• Clean Technology
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• v.25 no.1
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• pp.56-62
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• 2019

The equilibrium, kinetic and thermodynamic parameters of adsorption of murexide by granular activated carbon were investigated. The experiment was carried out by batch experiment with the variables of the amount of the adsorbent, the initial concentration of the dye, the contact time and the temperature. The isothermal adsorption equilibrium was best applied to the Freundlich equation in the range of 293 ~ 313 K. From the separation factor (${\beta}$) of Freundlich equation, it was found that adsorption of murexide by granular activated carbon could be the appropriate treatment method. The adsorption energy (E) obtained from the Dubinin- Radushkevich equation shows that the adsorption process is a physical adsorption process. From the kinetic analysis of the adsorption process, pseudo second order model is more consistent than pseudo first order model. It was found that the adsorption process proceeded to a spontaneous process and an endothermic process through Gibbs free energy change ($-0.1096{\sim}-10.5348kJ\;mol^{-1}$) and enthalpy change ($+151.29kJ\;mol^{-1}$). In addition, since the Gibbs free energy change decreased with increasing temperature, adsorption reaction of murexide by granular activated carbon increased spontaneously with increasing temperature. The entropy change ($147.62J\;mol^{-1}\;K^{-1}$) represented the increasing of randomness at the solid-solution interface during the adsorption reaction of murexide by activated carbon.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.667-675
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• 2020

An Alum-sludge based adsorbent (ASBA) was synthesized by the hydrothermal treatment of alum sludge obtained from settling basin in water treatment plant. ASBA was applied to remove fluoride and arsenic in artificially-contaminated aqueous solutions and mine drainage. The mineralogical crystal structure, composition, and specific surface area of ASBA were identified. The result revealed that ASBA has irregular pores and a specific surface area of 87.25 ㎡ g-1 on its surface, which is advantageous for quick and facile adsorption. The main mineral components of the adsorbent were found to be quartz(SiO2), montmorillonite((Al,Mg)2Si4O10(OH)2·4H2O) and albite(NaAlSi3O8). The effects of pH, reaction time, initial concentration, and temperature on removal of fluoride and arsenic were examined. The results of the experiments showed that, the adsorbed amount of fluoride and arsenic gradually decreased with increasing pH. Based on the results of kinetic and isotherm experiments, the maximum adsorption capacity of fluoride and arsenic were 7.6 and 5.6 mg g-1, respectively. Developed models of fluoride and arsenic were suitable for the Langmuir and Freundlich models. Moreover, As for fluoride and arsenic, the increase rate of adsorption concentration decreased after 8 and 12 hr, respectively, after the start of the reaction. Also, the thermodynamic data showed that the amount of fluoride and arsenic adsorbed onto ASBA increased with increasing temperature from 25℃ to 35℃, indicating that the adsorption was endothermic and non-spontaneous reaction. As a result of regeneration experiments, ASBA can be regenerated by 1N of NaOH. In the actual mine drainage experiment, it was found that it has relatively high removal rates of 77% and 69%. The experimental results show ASBA is effective as an adsorbent for removal fluoride and arsenic from mine drainage, which has a small flow rate and acid/neutral pH environment.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.783-791
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• 2008

The dynamic characteristics of adsorption using an adsorption bed packed with Li-X zeolite (UOP) were studied through the breakthrough experiments of $H_2/CH_4$ (90:10 vol%), $H_2/CO$ (90:10 vol%) and $H_2/CO_2$ (80:20 vol%) mixtures. Effects of feed flow rate (6.24~10.24 LPM) and adsorption pressure (6.1 bar~10.1 bar) in the Li-X zeolite bed with 2.7 cm of inside diameter and 80 cm of bed length were observed. The smaller feed rate or the higher operating pressure, resulted in the longer of the breakthrough time and the breakthrough curve have tailing due to temperature variance in the bed. The adsorption dynamics of the Li-X zeolite bed were predicted by using LDF model with feed flow and pressure dependent diffusivity. The prediction and experimental data were analyzed with a nonisothermal, nonadiabatic model, dual-site langmuir (DSL) isotherm

• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.35-40
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• 2012

In this study, adsorption characteristics of expanded graphite (EG) were investigated by a series of batch adsorption tests using p-Xylene as a model volatile organic compounds (VOCs). After acid treatment, graphite were expanded at various temperature from $600^{\circ}C$ to $1000^{\circ}C$ for one minute. The optimal temperature was $800^{\circ}C$, where the expansion ratio reached 195 times of original volume. The BET specific surface area of EG was $92.4m^2/g$, which was only 1/10 of granular activated carbon (GAC), however the adsorption of p-Xylene by EG was almost completed within 5 minutes while that of GAC continued for 7 days because the majority of pores of EG was consisted with meso- and macro-pores. According to the Langmuir isotherm analysis, the maximum specific adsorption of p-Xylene onto EG was 24.0 mg/L with the adsorption constant of 7.94. In conclusion, the adsorption capacity of EG was much less than that of GAC due to the significantly lower specific surface area, but the first order kinetic constant was more than 500 times larger than GAC. Overall, EG might be effective where the fast adsorption is required.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2029-2035
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• 2014

In this study, we conducted the adsorption equilibrium and batch experiments of dissolved organic carbon (DOC) in the wastewater by granular activated carbon (GAC). The components of organic compound were Beef extract (1.8 mg/L), Peptone (2.7 mg/L), Humic acid (4.2 mg/L), Tannic acid (4.2 mg/L), Sodium lignin sulfonate (2.4 mg/L), Sodium lauryle sulfate (0.94 mg/L), Arabic gum powder (4.7 mg/L), Arabic acid (polysaccharide) (5.0 mg/L), $(NH_4)_2SO_4$ (7.1 mg/L), $K_2HPO_4$ (7.0 mg/L), $NH_4HCO_3$ (19.8 mg/L), $MgSO_4{\cdot}7H_2O$ (0.71 mg/L), The adsorption characteristics of DOC in synthetic wastewater was described using the mathematical model through a series of isotherm and batch experiments. It showed that there was linear adsorption region in the low DOC concentration (0~2.5 mg/L) and favorable adsorption region in high concentration (2.5~6 mg/L). The synthetic wastewater used was prepared using known quantities of organic and/or inorganic compounds. Adsorption modelling isotherms were predicted by the Freundlich, Langmuir, Sips and hybrid isotherm equations. Especially, hybrid isotherm of Linear and Sips equation was a good adsorption equilibrium in the region of the both the low concentration and high concentration. In applying carbon adsorption for treating water and wastewater, hybrid adsorption equation plus linear equation with Sips equation will be a good new adsorption equilibrium model. Linear driving force approximation (LDFA) kinetic equation with Hybrid (linear+Sips) adsorption isotherm model was successfully applied to predict the adsorption kinetics data in various GAC adsorbent amounts.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.543-550
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• 2016

Amine-type PP-g-VBC-EDA adsorbent, which possesses anionic exchangeable function, was prepared through photoinduced graft polymerization of vinylbenzyl chloride (VBC) onto polypropylene non-woven fabric and subsequent amination reaction using ethylenediamine (EDA). Adsorption characteristics of anionic nutrients on the PP-g-VBC-EDA adsorbent have been studied by batch adsorption experiments. The equilibrium data well fitted the Langmuir isotherm model, and the maximum monolayer sorption capacity was found to be 59.9 mg/g for $NO_3-N$ and 111.4 mg/g for $PO_4-P$. The adsorption energies were higher than 8 kJ/mol indicating anion-exchange process as the primary adsorption mechanism. The pseudo-second order kinetic model described well the kinetic data and resulted in the activation energy of 9.8-36.7 kJ/mol suggesting that the overall rates of $NO_3-N$ and $PO_4-P$ adsorption are controlled by the chemical process. Thermodynamic parameters such as ${\Delta}G^o$, ${\Delta}H^o$ and ${\Delta}S^o$ indicated that the adsorption nature of PP-g-VBC-EDA for anionic nutrients is spontaneous and exothermic. The PP-g-VBC-EDA could be regenerated by washing with 0.1 N HCl.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1319-1330
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• 2000

Activated carbons prepared by chemical activation of organic waste sludges with $ZnCl_2$ and $K_2S$ have been studied in terms of their pore development and adsorptivity. Pore development of the carbons prepared from organic waste sludges was characterized by the nitrogen adsorption at 77K. The $ZnCl_2$-activated carbon produced by chemical activation with zinc chloride exhibited type I isotherm characteristics according to the BDDT classification, suggesting the presence of micropores formed by activation process. The isotherms of the commercial powdered activated carbon and $K_2S$-activated carbon reveal a hysteresis similar to that of type IV in BDDT classification, indicating the formation of mesopores. This result implies that the major pores of $K_2S$-activated carbon are composed of meso and micropores, and a macropores are minor. The adsorptive capacities of metal on the $K_2S$-activated carbon prepared from organic waste sludges were found to be superior to those on a commercial granular activated carbon. The Langmuir and Freundlich isotherms yield a fairly good fit to the adsorption data, indicating a monolayer adsorption of metals onto $K_2S$-activated carbon. The adsorptive capacity of the $K_2S$-activated carbon was superior to $ZnCl_2$-activated carbon for $PO_4$-P, and vice versa for $NO_3$-N. From the results of the studies reported here, it can be concluded that activated carbons with adsorptivity superior to commercial granular activated carbons can be produced from organic waste sludge using a two-step carbonization/activation procedure with zinc chloride or potassium sulfide as the activating agents.

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.356-361
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• 2018

It is common to analyze volatile organic compound (VOC) or semi-VOC (SVOC) in a sample composed of a complex matrix consisting of multiple components such as bloods through a separation process. Adsorption is a physical phenomenon in which certain components accumulate on the surface of other phases. In order to overcome difficulties in the pretreatment process, an adsorption is frequently used. Solid phase microextraction (SPME) equipment with porous carbon carboxen (CAR) is an example of adsorption application. In this study, the adsorption of 4-octylphenol to carboxen was examined. To do so, the extraction efficiency for such solvents as dichloromethane ($CH_2Cl_2$, DCM), ethylacetate ($CH_3COOC_2H_5$, EA) and diethylether ($C_2H_5OC_2H_5$, $Et_2O$) was studied and also the derivatization reaction for 4-octylphenol with reagents of bistrimethylsilyltrifluoroacetamide (BSTFA), methylchloroformate (MCF) and pentafluorobenzylbromide (PFBBr) was compared. The combination of DCM and BSTFA showed good performance thus they were adopted for this study. Thermodynamic adsorption experiments showed that the adsorption process was endothermic and Freundlich isotherm equation was more suitable than Langmuir isotherm. It was also found that the adsorption followed a pseudo-$2^{nd}$ order kinetic model.

• Journal of Adhesion and Interface
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• v.25 no.1
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• pp.157-161
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• 2024

Amphiphilic gold nanoparticles, synthesized by the simultaneous binding of hydrophilic and hydrophobic ligands on their surfaces, find diverse applications in energy, bio, optical, electronic technologies, and various other fields. Particularly, these amphiphilic gold nanoparticles possess both hydrophilic and hydrophobic characteristics, enabling them to activate interface at the interface of immiscible fluids and form organized structures. The surface properties of gold nanoparticles play a crucial role in influencing the behaviors of amphiphilic gold nanoparticles at the interface of two fluids. Therefore, this study investigated the adsorption behaviors of gold nanoparticles at the organic solvent-water interface based on the surface characteristics of amphiphilic gold nanoparticles and the type of organic solvents. It was observed that the amount of adsorbed gold nanoparticles at the interface increased with the length of hydrocarbon chains in hydrophobic ligands and increased with shorter hydrocarbon chains in the organic solvent. Furthermore, using the Langmuir isotherm model, the study confirmed the formation of a monolayer by amphiphilic gold nanoparticles and obtained significant thermodynamic parameters simultaneously.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.179-185
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• 2009

In this research, the removal capacity of Cr(VI) by the reused powdered wastes (RPW) containing aluminium oxides was studied. As a pre-treatment process for the preparation of calcined wastes, calcination was conducted at $550^{\circ}C$ to remove organic fraction in the raw wastes. In order to study the adsorption trend of Cr(VI) ions from aqueous solutions, the pH-edge adsorption, adsorption kinetic and adsorption isotherm were investigated using a batch reactor in the presence of four different background electrolytes($NO_3\;^-,\;CO_3\;^{2-},\;SO_4\;^{2-},\;PO_4\;^{3-}$). Cr(VI) adsorption was greatly reduced in the presence of $SO_4\;^{2-}$ and $PO_4\;^{3-}$ over the entire pH range. Meanwhile the inhibition effect by $NO_3\;^-$ and $CO_3\;^{2-}$ was relatively lower than that by $SO_4\;^{2-}$ and $PO_4\;^{3-}$. Cr(VI) adsorption was maximum around pH 4.5 in the presence of $NO_3\;^-$ and $CO_3\;^{2-}$. As the concentration of background electrolytes increased, Cr(VI) adsorption decreased. This result mightly suggests that adsorption between the surface of RPW and Cr(VI) occurs through outer-sphere complex. Cr(VI) adsorption onto the RPW was well described by second-order kinetics. From the Langmuir isotherm at initial pH 3, the maximum adsorbed amount of Cr(VI) onto the RPW was 11.1, 10, 3.3, 5 mg/g in the presence of $NO_3\;^-,\;CO_3\;^{2-},\;SO_4\;^{2-}$, and $PO_4\;^{3-}$, respectively.