Water Treatment by Means of Activated Carbon, Prepared from Locally Available Waste Materials (II)
Man's natural water supplies are threatened by a large number of nonbiodegradable and toxic organic compounds. Proper environmental standards often can only be attained using tertiary treatment processes, such as adsorption on activated carbon. The latter is an expensive process, owing to the initial cost of activated carbon and the losses occurring during regeneration. Methods are being investigated at the Free University of Brussels for producing and activating carbon, using various types of waste as a raw material. Following materials have already been used : cacao hulls, sawdust, fruit stones, bark, and waste tyres. Both carbonization and activation have been conducted under the carefully controlled conditions of a fluidized bed reactor. The influence of the following process parameters has been investigated : pyrolysis temperature and time, activation temperature and time, and composition of the furnace atmosphere. The resulting activated carbons should exhibit the following qualities : high adsorption capacity and rate, good resistance to attrition, and possibility of regenerating the carbon. The properties of the carbon obtained have been evaluated by means of a number of standard tests (Iodine-index, BET-surface, Tannin-index, Methylene blue-index, and Phenol-index), and adsorption isotherms of phenol, pentachlorophenol, p. toluene sulphonate and dodecyl benzenesulphonate. In general the properties of the carbons obtained were comparable to those of commercial qualities. Some of the activated carbons tested will soon be evaluated using synthetic and real phenolic industrial wastewaters (1.5 % of phenol).