Gas-phase mercury removal through sulfur impregnated porous carbon

K. Suresh Kumar Reddy,Ahmed Al Shoaibi,C. Srinivasakannan 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

Gas phase mercury removal is a vital unit operation in gas processing industries. The present work attempts to prepare a sulfur impregnated carbon at optimized experimental conditions and compares its elemental adsorption capacity with the number of commercially available carbon based adsorbents. The effect of adsorption temperature on mercury adsorption capacity has been estimated for the prepared sulfur impregnated carbon. The adsorption capacity was found to increase with increase in adsorption temperature owing to the chemisorption nature of the adsorption. The adsorption isotherms were generated at three different temperatures and were found to close adhere to the Langmuir Isotherm model. The adsorption capacity was found to increase until 140℃, while decrease beyond, which was attributed to the softening and agglomeration of sulfur. The maximum adsorption capacity of 4325 mg/g was observed at a temperature of 140℃. A comparison of the relative adsorption capacity of various adsorbent at 30℃, revealed the adsorption capacity of the sulfur impregnated carbon prepared in the present work much higher than the commercially available carbons. The high adsorption capacities with simple preparation techniques favor the commercial mercury adoption process.

천연 제올라이트의 수환경 개선용 기능성 소재로의 활용에 관한 연구 (2): 국내산 제올라이트의 중금속 이온 흡착 특성

노진환 ( No Jin Hwan ) 한국광물학회 2003 광물과 암석 (J.Miner.Soc.Korea) Vol.16 No.3

The adsorption property and ability of domestic zeolites for some heavy metal ions (Ag, Pb, Cr, Cu, Zn, Mn), which may cause a serious environmental problem in industrial wastewater, were evaluated on ore unit through a series of adsorption experiments together with careful examinations of mineral composition and properties of the zeolites. Though the adsorption behavior basically took place in the form of a cation exchange reaction, the higher CEC value does not necessarily to imply the higher adsorption capacity for a specific heavy metal. A general trend of the adsorption selectivity for heavy metals in the zeolites is determined to be as follow: Ag≥Pb>Cr,Cu≥Zn>Mn, but the adsorption properties of heavy metal ions somewhat depend on the species and composition of zeolite. Clinoptilolite tends to adsorb selectively Cu in case of Cr and Cu, whereas heulandite prefers Cr to Cu. A dominant adsorption selectivity of the zeolite ores for Ag and Pb is generally conspicuous regardless of their zeolite species and composition. The zeolite ores exhibit a preferential adsorption especially for Ag^(+) so as not to regenerate when treated with Na^(+). In the adsorption capacity for heavy meta ions, the zeolites differ in great depending on their species: ferrierite>clinoptilolite>heulandite. Considering the CEC value of mordenite, the mordenite-rich ore appears to be similar to the clinoptilolite ore in the adsorption capacity. The adsorption capacity for heavy metals is not positively proportional to the CEC values of the zeolites measured by the exchange reaction with ammonium ion. In addition, the adsorption capacity roughly tends to depend on the zeolite contents, i.e., the grade of zeolite ore, but the trend is not consistent at all in some ores. These may be caused by the adsorption selectivity for some specific heavy metals, the presence of possible stacking micro-faults and natural cations such as K hardly to exchange in the zeolite. Considering the economic availability and functional effectiveness as natural zeolite resources, clinoptilolite ores could be applicable to utilize the domestic zeolites for the removal of heavy metals.

공기 중 유기용제 농도수준이 방독마스크 정화통의 활성탄 흡착용량에 미치는 영향

박두용,Park, Doo-Yong 한국환경보건학회 2011 한국환경보건학회지 Vol.37 No.1

The adsorption capacity of charcoal is a function of the airborne concentration of the target chemical. To evaluate the adsorption capacity of charcoal packed in the cartridges of air purifying respirators, breakthrough tests were conducted with carbon tetrachloride for three commercial cartridges (3M models #7251, #6000 and AX) at 25, 50, 100, 250 and 500 ppm. Adsorption capacities were calculated using a mass transfer balance equation derived from the curve fitting to the breakthrough curves obtained experimentally. Carbon micropore volumes were estimated by iteration to fit the Dubinin/Radushkevich (D/R) adsorption isotherm. They were 0.6566, 0.5727 and 0.3087 g/cc for #7251, #6000 and the AX cartridge, respectively. Above 100 ppm (at high challenge concentrations), #7251 and #6000 showed higher adsorption capacities. However, as the challenge concentration decreased, the adsorption capacities of #7251 and #6000 sharply dropped. On the other hand, the adsorption capacity of the AX cartridge showed little change with the decrease of the challenge concentration. Thus, the AX showed a higher adsorption capacity than #7251 and #6000 at the 5-50 ppm level. It is concluded that service-life tests of cartridges and adsorption capacity tests of charcoal should be conducted at challenge concentration levels reflecting actual working environmental conditions. Alternatively, it is recommended to use the D/R adsorption isotherm to extrapolate adsorption capacity at low concentration levels from the high concentration levels at which breakthrough tests are conducted, at a minimum of two different concentration levels.

Efficient removal of methylene blue in aqueous solution by freeze-dried calcium alginate beads

Yafei Zhao,Hongsong Zhang,Guangxue Liu,Zonggao Hu,Rouwen Guan,Bing Zhang 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.11

Novel porous calcium alginate beads were prepared via crosslinking of calcium followed by freeze drying for investigating the adsorption performance for methylene blue. These beads possessed reduced shrinkage, highly porous lamellar structure and high specific surface area, and exhibited enhanced adsorption capacity and much faster adsorption rate compared to the non-porous beads obtained with conventional oven drying method. Methylene blue adsorption capacity increased with increasing of initial concentration and pH, while decreased with increasing of temperature. The adsorption process fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm. The maximum adsorption capacity was 961.5mg g−1 at 298.15 K. After eight successive adsorption-desorption cycles, the adsorption capacity had negligible decrease. Owing to the high adsorption capability, rapid adsorption rate, easy recovery and reusability, the freeze-dried beads imply a prospective, biodegradable and attractive adsorbent for removing contaminants from wastewater.

대기용 활성탄의 흡착능 평가 방법과 다성분 VOCs 유입 조건에서의 기준 제안

김나현,안해영,이태호,송지현 한국냄새환경학회 2022 실내환경 및 냄새 학회지 Vol.21 No.4

Quality standards of activated carbon for gas-phase applications have been deleted from the Korean national standard list since 2007, and the iodine adsorption test is the only measure currently used for quality assurance. This study was performed to propose a suitable test method and a quality standard for gas-phase activated carbon. The "1/2 saturated vapor adsorption" test has been developed as a simple and convenient method to determine the adsorption capacity of activated carbon. In this study, the developed test method was evaluated using model VOCs including toluene, methyl ethyl ketone (MEK), and ethyl acetate (EA). A virgin activated carbon revealed adsorption capacities of 344 mg/g, 322 mg/g, and 328 mg/g for toluene, EA, and MEK, respectively, and the adsorption capacity for a mixture of the three VOCs was 334 mg/g. When a regenerated activated carbon was applied, the adsorption capacities dramatically decreased to 62 mg/g, 52 mg/g, and 61 mg/ g for toluene, EA, and MEK, respectively. In addition, the 1/2 solvent vapor adsorption tests using 13 different specimens of activated carbon showed that their capacities were closely related to the iodine adsorption numbers, and this study suggested the adsorption capacity of 300 mg/g as a new quality standard. The novel test method and its standard may help to guarantee the quality of gas-phase activated carbon used for VOCs abatement processes. .

오존수 산화를 이용한 활성탄 흡착탑의 현장 재생 시 흡착용량 및 구조특성의 변화

이진주 ( Jinjoo Lee ),이기세 ( Kisay Lee ) 한국공업화학회 2020 공업화학 Vol.31 No.3

하폐수처리 및 정수처리에 사용되는 활성탄 흡착 공정에서 기존의 활성탄 열재생법 비해 활성탄 손실과 불완전 연소로 인한 오염물질 발생도 적으며, 사용 활성탄의 인발-재생-재충진에 소요되는 시간의 절약이 가능한 재생 방법으로 오존수를 이용한 in situ regeneration에 대한 기초연구를 수행하였다. 활성탄 흡착 컬럼 상에서 페놀(phenol) 및 PEG를 흡착 파과 시킨 후 오존수 접촉으로 흡착물질을 분해 제거하는 흡착-재생 싸이클을 반복하였다. 오존수 접촉에 의한 재생 횟수가 증가할수록 페놀 흡착용량은 어느 정도 감소하지만, 일정 수준으로의 감소 후에는 구조 변화가 안정화되어 추가적인 감소가 일어나지 않았다. 흡착 용량이 감소하는 이유는 오존과의 반응에 의해 활성탄의 미세공 크기가 증가하면서 비표면적이 감소하기 때문으로 나타났다. 이러한 세공 크기의 변화와 비표면적의 변화로 인하여 재생 후 in-pore adsorption이 우세한 페놀과 같은 저분자량 물질의 흡착효율은 감소하게 되나 external adsorption 비율이 큰 PEG와 같은 고분자량 물질의 흡착효율은 크게 영향을 받지 않았다. 세공 크기 및 비표면적의 변화는 오존수와의 접촉시간이 길어질수록 심화되므로 제거하려는 물질의 크기를 고려하고 접촉시간을 조절함으로써 흡착 효율의 유지를 제어하는 것이 필요하다. An in situ regeneration of activated carbon bed using an ozonated water was studied in order for avoiding the carbon loss, contaminant emission and time consuming for discharge-regeneration-repacking in a conventional thermal regeneration process. Using phenol and polyethylene glycol (PEG) as adsorbates, the adsorption breakthrough and in situ regeneration with the ozonated water were repeated. These organics were supposed to degrade by the oxidation reaction of ozone, regenerating the bed for reuse. As the number of regeneration increased, the adsorption capacity for phenol was reduced, but the change was stabilized showing no further reduction after reaching a certain degree of decrement. The reduction of adsorption capacity was due to the increase of pore size resulting in the decrease of specific surface area during ozonation. The adsorption capacity of phenol decreased after the ozonated regeneration because the in-pore adsorption was prevalent for small molecules like phenol. However, PEG did not show such decrease and the adsorption capacity was constantly maintained after several cycles of the ozonated regeneration probably because the external surface adsorption was the major mechanism for large molecules like PEG. Since the reduction in the pore size and specific surface area for small molecules were proportional to the duration of contact time with the ozonated water, careful considerations of the solute size to be removed and controlling the contact time were necessary to enhance the performance of the ozonated in situ regeneration of activated carbon bed.

Applicability of Industrial Sisal Fiber Waste Derived Activated Carbon for the Adsorption of Volatile Organic Compounds (VOCs)

Melike Dizbay-Onat,Evan Floyd,Uday K. Vaidya,Claudiu T. Lungu 한국섬유공학회 2018 Fibers and polymers Vol.19 No.4

Agricultural waste produced by the industry is a huge threat for the global environment. Utilization of agricultural waste is necessary and there is an urgent need to develop new techniques to solve this important problem. The main objective of this research was to evaluate the applicability of the activated carbon (AC) derived from industrial sisal fiber waste as passive samplers in monitoring toluene by comparing them to industry standard wafer and granular activated carbon (GAC). Carbonization time and ball milling effect on sisal fiber derived AC sample adsorption properties were investigated. Toluene adsorption isotherms were used to predict toluene adsorption capacities. Surface characteristics including surface area and pore volume were used to determine the relationships between them and adsorption capacity. Even though prepared AC samples have mesoporous structure, commercial samples have microporous structure. Surface area from 1245 m2/g to 1297 m2/g and toluene adsorption capacity from 21.4 % to 26.6 % was improved by increasing carbonization time from 1 h to 3 h at 650 oC carbonization temperature and 94.4 ml/min flow rate. Conversely, ball milling technique had negative effect by decreasing the surface area (674 m2/g) and the adsorption capacity of toluene (12.27 %). It is concluded that industrial sisal fiber waste have great potential as a precursor of AC for application in passive monitoring against toluene, particularly the produced mesoporous AC with 3 h carbonization time performs higher adsorption capacity (26.6 %) than commercially available microporous passive sampler (24.1 %) and GAC (22.8 %).

K계열 함침 탄소계 흡착제의 실내 저농도 이산화탄소 흡착성능 강화

정세은,이유리,원유섭,김재영,장재준,김하나,조성호,박영철,남형석,Jeong, Se-Eun,Wang, Shuang,Lee, Yu-Ri,Won, Yooseob,Kim, Jae-Young,Jang, Jae Jun,Kim, Hana,Jo, Sung-ho,Park, Young Cheol,Nam, Hyungseok 한국화학공학회 2022 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.60 No.4

Relatively high indoor CO₂ concentration (>1,000 ppm) has a negative impact on human health. In this work, indoor CO₂ adsorbent was developed by impregnating KOH or K₂CO₃ on commercial activated carbon, named as KOH/AC and K₂CO₃/AC. Commercial activated carbon (AC) showed relatively high BET surface area (929 m²/g) whereas KOH/AC and K₂CO₃/AC presented lower BET surface area of 13.6 m²/g and 289 m²/g. Two experimental methods of TGA (2,000 ppmCO₂, weight basis) and chamber test (initial concentration: 2,000 ppmCO₂, CO₂ IR analyzer) were used to investigate the adsorption capacity. KOH/AC and K₂CO₃/AC exhibited similar adsorption capacities (145~150 mg_CO2/g), higher than K₂CO₃/Al+Si supports adsorbent (84.1 mg_CO2/g_sample). Similarly, chamber test also showed similar trend. Both KOH/AC and K₂CO₃/AC represented higher adsorption capacities (KOH/AC: 93.5 mg_CO2/g K₂CO₃/AC: 94.5 mg_CO2/g_sample) K₂CO₃/Al+Si supports. This is due to the KOH or K₂CO₃ impregnation increased alkaline active sites (chemical adsorption), which is beneficial for CO₂ adsorption. In addition, the regeneration test results showed both K-based adsorbents pose a good regeneration and reusability. Finally, the current study suggested that both KOH/AC and K₂CO₃/AC have a great potential to be used as CO₂ adsorbent for indoor CO₂ adsorption.

고정층 활성탄 흡착반응기에서 기상 톨루엔의 흡착특성

임진관,이송우,감상규,이동환,이민규 한국환경과학회 2005 한국환경과학회지 Vol.14 No.1

Adsorption characteristics of toluene vapor, which is one of important source of volatile organic compounds (VOCs), by activated carbon were investigated using a fixed bed adsorption column. The operating parameters such as breakthrough curve, adsorption capacity. mass transfer zone (MTZ), and length of unused bed (LUB) were studied. The experimental results showed that the breakthrough time decreased with increasing inlet toluene concentration and gas flow rate. MTZ and LUB increased with the increase of inlet concentration, gas flow rate, and particle size of activated carbon. The adsorption capacity increased with the increase of inlet toluene concentration, while it decreased with increasing particle size. However, it was kept at constant value regardless of the increase of gas flow rate. Adsorption isotherm of toluene vapor could be represented by the Freundlich adsorption equation fairly well. From the adsorption experiments using some VOC gases such as toluene, xylene, butyl acetate. butanol and acetone, it was also found that the adsorption capacity was higher in the case of gas with higher boiling point and lower vapor pressure.

담수조건에서 미세플라스틱인 폴리에틸렌과 폴리프로필렌의 납 흡착특성

엄주현 ( Ju-hyun Eom ),서동철 ( Dong-cheol Seo ) 한국환경농학회 2018 한국환경농학회 학술대회집 Vol.2018 No.-

In the both marine and freshwater environments, microplastics and heavy metals such as Pb, Cd, Cr and Hg are considered a global threat to various marine and freshwater animals, and the interaction between these two pollutants are poorly understood. Microplastics such as polyethylene and polypropylene have received less attention in the freshwater environments than in the marine environments. The objective of this research was to investigate the Pb absorption capacity by microplastic polyethylene and polypropylene to estimate the Pb adsorption behavior by microplastic in freshwater ecosystems. The Pb adsorption characteristics by polyethylene and polypropylene were evaluated using both the Freundlich and Langmuir adsorption isotherm equations. Langmuir model for polyethylene and polypropylene provides a slightly better fit than the Freundlich model for Pb adsorption in all stages. The results demonstrate that the adsorption characteristic of Pb by polyethylene and polypropylene is mainly monolayer adsorption. The maximum Pb adsorption capacity of polyethylene was higher than that in polypropylene.