Preparation of activated carbons from oil-palm shells, physical activation as well as by combined steam and chemical activation was investigated in great detail to study the process parameters. In physical activation, a two-step procedure was used: pyrolysis followed by activation. Steam was used as the physical activation agent. The resulting activated carbons were studied using scanning electron microscope (SEM) for its morphology and characterized by accelerated surface area and porosimetry

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... ystem to determine the pore surface areas and pore size distributions. Pyrolysis develops the rudimentary pore structure in the char. The pyrolysis parameters will influence the active surface area of the chars and therefore the reactivity of the chars. Activation, after pyrolysis, is used to increase the pore surface area and pore volume of the activated carbon. A combined chemical and physical activation process was investigated. Potassium carbonate was used as the chemical activation agent. The results indicated that the catalytic effect of potassium and the thermal decomposition of carbonic anion in chemical activation played different roles on micropore and nonmicropore structure development. The activated carbons were used to study the adsorption of phenol aqueous solution. It was found that the adsorption capacity increased linearly with the BET surface area. This linear relationship was not applicable to activated carbons prepared under varying activation parameters. The aqueous phase adsorption capacity of the combined physically and chemically activated carbon was found not to be significantly greater than the physically activated carbons due to the blockage effect to the pore surface by the products of chemical reaction. Amongst all the activated carbons prepared, the highest BET ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library iv surface area was 1432 m 2 /g. For aqueous phase adsorption tests, the highest phenol adsorption capacity was 275 mg of phenol per gram of activated carbon at 30 o C. The use of the activated carbon in one component aqueous phase adsorption was studied systematically. This study included the thermodynamic, kinetic and dynamic aspects. Gas chromatography-mass spectrometry was used to analyze the chemicals in the aqueous phase. Results from the aqueous phase adsorption indicated that the equilibrium data could be correlated by the Langmuir isotherm. The correlation of the kinetic adsorption data with the Langmuir isotherm confirmed that the Langmuir equation was adequate to depict the behaviour of single component system. Batch kinetic experimental data showed a dual-rate nature of adsorption onto the activated carbon. A proposed branched pore kinetic model fitted the experimental data well and was able to predict the performance of phenol -activated carbon system. The model is called the concentration dependent branched pore kinetic model (CDBPKM). Regression analysis to estimate the adsorption parameters was used to optimize the correlation between the experimental data and the CDBPKM model. In the CDBPKM, the concentration dependent effective diffusion coefficient was introduced into the traditional branched pore kinetic model. With this coefficient, the model can better predict the kinetic behaviour of the activated carbon in aqueous phase adsorption. CDBPKM simulated dual rates of concentration decay curves with correlation coefficients around 0.98. Theoretical study indicates that adsorption is controlled by the external mass transfer at the very early stage and then intraparticle diffusion is predominant till equilibrium is reached. Adsorption into the micropores becomes significant when the nonmicropore region is saturated. The most fundamental parameter affecting the concentration decay is the fraction of total adsorptive capacity in the ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library v nonmicropore region. This effect indicates the importance of adsorbent surface characteristics in the adsorption process. The potential application of activated carbon in aqueous phase adsorption was demonstrated by fixed bed adsorption study. Series of column tests were carried out for the adsorption of phenol by activated carbons. The effects of operation conditions of the fixed bed on the breakthrough curves were studied. A linear driving force model based on the solid phase concentration difference (LDFQ model) was used to simulate the fixed bed adsorption dynamics. The agreement between the model and the experimental data was good. Correlated mass transfer coefficient and fixed bed parameters provide information for fixed bed adsorption design.