In the current study, MIL-101(Cr)-SO3H[HCl] as metal-organic frameworks (MOFs) was fabricated via a hydrothermal method. The physicochemical properties of the synthesized material were characterized using XRD, FT-IR, FE-SEM, TEM, and BET surface area analysis. The XRD diffraction pattern of the prepared MIL-101(Cr)-SO3H[HCl] was similar to previously reported patterns of MIL-101(Cr) type materials, indicating successful synthesis of MIL-101(Cr)-SO3H[HCl]. The FT-IR spectrum revealed the molecular structure and functional groups of the synthesized MIL-101(Cr)-SO3H[HCl]. FE-SEM and TEM images indicated the formation of rectangular parallelopiped structures in the prepared MIL-101(Cr)-SO3H[HCl]. Furthermore, the EDS spectrum showed that the synthesized material consisted of the elements of Cr, O, S, and C. The fabricated MIL-101(Cr)-SO3H[HCl] was then employed as an adsorbent for the removal of Sr2+ and Cs+ from aqueous solutions. The adsorption kinetics and adsorption isotherm models were studied in detail. The maximum adsorption capacities of MIL-101(Cr)-SO3H[HCl] for Sr2+ and Cs+ according to pH (3, 5.3∼5.8, 10) were 35.05, 43.35, and 79.72 mg/g and 78.58, 74.58, and 169.74 mg/g, respectively. These results demonstrate the potential of the synthesized MOFs, which can be effectively applied as an adsorbent for the removal of Sr2+ and Cs+ ions from aqueous solutions and other diverse applications.

The characteristics of ammonia-nitrogen (NH4 +-N) adsorption by a zeolitic material synthesized from Jeju scoria using the fusion and hydrothermal method was studied. The synthetic zeolitic material (Z-SA) was identified as a Na-A zeolite by X-ray diffraction, X-ray fluorescence analysis and scanning electron microscopy images. The adsorption of NH4 +-N using Jeju scoria and different types of zeolite such as the Z-SA, natural zeolite, and commercial pure zeolite (Na-A zeolite, Z-CS) was compared. The equilibrium of NH4 +-N adsorption was reached within 30 min for Z-SA and Z-CS, and after 60 min for Jeju scoria and natural zeolite. The adsorption capacity of NH4 +-N increased with approaching to neutral when pH was in the range of 3-7, but decreased above 7. The removal efficiency of NH4 +-N increased with increasing Z-SA dosage, however, its adsorption capacity decreased. For initial NH4 +-N concentrations of 10-200 mg/L at pH 7, the adsorption rate of NH4 +-N was well described by the pseudo second-order kinetic model than the pseudo first-order kinetic model. The adsorption isotherm was well fitted by the Langmuir model. The maximum uptake of NH4 +-N obtained from the Langmuir model decreased in the order of Z-CS (46.8 mg/g) > Z-SA (31.3 mg/g) > natural zeolite (5.6 mg/g) > Jeju scoria (0.2 mg/g).

Zeolite material having XRD peaks of Na-A zeolite in the 2θ range of 7.18 to 34.18 can be synthesized from the waste catalyst using a fusion/hydrothermal method. The adsorption rate of Mn ions by a commercial Na-A zeolite and the synthesized zeolitic material increased as the adsorption temperature increased in the range of 10 ~ 40℃. The adsorption of Mn ion were very rapid in the first 30 min and then reached to the equilibrium state after approximately 60 min. The adsorption kinetics of Mn ions by the commercial Na-A zeolite and the zeolitic material were found to be well fitted to the pseudo-2nd order kinetic model. Equilibrium data by the commercial Na-A zeolite and the zeolitic material fit the Langmuir, Koble-Corrigan, and Redlich-Peterson isotherm models well rather than Freundlich isotherm model. The removal capacity of the Mn ions by the commercial Na-A zeolite and the zeolitic material obtained from the Langmuir model was 135.2 mg/g and 128.9 mg/g at 30℃, respectively. The adsorption capacity of Mn ions by the synthesized zeolitic material was almost similar to that of commercial Na-A zeolite. The synthesized zeolitic material could be applied as an economically feasible commercial adsorbent.

The characteristics of heavy metal ion (Ni2+, Zn2+, and Cr3+) adsorption by zeolite synthesized from Jeju scoria using the fusion and hydrothermal method, were studied. The synthetic zeolite was identified as a Na-A zeolite by X-ray diffraction analysis and scanning electron microscopy images. The equilibrium of heavy metal ion adsorption by synthetic zeolite was reached within 60 min for Ni2+ and Zn2+, and 90 min for Cr3+. The uptake of heavy metal ions increased with increasing pH in the range of pH 3-6 and the uptake decreased in the order of Cr3+ > Zn2+ > Ni2+. For initial heavy metal concentrations of 20-250 mg/L at nonadjusted pH, the adsoption of heavy metal ions was well described by the pseudo second-order kinetic model and was well fitted by the Langmuir isotherm model. The maximum uptake of heavy metal ions obtained from the Langmuir model, decreased in the order of Zn2+ > Ni2+ > Cr3+, differing from the effect of pH on the uptake, which was mainly based on the different pH of the solutions.

The adsorption and leaching characteristics of five ionic pesticides including four acidic pesticides (2,4-D, dicamba, MCPA, and MCPP) and one amphoteric pesticide (imazaquin) in agricultural soils were investigated. Soils around spring waters that were heavily affected by pesticide run-off and soils around wells considering the regional characteristics in Jeju Island were collected at 24 stations. The Freundlich constant, KF value, which is a measure of the adsorption capacity, decreased in the order of 2,4-D > MCPA > MCPP > dicamba > imazaquin. The adsorption capacity of these ionic pesticides decreased with increasing pH owing to the effects of ionization of pesticides and different ionizable functional groups of soils. The leaching of ionic pesticides in the soil column showed a reverse relationship with their adsorption in soils, namely, the ionic pesticides were leached more quickly for the pesticides with lower adsorption capacity. The groundwater contamination potential of the ionic pesticides was evaluated in the order of imazaquin > MCPA > MCPP > dicamba > 2.4-D according to the groundwater ubiquity score based on soil Koc and the half-life of the pesticide.

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.

Arsenic is among the heavy metals commonly found in aqueous environments. Iron oxide is known as an efficient adsorbent for the arsenic. A new synthetic method was applied to provide iron oxide giving a large specific surface area. The mixing method affects the formation of iron oxide. Ultrasonic waves assisted the formation of very fine iron oxide in an organic phase. The synthesized iron oxide is amorphous type with a high surface area of more than 181.3 m2/g. Sorption capacity of the synthesized adsorbent was relatively very high for arsenic and varied depending on the oxidation state of arsenic: a higher capacity was obtained with As(V). Lower solution pH provided a higher sorption capacity for As(V). The competitive effect of co-exist anions such as chloride, nitrate, and sulfate was minimal in sorption capacity of the iron oxide for arsenic.

In this study, PAN-SZ (polyacrylonitrile scoria zeolite) beads were prepared by immobilizing Na-A zeolite (SZ-A) synthesized from Jeju volcanic rocks (scoria) on the polymer PAN. FT-IR and TGA analysis results confirmed that the SZ-A was immobilized in the PAN-SZ beads. SEM images showed that the PAN-SZ beads are a spherical shape with 2 mm diameter and exhibit a porous inner structure inside the bead. The most suitable mixing ratio of PAN to SZ-A as the adsorbent for removing Sr ions was PAN/SZ-A = 0.2 g/0.3 g. The adsorption kinetic data for Cu and Sr ions were fitted well with the pseudo-second-order model. The Cu and Sr ion uptakes followed a Langmuir isotherm model and the maximum adsorption capacities at 20℃ were 84.03 mg/g and 75.19 mg/g, respectively. The amount of Sr ion adsorbed by SZ-A on the PAN-SZ beads was about 160 mg/g, which was similar to that adsorbed by SZ-A powder. Thus, the PAN-SZ beads prepared in this study are considered to be effective adsorbents for removing metal ions in aqueous solutions.

The adsorption characteristics of bisphenol A (BPA) were investigated using activated carbon based on waste citrus peel (which is abandoned in large quantities in Jeju Island), denoted as WCP-AC, and surface-modified with various P2O5 concentrations (WCP-SM-AC). Moreover, coconut-based activated carbon (which is marketed in large amounts) was surface-modified in an identical manner for comparison. The adsorption equilibrium of BPA using the activated carbons before and after surface modification was obtained at nearly 48 h. The adsorption process of BPA by activated carbons and surface-modified activated carbons was well-described by the pseudo second-order kinetic model. The experimental data in the adsorption isotherm followed the Langmuir isotherm model. With increasing P2O5 concentration (250-2,000 mg/L), the amounts of BPA adsorbed by WCP-SM-AC increased till 1,000 mg/L of P2O5; however, above 1,000 mg/L of P2O5, the same amounts adsorbed at 1,000 mg/L of P2O5 were obtained. With increasing reaction temperature, the reaction rate increased, but the adsorbed amounts decreased, especially for the activated carbon before surface modification. The amounts of BPA adsorbed by WCP-AC and WCP-SM-AC were similar in the pH range of 5-9, but significantly decreased at pH 11, and increased with increasing ionic strength due to screening and salting-out effects.

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.

When the reinforced concrete structure is in a high salinity environment, chlorine ions penetrate from the surroundings, resulting in corrosion of the reinforcing bars, resulting in low durability. Therefore, studies on the immobilization of chlorine ions are underway, and anion exchange resin, one of them, was used in this study. In this study, chloride ion fixing ability was confirmed by replacing OPC, conventional bead anion exchange resin, and powder anion exchange resin with mortar and then using an electron probe X-ray micro-analyzer. The bead anion exchange resin replaced 3% of the fine aggregate volume and the powder anion exchange resin 5% of the cement volume. The fabricated specimens were cured for 28 days, immersed in NaCl solution for 28 days, and confirmed by electron probe X-ray micro-analyzer.

The present study set out to investigate the adsorption of Cd(II) ions in an aqueous solution by using Peanut Husk Biochar (PHB). An FT-IR analysis revealed that the PHB contained carboxylic and carbonyl groups, O-H carboxylic acids, and bonded-OH groups, such that it could easily adsorb heavy metals. The adsorption of Cd(II) using PHB proved to be a better fit to the Langmuir isotherm than to the Freundlich isotherm. The maximum Langmuir adsorption capacity was 33.89 mg/g for Cd(II). The negative value of ΔGo confirm that the process whereby Cd(II) is adsorbed onto PHB is feasible and spontaneous in nature. In addition, the value of ΔGo increase with the temperature, suggesting that a lower temperature is more favorable to the adsorption process. The negative value of ΔHo indicates that the adsorption phenomenon is exothermic while the negative value of ΔSo suggests that the process is enthalpy-driven. As an alternative to commercial activated carbon, PHB could be used as a low-cost and environmentally friendly adsorbent for removing Cd(II) from aqueous solutions.

The objective of this study was to investigate the adsorption potential of chicken feathers for the removal of OrangeⅡ (AO7) from aqueous solutions. Batch experiments were performed as a function of different experimental parameters such as initial pH, reaction time, feather dose, initial OrangeⅡ concentration and temperature. The highest OrangeⅡ uptake was observed at pH 1.0. Most of the OrangeⅡ was adsorbed at 2 h and an adsorption equilibrium was reached at 6 h. As the amount of chicken feather was increased, the removal efficiency of Orange II increased up to 99%, but its uptake decreased. By increasing the initial concentration and temperature, OrangeⅡ uptake was increased. The experimental adsorption isotherm exhibited a better fit with the Langmuir isotherm than with the Freundlich isotherm, and maximum adsorption capacity from the Langmuir constant was determined to be 0.179244 mmol/g at 30℃. The adsorption energy obtained from the Dubinin-Radushkevich model was 7.9 kJ/mol at 20℃ and 30℃ which indicates the predominance of physical adsorption. Thermodynamic parameters such as ΔGo, ΔHo, and ΔSo were -12.28 kJ/mol, 20.64 kJ/mol and 112.32 J/mol K at 30℃, respectively. This indicates that the process of OrangeⅡ adsorption by chicken feathers was spontaneous and endothermic. Our results suggest that as a low-cost biomaterials, chicken feather is an attractive candidate for OrangeⅡ removal from aqueous solutions.

Removal of siloxane compounds is very important to protecting the biogas energy conversion system from decreased efficiency and parts damage. Among various siloxane removal technologies, adsorption towers are mostly used for performance and ease of operation. However, due to the difficulty of measuring the concentration of siloxane compounds in the gas stream and the complicated matrix of siloxane compounds, adsorption characteristics are not well known. In this study, the adsorption characteristics for multi siloxane components are experimentally studied. Four siloxane components are vaporized in the nitrogen stream supplied continuously to a lab-scale adsorption tank with commercially available silica gel or activated carbon and an FTIR (Fourier-transform infrared spectroscopy) analyzer was used for the online siloxane analysis to find out the adsorption characteristics. While a mixture of L2, L5, D4 and D5 adsorption capacity of silica gel and activated carbon are similar -11.13 and 11.56wt% respectively-adsorption characteristics of each adsorbent was well distinguished in terms of breakthrough behavior. Silica gel shows sequential breakthrough for each siloxane compound and a more noticeable unique time range for Rc > 1, while relatively simultaneous breakthrough was shown for activated carbon adsorbents.

In this study, the low-temperature vacuum swing adsorption (low temp. VSA) process was applied to the activated carbon adsorption tower for treatment of volatile organic compounds (VOCs) to extend the replacement period of the adsorbent and to solve the difficulties of operation management. A practical application study was performed based on continuous operation in the field. The VSA process removes the adsorbate by reducing the pressure at a relatively low temperature (90℃ or less) to compensate for the disadvantages of the conventional thermal swing adsorption (TSA) process. A pilot scale VSA process with a size of 30 m and 2 min−1 was applied to the small scale painting plant, which is the main source of VOCs, and subject to 100 adsorption/desorption cycles. After the sampling of activated carbon every 20 cycles, the specific surface area and derivative thermogravimetric analysis (DTA) analysis were investigated to analyze the change of activated carbon characteristics with increasing cycles. During 100 continuous cycles, toluene gas was arbitrarily supplied to the pilot VSA process to compare toluene adsorption capacity with respect to raw activated carbon. More than 99% of the VOCs emitted from the paint plant were adsorbed and removed during the operation of the VSA process. The increase in cycle did not affect the specific surface area and micropores of activated carbon. However, the physical adsorption amount of the non-desorbed adsorbate remaining in the micropores tends to increase; therefore, it is considered that the effective adsorption amount decreases as the number of regeneration increases. As a result of the toluene adsorption test of the pilot plant after 100 consecutive cycles, 91% removal efficiency relative to the raw activated carbon was maintained. Thus, stable application of low-temperature VSA equipment is feasible in field application.

In this study, a metal-organic framework (MOF) material NH2-MIL-101(Fe) was synthesized using the solvothermal method, and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectrophotometry, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and surface area measurements. The XRD pattern of the synthesized NH2-MIL-101(Fe) was similar to the previously reported patterns of MIL-101 type materials, which indicated the successful synthesis of NH2-MIL-101(Fe). The FT-IR spectrum showed the molecular structure and functional groups of the synthesized NH2-MIL-101(Fe). The UV-visible absorbance spectrum indicated that the synthesized material could be activated as a photocatalyst under visible light irradiation. FE-SEM and TEM images showed the formation of hexagonal microspindle structures in the synthesized NH2-MIL-101(Fe). Furthermore, the EDS spectrum indicated that the synthesized material consisted of Fe, N, O, and C elements. The synthesized NH2-MIL-101(Fe) was then employed as an adsorbent and photocatalyst for the removal of Indigo carmine and Rhodamine B from aqueous solutions. The initial 30 min of adsorption for Indigo carmine and Rhodamine B without light irradiation achieved removal efficiencies of 83.6% and 70.7%, respectively. The removal efficiencies thereafter gradually increased with visible light irradiation for 180 min, and the overall removal efficiencies for Indigo carmine and Rhodamine B were 94.2% and 83.5%, respectively. These results indicate that the synthesized MOF material can be effectively applied as an adsorbent and photocatalyst for the removal of dyes.

Agricultural soils around springwaters heavily affected by pesticide run-off and around wells considering the regional characteristics were collected at 24 stations in Jeju Island, and the physicochemical properties and adsorption and leaching characteristics of four nonionic pesticides (diazinon, fenitrothion, alachlor, and metalaxyl) were investigated. The values of the major soil factors affecting the adsorption and leaching of pesticides, namely, soil pH(H2O), organic matter content, and cation exchange capacity (CEC), were in the range of 4.64 ∼ 8.30, 0.9 ∼ 13.1% and 12.7 ∼ 31.7 meq/100 g, respectively. The Freundlich constant, KF value, which gives a measure of the adsorption capacity, decreased in the order of fenitrothion > diazinon > alachlor > metalaxyl, which was identical to their lower water solubility. Among the collected soils, the KF value was very highly correlated with organic matter content (r2 = 0.800 ∼ 0.876) and CEC (r2 = 0.715 ∼ 0.825) and showed a high correlation with clay content (r2 = 0.473 ∼ 0.575) and soil pH(H2O) (r2 = 0.401 ∼ 0.452). The leaching of pesticides in the soil column showed a reverse relationhip with their adsorption in soils, i.e., the pesticides leached more quickly for the soils with lower values of organic matter content and CEC among the soils and for the pesticides with higher water solubility.

Waste citrus peel-based activated carbon (WCAC) was prepared from waste citrus peels by activation with KOH. The removal of Cu and Pb ions from aqueous solution by the prepared WCAC was investigated in batch experiments. The solution pH significantly influenced Cu and Pb adsorption capacity and the optimum pH was 4 to 6. The adsorption of Cu and Pb ions by WCAC followed pseudo-second-order kinetics and the Langmuir isotherm model. The maximum adsorption capacity calculated by Langmuir isotherm model was 31.91 mg/g for Cu and 92.22 mg/g for Pb. As the temperature was increased from 303 K to 323 K, the ΔG˚ value decreased from –7.01 to –8.57 kJ/mol for Cu ions and from –0.87 to –2.06 kJ/mol for Pb ions. These results indicated that the adsorption of Cu and Pb by WCAC is a spontaneous process.

The adsorption characteristics of Cu ions were studied using the zeolite Na-A synthesized from Jeju volcanic rocks. The effects of various operating parameters such as initial concentration of Cu ions, contact time, solution pH, and solution temperature were investigated in batch experiments. The adsorption of Cu ions by Na-A zeolite was fitted well by pseudo-second-order kinetics and the Langmuir isotherm model. The maximum adsorption capacity determined using the Langmuir isotherm model was 152.95 mg/g. In addition, the adsorption of Cu ions by zeolite Na-A was primarily controlled by particle diffusion model in comparison with the film diffusion model. As the temperature increased from 303 K to 323 K, ΔG˚ decreased from -2.22 kJ/mol to –3.41 kJ/mol, indicating that the adsorption of Cu ions by Na-A zeolite is spontaneous process.

휘발성 유기화합물(VOCs)은 유기용매를 주로 사용하는 산업공정에서 배출되는 일반적인 대기오염물질 중 하나로 그 물질 자체가 독성 및 발암성을 지니기도 하고 오존 생성의 전구체로 작용하기도 하여 인체 건강과 환경에 부정적인 영향을 주고 있다. 또한 최근 초미세먼지 2차생성에 기여하고 있음이 알려짐에 따라 VOCs 저감에 대한 국제적인 관심은 더욱 높아지고 있는 실정이다. 중소규모 사업장에서는 VOCs 처리를 위해 주로 활성탄 흡착탑을 이용하고 있으며 활성탄의 짧은 파과점으로 일정기간 사용 후 교체가 필요하지만, 교체 비용 부담에 따른 적절한 유지관리가 미흡하여 VOCs가 직접 대기로 방출되는 문제가 발생되고 있다. 따라서 본 연구에서는 활성탄 파과 후 현장에서 재생이 가능한 흡탈착 공정에 대하여 연구를 수행하였다. 기존 재생 공정인 열탈착(TSA) 공정은 에너지 비용이 많이 소요되며 수분 또는 고온 가스를 사용해야하므로 재생 시간이 길고 부대시설이 필요한 단점이 있어 현장에서 흡착 후 직접 재생하기에는 다소 무리가 따른다. 저온 감압탈착(VSA) 공정은 상대적으로 저온(80∼90℃)에서 진공펌프를 이용하여 탈착하는 방식으로 감압시에 VOCs가 휘발하는 온도가 낮아지므로 상대적으로 낮은 온도에서 탈착이 가능하다. 이에 따라 현장에서 자체재생 가능한 탈착 방법으로 저온 VSA 기술을 적용하였으며, 30 CMM급 흡탈착 시스템을 제작하여 실제 도장 공장의 배출가스에 대한 현장 적용성 연구를 수행하였다. 또한 저온 VSA 공정을 통해 배출되는 탈착가스는 재생시 캐리어가스 유량이 상대적으로 적어 고농도로 배출되므로 회수하여 유기용매로 재활용할 경우 원료 절감에 따른 경제적 효과가 매우 크다. 따라서 VOCs를 회수하기 위한 방법으로 기액 접촉 효율이 높은 용매 직접접촉식 응축 방식을 적용하였으며, 30 LPM 직접접촉식 회수장치를 제작하고 실 탈착가스를 이용한 회수실험을 수행함으로써 본 기술에 대한 현장 적용 가능성에 대하여 평가해보고자 하였다.