Impact of the oxygen functional group of nitric acid‑treated activated carbon on KOH activation reaction

Ji‑Hyun Kim,Sang Youp Hwang,Jung Eun Park,Gi Bbum Lee,Ho Kim,Seokhwi Kim,Bum Ui Hong 한국탄소학회 2019 Carbon Letters Vol.29 No.3

To prepare activated carbon with a high specific surface area, oxygen functional groups (OFGs) that can serve as useful electron donors during KOH activation were treated with nitric acid and incorporated into activated carbon. OFGs are incorporated differently according to the surface characteristics of starting materials. Up to 22.46% OFGs are incorporated into wood-based activated carbons (WACs), the C=O, COOH contents was 1.90, 17.05%, respectively. Whereas up to 12.82% OFGs are incorporated into coconut shell-based activated carbons, the C=O, COOH contents was 4.12, 6.15%, respectively. The OFGs used for increasing the specific surface area are the carbonyl group, and as the content of the functional group increases, the carbonyl group spreads to the carboxyl group. The specific surface area of activated carbons increased by 10–68% with an increase in the carbonyl group up to 6% (maximum point of carbonyl group). On the other hand, the specific surface area for WACs increased when the carboxyl group was 10% or below, but decreased by 6–15% when it increased to 10% or excess.

Sorption of Pb2+ Ions on to Activated Carbons Prepared from Olive Stones

Amina. A. Attia,Mona. A. Shouman,Th. El-Nabarawy 한국탄소학회 2005 Carbon Letters Vol.6 No.3

The carbon sample "O", phosphoric acid-activated carbon "OP", zinc chloride-activated carbon "OZ", and two steam activated carbons "OS" and "OS2" with different burn-off of 25% and 58% respectively, were prepared from olive stones. The textural properties were determined from the results of nitrogen adsorption at 77 K and by analyzing these results through the application of different adsorption models. The chemistry of the carbon surfaces was determined from the base neutralization capacities, acid neutralization capacity and surface pH. The sorption of Pb2+ ions on to the carbons prepared was followed under dynamic and equilibrium conditions. The differences between the values of the textural parameters were attributed to the inapplicability of some adsorption models and to the heterogeneity of the microporous carbons. The sorption of Pb2+ ions is favored on carbon and activated carbons. However, chemically activated carbons are more effective compared with steam-activated ones. The sorption of Pb2+ ions were related to the chemistry of the surface rather than to the textural properties.

Equilibrium and Dynamic Adsorption of Methylene Blue from Aqueous Solutions by Surface Modified Activated Carbons

Meenakshi Goyal,Sukhmehar Singh,Roop C. Bansal 한국탄소학회 2004 Carbon Letters Vol.5 No.4

The equilibrium and dynamic adsorption of methylene blue from aqueous solutions by activated carbons have been studied. The equilibrium studies have been carried out on two samples of activated carbon fibres and two samples of granulated activated carbons. These activated carbons have different BET surface areas and are associated with varying amounts of carbon oxygen surface groups. The amounts of these surface groups was enhanced by oxidation with HNO3 and O2 gas at 350℃ and decreased by degassing at increasing temperatures of 400˚, 650˚ and 950℃. The adsorption increases on oxidation of the carbon surface and decreases on degassing. The increase in adsorption has been attributed to the formation of acidic carbon-oxygen surface groups and the decrease in adsorption on degassing to their elimination. The dynamic adsorption studies have been carried out on the two granulated activated carbons using two 50 mm diameter glass columns at a feed concentration of 300 mg/L and at different hydraulic loading rates (HLR) and bed heights. The minimum achievable concentrations are comparatively lower while the adsorption capacities are higher for GAC-S under the same operating conditions. The adsorption capacity of a carbon increases with increase in HLR but the rate of increase decreases at higher HLR values.

Carbonization and CO2 activation of scrap tires: Optimization of specific surface area by the Taguchi method

Zakaria Loloie,Mehrdad Mozaffarian,Mansooreh Soleimani,Neda Asassian 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

This research demonstrates the production of activated carbon from scrap tires via physical activation with carbon dioxide. A newly constructed apparatus was utilized for uninterrupted carbonization and activation processes. Taguchi experimental design (L16) was applied to conduct the experiments at different levels by altering six operating parameters. Carbonization temperature (550-700 oC), activation temperature (800-950 oC), process duration (30-120 min), CO2 flow rate (400 and 600 cc/min) and heating rate (5 and 10 oC/min) were the variables examined in this study. The effect of parameters on the specific surface area (SSA) of activated carbon was studied, and the influential parameters were identified employing analysis of variance (ANOVA). The optimum conditions for maximum SSA were: carbonization temperature=650 oC, carbonization time=60min, heating rate=5 oC/min, activation temperature= 900 oC, activation time=60min and CO2 flow rate=400 cc/min. The most effective parameter was activation temperature with an estimated impact of 49%. The activated carbon produced under optimum conditions was characterized by pore and surface structure analysis, iodine adsorption test, ash content, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The process yield for optimized activated carbon was 13.2% with the following properties: specific surface area=437m2/g, total pore volume=0.353 cc/g, iodine number=404.7mg/g and ash content=13.9% along with an amorphous structure and a lot of oxygen functional groups. These properties are comparable to those of commercial activated carbons.

열수가압탄화에 의해 제조한 폐목재 바이오차 (Bio-char) 활성탄의 특성화에 관한 연구

원민희,조우리,장진만,박지수,이재영 한국폐기물자원순환학회 2022 한국폐기물자원순환학회지 Vol.39 No.3

The market for activated carbon is growing due to environmental awareness and strengthening of environmental regulations. Biochar is a solid carbide that is produced through a hydrothermal carbonization (HTC) process. Wood is an ideal raw material for activated carbon and biomass waste wood because it has low energy consumption rates and does not require pre-treatment to remove moisture. The activated carbon samples in this study were prepared by a chemical activation process using KOH, which is mainly used for activation. The study analyzed the specific surface area, pore volume, pore size, and pore distribution by selecting four samples with high iodine adsorption capacity among the prepared activated carbon samples. The specific surface area for all four samples was between 1192.2 and 1387.1 m2/g, all of which were over 1,000 m2/g, and the pore volume was between 0.6510 and 0.8030 cm3/g. During this process, micropores with an average pore size of 21 to 25 Å were formed. SEM photography revealed that these pores were uniform and that the number of pores increased according to activation levels of the carbon samples. When the iodine adsorptivity and specific surface area of commercial activated carbon was compared with that of activated carbon prepared by waste wood biochar with KOH, the specific surface area was higher in the activated carbon samples prepared by waste wood biochar with KOH. These results indicate that the adsorption of activated carbon by waste wood biochar with KOH is successful when applied to activated carbon samples.

알칼리금속과 알칼리 토금속 촉매 담지 대나무 활성탄의 NO 가스 반응 특성

박영철 ( Young Cheol Bak ),최주홍 ( Joo Hong Choi ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.5

The impregnated alkali metal (Na, K), and the alkali earth metal (Ca, Mg) activated carbons were produced from the bamboo activated carbon by soaking method of alkali metals and alkali earth metals solution. The carbonization and activation of raw material was conducted at 900 oC. The specific surface area and the pore size distribution of the prepared activated carbons were measured. Also, NO and activated carbon reaction were conducted in a thermogravimetric analyzer in order to use for de-NOx agents of the used activated carbon. Carbon-NO reactions were carried out in the nonisothermal condition (the reaction temperature 20~850 oC, NO 1 kPa) and the isothermal condition (the reaction temperature 600, 650, 700, 750, 800, 850 oC, NO 0.1~1.8 kPa). As results, the specific volume and the surface area of the impregnated alkali bamboo activated carbons were decreased with increasing amounts of the alkali. In the NO reaction, the reaction rate of the impregnated alkali bamboo activated carbons was promoted to compare with that of the bamboo activated carbon [BA] in the order of BA(Ca)> BA(Na)> BA(K)> BA(Mg) > BA. Measured the reaction orders of NO concentration and the activation energy were 0.76[BA], 0.63[BA(Na)], 0.77[BA(K)], 0.4 [BA(Ca)], 0.30 [BA(Mg)], and 82.87 kJ/mol[BA], 37.85 kJ/mol[BA(Na)], 69.98 kJ/mol[BA(K)], 33.43 kJ/mol[B (Ca)], 88.90 kJ/mol [BA(Mg)], respectively.

Sorption of $Pb^{2+}$ Ions on to Activated Carbons Prepared from Olive Stones

Attia, Amina. A.,Shouman, Mona. A.,El-Nabarawy, Th. Korean Carbon Society 2005 Carbon Letters Vol.6 No.3

The carbon sample "O", phosphoric acid-activated carbon "OP", zinc chloride-activated carbon "OZ", and two steam activated carbons "OS" and "OS2" with different burn-off of 25% and 58% respectively, were prepared from olive stones. The textural properties were determined from the results of nitrogen adsorption at 77 K and by analyzing these results through the application of different adsorption models. The chemistry of the carbon surfaces was determined from the base neutralization capacities, acid neutralization capacity and surface pH. The sorption of $Pb^{2+}$ ions on to the carbons prepared was followed under dynamic and equilibrium conditions. The differences between the values of the textural parameters were attributed to the inapplicability of some adsorption models and to the heterogeneity of the microporous carbons. The sorption of $Pb^{2+}$ ions is favored on carbon and activated carbons. However, chemically activated carbons are more effective compared with steam-activated ones. The sorption of $Pb^{2+}$ ions were related to the chemistry of the surface rather than to the textural properties.

Vapor Phase Mercury Removal by Sulfur Impregnated Activated Carbons and Sulfur Impregnation Protocol

Lee, Si-Hyun,Cha, Sun-Young,Park, Yeong-Seong 한국탄소학회 2001 Carbon Letters Vol.2 No.1

Mercury has been identified as a potential health and environmental hazardous material. Activated carbon adsorption offers promising potential for the control of mercury emissions, and sulfur impregnated (sulfurized) activated carbons has been shown to be an effective sorbent for the removal of vapor phase $Hg{\circ}$ from sources. In this work, vapor phase mercury adsorption by sulfur impregnated activated carbons were investigated. Sulfur impregnated activated carbons were made by variation of impregnation temperature, and the comparison of adsorption characteristics with commercial virgin and sulfurized carbons were made. Factors affecting the adsorption capacity of virgin and sulfurized activated carbons such as pore characteristics, functional groups and sulfur impregnation conditions were discussed. It was found that the sulfur allotropes plays a critical role in adsorption of mercury vapor by sulfurized activated carbons.

배추를 이용한 활성탄 제조에 관한 연구

이성헌,이봉헌,박흥재 한국환경과학회 2001 한국환경과학회지 Vol.10 No.5

In recent years, the demand of activated carbon has been increasing steadily because of the environmental problems. Among them waste and water treatment and removal of poisonous gas were involved. Therefore, in this study, activated carbon was made from the waste chinese cabbage and measured the iodine adsorption ability, carbonization yield, and activation yield of the produced activated carbon. The result showed that the carbonization yield was decreased when carbonization temperature was increased and that the optimal carbonization temperature was 600℃. The optimal concentration of NaOH for removing ash in the raw sample was 1∼2N. The range of iodine adsorption number of activated carbon using chinese cabbage at 600℃ carbonization was 610.82㎎/g to 1019.58㎎/g. The activation result of carbonization sample showed that the optimal activation condition was the carbonization at 400℃ and the activation at 700℃. So the production of activated carbon using chinese cabbage was possible in the aspect of reuse of resource and decrease of environmental pollution compared to the commercial activated carbon.

분체공학,유동층,고분자,재료(무기, 유기) : 금속(Ag, Cu, Co)함유 활성탄소섬유의 미세공도와 금속입자의 거동

임광순 ( Im Gwang Sun ),엄상용 ( Eom Sang Yong ),유승곤 ( Yu Seung Gon ),( Dan D. Edie ) 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.4

Metal (Ag, Cu, Co)salts were mixed to reformed petroleum pitches for production of metal-containing carbon fibers. The carbon fiber was steam activated to investigate the microporosity and the behaviour of metal particles in activated carbon fiber. The melt spinning temperature of precursor pitch linearly increased as the metal content increased. Cobalt and copper-containing carbon fibers were decomposed after 400℃, silver-containing and non-metal containing carbon fibers were decomposed after 480℃ in air. The average pore diameter and specific surface area of non-metal containing activated carbon fibers were 20 Å and 1,100 ㎡/g. The activation rates of metal-containing carbon fibers increased by catalytic acceleration of metals. Average pore diameter and mesopore fraction of metal-containing activated carbon fiber increased as the metal content increased, however, specific surface area decreased. The metal-containing activated carbon fibers showed peaks corresponding to their own metal. Silver particles were uniformly distributed in activated carbon fibers, while copper and cobalt particles tended to coalesence and some of coalesced copper exited from activated carbon fibers resulting in macropores on the surface of activated carbon fibers during the steam activation.