• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.3
• /
• pp.218-225
• /
• 1996

Using water vapor adsorption data foe some typical Korean soils. we calculated the adsorption energy distribution functions and average adsorption energies for these soils using theory of adsorption on hetergeneous surfaces. As a local adsorption models the BET and a new Aranovich equations were applied. The distribution functions were broad, indicating rather high energetic inhomogeneity of the surface.

• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.2
• /
• pp.86-91
• /
• 1996

Water vapor adsorption isotherms were measured for samples of the A horizons of five typical Korean soils. The experimental data were fitted to the BET and Aranovich adsorption equations. The adsorption isotherms studied followed the BET equation for the relative water vapor pressures in 0.03-0.33 range and the Aranovich equation in 0.03-0.6 range. The calculated surface areas were higher for Aranovich than for BET and opposite relations were found for adsorption energies. For the description of the water adsorption on soils, the use of the Aranovich theory is recommended.

• Journal of the Korean Applied Science and Technology
• /
• v.23 no.4
• /
• pp.280-289
• /
• 2006

Multilayer adsorptions and BET adsorption are analyzed statistical-mechanically. Which ensemble is selected for the analysis is unimportant, because each ensemble yields the same results. However, the amount of mathematical manipulations and the matter of convenience vary from ensemble to ensemble. Hence, multilayer adsorptions and BET adsorption are examined using a canonical and a grand canonical ensembles, and an ensemble of subsystems. Also, the characteristics of multilayer and BET adsorptions are delineated.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.6
• /
• pp.673-679
• /
• 2008

In this study, Mesoporous silica were prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide(CTMABr) as a template. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of Mesoporous silica were determined by XRD, SEM, and BET. N$_2$ adsorption isotherm characteristics, including the specific surface area(S$_{BET}$), total pore volume(V$_T$), and average pore diameter(D$_{BJH}$), were determined by BET. Also, the adsorption character of Pb(II) and Cd(II) ion on Mesoporous silica were measured using ICP. As a result, a SBET of 100$\sim$1,500 m$^2$/g was determined from the N$_2$ adsorption isotherm. Also, the average pore diameter of 2$\sim$4 nm. The adsorption of Pb ion and Cd ion on Mesoporous silica become different depending on the pH of solution. The adsorption amount of Mesoporus silica had higher than that of silicagel.

• Environmental Engineering Research
• /
• v.22 no.1
• /
• pp.95-107
• /
• 2017

Adsorption equilibrium and kinetic behavior of two toxic heavy metals hexavalent chromium [Cr(VI)] and mercury [Hg(II)] on mustard oil cake (MOC) was studied. Isotherm of total chromium was of concave type (S1 type) suggesting cooperative adsorption. Total chromium adsorption followed BET isotherm model. Isotherm of Hg(II) was of L3 type with monolayer followed by multilayer formation due to blockage of pores of MOC at lower concentration of Hg(II). Combined BET-Langmuir and BET-Freundlich models were appropriate to predict Hg(II) adsorption data on MOC. Boyd's model confirmed that external mass transfer was rate limiting step for both total chromium and Hg(II) adsorptions with average diffusivity of $1.09{\times}10^{-16}$ and $0.97m^2/sec$, respectively. Desorption was more than 60% with Hg(II), but poor with chromium. The optimum pH for adsorptions of total chromium and Hg(II) were 2-3 and 5, respectively. At strong acidic pH, Cr(VI) was adsorbed by ion exchange mechanism and after adsorption reduced to Cr(III) and remained on MOC surface. Hg(II) removal was achieved by complexation of $HgCl_2$ with deprotonated amine ($-NH_2$) and carboxyl (COO-) groups of MOC.

• Journal of the Korean Chemical Society
• /
• v.35 no.3
• /
• pp.204-210
• /
• 1991

Multilayer adsorption isotherms of nitrogen and argon on the perovskite-type mixed oxides, synthesized by a citrate coprecipitation method, are determined at the liquid nitrogen temperature using a gravimetric adsorption apparatus. The volume of the adsorbed gas are plotted against the statistical thickness of the adsorbed layer, calculated from several universal adsorption isotherms one after another. The t-method area obtained from this plot is compared with the BET area and finally the appropriateness of universal adsorption isotherms is then discussed on the basis of the plot.

• Journal of the Korean Applied Science and Technology
• /
• v.16 no.1
• /
• pp.59-65
• /
• 1999

For a cosmetic plant wastewater containing surfactants of high concentration, adsorption treatment by granular activated carbon(GAC) having different pore size distribution was studied. Three sorts GACs were used and regenerated afterwards with methanol. Experiments were composed of batch process and column test for both virgin and regenerated GACs. Following conclusions were drawn from the study: Methylene blue activating substance(MBAS) adsorption data from the batch tests for three GACs are described well by BET isotherm and Freundich isotherm. Simulation with the BET isotherm shows that maximum adsorption appears to be affected not only by specific surface area but also by pore size distribution. Maximum adsorption from the BET isotherm for MBAS appears to diminish as the number of reactivation increases. The diminishing ratio of maximum adsorption appears to decrease as the pore size decreases. Recovery ratio of the methanol by vacuum evaporation from the spent methanol ranges from 95% to 97%.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.6
• /
• pp.620-625
• /
• 2005

This study is to investigate the correlation between pore structures of activated carbons and adsorption characteristics of acetone vapor using the dynamic adsorption method. The experimental results showed that the breakthrough time of ACT activated carbon made by Takeda was the longest, because ACT has more micropores below pore diametr $10{\AA}$ than the compared activated carbons. The equilibrium adsorption capacity had direct correlation to the breakthrough time. The relation between BET specific surface area and the equilibrium adsorption capacity was hard to say linear. Therefore, it was difficult to estimate the adsorption ability of activated carbons only by BET specific surface area. The correlation factor between the cumulative surface area and the equilibrium adsorption capacity decreased with enlarging the range of pore size, and there was the highest correlation factor in the range of below $10{\AA}$.

• Journal of the Korean Chemical Society
• /
• v.62 no.2
• /
• pp.79-86
• /
• 2018

This study reported the adsorption of Cu(II) ions onto activated carbon prepared from Myristica Fragrans shell (MFS AC) over independent variables of contact time, activating chemical (NaOH) concentration, initial adsorbate concentration, initial pH of adsorbate solution and adsorption temperature. The MFS AC structure, morphology and total surface area were characterized by FTIR, SEM and BET techniques, respectively. The Cu(II) ions adsorption on the MFS AC (activated using 0.5 M NaOH) fitted best to Freundlich adsorption isotherm (FAI), and the FAI constant obtained was 0.845 L/g at $30^{\circ}C$ and pH 4.5. It followed the pseudo first order of adsorption kinetic (PFOAK) model, and the PFOAK based adsorption capacity was 107.65 mg/g. Thermodynamic study confirmed the Cu(II) ions adsorption should be exothermic and non-spontaneous process, physical adsorption should be taken place. The total surface area and pore volume based on BET analysis was $99.85m^2/g$ and 0.086 cc/g, respectively.

• YAKHAK HOEJI
• /
• v.37 no.1
• /
• pp.66-75
• /
• 1993

Dental abrasive, dicalcium phosphate dehydrate (DCPD) was prepared and the several important factors affecting on the quality of toothpaste were investigated by means of set test, glycerine absorption, Coulter counter test, color difference, BET adsorption, mercury porosimetery, and rheogram comparing with two foreign DCPDs, MFO4 and Dentphos K. Sample DCPD was prepared by reaction between 85% H$_{3}$PO$_{4}$ and 15% milk of lime at $39^{\circ}C$ (pH6.5), and stabilized with TSPP and TMP. The physicochemical properties of Sample DCPD were obtained as follows: whiteness (98.99), average particle size (15.5 $\mu\textrm{m}$), pH (7.9), remainder particle weight (0.49w/w%), glycerine absorption value (64 ml), and set test (passed). N$_{2}$ adsorption curves (BET) of three kinds of DCPD showed non-porous type III isotherm. BET adsorption parameters of sample DCPD showed that surface area was 24.9 m$^{2}$/g, total pore volume 0.09 cm$^{3}$/g and average pore radius 72.0 $\AA$. The rheogram of the toothpaste containing each DCPD showed bulged plastic flow with yield vlaue and thixotropic behavior. These results meet standard requirements as abrasive standard, and suggested that synthesized sample DCPD could be used a dental abrasive such as a high quality grade in practice as foreign DCPDs.