• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1447-1450
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• 1999

Countercurrent oxygen reaction (COR) was developed and evaluated for regeneration of exhausted activated carbon. Whether the regeneration technique is feasible or not is affected strongly by gradual loss and physical changes of activated carbon, energy consumption, and effective removal of adsorbed materials during the process. Various parameters such as reaction temperature, the loss of activated carbon, surface area, pore volume, surface structure, adsorptive property, etc. were examined to determine the effectiveness of COR. The results of these tests showed that the parameters were strongly dependent on oxidant flow rate, and suggest that the newly developed COR is comparable and, in some ways, possibly superior to conventional regeneration techniques because the overall process runs in a single step and is less energy intensive, and also because the adsorptive capacity of exhausted activated carbon was completely recovered.

• Membrane Journal
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• v.32 no.5
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• pp.348-356
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• 2022

With the development of the bio industry, membrane chromatography with a high adsorption efficiency is emerging to replace the existing column chromatography used in the downstream processes of pharmaceuticals, food, etc. In this study, through the deacetylation reaction of two commercial cellulose acetate (CA) membranes with different pore sizes, the porous regenerated cellulose (RC) supports for membrane chromatography were obtained to attach the anion exchange ligands. The adsorptive membranes for anion exchange were prepared by attaching an anion exchange ligand ([3-(methacryloylamino) propyl] trimethylammonium chloride) containing quaternary ammonium groups on the RC supports by grafting and UV polymerization. The protein adsorption capacities of the prepared membranes were obtained through both the static binding capacity (SBC) and the dynamic adsorption capacity (DBC) measurement. As a result, the membrane chromatography with the smaller the pore size, the larger the surface area showed the highest protein adsorption capacity. Membrane chromatography which was prepared by using deacetylated commercial CA support with MAPTAC ligand (i.e., RC 0.8 + MAPTAC: 43.69 mg/ml, RC 3.0 + MAPTAC: 36.33 mg/ml) showed a higher adsorption capacity compared to commercial membrane chromatography (28.38 mg/ml).

• Membrane and Water Treatment
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• v.13 no.5
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• pp.227-233
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• 2022

The objective of the study, to develop adsorbent based purifier for removal of radiological and nuclear contaminants from contaminated water. In this regard, 3-aminopropyl silica functionalized with ethylenediamine tetraacetic acid (APS-EDTA) adsorbent prepared and characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Prepared APS-EDTA used for adsorptive studies of Cs(I), Co(II), Sr(II), Ni(II) and Cd(II) from contaminated water. The effect on adsorption of various parameters viz. contact time, initial concentration of metal ions and pH were also analyzed. The batch method has been employed using metal ions in solution from 1000-10000 ㎍/L, contact time 5-60 min., pH 4-10 and material quantities 50-200 mg at room temperature. The obtained adsorption data were used for drawing Freundlich and Langmuir isotherms model and both models were found suitable for explaining the metal ions adsorption on APS-EDTA. The adsorption data were followed pseudo second order reaction kinetics. The maximum adsorption capacity obtained 1.3037-1.4974 mg/g for above said metal ions. The results show that APS-EDTA have great potential to remove Cd(II), Co(II), Cs(I), Ni(II) and Sr(II) from aqueous solutions through chemisorption and physio-sorption.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.133-144
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• 2022

Fast-paced industrial and agricultural development generates large quantities of hazardous heavy metals (HMs), which are extremely damaging to individuals and the environment. Research in both academia and industry has been spurred by the need for HMs to be removed from water bodies. Advanced materials are being developed to replace existing water purification technologies or to introduce cutting-edge solutions that solve challenges such as cost efficacy, easy production, diverse metal removal, and regenerability. Water treatment industries are increasingly interested in activated carbon because of its high adsorption capacity for HMs adsorption. Furthermore, because of its huge surface area, abundant functional groups on surface, and optimal pore diameter, the modified activated carbon has the potential to be used as an efficient adsorbent. Metal-organic frameworks (MOFs), a novel organic-inorganic hybrid porous materials, sparked an interest in the elimination of HMs via adsorption. This is due to the their highly porous nature, large surface area, abundance of exposed adsorptive sites, and post-synthetic modification (PSM) ability. This review introduces PSM methods for MOFs, chemical modification of activated carbons (ACs), and current advancements in the elimination of Pb²⁺, Hg²⁺, and Cd²⁺ ions from water using modified MOFs and ACs via adsorption.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.943-962
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• 2014

Industrial gas drying, dilute gas mixtures purification, air fractionation, hydrogen production from steam reformers and petroleum refinery off-gases, etc are conducted by using adsorptive separation technology. The pressure swing adsorption (PSA) has certain advantages over the other methods, such as absorption and membrane, that are a low energy requirement and cost-effectiveness. A key component of PSA systems is adsorbents that should be highly selective to a gas being separated from its mixture streams and have isotherms suitable for the operation principle. The six standard types of isotherms have been examined in this review, and among them the best behavior in the adsorption of $CO_2$ as a function of pressure was proposed in aspects of maximizing a working capacity upon excursion between adsorption and desorption cycles. Zeolites and molecular sieves are historically typical adsorbents for such PSA applications in gas and related industries, and their physicochemical features, e.g., framework, channel structure, pore size, Si-to-Al ratio (SAR), and specific surface area, are strongly associated with the extent of $CO_2$ adsorption at given conditions and those points have been extensively described with literature data. A great body of data of $CO_2$ adsorption on the nanoporous zeolitic materials have been collected according to pressure ranges adsorbed, and these isotherms have been discussed to get an insight into a better $CO_2$ adsorbent for PSA processes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.1
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• pp.63-68
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• 1982

This study was aimed ultimately to develop an adsorption process treating heavy metal industrial wastewater by utilizing domestically abundant natural zeolite and the study was conducted in a series of investigations. Presented if1 this paper are the results of the preliminary batch mode test. Factors affecting an adsorption process of heavy metals of aqueous waste stream by zeolite are numerous. Factors such as hydrogen ion concentration and temperature are taken into consideration in the investigation to evaluate adsorptive capacity. The mechanisms of adsorption may better be described by an evaluation of adsorption isotherm andi of adsorption kinetics. It is observed from the preliminary investigation that an optimum adsorption occurs at higher pH's than 4. It is further demonstrated that $Cd^{+2}$ adsorption by zeolite follows the BET model better than the Freundlich and the Langmuir model and that the reaction time of at least 10 minutes is required. It is interesting to note that higher adsorptive capacity was found at higher temperature, suggesting that the adsorption is not only due to simple physisorption but also due to chemisorption.

• Clean Technology
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• v.15 no.1
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• pp.60-66
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• 2009

Adsorptive removal of tetrahydrothiophene (THT) and tert-butylmercaptan (TBM) that were widely used sulfur odorants in pipeline natural gas was studied using various ion-exchanged NaY zeolites at ambient temperature and atmospheric pressure. In order to improve the adsorption ability, ion exchange was performed on NaY zeolites with alkali metal cations of $Li^+,\;Na^+,\;K^+$ and transition metal cations of $Cu^{2+},\;Ni^{2+},\;Co^{2+},\;Ag^+$. Among the adsorbents tested, Cu-NaY and Ag-NaY showed good adsorption capacities for THT and TBM. These good behaviors of removal of sulfur compound for Cu-NaY and Ag-NaY zeolites probably was influenced by their acidity. The adsorption capacity for THT and TBM on the best adsorbent Cu-NaY-0.5, which was ion exchanged with 0.5 M copper nitrate solution, was 1.85 and 0.78 mmol-S/g at breakthrough, respectively. It was the best sulfur capacity so far in removing organic sulfur compounds from fuel gas by adsorption on zeolites. While the desorption activation energy of TBM on the Cu-NaY-0.5 was higher than NaY zeolite, the difference of THT desorption activation energy between two zeolites was comparatively small.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.534-539
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• 2010

The adsorptive removal of organic sulfur compounds including tert-butylmercaptane(TBM), tetrahydrothiophene(THT) and dimethylsulfide(DMS) in methane was investigated over NaY and copper-exchanged NaY(CuNaY) zeolites at 303 K and atmospheric pressure. In the ternary adsorption system, the preferential adsorption of THT over other sulfur compounds on NaY and the concurrent adsorption of all sulfur compounds on CuNaY were achieved, which could be explained by the breakthrough curve, the temperature-programmed desorption, and the apparent activation energy for desorption. The sulfur uptake capacity of CuNaY(2.90~3.20 mmol/g) was much higher than that of NaY(0.70~0.90 mmol/g). A comparative study indicated that the $Cu^{1+}$ sites and acidity of CuNaY were probably responsible for the strong interaction with sulfur atom and high sulfur uptake abilities.

• Membrane and Water Treatment
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• v.7 no.3
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• pp.209-221
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• 2016

As a highly hydrophilic fibrillar mineral in nature, attapulgite (ATP) is a promising new additive for preparation of ultrafiltration (UF) hybrid membrane. In this work, ATP particles, which were grafted with a new Gemini surfactant of Ethyl Stearate-di(octadecyl dimethyl ammonium chloride) to detach the crystal bundles to single crystal and enhance the uniform dispersion in an organic polymer matrix, were incorporated into poly(vinylidene fluoride) (PVDF) matrix, and PVDF/Gemini-ATP hybrid membranes for adsorptive removal of Ni(II) ions from aqueous solution were prepared via a phase inversion method. Chemical composition, crystalization and morphology of the modified ATP were characterized by Fourier transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and X-ray diffraction (XRD), respectively. The morphology of the hybrid membrane was characterized by Scanning electron microscopy (SEM), the performance of permeability, hydrophilicity and adsorption of Ni(II) ions were studied, and the adsorption kinetics of the PVDF/ATP hybrid membranes were particular concerned. The results showed that the hybrid membrane displayed a good thermal stability and hydrophilicity. Comparing with PVDF membrane, the hybrid membrane possessed good adsorption capacity for Ni(II) ions, and the adsorption kinetics fit well with Lagergren second-order equation.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.588-594
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• 2005

We have investigated Y zeolite and activated carbon for an adsorptive desulfurization of diesel. In batch experiments, cation ($Cu^{2+}$, $Ni^{2+}$) exchanged Y zeolites showed high equilibrium adsorption capacity for sulfur compounds in model diesel, which contained BT, DBT and 4,6-DMDBT of each 50 ppmw in n-octane. But the cation exchanged Y zeolites lost its capacity in commercial diesel (186 ppmw). On the other hand, activated carbon showed reasonable adsorption capacity for sulfur compounds in both model and commercial diesel. The adsorption capacity of sulfur on Ni-Y zeolite was decreased with the increase of benzene concentration in model diesel but the sorption capacity on activated carbon was insensitive to aromatic concentration. In breakthrough test, activated carbon of 1 g could treat 15 ml of commercial diesel with 186 ppmw sulfur. Toluene showed good solvent for regenerating activated carbon among several solvents.