu, GAC-Fe, GAC-Cu(OH)2, GAC-Fe(OH)3 were prepared and compared with GAC. According to SEM-EDS, the increase of Cu or Fe was confirmed after surface modification and higher weight was observed for Cu and Fe hydroxide(GAC-Cu(OH)2 and GAC-Fe(OH)3, respectively). BET analysis showed that the surface modification reduced specific surface area and total pore volumes. The highest removal efficiency(71.4%) was obtained in GAC-Cu which is improved by 17.9% whereas the use of Fe showed lower removal efficiency compared to GAC. PFOA removal was decreased with increase of solution pH indicating electrostatic interaction governs at low pH and its effect was decreased when the point of zero charges(pzc) was negatively increased with an increase of pH. The enhanced removal of PFOA was clearly observed in solution pH 7, confirming the Cu in the surface of GAC plays a role on the PFOA adsorption. The maximum uptake was calculated as 257 and 345 μg/g for GAC and GAC-Cu using Langmuir isotherm. 40% and 80% of removal were accomplished within 1 h and 48 h. According to R2, only the linear pseudo-second-order(pso) kinetic model showed 0.98 whereas the others obtained less than 0.870.

The adsorption of molecular hydrogen on the monolayer graphene sheet under varied temperature and pressure was studied using molecular dynamics simulations (MDS). A novel method for obtaining potential energy distributions (PEDs) of systems was developed to estimate the gravimetric density or weight percentage of hydrogen. The Tersoff and Lennard–Jones (LJ) potentials were used to describe interatomic interactions of carbon–carbon atoms in the graphene sheet and the interactions between graphene and hydrogen molecules, respectively. The results estimated by the use of novel method in conjunction with MDS developed herein were found to be in excellent agreement with the existing experimental results. The effect of pressure and temperature was studied on the adsorption energy and gravimetric density for hydrogen storage. In particular, we focused on hydrogen adsorption on graphene layer considering the respective low temperature and pressure in the range of 77–300 K and 1–10 MPa for gas storage purpose which indicate the combination of optimal extreme conditions. Adsorption isotherms were plotted at 77 K, 100 K, 200 K, and 300 K temperatures and up to 10 MPa pressure. The simulation results indicate that the reduction in temperature and increase in pressure favor the gravimetric density and adsorption energies. At 77 K and 10 MPa, the maximum gravimetric density of 6.71% was observed. Adsorption isotherms were also analyzed using Langmuir, Freundlich, Sips, Toth, and Fritz–Schlunder equations. Error analysis was performed for the determination of isotherm parameters using the sum of the squares of errors (SSE), the hybrid fractional error function (HYBRID), the average relative error (ARE), the Marquardt’s percent standard deviation (MPSD), and the sum of the absolute errors (SAE).

본 연구에서는 Na형 Faujasite 제올라이트 분리막의 프로필렌/프로페인 분리 거동을 예측하기 위하여 제올라이트 13X 입자의 프로필렌 및 프로페인 단일기체에 대한 중량식흡착 거동을 관찰하고자 하였다. 제올라이트 13X 입자의 프로필렌 및 프로페인에 대한 중량식흡착 거동은 자성부유평형저울(MSB)을 이용하여 323, 343, 363 K의 온도와 0.02-1 bar의 압력 범위에서 0.1 bar씩 증가시키면서 측정되었다. 그 결과, 온도가 증가할수록 프로필렌 및 프로페인의 흡착량은 감소하였으며, 프로필렌/프로페인의 흡착 선택도는 증가하였다. 또한 흡착 온도가 증가함에 따라 프로필렌과 프로페인의 확산계수는 증가하여 아레니우스 식을 따랐고, 프로필렌/프로페인 확산 선택도는 323 K에서 0.9753으로 최대값을 가졌다. 흡착 특성을 통해 분리막의 투과선택도를 계산하였고, Na형 Faujasite 제올라이트 분리막의 단일 기체 투과 특성과 비교하였다. 그 결과 계산된 투과선택도와 측정된 투과선택도가 모두 323 K에서 최대값을 갖는 것을 확인하였다. 따라서 본 연구에서는 중량식 흡착법으로 예측된 분리막의 프로필렌/프로페인 분리거동 예측이 합리적이며 또한 표면확산에 기반한 프로필렌/프로페인 분리용 제올라이트 분리막의 분리성능예측에 적용될 수 있음을 알 수 있었다.

Coloured wastewater is released as a direct result of the production of dyes as well as from various other chemical industries. Many dyes and their breakdown products may be toxic for living organisms. Activated carbon is one of the best materials for removal of dyes from aqueous solutions. The present study describes the adsorption behaviour of methylene blue dye on three microporous activated carbons, where two samples (AC-1 and AC-2) were prepared by a polymer blend technique and the other is a microporous activated carbon (ARY-3) sample from viscose rayon yarn prepared by chemical-physical activation. The effects of contact time and activated carbon dosage on decolourisation capacity have been studied. The results show that activated carbon having mixed microporosity and mesoporosity show tremendous decolourisation capacity for methylene blue. In addition, the activated carbon in the powder form prepared by the polymer blend technique shows better decolourisation capacity for methylene blue than the activated rayon yarn sample.

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.

The VOCs(Volatile Organic Compounds) is one of the major cause for the atmosphere pollution. Breakthrough behavior of benzene and toluene in adsorption bed packed with activated carbon was experimentally studied. Composition and temperature of the gas flowing in the bed was measured and breakthrough curves for each component was obtained. Breakthrough time of benzene was earlier than that of toluene due to relatively weak adsorptivity. The relationship between breakthrough time and flow rate was obtained. The shape of temperature change with time was dependent on the position in the bed. Temperature changed faster and sharper in the inlet than in the outlet. It was noted that breakthrough behavior could be affected by the heat transfer properties.

The purpose of this study is to explore the time dependant behaviors of chloride ions adsorption with cement hydrates, focused on its mechanism. AFt phase and CH phase were not able to absorb chloride ion, however, C-S-H phase and AFm phase had a significant chloride adsorption capacity. Based on the results, this study suggested theoretical approach to depict chloride adsorption behavior with elapsed time of C-S-H phase and AFm phase effectively. AFm phase showed a slow chemical adsorption in 40 days, while C-S-H phase showed binding behavior with 3 stages including the stage of instantaneous physical adsorption other stages.

Chloride binding capacity in cementitious materials is a crucial factor for service life prediction of marine concrete. C-S-H phase have significant physical binding capacity for chloride ions. In this study, specific surface area of C-S-H with various Ca/Si ratio was measured. This study suggested effective way to compute maximum adsorption of bound chloride by C-S-H based on theory single molecular layer. In addition, surface potential is very important as a main mechanism for chloride binding adsorption. Thus, intrinsic equilibrium constant was obtained and surface potential of C-S-H was calculated in chemical equilibrium solution by means of PHREEQC. Based on the experiment results, to develop integrated system for prediction of chloride binding behaviors is final goals.

포항지역 널리 분포하고 있는 규질이암으로부터 상업화를 위한 50리터 bench scale 수열장치를 사용하여 Na-A형 제올라이트의 합성을 성공적으로 수행하였고 또한 이 제올라이트를 이용하여 환경 개선재로 활용하는 연구를 수행하였다. 초기물질로 사용된 규질이암은 제올라이트의 주요 성분인 SiO2 및 Al2O3가 각각 70.7% 및 10.0% 함유되어 제올라이트의 합성에 유리한 조성을 가지고 있다. 이전의 실험실적 규모에서 수행된 동일한 조건인 Na2O/SiO2 = 0.6, SiO2/Al2O3 = 2.0, H2O/Na2O = 98.6의 조성비로 80℃에서 18시간 동안 합성한 결과, Na-A형 제올라이트의 결정도 및 결정형태는 실험실적 규모와 유사하였고, 회수율 및 양이온 교환능은 각각 95% 및 215 cmol/kg으로 실험실적 규모에서 보다 약간 우수한 결과를 나타냈다. 합성된 Na-A형 제올라이트를 이용하여 모사폐액(Pb, Cd, Cu, Zn 및 Mn)에 중금속 제거율을 조사한 결과, 중금속 제거율은 Pb 〉 Cd 〉 Cu = Zn 〉 Mn의 순서이었다. Mn을 제외한 다른 중금속들은 1500 mg/L에서 99% 이상의 제거율을 보였고, Mn의 경우도 98%의 제거율을 보여 합성된 Na-A형 제올라이트는 중금속 흡착제로서 우수한 특성을 나타냈다.

The interfacial characteristics between various heavy metals and hydrous FeS were investigated. Heavy metals which have lower sulfide solubilities than FeS undergoes the lattice exchange reaction when these metal ions contact FeS in the aqueous phase. For heavy metals which have higher sulfide solubilities than FeS, these metal ions adsorb on the surface of FeS. Such characteristic reactions were interpreted by the solid solution formation theory. The presence of ligand such as EDTA reduced largely metal removal efficiency due to formation of metal-ligand complex in the solution. In an attempt to elucidate the interfacial characteristics, zeta potential of the hydrous FeS in the absence and in the presence of various metal ions were measured and analyzed.