Power generation in MFCs with architectures based on tubular cathodes or fully tubular reactors

2011 ◽  
Vol 64 (11) ◽  
pp. 2253-2258 ◽  
Author(s):  
Y. Zuo ◽  
B. E. Logan
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Power Density ◽  
Specific Surface Area ◽  
Microbial Fuel Cells ◽  
High Surface ◽  
Tubular Reactor ◽  
Total Surface Area ◽  
Carbon Cloth ◽  
Surface Areas

Tubular cathodes provide a method to obtain high surface areas for scaling up microbial fuel cells (MFCs), but the importance of the cathode shape is not known. We therefore examined power production using cathodes in various configurations (tubes or flat). The MFC with a single internal carbon cloth tube cathode (71 W/m3) produced more power than previously obtained with an ultrafiltration membrane (8 W/m3) due to the better performance of carbon material. This power density was slightly less than that of a flat carbon cloth cathode (81 W/m3; 88 m2/m3) due to the lower total surface area of the tube (68 m2/m3) and not as a result of the tubular cathode shape. Adding a second tube increased power (83 W/m3) in proportion to specific surface area (93 m2/m3). Wrapping the cathode completely around the anode formed a fully tubular MFC (external tubular reactor) with a higher surface area that produced 128 W/m3. Volumetric power density was highly correlated with cathode specific surface area (R2 = 0.93, p = 0.008) and did not depend on the cathode shape (tubes, completely tubular, or flat). Thus, future MFC designs should focus on increasing cathode specific surface area.

scholarly journals Adsorption of pharmaceuticals from aqueous solutions using biochar derived from cotton gin waste and guayule bagasse

Biochar ◽  
2020 ◽  
Author(s):  
Marlene C. Ndoun ◽  
Herschel A. Elliott ◽  
Heather E. Preisendanz ◽  
Clinton F. Williams ◽  
Allan Knopf ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Functional Groups ◽  
Specific Surface Area ◽  
High Surface ◽  
Strong Interactions ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Cotton Gin Waste ◽  
Cotton Gin

Abstract Biochars produced from cotton gin waste (CG) and guayule bagasse (GB) were characterized and explored as potential adsorbents for the removal of pharmaceuticals (sulfapyridine-SPY, docusate-DCT and erythromycin-ETM) from aqueous solution. An increase in biochar pyrolysis temperature from 350 οC to 700 οC led to an increase in pH, specific surface area, and surface hydrophobicity. The electronegative surface of all tested biochars indicated that non-Coulombic mechanisms were involved in adsorption of the anionic or uncharged pharmaceuticals under experimental conditions. The adsorption capacities of Sulfapyridine (SPY), Docusate (DCT) and Erythromycin (ETM) on biochar were influenced by the contact time and solution pH, as well as biochar specific surface area and functional groups. Adsorption of these pharmaceutical compounds was dominated by a complex interplay of three mechanisms: hydrophobic partitioning, hydrogen bonding and π–π electron donor–acceptor (EDA) interactions. Despite weaker π–π EDA interactions, reduced hydrophobicity of SPY− and increased electrostatic repulsion between anionic SPY− and the electronegative CG biochar surface at higher pH, the adsorption of SPY unexpectedly increased from 40% to 70% with an increase in pH from 7 to 10. Under alkaline conditions, adsorption was dominated by the formation of strong negative charge-assisted H-bonding between the sulfonamide moiety of SPY and surface carboxylic groups. There seemed to be no appreciable and consistent differences in the extent of DCT and ETM adsorption as the pH changed. Results suggest the CG and GB biochars could act as effective adsorbents for the removal of pharmaceuticals from reclaimed water prior to irrigation. High surface area biochars with physico-chemical properties (e.g., presence of functional groups, high cation and anion exchange capacities) conducive to strong interactions with polar-nonpolar functionality of pharmaceuticals could be used to achieve significant contaminant removal from water. Graphic Abstract

Surface Analysis of Etched Molar Enamel by Gas Adsorption

2008 ◽  
Vol 87 (6) ◽  
pp. 532-536 ◽  
Author(s):  
M.F. Orellana ◽  
A.E. Nelson ◽  
J.P.R. Carey ◽  
G. Heo ◽  
D.G Boychuk ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Gas Adsorption ◽  
Third Molar ◽  
Dental Enamel ◽  
Total Surface Area ◽  
Gas Absorption ◽  
Etch Pattern

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson’s Correlation Coefficient showed a lack of relationship between etch pattern and total surface area.

Nanoporous zero-valent iron

2005 ◽  
Vol 20 (12) ◽  
pp. 3238-3243 ◽  
Author(s):  
Jiasheng Cao ◽  
Patrick Clasen ◽  
Wei-xian Zhang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Performance Enhancement ◽  
Zero Valent Iron ◽  
Iron Particles ◽  
Surface Areas ◽  
Batch Tests ◽  
Resin Beads ◽  
Solid Iron

Hollow and nanoporous particles of zero-valent iron (ZVI) were prepared with template-directed synthesis. Polymer resin beads (0.4 mm diameter) were coated with nanoscale iron particles by reductive precipitation of ferrous iron [Fe(II)] with sodium borohydride. The resin was calcinated at 400 °C to produce hollow and nanoporous iron spheres. The nanoporous iron oxides were then reduced to metallic iron by hydrogen at 500 °C. Scanning electron microscope images of the reduced iron spheres showed that the particles were hollow. The shell thickness was approximately 5 μm and highly porous. Brunauer–Emmett–Teller specific surface area was 2100 m2/kg. In comparison, the theoretical specific surface area of solid iron particles of the same size is just 1.9 m2/kg. Batch tests showed that the surface area normalized reactivity of the porous particles were 14–31% higher than microscale iron particles with similar surface areas for the transformation of hexavalent chromium [Cr(VI)], azo dye Orange II {4-[(2-hydroxyl-1-naphthalenyl)azo]-benzenesulfonic acid monosodium}, and trichloroethene. The combined performance enhancement (larger surface area and higher surface activity) is significant (>1200 times).

Effect of ZnO Particle Size on the Curing of Carboxylated NBR and Carboxylated SBR

2004 ◽  
Vol 77 (2) ◽  
pp. 214-226 ◽  
Author(s):  
G. R. Hamed ◽  
K.-C. Hua
Keyword(s):  
Zinc Oxide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Cure Rate ◽  
Surface Areas ◽  
Diffusion Limited ◽  
Rate Of Dissolution ◽  
Oxide Particles ◽  
And Diffusion

Abstract A carboxylated nitrile rubber (XNBR) and a carboxylated SBR (XSBR) were mixed with zinc oxide particles of different specific surface areas (“S”, 35 m2/g; “M”, 3.5m2/g; “L”, 0.5 m2/g) and cure behavior at 165 ºC studied using oscillating disc rheometry. Without added zinc oxide, both raw rubbers slowly stiffen over many hours of heating. This is probably due to condensation of carboxyl groups to form anhydride crosslinks. XNBR compositions containing the finely divided “S” crosslink much more rapidly. Full cure is reached after about 10 minutes of heating. Cure rate decreases markedly as the specific surface area of the ZnO decreases. A composition containing “M” at twice stoichiometry requires about an hour to cure well, while with “L”, about 10 hours are required. In contrast, curing of the XSBR depends little on the specific surface area of the ZnO, either with “S” or “L”, curing is essentially complete after 30 minutes. After simply mixing ZnO into either rubber, it remains as a dispersed particulate. With XNBR, curing appears to be controlled by the rate of dissolution and diffusion of ZnO, while, with XSBR, reaction is not diffusion limited and may be confined to regions near particle surfaces.

Structure and Catalytic Soot Combustion of Perovskite La-Mn-O Hollow Microfibers via Gel-Precursor Transformation Process

2012 ◽  
Vol 538-541 ◽  
pp. 2289-2292
Author(s):  
Xiao Xiao Meng ◽  
Feng Lin He ◽  
Jiang Ying Shen ◽  
Xiang Qian Shen
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
Thermo Gravimetric Analysis ◽  
Transformation Process ◽  
High Catalytic Activity ◽  
Gravimetric Analysis ◽  
Soot Combustion ◽  
Aspect Ratios

The nanocrystalline perovskite La-Mn-O hollow microfibers were prepared by the gel-precursor transformation process from reagents of metal salts and citric acid. The gel precursor and resultant products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The specific surface area was measured by the Brunauere-Emmette-Teller method. The catalytic performance of soot combustion was evaluated by thermo-gravimetric analysis under model conditions. The nanocrystalline La-Mn-O hollow microfibers calcined at 650 °C for 6 h are characterized with diameters of 2-8 µm, aspect ratios (length/diameter) about 5-15, a micro-tunnel with an estimated ratio 1/3 of the hollow diameter to fiber diameter, and a high specific surface area of 36.7 m2/g that is 1.9 times higher than the counterpart nanosized powder. This nanocrystalline La-Mn-O hollow microfibers catalyst exhibit a high catalytic activity for the soot combustion, with a low T50 of 397°C, which is largely owing to the high surface area and the micro-tunnel structure.

A Comparison of Methods for Determining Surface Areas of Carbon Black

1973 ◽  
Vol 46 (1) ◽  
pp. 192-203 ◽  
Author(s):  
R. A. Klyne ◽  
B. D. Simpson ◽  
M. L. Studebaker
Keyword(s):  
Carbon Black ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Surface Areas ◽  
Furnace Black ◽  
Area Increase ◽  
Experimental Errors ◽  
Specific Surface Areas ◽  
Surface Area Increase

Abstract 1. The various tint tests correlate with each other—it does not make much difference which of the three procedures is used. The discrimination between similar blacks is comparable. Specific surface areas obtained by the three methods are comparable and differences appear to be due to experimental errors. (Compare Figures 5–7). 2. Surface areas larger than some 90 to 100 m2/g cannot be reliably determined from tint strength measurements alone. 3. Structure exerts a pronounced effect on tint strength of furnace blacks, especially above 90 to 100 m2/g. Porosity and/or composition are apparently also variables which affect tinting strength. 4. Densichron reflectance on the dry carbon black can be used to estimate specific surface areas up to about 140 m2/g; but, since theabsoluteerrorincreases as the specific surface area increases, this method loses some of its reliability at values above about 110 m2/g. The relative error in reflectance determinations does not vary greatly over the furnace-black range. Densichron reflectance is influenced by composition, evidently due to composition-related differences in optical properties of the carbons. 5. In CTAB adsorption measurements, titration errors and handling errors tend to be rather constant for blacks of different surface area. Hence, CTAB permits better discrimination among blacks of small particle size. 6. The errors in Densichron reflectance surface area increase with specific surface area. Hence, the deviations between CTAB and reflectance surface area which are due to experimental error increase with the surface area of the sample.

scholarly journals A Case Study of Waste Scrap Tyre-Derived Carbon Black Tested for Nitrogen, Carbon Dioxide, and Cyclohexane Adsorption

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4445 ◽  
Author(s):  
Zuzana Jankovská ◽  
Marek Večeř ◽  
Ivan Koutník ◽  
Lenka Matějová
Keyword(s):  
Activated Carbon ◽  
Carbon Black ◽  
Specific Surface ◽  
Surface Area ◽  
Sorption Capacity ◽  
Specific Surface Area ◽  
Textural Properties ◽  
Pyrolytic Carbon ◽  
Surface Areas ◽  
Wide Range

Waste scrap tyres were thermally decomposed at the temperature of 600 °C and heating rate of 10 °C·min−1. Decomposition was followed by the TG analysis. The resulting pyrolytic carbon black was chemically activated by a KOH solution at 800 °C. Activated and non-activated carbon black were investigated using high pressure thermogravimetry, where adsorption isotherms of N2, CO2, and cyclohexane were determined. Isotherms were determined over a wide range of pressure, 0.03–4.5 MPa for N2 and 0.03–2 MPa for CO2. In non-activated carbon black, for the same pressure and temperature, a five times greater gas uptake of CO2 than N2 was determined. Contrary to non-activated carbon black, activated carbon black showed improved textural properties with a well-developed irregular mesoporous-macroporous structure with a significant amount of micropores. The sorption capacity of pyrolytic carbon black was also increased by activation. The uptake of CO2 was three times and for cyclohexane ten times higher in activated carbon black than in the non-activated one. Specific surface areas evaluated from linearized forms of Langmuir isotherm and the BET isotherm revealed that for both methods, the values are comparable for non-activated carbon black measured by CO2 and for activated carbon black measured by cyclohexane. It was found out that the N2 sorption capacity of carbon black depends only on its specific surface area size, contrary to CO2 sorption capacity, which is affected by both the size of specific surface area and the nature of carbon black.

scholarly journals N, S-Codoped Activated Carbon Material with Ultra-High Surface Area for High-Performance Supercapacitors

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1982
Author(s):  
Qinghua Yuan ◽  
Zhuwen Ma ◽  
Junbiao Chen ◽  
Zhenrui Huang ◽  
Zeming Fang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Material ◽  
High Surface ◽  
Koh Activation ◽  
Supercapacitor Electrode ◽  
Tobacco Stalk

The recycling of macromolecular biowastes has been a problem for the agriculture industry. In this study, a novel N, S-codoped activated carbon material with an ultrahigh specific area was produced for the application of a supercapacitor electrode, using tobacco stalk biowastes as the carbon source, KOH as the activating agents and thiourea as the doping agent. Tobacco stalk is mainly composed of cellulose, but also contains many small molecules and inorganic salts. KOH activation resulted in many mesopores, giving the tobacco stem-activated carbon a large specific surface area and double-layer capacitance. The specific surface area of the samples reached up to 3733 m2·g−1, while the maximum specific capacitance of the samples obtained was up to 281.3 F·g−1 in the 3-electrode tests (1 A·g−1). The doping of N and S elements raised the specific capacitance significantly, which could be increased to a value as high as 422.5 F·g−1 at a current density of 1 A·g−1 in the 3-electrode tests, but N, S-codoping also led to instability. The results of this article prove that tobacco stalks could be efficiently reused in the field of supercapacitors.

Experimental Studies of Carbon Electrodes With Various Surface Area for Li–O2 Batteries

2019 ◽  
Vol 16 (4) ◽  
Author(s):  
Fangzhou Wang ◽  
P. K. Kahol ◽  
Ram Gupta ◽  
Xianglin Li
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Discharge Capacity ◽  
Carbon Materials ◽  
High Specific Surface Area ◽  
Acetylene Black ◽  
Carbon Electrodes ◽  
Tea Leaves ◽  
Surface Areas

Li−O2 batteries with carbon electrodes made from three commercial carbons and carbon made from waste tea leaves are investigated in this study. The waste tea leaves are recycled from household tea leaves and activated using KOH. The carbon materials have various specific surface areas, and porous structures are characterized by the N2 adsorption/desorption. Vulcan XC 72 carbon shows a higher specific surface area (264.1 m2/g) than the acetylene black (76.5 m2/g) and Super P (60.9 m2/g). The activated tea leaves have an extremely high specific surface area of 2868.4 m2/g. First, we find that the commercial carbons achieve similar discharge capacities of ∼2.50 Ah/g at 0.5 mA/cm2. The micropores in carbon materials result in a high specific surface area but cannot help to achieve higher discharge capacity because it cannot accommodate the solid discharge product (Li2O2). Mixing the acetylene black and the Vulcan XC 72 improves the discharge capacity due to the optimized porous structure. The discharge capacity increases by 42% (from 2.73 ± 0.46 to 3.88 ± 0.22 Ah/g) at 0.5 mA/cm2 when the mass fraction of Vulcan XC 72 changes from 0 to 0.3. Second, the electrode made from activated tea leaves is demonstrated for the first time in Li−O2 batteries. Mixtures of activated tea leaves and acetylene black confirm that mixtures of carbon material with different specific surface areas can increase the discharge capacity. Moreover, carbon made from recycled tea leaves can reduce the cost of the electrode, making electrodes more economically achievable. This study practically enhances the discharge capacity of Li−O2 batteries using mixed carbons and provides a method for fabricating carbon electrodes with lower cost and better environmental friendliness.

Valorization of cellulose-doped lignin: application of cellulose-doped lignin-derived activated carbon in capacitors and investigation of its textural properties and electrochemical performance

2021 ◽  
Author(s):  
Liangcai Wang ◽  
Xin Feng ◽  
Huanhuan Ma ◽  
Jielong Wu ◽  
Yu Chen ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Wall Thickness ◽  
Textural Properties ◽  
Pore Wall ◽  
Surface Areas ◽  
Pore Wall Thickness

Abstract This work provides an idea for efficient and harmless utilization of lignin and further evaluated the textural properties of lignin-derived activated carbon/specific capacitance relationship. The yield of cellulose-doped apricot shell lignin (ASLC) was 30.42%. H3PO4/KOH was used to assist the preparation of ASLC-derived activated carbon (AAC) for capacitors. The specific surface areas of the as-obtained AAC-P-3 and AAC-K-2 were 1475.16 m2/g and 2136.56 m2/g, respectively. The specific capacitances of AAC-P-3 and AAC-K-2 were 169.14 F/g and 236.00 F/g, respectively, upon the current density of 0.50 A/g. In capacitors containing aqueous KOH as the electrolyte, the AR2 (0.983) between specific surface area and specific capacitance was highest, followed by the AR2 (0.978) between Vmicro/Vmeso and specific capacitance, the AR2 (0.975) between pore-wall thickness and specific capacitance. Consequently, the specific capacitances of the AACs depend not only the specific surface area, but also on the Vmicro/Vmeso, pore-wall thickness, and Vmicro.

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