• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.78-82
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• 2003

Development of hematite-coated sand was evaluated for the application of the PRB (permeable reactive barrier) in the arsenic-contaminated subsurface of the metal mining areas. The removal efficiency of As(III) and As(V), the effect of anion competition and the capability of arsenic removal in the flow system were investigated through the experiments of adsorption isotherm, arsenic removal kinetics against anion competition and column removal. Hematite-coated sand followed a linear adsorption isotherm with high adsorption capacity at low level concentrations of arsenic (< 1.0 mg/l). When As(III) and As(V) underwent adsorption reactions in the presence of anions (sulfate, nitrate and bicarbonate), sulfate caused strong inhibition of arsenic removal, and bicarbonate and nitrate caused weak inhibition due to specific and nonspecific adsorption onto hematite, respectively. In the column experiments, high content of hematite-coated sand enhance the arsenic removal, but the amount of the arsenic removal decreased due to the higher affinity of As(V) than As(III) and reduced adsorption kinetics in the flow system, Therefore, the amount of hematite-coated sand, the adsorption affinity of arsenic species and removal kinetics determined the removal efficiency of arsenic in the flow system. arsenic, hematite-coated sand, permeable reactive barrier, anion competition, adsorption.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.455-460
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• 2008

Powered activated carbon(PAC) has been widely applied for controling odor causing compounds(OCCs) from water treatment plants. Because of their volatility, the OCCs can also be removed from water by air stripping methods. In this study, OCCs removal was tested with PAC adsorption, air stripping, and both PAC adsorption and air stripping from the Taecheong lake water. Removal efficiency of OCCs in terms of threshold odor number(TON) were 39.6% by both PAC (15mg/L) adsorption and aeration for 30 min, 33.6% by PAC(15mg/L) adsorption alone for 30 min, and 22.9% by aeration alone for 30 min, respectively. OCCs could be removed up to 50% by aeration for 120 min without PAC adsorption. At an extended aeration with 15mg/L of PAC, OCCs removal occurred mainly by PAC adsorption within 30 min aeration while it continued by air stripping afterward. At simulated jar tests with the raw water, removal efficiencies of geosmin and MIB were 48.3, 36.1% by coagulation and sedimentation without PAC addition. With 15mg/L of PAC on the same jar tests, the removal efficiencies were 83.1, 60.1%, respectively. Without PAC, OCCs could be possibly removed by stripping during the agitation processes.

• Advances in environmental research
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• v.12 no.2
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• pp.77-93
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• 2023

The water can be contaminated by natural sources or by industrial effluents. One such contaminant is fluoride. Fluoride contamination in the water environment due to natural and artificial activities has been recognized as one of the major problems worldwide. Among the commonly used treatment technologies applied for fluoride removal, the adsorption technique has been explored widely and offers a highly efficient simple and low-cost process for fluoride removal from water. This review paper the recent developments in fluoride removal from surface water by adsorption methods. Studies on fluoride removal from aqueous solutions using various carbon materials are reviewed. Various adsorbents with high fluoride removal capacity have been developed, however, there is still an urgent need to transfer the removal process to an industrial scale. Regeneration studies need to be performed to more extent to recover the adsorbent in field conditions, enhancing the economic feasibility of the process. Based on the review, technical strategies of the adsorption method including the Nano-surface effect, structural memory effect, anti-competitive adsorption and ionic sieve effect can be proposed. The design of adsorbents through these strategies can greatly improve the removal efficiency of fluoride in water and guide the development of new efficient methods for fluoride removal in the future. This paper describes brief discussions on various low-cost adsorbents used for the effective removal of fluoride from water.

• Journal of Environmental Science International
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• v.2 no.4
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• pp.357-365
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• 1993

This study was conducted for the efficient utilization of biomaterials such as starch residue, tangerine skin, and green tea residue, which are agricultral by-products discarded in Cheju Province annually, as adsorbents and biomaterials were examined for their removal ability of heavy metal ions in waste water by batch adsorption experiments. The removal efficiency of biomaterials for heavy metal ions was above 80-90% and almost similar to activated carbon and the adsorption ability of those treated with 포르말린 was improved in the green tea residue only for $Pb^{2+}$, $Cu^{2+}$, and $Zn^{2+}$. In the conditions of pH, the removal efficiency of heavy metal ions was high in the range of 5-7. In the solutions which heavy metal ions were mixed, the removal efficiency was similar at $Ag^+$, $Pb^{+2}$ and reduced to about 10% at the other ions, as compared with the solutions they were not mixed. Adsorption isotherm of biomaterials was generally obeyed to Freundlich formular than Langmuir formular and Freundlich constant, 1/n were obtained in the range of 0.1-0.5.

• Carbon letters
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• v.19
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• pp.12-22
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• 2016

Date palm leaflets were used as a precursor to prepare dehydrated carbon (DC) via phosphoric acid treatment at 150℃. DC, acidified with H₃PO₄, was converted to activated carbon (AC) at 500℃ under a nitrogen atmosphere. DC shows very low surface area (6.1 m²/g) while AC possesses very high surface area (829 m²/g). The removal of lisinopril (LIS) and chlorpheniramine (CP) from an aqueous solution was tested at different pH, contact time, concentration, and temperature on both carbons. The optimal initial pH for LIS removal was 4.0 and 5.0 for DC and AC, respectively. However, for CP, initial pH 9.0 showed maximum adsorption on both carbons. Adsorption kinetics showed faster removal on AC than DC with adsorption data closely following the pseudo second order kinetic model. Adsorption increases with temperature (25℃–45℃) and activation energy (E_a) is in a range of 19–25 kJ mol/L. Equilibrium studies show higher adsorption on AC than DC. Thermodynamic parameters show that drug removal is endothermic and spontaneous with physical adsorption dominating the adsorption process. Column adsorption data show good fitting to the Thomas model. Despite its very low surface area, DC shows ~70% of AC drug adsorption capacity in addition of being inexpensive and easily prepared.

• Journal of Korea Soil Environment Society
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• v.4 no.3
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• pp.17-24
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• 1999

The effects of hydrophobic chain length and its structure of nonionic surfactants on surfactant adsorption and contaminated diesel removal were studied in kaolin soil. Hydrocarbon chain length and double bond in hydrophobic tail group of nonionic surfactants affected surfactant adsorption and diesel removal efficiency from kaolin soil. The degrees of surfactant adsorption and diesel removal were closely related each other. Among nonionic surfactants we studied, surfactants with shorter hydrophobic chain length and higher HLB value showed lower degree of adsorption and higher efficiency of diesel removal. The existence of unsaturated carbons in the structure of hydrophobic chain enhanced diesel removal by reducing surfactant adsorption to kaolin soil. The best diesel removal was obtained after adsorption saturation was reached. If surfactant concentration was higher than a critical value, diesel removal was reduced probably because of precipitation. liquid crystal formation, or coacervation of surfactants at high concentration.

• Membrane and Water Treatment
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• v.8 no.3
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• pp.259-277
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• 2017

Adsorption is a widely used technique for the removal of dyes from wastewaters by variety of adsorbents. In this work, the main focus is on the potential assessment of anion exchange membrane for the removal of different dyes using batch system and investigation of experimental data by applying various kinetic and thermodynamic models. The removal of anionic dyes i.e., Eosin-B, Eriochrome Black-T and Congo Red by anion exchange membrane BII from aqueous solution was carried out and effect of various parameters such as contact time, membrane dosage, temperature and ionic strength on the percentage removal of anionic dyes was studied. The experimental data was assessed by kinetic models namely pseudo-first-order, pseudo-second-order, Elovich liquid film diffusion, Bangham and the modified Freundlich models equation have been used to analyze the experimental data. These results indicate that the adsorption of these anionic dyes on BII follows pseudo-second-order kinetics with maximum values of regression coefficient (0.992-0.998) for all the systems. The adsorption of dyes was more suitable to be controlled by a liquid film diffusion mechanism. The adsorptive removal of dye Eosin-B and Eriochrome Black-T were decreased with temperature and thermodynamic parameters such as free energy (${\Delta}G^o$), enthalpy (${\Delta}H^o$) and entropy (${\Delta}S^o$) for adsorption of dyes on membrane BII were calculated at 298 K, 308 K and 318 K. The values of enthalpy and entropy were negative for EB and EBT representing that the adsorption of these dyes on BII is physiosorptive and exothermic in nature. Whereas the positive values of enthalpy and entropy for CR adsorption on BII, indicating that its adsorption is endothermic and spontaneous in nature. It is evident from this study that anion exchange membrane has shown good potential for the removal of dyes from aqueous solution and it can be used as adsorbent for dues removal on commercial levels.

• Environmental Engineering Research
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• v.18 no.3
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• pp.163-168
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• 2013

In this study, an innovative media, iron mixed ceramic pellet (IMCP) has been developed for arsenic (As) removal from groundwater. A porous, solid-phase IMCP (2-3 mm) was manufactured by combining clay soil, rice bran, and Fe(0) powder at $600^{\circ}C$. Both the As(III) and As(V) adsorption characteristics of IMCP were studied in several batch experiments. Structural analysis of the IMCP was conducted using X-ray absorption fine structure (XAFS) analysis to understand the mechanism of As removal. The adsorption of As was found to be dependent on pH, and exhibited strong adsorption of both As(III) and As(V) at pH 5-7. The adsorption process was described to follow a pseudo-second-order reaction, and the adsorption rate of As(V) was greater than that of As(III). The adsorption data were fit well with both Freundlich and Langmuir isotherm models. The maximum adsorption capacities of As(III) and As(V) from the Langmuir isotherm were found to be 4.0 and 4.5 mg/g, respectively. Phosphorus in the water had an adverse effect on both As(III) and As(V) adsorption. Scanning electron microscopy results revealed that iron(III) oxides/hydroxides are aggregated on the surface of IMCP. XAFS analysis showed a partial oxidation of As(III) and adsorption of As(V) onto the iron oxide in the IMCP.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2198-2206
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• 2018

We addressed the development of a novel, low-cost, and high-efficient material from hybrid materials, known as microcapsules. Microcapsules are a composite adsorbent made of a mixture of tannin, sericite and chitosan. The FT-IR analysis showed that the microcapsules contain hydroxyl, carboxyl, carbonyl, and amino groups, which play an important role in the adsorption of heavy metals. The microcapsules were able to remove 99% of Pb(II) in 30 min, and obtained a removal efficiency of more than (13-50)%, compared with the single adsorbents of tannin, chitosan, and sericite. In adsorption kinetic analysis, pseudo-second-order adsorption was more suitable than pseudo-first-order adsorption, and chemical adsorption did not limit the adsorption rate of Pb(II) ion. In isothermal adsorption, Langmuir adsorption was more suitable than Freundlich adsorption, and the maximum Langmuir adsorption capacity was 167.82 (mg/g). Furthermore, desorption and reusability studies, as well as the applicability of the material for wastewater treatment, demonstrated that microcapsules offer a promising hybrid material for the efficient removal of significant water pollutants, i.e., Pb(II) from aqueous solutions.

• Journal of Hydrogen and New Energy
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• v.35 no.2
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• pp.115-120
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• 2024

In this study, the extent of water removal in the high-moisture coal was measured. The simplified adsorption model was developed to predict the extent of water removal. The water removal was observed to increase up to 25% at saturation condition of 25℃. The modeling work shows that adsorption contributes the water removal only by 3%, whereas other factors such as CO₂ solubility and wettability would be responsible for the water removal.