Chih-Ta Wang | PubMed Health

PubMed2003

Decolorization of Congo Red with three-dimensional flow-by packed-bed electrodes.

The electrochemical removal of the color of the dyestuff Congo Red was investigated experimentally by using packed graphite anodes as well as packed graphite or C-304 stainless steel cathodes in an undivided reactor. The effects of the applied apparent current density, the amount of chloride ion addition, the pH value of the solution, the cathode material, the operating temperature, the volumetric flow rate and the initial concentration of Congo Red on the removal efficiencies were investigated in this study. Experimental results showed that the main pathway of color removal was by the hypochlorite generated in-situ at the anodes. Compared with the indirect oxidation, the color removal due to direct oxidation was insignificant. Cathodic oxidation by using graphite cathodes had little influence on the removal rate in an undivided electrochemical cell.

Coloring Agents↗

PubMed2003

The feasibility study of the octane-enhancing process: isobutylene dimerization using C4 mixture.

The dimerization of isobutylene to diisobutylene in C4 mixture was evaluated using various catalysts such as nickel salts system, zeolite system and acidic ion exchange resin. There were shown that the strong acidic type ion exchange resin (Amberlyst 15) under 6 kg/cm2 and 60 degrees C gave rise to 90% conversion and more than 60% selectivity to diisobutylene with acceptable amounts of oligomer as a best catalyst. Therefore, Amberlyst 15 was employed to investigate the optimum reaction condition. In the batch reaction, since the catalyst activity was increased with the increasing reaction temperature, the reaction time should be shortened appropriately to prevent a high yield of oligomer. The reaction rate was increased by the increased amount of catalyst without much change in the product composition. The formation of oligomer was inhibited when a small amount of organic solvents (methyl tert-butyl ether) are attended. In the fixed-bed study, the results indicate that the increase in reaction temperature was accompanied by the increase in reaction rate, however, the selectivity to the dimer was affected. Higher WHSV will enhance the selectivity but reduce the conversion. Conclusively, the appropriate reaction condition was 45 degrees C with WHSV of 10.

Air Pollution↗