• Membrane and Water Treatment
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• v.5 no.4
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• pp.295-304
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• 2014

Adipic acid (hexane-1,6-dioic acid) is one of the most used chemical in industrial applications. This must be separated from any environmental contaminant. In this study, adipic acid separation from wastewater by adsorption method onto Perlite or Perlite + Mn or Perlite + Cu composites was investigated. Adsorption of Adipic acid was investigated in terms of equilibrium, and thermodynamic conditions. For thermodynamic investigations the experiments carried out at three different temperatures (298 K, 318 K, 328 K). In the equilibrium studies, 2 g of perlite and its composites were determined as the optimal adsorbent amount. Freundlich and Langmuir isotherms were applied to the experimental data. Freundlich isotherms for all temperatures used in this work gave some deviations with R square values under 0.98 where as Langmuir isotherm gave good results with R square values upper 0.99 at different temperatures. As a result of thermodynamic studies, adsorption enthalpy (${\Delta}H$), adsorption entropy (${\Delta}S$), and adsorption free energy (${\Delta}G$) have been calculated for each adsorbents.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.623-631
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• 2012

The adsorption behavior of Eosin Y on activated carbon (AC) in batch system was investigated. The adsorption isotherm could be well fitted by the Langmuir adsorption equation. The kinetics of adsorption followed the pseudo-second-order model. The temperature variation was used to evaluate the values of free energy (${\Delta}G^{\circ}$), enthalpy (${\Delta}H^{\circ}$) and entropy (${\Delta}S^{\circ}$). The positive value of enthalpy change ${\Delta}H^{\circ}$ for the process confirms the endothermic nature of the process and more favourable at higher temperature, the positive entropy of adsorption ${\Delta}S^{\circ}$ reflects the affinity of the AC material toward Eosin Y and the negative free energy values ${\Delta}G^{\circ}$ indicate that the adsorption process is spontaneous. With the increase of the amount of AC, removal efficiency of Eosin Y was increased, but adsorption capacity was decreased. And adsorption capacity was increased with the decrease of particle size. With the increase of the amount of AC, removal efficiency of Eosin Y was increased, but adsorption capacity was decreased. And adsorption capacity was increased with the decrease of particle size.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1087-1094
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• 2008

This article presents a multi-scale simulation approach starting from the molecular level for the adsorption process development, specifically, in n-hexane adsorption on activated carbon. A grand canonical Monte-Carlo(GCMC) method is used for the prediction of adsorption isotherms of n-hexane on activated carbon at the molecular level. Geometric effects and hydrodynamic properties of the adsorption column are examined by means of the two dimensional CFD(computational fluid dynamics) simulation. The adsorption isotherms from the molecular simulation and the axial diffusivity from the CFD simulation are exploited for the process simulation where the elution curve of n-hexane is obtained. For the first moment(mean residence time) of the pulse-response with respect to temperature and flowrate, the process simulation results obtained from this three-steps multiscale simulation approach show a good agreement with experimental data within 20% of maximum difference. The multi-scale simulation approach addressed in this study will be useful to accelerate the adsorption process development, while reducing the number of experiments required.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.113-121
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• 2020

In batch experiments, the adsorption of 7-epi-10-deacetylpaclitaxel was studied using Sylopute. Experimental equilibrium data were applied to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. Among the four isotherm models tested, the Langmuir isotherm model gave the highest accuracy. The adsorption capacity was found to decrease with increases in temperature and the adsorption of 7-epi-10-deacetylpaclitaxel onto Sylopute was a favorable physical process. Adsorption kinetic data agreed very well with the pseudo-second-order kinetic model, while boundary layer diffusion and intraparticle diffusion did not play a key role in the adsorption process. The process of 7-epi-10-deacetylpaclitaxel adsorption onto Sylopute was exothermic and nonspontaneous. Also, the adsorption isosteric heat was independent of surface loading indicating an energetically homogeneous adsorbent.

• Journal of Soil and Groundwater Environment
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• v.19 no.1
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• pp.46-53
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• 2014

The purpose of this study is to promote utilization of paper mill sludge as an adsorbent for stabilizing heavy metals in contaminated water by measuring the adsorption capacity of paper mill sludge for cadmium and arsenic. To measure adsorption capacity of paper mill sludge, sorption isotherm experiments were analyzed by Langmuir and Freundlich isotherm models. Also, two methods of chemical modifications were applied to improve the adsorption capacities of paper-mill-sludge: the first method used sodium hydroxide (NaOH), called PMS-1, and the second method used the NaOH and tartaric acid ($C_4H_6O_6$) together, called PMS-2. For Cd adsorption, PMS-1 presented the increase of reactivity while PMS-2 presented the decline of reactivity compared to that of untreated paper-mill-sludge. In case of As adsorption, both PMS-1 and PMS-2 showed the decrease of adsorption capacities. This is because zeta-potential of paper mill sludge was changed to more negative values during chemical modification process due to the hydroxyl group in NaOH and the carboxyl group in $C_4H_6O_6$, respectively. Therefore, we may conclude that the chemical treatment process increases adsorption capacity of paper mill sludge for cation heavy metals such as Cd but not for As.

• Journal of Environmental Science International
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• v.17 no.1
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• pp.67-75
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• 2008

Adsorption process is largely influenced by pore structures of adsorbents and physical properties of adsorbates and adsorbents. The previous studies of this laboratory was focused on the role of pore structures of adsorbents. And we found some pores of adsorbates which have larger pore diameters than the diameter of adsorbate are filled with easily. In this study the effects of physical and chemical properties of adsorbates and adsorbents, such as pore size distribution, vapor pressure on adsorption were investigated more thoroughly at the concentration of adsorbate of 1000 ppm. The adsorption in the pore ranges of $2{\sim}4$ times of adsorbates's diameter could be explained by space filling concept. But there was some condensation phenomena at larger pore ranges. The errors between the adsorbed amount of non-polar adsorbates and the calculated amounts by considering factors were found to be 44.46%, positively, and -142%, negatively. When vapor pressure is considered, the errors between the adsorbed amount of non-polar adsorbates and the calculated amounts were in the range of $1.69%{\sim}32.25%$ positively, and negatively $-1.08%{\sim}-63.10%$.

• Environmental Engineering Research
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• v.7 no.1
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• pp.33-37
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• 2002

The two kinds of pellet-type red-mud adsorbents (bead-type, crushed-type) were from red mud, which is generated as a by-product during the production of aluminum hydroxide from bauxite ore. The adsorption experiments of Pb^{2+} ion in the aqueous solution by these red-mud adsorbents were studied with a continuous adsorption ccolumn. As a result, the crushed-type adsorbent shows better performance in adsorption of Pb^{2+} than the bead-type adsorbent between the two types of the pellet-type adsorbents. The continusous adsorption experiment shows that the pellet-type adsorbents made from red mud have good performance for removal of Pd^{2+}. The breakthrough curves of the red-mud adsorbents were compared with that of activated carbon.

• Carbon letters
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• v.2 no.1
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• pp.44-54
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• 2001

The characteristics of adsorption and desorption of benzene and toluene were investigated at a fixed bed packed with the activated carbon and activated carbon fiber. Through breakthrough experiments under various feed concentration conditions, it was found that the slope of mass transfer zone and the tailing in the breakthrough curves were different from the feed conditions due to different heats of adsorption. In hot nitrogen desorption, the regeneration time and mass transfer zone of the toluene desorption curve were longer than those of the benzene desorption curve because of the difference in adsorption affinity. With an increase in the regeneration temperature, the height of roll-up and the sharpness of desorption curves increased but the regeneration times decreased. The adsorption capacities of the activated carbon and activated carbon fiber after three-time thermal regenerations decreased about 25% and 37% for benzene and 18% and 25% for toluene, respectively. To investigate the effect of the regeneration temperature on the energetic efficiency, the characteristic desorption temperatures of toluene and benzene were investigated by calculating purge gas consumption and temperature.

• Journal of the Korean Chemical Society
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• v.57 no.1
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• pp.104-108
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• 2013

The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and a mixture of GAC and NaACF (GAC/NaACF) have been studied. The surface properties, such as morphology, surface functional groups, and composition of various adsorbents were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The specific surface area, total pore volume, and pore size distribution were investigated using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, NaACF showed a high adsorption capacity and rate for heavy metal ions due to the improvement of its ion-exchange capabilities by additional oxygen functional groups. Moreover, the GAC and NaACF mixture was used as an adsorbent to determine the adsorbent-adsorbate interaction in the presence of two competitive adsorbents.

• Biomaterials and Biomechanics in Bioengineering
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• v.3 no.1
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• pp.59-69
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• 2016

A surface resisting protein adsorption and cell adhesion is highly desirable for many biomedical applications such as diagnostic devices, biosensors and blood-contacting devices. In this study, a surface conjugated with sulfobetaine molecules was fabricated via the click reaction for the anti-fouling purpose. An alkyne-containing substrate (Alkyne-PPX) was generated by chemical vapor deposition of 4-ethynyl-[2,2]paracyclophane. Azide-ended mono-sulfobetaine molecules were synthesized and then conjugated on Alkyne-PPX via the click reaction. The protein adsorption from 10% serum was reduced by 57%, while the attachment of L929 cells was reduced by 83% onto the sulfobetaine-PPX surface compared to the protein adsorption and cell adhesion on Alkyne-PPX. In conclusion, we demonstrate that conjugation of mono-sulfobetaine molecules via the click chemistry is an effective way for reduction of non-specific protein adsorption and cell attachment.