Year

1990

Degree Name

Master of Science (Hons.)

Department

Department of Geology

Abstract

Activated carbon products are used as adsorbents in the removal of pollutants from water, where advantage is taken of the enhanced retention of organic solutes in the pore system of the carbon. The need for such processes will increase in Indonesia.

The possibility of the use of Indonesian coals as raw materials for manufacturing activated carbon has been studied, measuring yield and iodine number, utilizing chemical impregnation techniques to enhance iodine number.

The mechanisms of adsorption and of activation shown to be related to a combination of porosity and surface properties. The coal resources of Indonesia are largely low in rank. Although they have geographic distribution, most reserves are present in Sumatra and east Kalimantan. Type variation within the coals is restricted.

The technical literature reports considerable success with such techniques and the initial intention was to optimize the variables of the process for practical application. Using a sample of industrial carbon (Calgon) as a reference, several relatively low rank Indonesian coals were coarsely ground, impregnated with potassium chloride and carbonized at 900 C. Results were disappointing.

Techniques therefore reverted to those used by other workers, using finely crushed coal for impregnation tests. Various methods of impregnation and washing were used and carbonization times ranging up to 12 hours were applied.

Increases in iodine number to any level that could be considered effective were associated with substantial gasification and low yield, particularly with Victorian brown coal. These effects were rank related, in a manner similar to other investigations but with lower weight loss.

Series of tests were then done on a range of coals from Indonesia and Australia of varying rank, with Victorian brown coal in parallel and using varying practices, with and without nitrogen purging. Results supported the conclusions already made.

Optical microscopy showed porosity trends consistent with increased gasification over extended carbonization times. E.D.X demostrated clearly the presence of potassium on and within the grains, after carbonization, whether the coal had been washed before charging or not

The techniques did not achieve the desired result of producing highly activated carbon at high yields. This conflicts with much technical literature.

The coals of Indonesia are distributed widely through the archipelago and are of grades suitable for the production of activated carbon but further work is needed before a commercial process can be designed.

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