Advances in Water Treatment and Enviromental Management

ADSORPTION OF TRIHALOMETHANES ON TO ZEOLITES 189Table 2 Freundlich isotherm constants forsilicalite/chloroform/water andGAC/ chloroform/watera Faust et al, 1987, p214b this paper, Figure 4performance of silicalite and GAC. The kinetic data in Figure 5 indicates a somewhatmore rapid uptake of THM by carbon than by silicalite. Whilst the same weight ofadsorbent and the same degree of turbulence were used in each case, differencesin particle density resulted in fewer particles of silicalite than carbon being used.Other experiments carried out using silicalite alone show the pronoun-ced influenceof particle size on rate of uptake. These experiments examined the rate-controllingsteps in the adsorption process, to determine the extent of control by internal orexternal mass transfer. Varying the degree of liquid turbulence during shakingproduced only a marginal difference in rate of uptake, whereas crushing andsieving the silicalite to a smaller particle size greatly increased the rate of uptake.Much further work is to be carried out on multicomponent equilibrium studies,and batch and column experiments to determine kinetic data. These initial results,however, indicate an adsorption performance for silicalite broadly comparable toGAC.The economics of industrial applications cannot currently be evaluated as bulkmanufacturing costs for silicalite are not available. However, the manufacturingprocess for silicalite and similar silica-based polymorphs is relatively simple (Flanigenand Grose, 1977), and production costs should be comparable with many otherzeolitic adsorbents which find widespread application in the process industries.Ease of regeneration for silicalite should also yield reduced operating costs in anindustrial situation.CONCLUSIONSFundamental data so far obtained indicates that silicalite, a crystalline zeoliticadsorbent, should be capable of effectively removing trace chloro-organic compounds,