• Bulletin of the Korean Chemical Society
• /
• v.26 no.7
• /
• pp.1075-1078
• /
• 2005

Hydrogen adsorption on various porous materials have been studied with a volumetric method at low temperature in the pressure of 0-760 torr. Their hydrogen uptakes depend at least partly on microporosity rather than total porosity. However, it is also necessary to consider other parameters such as pore size and pore architecture to explain the adsorption capacity. The heat of adsorption and adsorption-desorption-readsorption experiments show that the hydrogen adsorption over the porous materials are composed of physisorption with negligible contribution of chemisorption. Among the porous materials studied in this work, SAPO-34 has the highest adsorption capacity of 160 mL/g at 77 K and 1 atm probably due to high micropore surface area, micropore volume and narrow pore diameter.

• Journal of the Korean Ceramic Society
• /
• v.33 no.4
• /
• pp.432-440
• /
• 1996

ZrO2 gel was prepared under pH 10 alkaline condition by sol-gel process and was investigated as a function of calcination temperature and effect of calcination temperature on cobalt adsorption capacity. The ZrO2 powder prepared by sol-gel process was calcined at 600, 800, 1000, 1200, 140$0^{\circ}C$ and analyzed by X-ray diffractometry. SEM specific surface area by BET nitrogen adsorption FT-IR and TG-DTA technique. It was shown that cobalt adsorption capacity of ZrO2 prepared under pH 10 alkaline condition and then calcined at $600^{\circ}C$ in high temperature was determined to be larger than that of ZrO2 at various calcination temperature. The specific surface area of ZrO2 calcined at $600^{\circ}C$ was 24.03m2/g and cobalt adsorption capacity at 25$0^{\circ}C$ high-temperature water was 0.16m-eq/g.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.1
• /
• pp.1-8
• /
• 2020

In this study, the physicochemical characteristics and fluoride adsorption capacity of the bone char pyrolyzed at different temperatures; 200℃, 300℃, 350℃, 400℃, 500℃, 600℃, and 700℃ were investigated. Analytical studies of the synthesized bone char including; SEM-EDS, XRD, BET and FT-IR, showed the presence of hydroxyapatite(HAP), which is the main substance that adsorbs fluoride from aqueous solutions containing high fluoride concentrations. Bone char pyrolyzed from 350~700℃ specifically revealed that, the lower the temperature, the higher the fluoride adsorption capacity and vice versa. The loss of the fluoride adsorption function of HAP (OH^- band in the FTIR analysis) was interpreted as the main reason behind this inverse correlation between temperature and fluoride adsorption. Bone char produced at 350℃ hence exhibited a fluoride adsorption capacity of 10.56 mgF/g, resulting in significantly higher adsorption compared to previous studies.

• Carbon letters
• /
• v.9 no.3
• /
• pp.203-209
• /
• 2008

The objective of this work is to study the feasibility of the preparation of the activated carbon (AC) from coconut tree flowers using high temperature fluidized bed reactor (HTFBR). The activating agent used in this work is steam. The reactor was operated at various activation temperature (650, 700, 750, 800 and $850^{\circ}C$) and activation time (30, 60, 120 and 240 min) for the production of AC from coconut tree flowers. Effect of activation time and activation temperature on the quality of the AC preparation was observed. Prepared AC was characterized in-terms of iodine number, methylene blue number, methyl violet number, ethylene glycol mono ethyl ether (EGME) surface area and SEM photographs. The best quality of AC from coconut tree flowers (CFC) was obtained at an activation temperature and time of $850^{\circ}C$ and 1 hr restectively. The effectiveness of carbon prepared from coconut tree flowers in adsorbing crystal violet from aqueous solution has been studied as a function of agitation time, carbon dosage, and pH. The adsorption of crystal violet onto AC followed second order kinetic model. Adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity $q_m$ was 277.78 mg/g., equilibrium time was found to be 180 min. This adsorbent from coconut tree flowers was found to be effective for the removal of CV dye.

• Carbon letters
• /
• v.19
• /
• pp.12-22
• /
• 2016

Date palm leaflets were used as a precursor to prepare dehydrated carbon (DC) via phosphoric acid treatment at 150℃. DC, acidified with H₃PO₄, was converted to activated carbon (AC) at 500℃ under a nitrogen atmosphere. DC shows very low surface area (6.1 m²/g) while AC possesses very high surface area (829 m²/g). The removal of lisinopril (LIS) and chlorpheniramine (CP) from an aqueous solution was tested at different pH, contact time, concentration, and temperature on both carbons. The optimal initial pH for LIS removal was 4.0 and 5.0 for DC and AC, respectively. However, for CP, initial pH 9.0 showed maximum adsorption on both carbons. Adsorption kinetics showed faster removal on AC than DC with adsorption data closely following the pseudo second order kinetic model. Adsorption increases with temperature (25℃–45℃) and activation energy (E_a) is in a range of 19–25 kJ mol/L. Equilibrium studies show higher adsorption on AC than DC. Thermodynamic parameters show that drug removal is endothermic and spontaneous with physical adsorption dominating the adsorption process. Column adsorption data show good fitting to the Thomas model. Despite its very low surface area, DC shows ~70% of AC drug adsorption capacity in addition of being inexpensive and easily prepared.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.2 s.257
• /
• pp.116-124
• /
• 2007

An adsorption chiller is expected to have high energy-efficiency in utilizing the waste heat exhausted from a process. The objective of this paper is to investigate the performance of silica gel-water adsorption chiller from the cycle simulation and to provide a guideline for design of the adsorption chiller. The effect of cycle time, inlet temperature and water flow rate on the cooling capacity and COP is quantified during the cycle operation. It is found that the performance of adsorption chiller is more sensitive to the change of inlet water temperature rather than the water flow rate. It is concluded that the COP is 0.57 in the standard conditions(hot water $80^{\circ}C$, cooling water $30^{\circ}C$, chilled water inlet temperatures $14^{\circ}C$ and cycle time 420sec).

• Transactions of the Korean hydrogen and new energy society
• /
• v.30 no.5
• /
• pp.411-417
• /
• 2019

An adsorption chiller is connected to the fuel processing/fuel cell system to increase the energy efficiency of the system. Since, the minimum temperature of $70^{\circ}C$ is needed to operate the adsorption chiller, HT-PEMFC is used as a heating source and $80^{\circ}C$ hot water in the water tank at the system is supplied to the chiller. Experimentally measured COP of the adsorption chiller was between 0.4-0.5 and the total calcuated efficiency of the connected system was between 60% and 70% comparing to 47% without adsorption chilling system.

• Journal of the Korean Wood Science and Technology
• /
• v.33 no.3 s.131
• /
• pp.45-52
• /
• 2005

This research was performed to evaluate adsorption behavior of woody charcoals obtained from wood powder, fiber and bark of spruce (Abies sibirica Ledeb). The wood materials were carbonized at various temperatures for 1 hour using experimental rotary kiln without any inert gas. The adsorption capacity of iodine and toluene, specific surface area and removal efficiency of acetic acid and ammonia gas of those charcoals were measured. The higher was the temperature for carbonization, the lower yields of charcoals were. Ash content of bark charcoal was higher than that of wood powder charcoal or fiber charcoal. Elemental analysis of woody charcoal revealed that the content of carbon was gradually lincreased as carbonization temperature was higher. When carbonization temperature was higher, adsorption capacity of woody charcoals for iodine was much improved. Wood powder charcoal and fiber charcoal were more effective for iodine adsorption rather than bark charcoal. Capacity of toluene adsorption was the highest in the charcoal of $600^{\circ}C$. Charcoals produced at high temperature efficiently removed acetic acid gas, while charcoals carbonized at low temperature such as $400^{\circ}C$ were proper to remove ammonia gas. This difference may be explained that the acidity of charcoals depends on the carbonization temperature: charcoals of low temperature indicate acidic property, while those of high temperature turned to alkaline.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2000.02a
• /
• pp.157-157
• /
• 2000

The adsorption processes of methyl chloride on Si(100)-2$\times$1 have been studied by low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and semiempirical PM3 calculations. The dissociative adsorption of the methyl chloride on Si(100) takes place without breaking of the silicon dimer with high efficiency. For adsorption at the room temperature, the existence of a precursor state is confirmed by the behavior of the sticking probability depending on the coverage and temperature. From AES measurements, the determined activation barrier of adsorption ($\Delta$ Hads) is -28.4 kj/mol. This results indicate that the dissociative process is nonactivated. The optimized precursor state of CH3Cl on the Si(100)-2$\times$1 surface was determined by PM3 calculations based on a cluster model.

• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.5
• /
• pp.575-584
• /
• 2007

The adsorption capability of iron phthalocyanine derivatives were investigated by means of X-ray diffractometor (XRD), IR (infrared) spectroscopy, scanning electron microscopy (SEM) and temperature programmed desorption (TPD). According to TPD results, iron phthalocyanine derivatives showed two desorption peaks at low temperature ($100{\sim}150^{\circ}C$) and high temperature ($350{\sim}400^{\circ}C$) indicating that there were two kinds of acidities. Tetracarboxylic iron phthalocyanine (Fe-TCPC) have a stronger desorption peak (chemical adsorption) at the high temperature and a weaker desorption peak (physical adsorption) at the low temperature than iron phthalocyanine (Fe-PC). The specific surface areas of Fe-TCPC and Fe-PC were $26.46\;m^2/g\;and\;11.77\;m^2/g$, respectively. The pore volumes of Fe-TCPC and Fe-PC were $0.14\;cm^3/g\;and\;0.06\;cm^3/g$, respectively. The adsorption capability of triethyl amine calculated by breakthrough curve at 220 ppm of equilibrium concentration was 29.2 mmoL/g for Fe-TCPC and 0.8 mmoL/g for Fe-PC. The removal efficiency of dimethyl sulfide of Fe-TCPC and Fe-PC in batch experiment of 225 ppm of initial concentration were 44.9% and 28.9%, respectively. The removal efficiency of trimethyl amine of Fe-TCPC and Fe-PC in batch experiment of 118 ppm of initial concentration were approximately 100.0% and 33.9%, respectively.