• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.168-171
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• 2003

This research was conducted to assess the performance of the mixed reactive materials with sand, iron filings, and HDTMA-bentonite for trichloroethylene (TCE) and chromate removal under controlled groundwater flow conditions. TCE and chromate removal rates with the mixtures of iron filing/HDTMA-bentonite were highest among four columns due to reduction by iron filings and sorption by HDTMA-bentonite. The greater capacity of the mixed iron filing/HDTMA-bentonite compared HDTMA-bentonite was due to an enhanced chromate reduction in addition to chromate sorption. The presence of chromate caused greater inhibition of TCE removal in the column with iron filings, while the presence of TCE caused less inhibition of TCE. Also, nitrate caused the decrease in TCE removal relative to chloride. Nitrate ions may also significantly affect TCE reduction rates by competing for electrons with the chlorinated compounds. The anion and co-existed contaminants competing effects should be considered when designed permeable reactive barriers (PRBs) composed of zero valent iron for field applications to remediate TCE and chromate.

• Environmental Engineering Research
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• v.25 no.1
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• pp.104-113
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• 2020

Adsorptive breakthrough modelling is essential for design of a sorption packed bed. In this work, breakthrough modelling of the furfural uptake in bagasse fly ash (BFA) packed bed has been performed. Effect of various parameters like bed height (Z = 15-60 cm), flow rate (Q = 0.02-0.04 L/min) and initial furfural concentration (C_o = 50-200 mg/L) on the breakthrough curve of furfural sorption in a BFA packed bed have been studied. Enhanced breakthrough performance was observed for the higher value of Z, and lower values of C_o and Q. For C_o = 100 mg/L, packed bed operated at Q = 0.03 L/min and Z = 60 cm was found to have lowest adsorbent utilization rate of 5.61 g/L with highest breakthrough volume of 14.67 L. Bed depth service time and Thomas models well represented the experimental data points under all experimental conditions. It can be concluded that BFA can be utilized efficiently in continuous system for the removal of furfural. Overall, more than 99% of furfural was adsorbed in BFA packed bed at experimental conditions.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.994-1001
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• 2012

The Effects of operating variables on reactivity of two $CO_2$ absorbents (PKM1-SU and P4-600) for SEWGS process were investigated in a pressurized fluidized bed reactor. For both $CO_2$ absorbents, $CO_2$ sorption capacity decreased as the number of absorption-regeneration cycles increased. PKM1-SU absorbent represented higher $CO_2$ sorption capacity than that of P4-600 absorbent. However, P4-600 absorbent represented better performance than PKM1-SU absorbent from the view points of regeneration temperature and regeneration rate. For PKM1-SU absorbent, $CO_2$ sorption capacity increased as the steam concentration increased. However, $CO_2$ sorption capacity increased initially as the steam concentration increased from 5% to 10%, but maintained thereafter for P4-600 absorbent. For both $CO_2$ absorbents, $CO_2$ sorption capacity increased as the final regeneration temperature increased. For PKM1-SU absorbent, $CO_2$ sorption capacity increased as the pressure increased and the increment tendency was drastic at higher pressure than 15 bar.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.515-532
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• 2023

Bentonite, predominantly consists of expandable clay minerals, is considered to be the suitable buffering material in high-level radioactive waste disposal repository due to its large swelling property and low permeability. Additionally, the bentonite has large cation exchange capacity and specific surface area, and thus, it effectively retards the transport of leaked radionuclides to surrounding environments. This study aims to review the thermodynamic sorption models for four radionuclides (U, Am, Se, and Eu) and eight bentonites. Then, the thermodynamic sorption models and optimized sorption parameters were precisely analyzed by considering the experimental conditions in previous study. Here, the optimized sorption parameters showed that thermodynamic sorption models were related to experimental conditions such as types and concentrations of radionuclides, ionic strength, major competing cation, temperature, solid-to-liquid ratio, carbonate species, and mineralogical properties of bentonite. These results implied that the thermodynamic sorption models suggested by the optimization at specific experimental conditions had large uncertainty for application to various environmental conditions.

• Membrane Journal
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• v.17 no.4
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• pp.294-301
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• 2007

To improve oxidative stability of non-fluorinated styrene-based polymer electrolyte membranes, copolymerized membranes were prepared using styrene derivatives such as p-methylstyrene, t-butylstyrene, and ${\alpha}-methylstyrene$ by monomer sorption method. Prepared membrane was characterized by measurement of weight gain ratio, water content, ion-exchange capacity, proton conductivity, and oxidative stability under the accelerated condition. It was found that each step of monomer sorption method including sorption, polymerization and sulfonation could be affected by the properties and the structures of styrenederivatives. Due to difficulty of polymerization, ${\alpha}$-methylstyrene was copolymerized with styrene or p-methylstyrene. Prepared membrane using ${\alpha}-methylstyrene$ and styrene showed higher performance and stability comparing to copolymerized membrane with styrene. However, copolymerized membranes with ${\alpha}-methylstyrene$ did not showed much improved oxidative stability comparing to styrene membrane due to their lower molecular weight. The t-butylstyrene membrane showed a low performance due to substituted bulky-butyl group which prevents sorption and sulfonation reaction. However, copolymerized t-butylstyrene membranes with p-methylstyrene showed good performance and much improved stability than the styrene membranes.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.1
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• pp.49-57
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• 2013

The present study was conducted to investigate phosphate removal from aqueous solution using industrial wastes, red mud (RM), acid treated red mud (ATRM) and converter furnace steel slag (CFSS). The chemical composition of adsorbents was analyzed using X-ray fluorescence (XRF). Batch experiments and elution experiments using water tank were performed to examine environmental factors that influences on phosphate removal. Kinetic sorption data of RM, ATRM, and CFSS were described well by the pseudo second-order kinetic sorption model, and equilibrium sorption data of all adsorbents obeyed Freundlich isotherm model. The adsorption capacities of adsorbents followed order: ATRM (7.06 mg/g)>RM (4.34 mg/g)>CFSS (1.88 mg/g). Increasing pH from 3 to 11, the amount of adsorbed phosphate on all RM, ATRM, and CFSS were decreased. The presence of sulfate and carbonate decreased the phosphate removal of RM and ATRM but did not influence on the performance of CFSS. The phosphate removal of RM, ATRM, and CFSS was greater in seawater than deionized water, resulting from the presence of cations in seawater. The water tank elution experiments showed that RM capping blocked the elution of phosphate effectively. It was concluded that the adsorbents can be successfully used for the removal of the phosphate from the aqueous solutions.

• Journal of Environmental Science International
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• v.21 no.6
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• pp.705-711
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• 2012

Adsorption experiment of carbon dioxide was performed on MCM41 silica with a 30 wt.% EDA(ethylenediamine) loading at different $CO_2$ inlet concentration and various adsorption temperature. The surface characteristics of $CO_2$ capturing agent were carried out using BET analysis, X-ray diffraction and FT-IR. The results of BET showed 781 $m^2/g$ for MCM41 and 464 $m^2/g$ for EDA/MCM41. X-ray diffraction results reveled typical hexagonal pore system. The higher sorption capacity of EDA/MCM41 was about 80 $mg_{CO2}/g_{sorbent}$ with 50% $CO_2$ inlet concentration and 303 K adsorption temperature. The isosteric heat of adsorption in 303-353 K ranged from -25.47 to -28.24 KJ/mole for EDA/MCM41, which indicates $CO_2$-EDA/MCM41 interaction with exothermic adsorption process. Finally, the performance of EDA/MCM41 in 10 consecutive sorption-desorption runs was a stable with only a minor drop in its sorption capacity.

• Advances in environmental research
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• v.1 no.2
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• pp.167-179
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• 2012

Pistachio shell (Pistacia vera) (PS), a low-cost material, has been utilized for the removal of the Cr(VI) ions after treatment with citric acid. Batch experimental steps were applied to obtain Cr(VI) ion adsorption details for the equilibrium between Cr(VI) and modified pistachio shell (MPS). The influences of contact time, pH, adsorbent dose and initial chromium concentration on the adsorption performance of MPS was investigated in detail. The results displayed that adsorption of Cr(VI) by MPS reached to equilibrium after 2 h and after that a little change of Cr(VI) removal efficiency was observed. The sorption percent is higher at lower pH and lower chromium concentration. Two possible mechanisms for reduction of Cr(VI) to Cr(III) can be suggested in Cr(VI) removal. In the first mechanism, Cr(VI) is reduced to Cr(III) by surface electron-donor groups of the adsorbent and the reduced Cr(III) forms complexes with adsorbent or remains in the solution. This Cr(III) is not adsorbed by adsorbent at pH 1.8. But in second mechanism, the adsorption-coupled reduction of Cr(VI) to Cr(III) occurred on the adsorbent sites. The equilibrium sorption capacity of Cr(VI) ion after 2 h was 64.35 mg/g for MPS.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.441-449
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• 2019

In this study, cellulose acetate (CA) / nylon66 (NYL66) (95/5) blend membranes with different thicknesses were prepared by a solvent evaporation method. The effects of membrane thickness (almost $7-25{\mu}m$), feed concentration (70-95 wt.% isopropanol), and feed temperature ($30-60^{\circ}C$) were investigated on the performance of membrane in the separation of isopropanol-water mixtures. With regard to the results of sorption experiments, it was found that the increase of feed temperature enhanced the overall sorption while by increasing feed concentration, the overall sorption passed through a maximum value at 70 wt. % isopropanol (IPA). The best separation factor 3080.51 was gained at high isopropanol concentration 95 wt.%, low feed temperature $30^{\circ}C$, and high membrane thickness $24.62{\mu}m$. Regarding the pervaporation separation index, the obtained results showed that proper values for the thickness of membrane, feed temperature, and isopropanol concentration in feed were $24.62{\mu}m$, $40^{\circ}C$, and 70 wt.%, respectively.

• Membrane Journal
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• v.10 no.4
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• pp.198-204
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• 2000

Pervaporation membranes were fabricated by low temperature plasma treatment the concentrate butanol solution from fermentation process. Effects of power, reaction time, and monomer flow rate were examined to optimize the (W!FM)t value as 4.0389 x 109 J . min/kg. Various organic compounds were tested in plasma treatment. Contact angle and relative sorption ratio were examined in terms of membrane performance. With the increase of contact angle and relative sorption ratio separation factor was enhanced from 0.186 to 3.525. and butanol flux increased from 0.042 to 0.567 kglm2. hr. Hydrophobicity of the membrane increased the affinity with butanoL Heat of mixing for monomer with butanol was examined, but failed to find the trend, because plasma polymerization of monomer produced the new compounds much different from monomers.