During a 4-year period (2001-2005) 09 animals were surgically treated because of abdominal wall defects (hernia). Out of 9animals 8 were bovines and one caprine. In each case the defect was repaired with carbon fibre mesh. All the cases weresuccessfully treated and no complication was observed up to six months postoperatively.
CTC grade, 12×30 BSS particle size and 104 m2/g surface area, was impregnated with metal salts such Cu, Cr, Ag, Mo andZn, and an organic compound Triethylene diamine (TEDA) to prepare different carbon systems such as whetlerite, whetlerite/TEDA, whetlerite/KI/KOH and ASZMT. The prepared adsorbents along with active carbon were characterized for surfacearea and pore volume by N2 adsorption at liquid nitrogen temperature. These carbon systems were compared for their CT(concentration X time) values at 12.73 to 53.05 cm/sec space velocities and 2 to 5 cm carbon column bed heights. The carbon3.712 mg/L iodine vapour concentration and 12.73 cm/sec space velocity. The study clearly indicated the adsorption capacitiesof carbon systems to be directly proportional to their surface area values. Dead layer with all the prepared carbon systems wasfound to be less than 2.0 cm indicating it to be minimum bed height to have protection against I2 vapours. Effect of carbon bedheight and flow rate was also studied. The active carbon showed maximum protection at all bed heights and flow rates incomparison to all other impregnated carbon systems, showing that only physical adsorption is responsible for the removal ofiodine vapours.
Samples of active carbon of 1150 m2/g surface area were impregnated with ammoniacal salts of copper, chromium and silver,with and without triethylenediamine. The samples of impregnated carbon were aged at 50oC, with and without 90% RH(relative humidity), for a little more than one year and chemically evaluated periodically. Initially copper (II) and chromium(VI) reduced very fast in the samples in humid atmosphere to the extent of 30% and 60% respectively in four months. Thesevalues were found to be unaffected by the presence of triethylenediamine (TEDA) indicating that the chemical did not retardwas significantly less (10-12%, w/w) in four months. It was quite evident; therefore, that the moisture was mainly responsiblefor the reduction of chromium (VI) and coper (II) species in impregnated carbons. The prolonged ageing of the samples withand without triethylenediamme after four months with and without humid atmosphere showed that the extent of reduction ofchromium (VI) was very low, i.e. 5-10% and of coper (II) was 2-25%. Silver is not reduced due to carbon, as it remainedunchanged in concentration on storage. The impregnated carbon samples (100 g) without triethylenediamine, which were agedconcentration of 4 mg/L and airflow rate of 30 lpm showed a high degree of protection (80- 110 minutes).
Carbon materials of various morphologies were synthesized by pyrolysis of Soap-nut seeds (Sapindus mukorossi), JackFruit seeds (Artocarpus heterophyllus), Date-seeds (Phoenix dactylifera), Neem seeds (Azadirachta indica), Tea leaves(Ehretia microphylla), Bamboo stem (Bambusa bambus) and Coconut fiber (Cocos nucifera), without using any catalyst.Carbon materials thus formed were characterized by SEM XRD and Raman. Carbon thus synthesized varied in size (in .m)but all showed highly porous morphology. These carbon materials were utilized as the anode in Lithium secondary battery.Amongst the various precursors, carbon fibers obtained from Soap-nut seeds (Sapindus mukorossi) and Bamboo stem(Bambusa bambus), even after 100th cycles, showed the highest capacity of 130.29 mAh/g and 92.74 mAh/g respectively.Morphology, surface areas and porosity of carbon materials obtained from these precursors were analyzed to providenmaterials assist in the intercalation of lithium. Size of cavity (or pore size of channels type structure) present in carbonmaterials were found to facilitate the intercalation of lithium.
In order to investigate functional groups on the surface of Multi-walled Carbon Nanotubes (MWCNTs) induced byoxyfluorination, XPS (X-ray photoelectron spectroscopy) analysis was carried out. All core level spectra of MWCNTs weredeconvoluted to several Pseudo-Voigt functions (sum of Gaussian-Lorentzian functions). Both O1s and F1s binding energy ofconcentration increased as increment of fluorine mixing ratio. The shape and intensity of OF10-MWCNTs are similar withthose of as-received MWCNTs. However, the intensity and binding energies of main peak position of OF20-MWCNTs andOF30-MWCNTs were dramatically increased by oxyfluorination.
oC followed by gasification with steam at950oC to burn-of’s=17, 32, 49 and 65%. The textural parameters of these activated carbons were determined from nitrogenadsorption results at 77 K. The total pore volume and the mean pore radius increased with the increase of % burn-of whereasthe surface area increased with the increase of burn- off from 17 to 32 and further to 49%. Further increase of burn-off to 65%was associated with a considerable decrease in surface area as a result of pronounced pore widening due to pore erosion. Thesurface pH values of the carbons investigated range between 7.1 and 8.2. The adsorption of oxamyl onto the activated carbonadsorption of oxamyl proved to be of the physical type and took place in non-micropores. The amount of oxamyl adsorbedexpressed as qm depends to a large extent to the surface area located in non-micropores S.n, where a straight line relationshippassing through the origin was obtained.
A method for evaluating bulk sensitive structural characteristics of unpurified, as-purified, and acid treated single walledcarbon nanotubes (SWNTs) was described in the present study. The optical spectra of SWNT solutions were well resolvedafter prolonged sonication and they were correlated to the diameter and the distribution of nanotubes. The acid-treatedSWNTs were similar to as-purified SWNTs in terms of catalyst residue, radial breathing mode (RBM) in the Raman spectra,and the first band gap energy of semiconducting tubes in the optical spectra. The solution phase optical spectra were moresensitive to changes in the small diameter and metallic tubes after the acid treatment than were the RBM spectra.
In the present study, electrospun PAN precursor webs and the stabilized and carbonized nanofiber webs processed underdiferent heat-treatment conditions were characterized by means of weight loss measurement, elemental analysis, scanningelectron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), diferentialscanning calorimetry (DSC), thermogravimentric analysis (TGA), and X-ray diffraction (XRD) analysis. The result indicatedthat stabilization and carbonization processes with different temperatures and heating rates significantly influenced thecarbonized nanofiber webs from PAN precursor webs. It was noted that the filament diameter and the carbon content of acarbonized nanofiber web as well as its weight change may be effectively monitored by controlling both stabilization andcarbonization processes.
The oxygen and nitrogen enriched activated carbons were obtained from modification of commercial activated carbon by usingnitric acid, sodium hydroxide and urea. Zeta-potentials of modified activated carbons were investigated in relation to copper ionadsorption. The structural properties of modified activated carbons were not so much changed, but the zeta-potentials andthan other activated carbons in the entire pH region, and the pHIEP was shifted from pH 4.8 to 2.6, resulted in the largest copperion adsorption capacities compare with other activated carbons in the range of pH 3~6.5. In case of urea modified activatedcarbon, copper ion adsorption was larger than that of the as-received activated carbon from pH 2 to pH 6.5 even though the pHIEPwas shifted to pH 6.0, it was due to the coordination process operated between nitrogen functional groups and copper ion. Theadsorption capacity of copper ion was much influenced by zeta-potential and pHIEP of carbon adsorbent.
In this study, graphite composites were fabricated by warm pres molding method to realize comercialization ofPEM fuel cells. Graphite composites have ben considered as alternative economic materials for bipolar plate of PEMfuel cells. Graphite powder that enables to provide electrical conductivity was selected as the main substance. Thegraphite powder was mixed with phenolic resin and the mixture was pressed using a warm press method.First of all, the graphite powder was pulverized with a ball mill for the dense packing of composite. As the bal milingtime increases, the average size of particles decreases and the size distribution becomes narow. This alows forimprovement of the uniformity of graphite composite. However, the surface electrical resistivity of graphite compositethe surface due to the friction and collision of particles during pulverizing. We found that the contact electrical resistiv-ity of graphite particles increases as the particle size decreases.The contact electrical resistivity of graphite powders was reduced due to high molding presure by warm pres mold-ing. This leads to improvement of the mechanical properties of graphite composite. Hydrogen gas impermeability wasmeasured with the graphite composite, showing a possibility of the application for bipolar plate in fuel cell. And, I-Vcurves of the graphite composite bipolar plate exhibit a similar performance to the graphite bipolar plate.
Carbon/silicon composites were synthesized by mixing silicon powders with petroleum pitch and subsequent heat-treatment. The resultant composites were composed of carbon and nano-size crystalline silicon identified by XRD andEDX. FIB images and SEM images were taken respectively to detect the existence of silicon impregnated in carbonand the distribution of silicon on the carbon surface. The obtained carbon/silicon materials were assembled as half cellanodes for lithium ion secondary battery and their electrochemical properties were tested. The pitch/silicon compositeoC and mixed with 55.5 wt.% of graphite showed relatively good electrochemicalproperties such as the initial efficiency of 78%, the initial discharge capacity of 605 mAh/g, and the discharge capacityof 500 mAh/g after 20 cycles.