Non-competitive adsorption of polycyclic aromatic hydrocarbons (PAHs) from water onto activated carbon was studied alongside the performance of CO2-activated petroleum coke as a low-cost adsorbent. PAH adsorption was a two-stage process: a short, fast initial period followed by a long, slow period corresponding to the intra-particle diffusion of PAH molecules in macropores and micropores. The adsorption capacity was determined by total surface area accessible to PAH and the availability of active surface chemical groups. The positive dependence of adsorption capacity on surface oxygen groups and temperature was observed, suggesting a chemical nature of PAH adsorption. The interaction between PAH-activated carbon was however, weak and energetically similar to that of hydrogen bonds. Overall, PAH adsorption was an exothermic process that combined physisorption and chemisorption. CO2-activated petroleum coke had a greater SSA-normalized capacity than coal-derived commercial activated carbon (0.26 vs. 0.19 mg/m2). The capacity was significantly increased by post-oxidation to 0.62 mg/m2.

Non-competitive adsorption of polycyclic aromatic hydrocarbons (PAHs) from water onto activated carbon was studied alongside the performance of CO2-activated petroleum coke as a low-cost adsorbent. PAH adsorption was a two-stage process: a short, fast initial period followed by a long, slow period corresponding to the intra-particle diffusion of PAH molecules in macropores and micropores. The adsorption capacity was determined by total surface area accessible to PAH and the availability of active surface chemical groups. The positive dependence of adsorption capacity on surface oxygen groups and temperature was observed, suggesting a chemical nature of PAH adsorption. The interaction between PAH-activated carbon was however, weak and energetically similar to that of hydrogen bonds. Overall, PAH adsorption was an exothermic process that combined physisorption and chemisorption. CO2-activated petroleum coke had a greater SSA-normalized capacity than coal-derived commercial activated carbon (0.26 vs. 0.19 mg/m2). The capacity was significantly increased by post-oxidation to 0.62 mg/m2.

Petroleum coke-derived activated carbons were prepared and used for the adsorptive removal of a single-ring naphthenic acid (NA) from synthetic oil sands tailings pond water (TPW). The overall adsorption process was found to be intra-particle diffusion-controlled. The Weber-Morris intra-particle diffusion rate constants decreased from 7.43 to 1.23 mg/g min0.5 after activated carbon was post-oxidized with oxygen, suggesting a hindering effect of oxygen surface groups. The Freundlich model fit of the equilibrium adsorption isotherms and the small negative ΔHo pointed to a physisorption-dominated process and the importance of specific surface area. It was estimated that about 2.7 g/L of basic CO2-activated carbon is needed to reduce NA concentration from 120 mg/L to 2.5 mg/L (~98% removal) in synthetic TPW. However, equilibrium adsorption capacity was found to vary significantly after oxygen or nitrogen groups were introduced onto the surface. Therefore, there is a potential for enhanced adsorption by chemical functionalization of carbon.

The technical feasibility of producing sulphur-impregnated activated carbons (SIACs) from high-sulphur fluid coke by chemical activation was investigated. Using KOH and SO2, the activation process was able to produce SIACs with controllable specific surface area (SBET), pore size distribution and sulphur content. The highest SBET was over 2500 m2/g and the highest sulphur content was 8.1 wt%. K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy was employed to characterize the sulphur in fluid cokes and SIACs. The results revealed that the sulphur on fluid coke surface was mainly in the form of organic sulphide and thiophene (total 91-95 %), in addition to some sulphate (5 - 9%). The study of KOH-treated fluid coke suggested that KOH was effective in converting organic sulphide and thiophene to water soluble inorganic species which were readily removed by acid and water washing. SO2 treatment of fluid coke added sulphur to fluid coke through SO2-carbon reaction. Elemental sulphur was the main product, while part of the thiophene, sulphide and sulphate in the raw coke remained in the product. In KOH-SO2 activation, disulphide, sulphide, sulphonate and sulphate were identified on SIAC surface; no thiophene was found, suggesting a complete removal of thiophene. Sulphur content in specific forms in SIACs was therefore controllable by varying the ratio of KOH, SO2 and fluid coke. SIACs produced from KOH-SO2 activation showed a comparable Hg2+ adsorption capacity (43 – 72 mg/g) with those reported in the literature (35-100 mg/g) and that of a commercial SIAC (41 mg/g). Although a larger SBET often resulted in a greater Hg2+ adsorption capacity, the benefit started to diminish when SBET was greater than about 1000 m2/g. A statistically significant and positive correlation was found between Hg2+ adsorption capacity and total sulphur content. Elemental sulphur and reduced sulphur were largely responsible for the enhanced Hg2+ adsorption.

Petroleum coke-derived activated carbons were prepared and used for the adsorptive removal of a single-ring naphthenic acid (NA) from synthetic oil sands tailings pond water (TPW). The overall adsorption process was found to be intra-particle diffusion-controlled. The Weber-Morris intra-particle diffusion rate constants decreased from 7.43 to 1.23 mg/g min0.5 after activated carbon was post-oxidized with oxygen, suggesting a hindering effect of oxygen surface groups. The Freundlich model fit of the equilibrium adsorption isotherms and the small negative ΔHo pointed to a physisorption-dominated process and the importance of specific surface area. It was estimated that about 2.7 g/L of basic CO2-activated carbon is needed to reduce NA concentration from 120 mg/L to 2.5 mg/L (~98% removal) in synthetic TPW. However, equilibrium adsorption capacity was found to vary significantly after oxygen or nitrogen groups were introduced onto the surface. Therefore, there is a potential for enhanced adsorption by chemical functionalization of carbon.

In this study, characterization of activated carbon produced from apricot stones by chemical activation technique using phosphoric acid (H3PO4) as activating agent, at relatively low temperatures (300, 400 and 500oC), was investigated. To produce activated carbon acid impregnated samples were heated / at a heating rate of 20oC/min to the final carbonization temperatures, 300oC, 400oC and 500oC. For each temperature four different carbonization time (90, 120, 180 and 210 min.) were used to produce twelve different activated carbons. The pore structures of activated carbons were determined as follows: The volume and area of macropores in the pore diameter range of 8180-50 nm were determined by mercury intrusion porosimetry. Mesopore (in the range of 50-2 nm) areas and volumes were determined by N2 gas adsorption technique at -195.6oC, BET surface areas of the samples were also determined, in the relative pressure range of 0.05 to 0.02, by the same technique. The pore volume and the area of the micropores with diameters less than 2 nm were determined by CO2 adsorption measurements at 0oC by the application of Dubinin Radushkevich equation. N2 (BET) and CO2 (D-R) surface areas of the samples were in the range of 444-709m2/g and 433-650m2/g, respectively. AC4.2 sample (carbonization temperature of 400oC and carbonization time of 120 min.) was found to have the maximum BET and CO2 area as 709m2/g and 650m2/g, respectively. Surface areas of the samples consisting of around 10% mesopores and over 90% micropores. N2 adsorption isotherms also confirm that pores are in the micropore range.

In this study, the pore structures and surface areas of activated carbons produced from hazelnut shell and hazelnut husk by chemical activation technique using phosphoric acid (H3PO4), at relatively low temperatures (300, 400 and 500oC), were investigated. Raw materials were impregnated with different H3PO4 solutions of 30%, 40%, 50% and 60% by weight. To produce activated carbon, acid impregnated samples were heated / at a heating rate of 20 oC/min to the final carbonization temperature and held at that temperature for 2 hours. The volume and surface areas of mesopores (2-50 nm) and BET surface areas of the samples were determined by N2 gas adsorption technique at -195.6oC. The pore volume and the area of the micropores with diameters less than 2 nm were determined by CO2 adsorption measurements at 0oC by the application of Dubinin Radushkevich equation. N2 (BET) surface areas of the hazelnut shell and hazelnut husk based activated carbons were in the range of 242-596 m2/g and 705-1565 m2/g, respectively. CO2 (D-R) surface areas of the hazelnut shell and hazelnut husk based activated carbons were in the range of 433-576 m2/g and 376-724 m2/g, respectively. The highest BET surface area was obtained as 596 m2/g among hazelnut shell based samples (HS 60.4 / shell impregnated with 60 wt.% H3PO4, carbonized at 400 &ordm / C) and as 1565 m2/g among hazelnut husk based samples (HH 40.4 / husk impregnated with 40 wt.% H3PO4, carbonized at 400 &ordm / C). Hazelnut shell based activated carbons were mainly microporous while hazelnut husk based ones were mesoporous.

In this work, adsorption of cadmium and lead from waste solutions by activated carbon was investigated. The activated carbons were produced from ion exchange resins and agricultural wastes in previous thesis studies under different conditions. BET surface areas of the activated carbons were given in previous studies. They were further characterized in this study. Slurry pH was measured by change in pH of water in which activated carbon was added. Methylene blue numbers were determined by adsorption of methylene blue onto activated carbons. Isoelectric points were determined by measuring zeta potential of activated carbons at different equilibrium pH. Results of the first part of sorption experiments showed a strong dependency of adsorption on pH since adsorption mechanism was exchange of heavy metal ions with H+ ions on the surface. Activated carbon produced from hazelnut shell had the highest removal efficiency with 95% Pb removal and 50% Cd removal at pH 6. However, activated carbon produced from apricot stone removed only 25% and 80% of Cd and Pb, respectively at the same pH. Initial concentration had positive effect on percent removal as shown by the second part of sorption experiments. This can be explained with saturation of available active sites as initial concentration increased. Activated carbon produced from hazelnut shell could remove 42% of Cd and 85% of Pb, but the one produced from synthetic resin couldn&amp / #8217 / t remove Cd and Pb more than 20% and 35%, respectively at initial concentration of 100 mg/l. Langmuir and Freundlich isotherms were plotted and both isotherms were in good agreement with experimental data.

Glucose syrups were produced from wheat starch at 45-90 min liquefaction times followed by 18 h saccharification to study the effect of liquefaction time on color formation and the use of several amounts (0.25%-1%) and types (NORIT, commercial / and hazelnut husk, apricot stone, hazelnut shell based / prepared in Chemical Engineering Department) of activated carbons for color removal. The fractional conversion values and color levels of glucose syrups increased with increasing liquefaction time. However, to reduce the color level to 100 ICUMSA units, the smallest amount of all types of activated carbons were required for, the glucose syrups with highest level of original color, which were produced at 90 min liquefaction time. Comparison of the performances of the activated carbons showed that hazelnut husk based one was as good as NORIT, while apricot stone based and hazelnut shell based activated carbons showed similar performances, which were somewhat poorer than that of NORIT and hazelnut shell based activated carbon.

The objective of this thesis is to study the effect of process conditions on structure and electrochemical properties of polyacrylonitrile (PAN)/carbon nanotube (CNT) composite film based electrodes developed for electrochemical capacitors. The process parameters like activation temperature, CNT loading in the composite films are varied to determine optimum process conditions for physical (CO2) and chemical (KOH) activation methods. The PAN/CNT precursors are stabilized in air, carbonized in inert atmosphere (argon), and activated by physical (CO2) and chemical (KOH) methods. The physical activation process is carried out by heat treating the carbon precursors in CO2 atmosphere at activation temperatures. In the chemical activation process, stabilized carbon precursors are immersed in aqueous solutions of activating media (KOH), dried, and subsequently heat treated in an inert atmosphere at the activation temperature. The structure and morphology are probed using scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The specific capacitance, power and energy density of the activated electrodes are evaluated with aqueous electrolytes (KOH) as well as organic electrolyte (ionic liquid in acetonitrile) in Cell Test. The surface area and pore size distribution of the activated composite electrodes are evaluated using nitrogen absorption. Specific capacitance dependence on factors such as surface area and pore size distribution are studied. A maximum specific capacitance of 300 F/g in KOH electrolyte and maximum energy density of 22 wh/kg in ionic liquid has been achieved. BET surface areas in excess of 2500 m2/g with controlled pore sizes in 1 - 5 nm range has been attained in this work.