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Soodabeh Khalili Ali Asghar Ghoreyshi Mohsen Jahanshahi Kasra Pirzadeh 《洁净——土壤、空气、水》2013,41(10):939-948
In this study, crude multi‐walled carbon nanotubes (MWCNT) was functionalized by a two‐step process; first using strong mixed acids (H2SO4/HNO3) and then treatment with 1,3‐phenylenediamine (mPDA). The equilibrium adsorption of CO2 on pristine MWCNT and amine functionalized MWCNT (MWCNT‐NH2) were investigated. Experiments were preformed via application of volumetric method in a dual sorption vessel at temperature range of 298–318 K and pressures up to 40 bars. The results obtained indicated that the equilibrium uptake of CO2 increased after functionalizing of MWCNT. The increase in CO2 capture by MWCNT‐NH2 was attributed to the existence of great affinity between CO2 molecules and amine sites on this adsorbent at low pressures. The experimental data were analyzed by means of Freundlich and Langmuir adsorption isotherm models. The data obtained revealed a fast kinetics for the adsorption of CO2 in which most of adsorption occurred at initial period of adsorption experiments. This renders MWCNT as a suitable adsorbent for practical applications. Values of isosteric heat of adsorption were evaluated based on Clausius–Clapeyron equation. The results demonstrated that both chemisorption and physisorption played important role in CO2 adsorption on MWCNT‐NH2, whereas the physisorption process was dominant for CO2 adsorption on MWCNT. 相似文献
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This work explored the performance of sesame stalk‐based carbon prepared at different carbonization temperatures and activated by potassium hydroxide in the removal of phenanthrene from an aqueous solution. At a carbon concentration of 10 mg/32 mL and a carbonization temperature of 700°C, the removal efficiency of phenanthrene approached 100%. Furthermore, with the presence of acenaphthene and naphthalene as co‐contaminants, the removal efficiency of phenanthrene by the prepared carbon was 99.60%, which was comparable to that by the commercial carbon. Hydrophobic interactions influenced phenanthrene removal, and partitioning appeared to be the dominant mechanism for phenanthrene removal from aqueous solution by sesame stalk‐based carbon. The results obtained from this work should provide insight into the reuse of agricultural residues, and also suggest a new avenue for the removal of polycyclic aromatic hydrocarbons from contaminated water utilizing carbon prepared from agricultural residue. 相似文献
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Dissolved organic carbon (DOC) distributions in water from Lake Ipê, MS, Brazil, were investigated. The samplings were performed monthly (surface, 1 m depth, and bottom) from June 1999 to June 2000. Absorbance at 285 nm and DOC concentrations in mg dm—3, p(DOC), were highly correlated for the three depths. 77% of the surface, 85% for 1 m and bottom samples presented a variation between 20 dm3 g—1 cm—1 and 50 dm3 g—1 cm—1 of A(285 nm)/p(DOC), that characterizes the dissolved organic matter in lake water as essentially fulvic. The ratio A(254 nm)/p(DOC) was also sensitive for fulvic matter, and an A(250 nm)/A(365 nm) = 4 ratio was characteristic of strongly colored waters. The ratios A(436 nm)/p(DOC) for the three depths also showed a significant correlation. The predominance of fulvic acid is explained by environmental characteristics such as the tropical climate, temperatures above 18 °C, and the lake environment. It was demonstrated that the variation in the water carbon content due to different compartments in the lake can be monitored by UV‐vis spectroscopy ratios. 相似文献
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Phenol is one of the main pollutants in phenol wastewater and has been proved non‐biodegradable. In this study, based on strongly ring‐opening capability of boron doped diamond film electrode, a highly efficient and energy‐saving method with ultra‐low carbon emission is established through a combination of electrochemical oxidation and biological degradation. On one hand, electrochemical oxidation as pretreatment can solve the critical problem that phenol wastewater is a biological recalcitrant. On the other hand, the relatively low current efficiency during the late stage of electrochemical oxidation can be solved by follow‐up biological treatment, thus reduce the energy consumption and the cost significantly. More importantly, the carboxylic acids (oxidized from phenol) can be fully used as carbon source (no additional carbon source is added) for microbial growth instead of being oxidized to carbon dioxide and water through selecting optimizing sequencing batch reactor access time, so the carbon emission is greatly reduced. The results showed that it can save about 76.5% energy consumption and about 51.2% chemical oxygen demand can be used to maintain microorganism self‐reproduction. This is significant that this combined technology not only runs highly effectively at low cost, but also reduces the emission of greenhouse gas, carbon dioxide, thus environment friendly with wide application prospects. 相似文献
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Carbon pools in stream‐riparian corridors: legacy of disturbance along mountain streams of south‐eastern Wyoming 
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下载免费PDF全文 Streams and their accompanying riparian environments are intrinsic components of terrestrial carbon cycling. However, they have been understudied in terms of the magnitude of their storage components and the role of disturbance in determining carbon storage capacity. This study presents partial carbon budgets for stream‐riparian corridors along six study reaches in mountain headwater streams of southeast Wyoming to evaluate the impact of tie‐driving, a historic disturbance legacy, on contemporary carbon storage. Detailed measurements of biomass were collected for in‐stream components of carbon including fine and coarse particulate organic matter and in‐stream large wood. Biomass was also estimated for riparian components including standing trees (live and dead), regenerating conifers, shrubs and herbaceous vegetation, downed wood, litter, and duff (partially decayed litter). Biomass was converted to carbon for all components and differences in storage were compared between tie‐driven and non‐driven reaches. Carbon content in riparian soils (to approximately 20 cm) was also measured. Twice the amount of carbon was stored in the riparian areas relative to the streams; most carbon was stored in standing trees (live and dead). While overall carbon storage within the riparian areas and streams were similar between disturbance conditions, the amount of carbon stored in large in‐stream wood and downed wood on the floodplain was significantly higher in systems that were not tie‐driven. The results of this study indicate that legacies of tie‐driving influence carbon storage within the region, while also capturing baseline estimates of carbon storage in the wake of recent bark beetle infestations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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The adsorption performance of β‐ionone on four types of granular activated carbon (GAC) in water was investigated through batch experiments. The effect of initial β‐ionone concentrations and natural organic matter (NOM) adsorbed on GAC, adsorption kinetic and isothermal models were also studied. The results showed that four types of GAC all had good adsorption performance for β‐ionone, the equilibrium adsorption amount of the GAC employed was in the order of YK > GK > MZ‐A > MZ‐B. The adsorption amount increased with increasing initial concentrations. The presence of NOM could reduce adsorption of β‐ionone to a certain extent, and small molecular weight (MW) fractions (particularly <1000 Da) exhibited a remarkably competitive effect on the adsorption of β‐ionone. The experimental data showed good correlation with pseudo‐first‐order model. Furthermore, adsorption of β‐ionone on GAC fitted Freundlich, Langmuir, and Tempkin isotherms in the range of experimental concentrations, but followed Freundlich isothermal model most appropriate. The thermodynamic parameters were calculated by the results of the experiment, which showed adsorption of β‐ionone on GAC as being endothermic and spontaneous. 相似文献
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A series of chlorinated mesoporous activated carbons were derived from waste tires by pyrolysis, activation, and chlorination at different temperatures. The physical and chemical properties of the samples were studied by Brunauer–Emmett–Teller (BET) analysis, Fourier Transform IR Spectroscopy (FT‐IR), point of zero charge measurement, thermogravimetric analysis, and by testing their behavior as adsorbents for toluene removal. Our results showed that the tire‐derived activated carbon samples have highly mesoporous volumes and surface areas, and chlorination treatment has a slight effect on the pore structure. Lewis acidity of the sample increases after chlorination and the chlorine content increases from 0.24 to 2.32% with chlorination temperature increasing from 50 to 400°C. The higher the chlorine content, the more is the toluene adsorption. In comparison with the commercial carbon (F‐400), all the samples have significantly higher adsorption capacity for toluene due to the presence of mesopores, inductive effect of the partial positive chemisorbed chlorine and resonance effects of C? Cl structures. The mesopores probably render easier diffusion of toluene molecule to inner carbon matrix and the strong π–π interaction between toluene and C? Cl resonance structure in the carbon significantly affects the interplay bonding process thus enhances the toluene removal. 相似文献
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Tidal flats, which are important reserved land resources, have a vital role in climate change. To evaluate the contribution of coastal saline soils to carbon sequestration, field tests were performed over a 3 year period at the Dafeng Wanggang Experimental Station in Jiangsu Province, China. Six artificial agro‐ecosystems, including wasteland (WL), freshwater fish culture (FC), Sesbania culture (SC), barley culture (BC), mixed culture of fish and Sesbania (MCFS) and mixed culture of fish and barley (MCFB), were established according to developmental processes of coastal saline soils. At the initial stage of tidal flat reclamation, the soil organic carbon (SOC) increased by 59.4 t ha?1 in the FC system during 3 years, which was much higher than that of the WL system (40.7 t ha?1). When the tidal flats evolved into high saline soils, the MCFS system sequestered SOC more effectively than the FC or SC systems with increases of 53.1, 16.9 and 8.3 t ha?1, respectively. Subsequently, in the low saline soils, the maximum soil carbon sequestration was obtained in the MCFB system (35.8 t ha?1) followed by the BC (17.5 t ha?1) and FC (13.5 t ha?1) systems. Therefore, proper development of tidal flats to farmland and the subsequent establishment of optimised artificial agro‐ecosystems make an important contribution to carbon sequestration and climate changes in coastal areas. 相似文献
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A simple and rapid soft‐templating coupled with one‐pot solvent thermal method is developed to synthesize S‐doped magnetic mesoporous carbon (S‐doped MMC). In this method, phenolic resin is used as a carbon precursor and Pluronic copolymer P123 is used as a template and 2,5‐dimercapto‐1,3,4‐thiadiazole is used as sulfur source. Prepared S‐doped MMC processes a high specific surface area, the Fe3O4 particles are well embedded in the mesoporous carbon walls that exhibit a strong magnetic response, and the hydrated iron nitrate loading amount of 0.808 g is the best. Batch adsorption experiments are carried out at different pH, initial concentration, temperature, and contact time on the adsorption of methyl orange (MO) by S‐doped MMC. The kinetic data of the adsorption process are better fitted with pseudo‐second‐order model than the pseudo‐first‐order model. Langmuir model is more suitable for the equilibrium data than Freundlich model. The thermodynamic parameters including ΔG0, ΔH0, and ΔS0 indicate that the adsorption is a feasible, spontaneous, and endothermic process. Finally, it is found that the coexistence of PO43?, NO3?, SO42?, Cl?, and CO32? does not influence the adsorption process. These results illustrate S‐doped MMC can be an efficient adsorbent for the removal of MO from wastewater. 相似文献
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