The use of low cost and ecofriendly adsorbent has been investigated as an alternative to the current expensive method ofremoving dyes from wastewater. Cow dung cakes were collected from the nearby village which was burnt in a mufle furnaceat 50oC to obtain the required ash. This paper deals with the removal of Reactive Blue 221, Acidoll Yellow 2GNL and OliveBGL which are mainly used in textile industry, from aqueous solution by cow dung ash without any pretreatment. Theadsorption was achieved under different pH, adsorbate concentration and the applicability of Langmuir and Freundlichisotherms were examined.
Carbon/TiO2 composites were prepared by Cl4 solvent mixing method with different mixing ratios. Since the carbon layersderived from pitch on the TiO2 particles were porous, the carbon/TiO2 composite series showed a god adsorptivity and photodecomposition activity. The BET surface area for the carbon layer in the sample increases to increasing with pitch contents.The SEM results present to the characterization of porous texture on the carbon/TiO2 composite and pitch distributions on thesurfaces for all the materials used. From XRD data, a weak and broad carbon peak of graphene with pristine anatase peakswere observed in the X-ray diffraction patterns for the carbon/TiO2. The EDX spectra show the presence of C, O and S withstrong Ti peaks. Most of these samples are richer in carbon and major Ti metal than any other elements. Finally, the excellentphotocatalytic activity of carbon/TiO2 with slope relationship between relative concentration (C/C0) of MB and t could beattributed to the homogeneous coated pitch on the external surface by CCl4 solvent method.
Molecular sieving carbon (MSC) for separating O2-N2 and CO2-CH4 has been prepared through chemical vapor deposition(CVD) of methane and benzene on activated carbon spheres (ACS) derived from polystyrene sulfonate beads. The validity ofthe material for assesment of molecular sieving behavior for O2-N2 and CO2-CH4 pair of gases was assessed by the kineticadsorption of the corresponding gases at 25oC. It was observed that methane cracking on ACS lead to deposition of carbonmostly in whole length of pores rather than in pore entrance, resulting in a reduction in adsorption capacity. MSC showinggood selectivity for CO2-CH4 and O2-N2 separation was obtained through benzene cracking on ACS with benzene entrantmentof 0.40×104 g/ml at cracking temperature of 725oC for a period of 90 minutes resulting in a selectivity of 3.31:1.00 for O2-N2and 8.00:1.00 for CO2-CH4 pair of gases respectively.
Microporous carbons with narrow pore size distribution have been successfully synthesized by using hydrolyzed andcomposites were prepared by solution route. Subsesequently, silica templates were removed by HF leaching. Resultingcarbons were steam activated. The porous carbons were characterized by nitrogen adsorption-desorption isotherm, SEM,FTIR analysis, iodine adsorption, thermogravimetry analysis, etc. Adsorption isotherms show that the porous carbon preparedfrom calcined silica as templates are microporous with 88% pores of size <2 nm porosity and are of type I isotherm, whileporous carbon prepared by using hydrolyzed silica are microporous with 89% microporosity, shows hysteresis loop at highrelative pressure indicating the presence of some mesoporosity in samples. The microporosity in porous carbon materials hasa bearing on the nature of silica templates used for pore formation.
The carbon brake discs were manufactured by densification the carbon fiber preform using PG-CVI technology withdensification time. The results indicate that the densification rate is more rapid before 100 hrs than after 200 hrs. The CT-scanning image and the SEM technology were used to observe the inner subtle structure. CT-images show the densitydistribution in the carbon brake disc clearly. The carbon brake disk made by PG-CVI is not very uniform. There is a densitygradient in the bulk. The high-density part in the carbon brake is really located in the friction surface, especially in the part ofinner circle. This density distribution is most suitable for the stator disc.
Oxidized PAN (OXI-PAN) fibers were used for the precursors of activated carbon fiber in study. How drying temper-ature affected the properties of carbon fibers on activating process of carbon fibers was investigated. The specific sur-face areas of activated carbon fibers have been determined on a series of chemicaly activated carbons with KOH andNaOH. The experimental data showed variations in specific surface area, iodine and silver adsorptions by the activatedods. This was because the ionic radius of iodine was smaller than the interior micropore size of activated carbon fibers.Silver adsorbed well in NaOH activated carbon fibers rather than KOH activated carbon fibers in this study.
Carbon nanofiber (CNF) grown catalytically was chemically activated with KOH to attain structural change of CNF.BET, it was found that KOH activation was effective to develop particular sizes of pores on the CNF surface, increas-ing the surface area of CNF. Activated CNF was aplied as an anode catalyst support of fuel cell. The efects of difer-ent activation conditions including the activation temperature and the activation time on the specific surface area of theCNF activated with KOH were investigated to obtain appropriate structure as a catalyst support. The 60 wt% Pt-Ru cat-alyst prepared was observed by using TEM and XRD.
The influences of various carbonization temperatures on electrical resistivity and morphologies of polyacrylonitrileobserved by a scaning electron microscope. The electrical resistivity behaviors of the webs were evaluated by a vol-ume resistivity tester. From the results, the volume resistivity of the carbon webs was ranged from 5.1×101 Ω·cm to3.0×102 Ω·cm, and the average diameter of the fiber webs was varied in the range of 310 to 160 nm with increasingthe carbonization temperature. These results could be explained that the graphitic region of carbon webs was formedafter carbonization at high temperatures. And the amorphous structure of polymeric fiber webs was significantlychanged to the graphitic crystalline, resulting in shrinking the size of fiber diameters.