• Economic and Environmental Geology
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• v.36 no.5
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• pp.381-385
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• 2003

We investigated possible application of waste ferrite in treating Cd and Pb in wastewater. Adsorption of Cd and Pb on Mn-Ferrite are influenced by several controlling factors such as contact time, heavy metal concentrations, pH and temperature. Both Cd and Pb achieved adsorption equilibrium within 5 minutes. Based upon this kinetic data, 24 hours of contact time was allowed for other experiment. The adsorption of Cd and Pb was high at high pH and high ion concentrations. The reaction was also affected by temperature. Adsorption isotherms fits well with the Freundlich isotherm equation. pH is the main controlling factor in Cd, Pb adsorption on the Mn-ferrite. Cd showed S type adsorption curve while Pb showed sorption edges, depending on the Pb concentrations.

• Polymer(Korea)
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• v.26 no.5
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• pp.661-669
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• 2002

The purpose of this research is to absorb and remove sulfur dioxide existing in the air by using ion exchange non-woven fabric. So we found out very appropriate condition of anionic exchange fabric scrubber by measuring amount of SO$_2$ adsorption under the atmosphere that concentration, velocity, and humidity was 100∼200 ppm, 0.6∼1.0 m/sec, and 30∼90 RH%, respectively. Ion exchange capacity of ion exchanger showed the maximum value, 3.75 meq/g at pH 4, and adsorption equilibrium time was the maximum value, 30 h when gas velocity was 0.6 m/sec, moreover, at 80$\^{C}$, adsorption equilibrium time tended to decrease more than 10 h. When concentration was 200 ppm, while reaction speed between SO$_2$ and ligand of fibrous ion exchanger was getting faster, adsorption break point had a tendency to get faster as well. In addition, when relative humidity in the scrubber was 90%, adsorption efficiency was 7.6%/h that seemed to be 30% higher than 4.6%/h coming from the condition that relative humidity had been 30%, and it was totally absorbed under 5 wt% NaOH solution in 5 minutes.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.697-702
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• 2011

Ion exchange resins have been synthesized from chloromethylated styrene-1,4-divinylbenzene (DVB) with 1%, 2%, 5% and 15%-crosslinkage and macrocyclic ligand of $OenNdien-H_4$ by copolymerization. The adsorption characteristics of uranium (${UO_2}^{2+}$), potassium ($K^+$) and neodymium ($Nd^{3+}$) metallic ions have been investigated. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, and crosslinkage on adsorption of metallic ions were also studied. The uranium ion showed the fast adsorption on the resins above pH 3. The optimum equilibrium time for the adsorption of metallic ions was about two hours. The adsorption selectivity determined in methanol solution was in increasing order uranium (${UO_2}^{2+}$) > potassium ($K^+$) > neodymium ($Nd^{3+}$) ion. Moreover, the adsorption was increased with the crosslinkage concentration in order of 1%, 2%, 5% and 15%-crosslinkage resin.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.838-846
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• 2016

Most of combustion processess used in industries require recovering or removing flue gas components. Recently a new MBA (moving bed adsorption) process for recovering $CO_2$ using zeolite 13X was developed. In this study, adsorption experiments for carbon dioxide, nitrogen, sulfur dioxide, and water vapor on zeolite 13X were carried out. Adsorption equilibrium and adsorption rate into solid particle were investigated. Langmuir, Toth, and Freundlich isotherm parameters were calculated from the experiment data at various temperatures. Experimental results were consistent with the theoretically predicted values. Also $CO_2$ adsorption amount was measured under the conditions with impurities such as $SO_2$ and $H_2O$. Binary adsorption data were well fitted to the extended Langmuir isotherm using parameters obtained from pure component experiment. However, $H_2O$ impurity less than, roughly, ${\sim}10^{-5}H_2O\;mol/g$ zeolite 13X enhanced slightly $CO_2$ adsorption. Spherical particle diffusion model well described experimentally measured adsorption rate. Diffusion coefficients and activation energies of $CO_2$, $SO_2$, $N_2$, $H_2O$ were obtained. Diffusion coefficients of $CO_2$ and $SO_2$ decreased with small amount of preadsorbed impurity. Parameter values from this study will be helpful to design of real commercial adsorption process.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.4
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• pp.197-200
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• 1974

PCP adsorption experiment was carried out with six soils various in clay mineral and organic matter content and soil pH. The results were as follows; 1. The major factor governing the PCP adsorption is pH 2. The adsorption was increased with organic matter content at a certain pH 3. The adsorption was less related to crystalline clay mineral species.

• Journal of Sericultural and Entomological Science
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• v.38 no.1
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• pp.25-30
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• 1996

The adsorption mechanism of Chromium(VI) uptake in silk fibroin fibers was discussed. The adsorption equilbrium of Chromium(VI) is significantly influenced by the initial adsorption rate and it showed 52% of the equilibrium uptake. The Chromium(VI) uptake by silk fibroin in increased with the acidic range of pH, which react upon Chromium(VI) oxidations. The enthalpy change in the Chromium(VI) on the temperatures, $\Delta$H, was found to be 39.7 KJ.mol-1, It means that the Chromium(VI) adsorption proceeds via a certain complex chemical reaction and the Chromium complex was found to be coordinated with carbonyl group of amides from the result of infrared spectra. The chroming of silk fibroin fibers in moderated in the conditions of 5$0^{\circ}C$, pH 2.4, and 3 hours, which prevent from the loss of physical properties. The equilibrium adsorption is attained at 5 X 10-3M of Chromium(VI) solutions.

• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.15-22
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• 2004

Yellow loess, Tidal plat sediment, and mud are blown to be high in adsorption though they have great distinction according to the ratio of clay minerals content and their kinds. Thus one of the samples for this study can be obtained by drying of Yellow loess, Tidal plat sediment, and the mud which is semifinished products that are from the progress of heat treatment and making homogeneity which can be found everywhere in our county. Another sample can be prepared by reducing pollutants with the adsorbent and by homing heavy metals of their on. With the samples, noxious heavy metals such as Pb, Cd, and essential trace elements such as Cu, Fe, Mn by each concentration is tested for adsorption according to pH, the kinds of adsorbents and the amount of injection. With the help of these steps, this study shows that the adsorbents, which are green, reducing the additional pollution and low in price, can be found. It also shows that the optimal condition for removing pollutants can be found and the basic materials for treating water can be offered. The results were as follows ; Yellow loess shows the rates of adsorption by more than 50% and Tidal plat sediment and Mud show it by more than 90%. Thus Tidal plat sediment and Mud are higher than Yellow loess the rates of adsorption. The pH should be treated in natural condition because the rates of adsorption of Pb, Cd, Cu, Mn excepting Fe in mud is higher in pH 7 than in pH 3 of Yellow loess, Tidal plat sediment, and Mud. The drying adsorbents are good to use because the rates of adsorption of heavy metals has tendency to be higher in the drying method than in the burning method. It is considered that the more the mont of the injection of the adsorbent is , the higher the rates of adsorption is, and one gram is reasonable for the amount of the injection of Tidal plat sediment and mud. Yellow loess is suitable for the treatment of the water that includes low concentration of heavy metals because it has the lower rate of adsorption as the concentration of noxious heavy metals is higher. It is thought that Tidal plat sediment and Mud is proper for the treatment of the water that includes high concentration of heavy metals because the rates of adsorption has not been changed as the concentration of heavy metals increases.

• Membrane and Water Treatment
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• v.15 no.1
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• pp.41-50
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• 2024

Presence of hazardous dyes in water cause considerable risks to the human health and environment due to their potential toxicity and ecological disruptions. Therefore, in the present research, to suggest an alternative method for the retention of toxic Azocarmine G (ACG) dye from aqueous media, natural and H₂SO₄-modified acacia sawdust were performed for the first time as low-cost and efficient adsorbents. Based on batch experiments, it was determined that the best conditions for the developed dye retention process were an initial pH of 2.0 and an equilibrium time of 240 min. Analysis of the data using both pseudo-first order and pseudo-second order kinetic models showed that the retention of ACG onto the adsorbents predominantly occurred through chemical adsorption. Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were employed to provide insights into the interaction between the adsorbate and adsorbent and the mechanism of the adsorption process. Maximum monolayer adsorption capacities of natural and H₂SO₄-modified acacia sawdust were determined as 28.01 and 64.90 mg g^-1, respectively by Langmuir isotherm model. Results of the study clearly indicated that the modification of acacia sawdust with H₂SO₄ leads to a substantial increase in the adsorption performance of anionic dyes.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.301-310
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• 2023

Ferrihydrite is an iron oxide mineral that is easily found in the natural environment, including acid mine drainage, and has a low crystallinity and high specific surface area, resulting in high reactivity with other ions, and can remove environmentally hazardous substances. However, because ferrihydrite is a metastable mineral, there is a possibility of releasing adsorbed ions by phase transformation to other minerals having low surface area and high crystallinity. In this study, the adsorption characteristics of arsenate, chromate, and selenate on ferrihydrite and the oxyanion removal efficiency of ferrihydrite were studied considering mineral phase transformation. At both pH 4 and 8, the adsorption of oxyanions used in the study were in good agreement with both Langmuir and Freundlich adsorption models except for selenate at pH 8. Due to the difference in surface charge according to pH, at pH 4 a higher amount of ions were adsorbed than at pH 8. The adsorption amount were in the order of arsenate, chromate, and selenate. These different adsorption models and adsorption amounts were due to different adsorption mechanisms for each oxyanions on the surface of ferrihydrite. These adsorption characteristics were closely related to changes in the mineral phase. At pH 4, a phase transformation to goethite or hematite was observed, but only a phase transformation to hematite was observed at pH 8. Among the oxyanion species on ferrihydrite, arsenate showed the highest adsorption capacity and hardly caused phase transformation during the experimental period after adsorption. Contrary to this, chromate and selenate showed faster mineral phase transformation than arsenate, and selenate had the lowest retardation effect among the three oxyanions. Ferrihydrite can effectively remove arsenate due to its high adsorption capacity and low phase transformation rate. However, the removal efficiency for other two oxyanions were low by the low adsorption amount and additional mineral phase transformation. For chromate, the efficient removal is expected only at low concentrations in low pH environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.667-674
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• 2020

The adsorption of reactive orange 16 (RO 16) dye by activated carbon was investigated using the amount of adsorbent, pH, initial concentration, contact time and temperature as adsorption variables. The investigated process parameters were separation coefficient, rate constant, rate controlling step, activation energy, enthalpy, entropy, and free energy. The adsorption of RO 16 was the highest at pH 3 due to the electrostatic attraction between the cations (H⁺) on the surface of the activated carbon and the sulfonate ions and hydroxy ions possessed by RO 16. Isotherm data were fitted into Langmuir, Freundlich and Temkin isotherm models by applying the evaluated separation factor of Langmuir (RL=0.459~0.491) and Freundlich (1/n=0.398~0.441). Therefore, the adsorption operation of RO 16 by activated carbon was confirmed as an appropriate removal method. Temkin's adsorption energy indicated that this adsorption process was physical adsorption. The adsorption kinetics studies showed that the adsorption of RO 16 follows the pseudo-second-order kinetic model and that the rate controlling step in the adsorption process was the intraparticle diffusion step. The positive enthalpy change indicated an endothermic process. The negative Gibbs free energy change decreased in the order of -3.16 <-11.60 <-14.01 kJ/mol as the temperature increased. Therefore, it was shown that the spontaneity of the adsorption process of RO 16 increases with increasing temperature.