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Characterization and Regeneration of Carbonaceous Substrate Produced from Biotic Precursors and its Use for the Waste Water Treatment

Alam, Sultan (2008) Characterization and Regeneration of Carbonaceous Substrate Produced from Biotic Precursors and its Use for the Waste Water Treatment. PhD thesis, University of Peshawar, Peshawar .

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Abstract

Low cost agricultural waste material (Corncobs-CC) and fast growing wood (Paulownia tomentosa-PT Populus caspica-PC, Ailanthus allissima-AA, Salvadora oleoides.S0) and animal bones were utilized for the preparation of activated carbon. Industrial spent carbon was also regenerated. The carbon samples were activated chemically and by thermal means (400-1000°C). The samples were characterized by pH, moisture content, ash content, bulk density, surface area (BET, DR, BJH, Langmuir) with pore volume, MR, XRD, SEMI and EDS. The BET (m29'1) surface area analysis of the carbon samples activated at 800 °C showed that SO has greatest surface area of 587 m2g-1. The surface area of other carbon samples activated at 800 T was found in the sequence: 418 for SO > 412 for CC > 398.29 for PC > 387 for AA > 219 for PT > 140.23 for ABC. DR method was used for the determination of micropore volume using NOWWin2 computer software. For the 800'C activated carbon samples the pore volume was in the sequence: 0.23 for PC > 0.220 for SO, RG > 0.21 for CC > 0.20 for AA, 0.11 for PT > 0.100 for ABC. FTIR analysis showed that the carbon surface carried the oxygen containing functional groups, which disappeared at high activation temperatures. 'Mc XRD analysis using ORIGIN-50 computer software showed that carbon, hydrogen, nitrogen, oxygen, boron, chromium, fluorine, nitrogen and molybdenum were present in the carbon samples. The EDS analysis showed high carbon contents in the sample activated at high temperature as compared to Raw and 400 °C activated samples while the contents of oxygen was found to decrease with the increase in activation temperature. Other elements like sulfur, potassium, chlorine, silica, iron, magnesium, copper, phosphorus, sodium, calcium, aluminum and molybdenum were found in trace amounts. The rate of adsorption of dyes on the carbon samples was high in the initial fifteen seconds and then declined due to its diffusion in to the micropores. From the first order kinetics the rate constants were determined which were found to be high at high temperatures of adsorption /sample activation. The high activation energy of the dye adsorption on the Raw and 400 T activated carbon samples was due to the presence of polar functional groups at the pore openings that blocked the entrance of the dye molecules, thus raising the energy barrier. Negative values of entropy of activation (AS') of the dyes adsorption reflected the affinity of the dye molecules towards the carbon surface which were found to decrease with the increase in adsorption temperature. The dye molecules thus have acquired a more stable oriented position on the surfaces at high temperature of adsorption/ sample activation. The linear plots of Bangham and intraparticle diffusion models showed that the adsorption of dye on the carbon surface is a diffusion controlled process. The Freundlich, Langmuir and DR models were used to estimate the adsorption parameters. The best fit of the isotherms, found from the correlation coefficients (r2 ) were in the sequence: DR > Langmuir > Freundlich. Distribution coefficients of the dyes on the surfaces of carbon activated at different temperatures were found to be in the sequence: Dc1000oc > Dc900oc > Dc800oc > Dc600oc > Dc400oc> DcRAW .The industrial waste water was treated by column adsorption. Thomas model was used to derive the adsorption capacity (mot g'') of the carbon samples for the dye and also for Ni+2, Cu+2 and Zn+2 adsorption from the industrial waste water.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Characterization, Regeneration, Carbonaceous, Substrate, Biotic, Precursors, Waste, Water, Treatment
Subjects:Physical Sciences (f) > Chemistry(f2)
ID Code:6732
Deposited By:Mr. Javed Memon
Deposited On:21 Jul 2011 14:30
Last Modified:21 Jul 2011 14:30

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