Studies on the removal of fluoride from water using granular polymer agglomerated adsorbents and chemically modified polymer ion exchange resin

Abstract

The present study is aimed at preparing three different adsorbents and applying them for fluoride removal. Commercially available acidic powdered activated alumina (PAA) was agglomerated to obtain granular polymer agglomerated alumina (GPAA) and powdered tri-calcium phosphate (PTCP) was agglomerated with Poly (vinyl acetate) to obtain granular polymer agglomerated tri-calcium phosphate (GTCP). Plain Amberlite IRA 400 anion exchange resin (PR), was chemically modified (CMR) by phosphorylation followed by alum impregnation and investigated for fluoride removal as a third adsorbent. Batch experiments were conducted with all the above mentioned adsorbents. Column studies were carried out to find out the suitability of the material for large scale applications. However, the presence of PO43- ion significantly interfered with the sorption of fluoride. Column regeneration studies indicated that all the three adsorbents could be completely regenerated and used for repeated cycle. It was surprising to note that the fluoride removal capacity of CMR was increased three fold after first regeneration and remained nearly the same, cycle after cycle. The study on kinetic data indicated that pseudosecond order rate was best followed by all the three adsorbents for fluoride adsorption. FTIR spectra of Amberlite IRA 400 plain resin, phosphorylated resin and aluminium sulphate impregnated phosphorylated resin were taken and analyzed. The scanning electron microscopy (SEM) technique was employed to observe the surface physical morphology of the three adsorbents. Ground water sample was collected from a village in Dharmapuri district of South India. Its characteristics were analyzed and subjected to defluoridation using the chemically modified resin. The defluoridation capacity of the wet resin was found to be 6.80 mg g-1which leads to the conclusion that the CMR could be a good adsorbent for fluoride removal from drinking water. newline newline newline