Abstract
Removal of fluoride ion by lime treatment from waste water is insufficient to meet waste water standard, so the adsorption process using activated alumina was studied. Adsorption capacity, mass-transfer rate, effectiveness of regeneration methods and performance of repeated column adsorption were measured and examined to seek the optimam operating condition.
Results obtained are as follows.
1. Sorption of fluoride ion on activated alumina consists of adsorption on pore surface and absorption into solid phase. The latter proceeds slowly and sorbed ion does not easily desorb. So, absortion into solid cannot be utilized in cyclic adsorption processes.
2. Rate of surface adsorption is pore-diffusion rate controlling. Intra-particle mass-transfer coefficient can be estimated from properties of pore structure of adsorbents and molecular diffusivity.
3. Spent adsorbents of activated alumina are preferably reclaimed using aluminium sulfate solution.Effects of concentration, volume and space velocity of regeneration solution on the degree of desorption are presented.
