• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2560-2564
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• 2011

Mesoporous silicon dioxide (meso-$SiO_2$) was prepared using cetyltrimethylammonium bromide as the structure-directing reagent and tetraethyl orthosicate as the silicon source. The influence of pH value on the adsorption behavior of bisphenol A (BPA) was investigated. The adsorption capacity of BPA onto meso-$SiO_2$ increases slightly with pH value from 2 to 6, and then gradually decreases as further improving pH value. The effect of temperature was also studied, and the adsorption capacity of BPA gradually declines with increasing temperature. The adsorption kinetics and thermodynamics of BPA were examined. It is found that the adsorption of BPA onto meso-$SiO_2$ is in good agreement with Langmuir adsorption model. The rate constant of adsorption is $5.17{\times}10^{-3}g\;mg^{-1}\;min^{-1}$, and the maximum adsorption capacity is as high as 353.4 $mg\;g^{-1}$ at 20 $^{\circ}C$.

• Journal of the Korean Applied Science and Technology
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• v.19 no.3
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• pp.213-221
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• 2002

Activated carbons with high surface area of 2,600 $m^{2}/g$ and high pore volume of 1.2 cc/g could be prepared by KOH activation of rice hulls at a KOH:char ratio of 4:1 and $850^{\circ}C$. In order to increase the adsorption capacity of hydrogen sulfide, which is one of the major malodorous component in the waste water treatment process, various contents of $Na_{2}CO_{3}$ and $KIO_{3}$ were impregnated to the rice-hull activated carbon. The impregnated activated carbon with 5 wt.% of $Na_{2}CO_{3}$ showed improved $H_{2}S$ adsorption capacity of 75 mg/g which is twice of that for the activated carbon without impregnation and the impregnated activated carbon with 2.4 wt.% of $KIO_{3}$ showed even higher $H_{2}S$ adsorption capacity of 97 mg/g. The improvement of $H_{2}S$ adsorption capacity by the introduction of those chemicals could be due to the $H_{2}S$ oxidation and chemical reaction with impregnated materials in addition to the physical adsorption of activated carbon.

• Membrane and Water Treatment
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• v.15 no.3
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• pp.107-115
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• 2024

This study proposes the recycling of MVS as a value-added product for the removal of phosphate from aqueous solutions. By comparing the phosphate adsorption capacity of each calcined adsorbent at each temperature of MVS, it was determined that the optimal heat treatment temperature of MVS to improve the phosphate adsorption capacity was 800 ℃. MVS-800 suggests an adsorption mechanism through calcium phosphate precipitation. Subsequent kinetic studies with MVS-800 showed that the PFO model was more appropriate than the PSO model. In the equilibrium adsorption experiment, through the analysis of Langmuir and Freundlich models, Langmuir can provide a more appropriate explanation for the phosphate adsorption of MVS-800. This means that the adsorption of phosphate by MVS-800 is uniform over all surfaces and the adsorption consists of a single layer. Thermodynamic analysis of thermally activated MVS-800 shows that phosphate adsorption is an endothermic and involuntary reaction. MVS-800 has the highest phosphate adsorption capacity under low pH conditions. The presence of anions in phosphate adsorption reduces the phosphate adsorption capacity of MVS-800 in the order of CO 3 2-, SO 4 2-, NO 3- and Cl-. Based on experimental data to date, MVS-800 is an environmentally friendly adsorbent for recycling waste resources and is considered to be an adsorbent with high adsorption capacity for removing phosphates from aqueous solutions. This paper combines the advantages of gray predictor and AI fuzzy. The gray predictor can be used to predict whether the bear point exceeds the allowable deviation range, and then perform appropriate control corrections to accelerate the bear point to return to the boundary layer and achieve.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1177-1185
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• 2010

To examine the potency of biosorbent, the adsorption capacity of Pseudomonas cepacia H42 isolated from fresh water plant root was compared with Saccharomyces cerevisiae SEY2102 on bases of biomass, concentration of heavy metal, presence of light metals, immobilized cell, and ion exchange resin. P. cepacia H42 biomass of 0.05-0.5 g/L increased adsorption and above 1.0 g/L of yeast biomass was the most effective in adsorption. By applying the same amount of biomass, lead showed the highest adsorption on two strains and the adsorption strength was lead>copper>cadmium on both strains. The high heavy metal concentration induced the high adsorption capacity. P. cepacia H42 adsorption was in the order of copper>lead>cadmium and lead>copper>cadmium by yeast in 10 mg/L. Both strain showed same adsorption strength in the order of lead>copper>cadmium in 100 mg/L and 1000 mg/L. The adsorption capacity of both yeast and P. cepacia H42 was decreased in the presence of light metals and the order of cadmium>copper>lead. $Mg^{2+}$ induced the least adsorption while $Na^+$ induced highest adsorption. The adsorption capacity of immobilized yeast and P. cepacia H42 was detected between 200-400 mL in flow volume and decreased in the presence of light metals. Ion exchange containing light metals caused 30-50% adsorption reduction on both strains.

• Journal of the Korean Wood Science and Technology
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• v.52 no.2
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• pp.118-133
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• 2024

The sapwood portion of fast-growing teak is mostly ignored due to its inferior quality. One of the possibilities for utilizing sapwood waste is to convert it into activated carbon that has good adsorption capabilities. The raw materials used in this research were sapwood of 14-year-old fast-growing teak sapwood (FTS) waste, which was taken from three trees from community forests in Wonosari, Gunungkidul, Yogyakarta Special Region. FTS waste was taken from the bottom of the tree up to a height of 1.3 m. The activation process is conducted with an activation temperature of 750℃, 850℃, and 950℃. The heating duration consists of three variations: 30 min, 60 min, and 90 min. The quality evaluation parameters of activated carbon include yield, moisture content, volatile matter content, ash content, fixed carbon content, adsorption capacity of benzene, adsorption capacity of methylene blue, and adsorption capacity of iodine. The results showed that the activated carbon produced had the following quality parameters: yield of 75.61%; moisture content of 1.27%; volatile matter content of 9.98%; ash content of 5.43%; fixed carbon content of 84.58%; benzene absorption capacity of 8.58%; methylene blue absorption capacity of 87.73 mg/g; and iodine adsorption capacity of 948.19 mg/g. It can be concluded that activated carbon from FTS waste has good iodine adsorption, which fulfilled the SNI 06-3730-1995 quality standard. Due to the iodine adsorption ability of FTS waste activated carbon, the conversion of FTS waste to activated carbon is categorized as a potential method to increase the value of this material.

• Journal of the Korean Ceramic Society
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• v.56 no.2
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• pp.146-152
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• 2019

In order to study the transport behavior of tripolyphosphate (TPP) in aqueous solutions, the adsorption process of TPP on synthetic goethite, which exists stably in supergene environment, has been systematically studied. The adsorption properties under different conditions (pH, electrolyte presence, and temperature) were investigated. The adsorption of TPP in the presence of humic acid (HA)/fulvic acid (FA) has also been discussed in this paper. The results indicated that the adsorption capacity quickly increased within the first hour and equilibrium was reached within 24 h. The adsorption capacity decreased from 1.98 to 0.27 mg·g^-1 upon increasing the pH from 8.5 to 11.0, whereas the adsorption of TPP on goethite hardly changed with increasing electrolyte concentration. The results of analysis of the kinetic and isothermal models showed that the adsorption was more in accord with the pseudo second-order equation and Freundlich model. The adsorption capacity decreased obviously regardless of the order of addition of TPP, HA, and goethite. Subsequent addition of FA led to a large increase in the adsorption capacity, which might be attributed to the adsorption ability of FA. According to the predictions of the kinetic and isothermal models and the spectroscopic evidence (X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM)), the adsorption mechanism may be mainly based on surface complexation and physical adsorption.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.269-273
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• 2001

Biosorption of Pb was evaluated for plants, Persicaria chinensis, Oenanthe javanica and Salvinia natnas. The adsorption equilibrium was reached in about 1hr for Pb and the highest adsorption capacity was 150mg Pb/g biomass at S.natans. Pb adsorption process showed a pseudo second order irreversible reaction. The highest initial adsorption rate was 2000mg pb/g biomass/hr at O.javanica. In spite of pH variation, Pb adsorption capacity by was selection, Pb was selectively adsorved. The selectivity of mixture solution showed the adsorption order of Pb>Cu>Cr>Cd. The Pb adsorption capacity of P. chinensis pretreated with NaOH was increased by 30% in comparison with that of no treatment.

• Journal of environmental and Sanitary engineering
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• v.15 no.3
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• pp.44-49
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• 2000

The purpose of this research is to evaluate the adsorption capacity of casts for heavy metals. The casts were excreted by earthworm, Lumbricus rubellus, after having eaten the paper sludge. Various batch experiments on adsorption were performed to compare cast and activated carbon. The pH increase in solution due to extractives from cast was 1.3 and the cation exchange capacity which implies adsorption capacity for solubles is greater on activated carbon than on cast. According to the results of batch experiment, the removal rates of Pb, Cu, Cr, Zn using the activated carbon and casts as adsorbent were 98%, 93%, 94%, 89%, 82% and 95%, 90%, 88%,80%, 66%, respectivity, and this removal were achived less than 90 minutes. It can be said that casts is so good adsorbent as activated carbon is, although adsorption carbon was found to be some large than those of casts through Freundlich isotherm applied for adsorption of soluble. As a result on the experiment of isothermic adsorption from the mixed component solution in the batch, the order of preferable elements in heavy metal adsorption was found to be Pb＞Cd＞Cu＞Cr＞Zn on activated carbon, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.6
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• pp.805-812
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• 1999

Adsorption characteristics of volatile organic compounds(VOCs) by activated carbon fiber(ACF) were investigated using a continuous system for benzene, toluene, xylene(BTX) generation. Studied characteristics for adsorption were equilibrium capacity, accumulative adsorption, and breakthrough curve. Operating variables were adsorption temperature(25~45$^{\circ}C$) and partial pressure(1.2~12 mmHg) of BTX. The experimental results show that the adsorption equilibrium capacity increases with increasing partial pressure of BTX and decreases with increasing temperature. It was also found that the break point was decreased with increasing partial pressure, temperature and gas flow rate due to an effect of mass transfer of adsorbate.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2468-2473
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• 2018

Nitrogen-doped activated carbon fibers (ACFs) were prepared by chemical vapor deposition using melamine powder and acetonitrile for introducing quaternary nitrogen on the commercial ACFs, subsequently heated at $950^{\circ}C$ and activated by steam. Adsorption experiments of nitrate in aqueous solution were also conducted to evaluate adsorption capacity of the prepared ACFs using ion chromatography. The amount of introduced nitrogen content and nitrogen species on activated carbon fibers was examined by CHN elemental analyzer and X-ray photoelectron spectroscopy, respectively. As a result, adsorption capacity of quaternary nitrogen-doped ACF (ST-ML-AN-ST) was 0.75 mmol/g, indicating ca. two-times higher than that of untreated ACF (0.38 mmol/g). According to the adsorption data, the Langmuir isotherm model was the best fit. The prepared samples were also regenerated using hydrochloric acid. After regeneration, the adsorption capacity of the nitrogen-doped ACF (ST-ML-AN-ST) showed ca. 80% on average, implying that a portion of nitrates was adsorbed on the prepared ACFs irreversibly.