Fluoride Adsorption onto Sulphonated Polystyrene

Abstract

Adequate fluoride (F-) taken in through food, soil and water is crucial for healthy bones and teeth building. Excess F- results in dental, skeletal and soft tissue damage unless controlled by its removal. People get exposed to excessive fluoride through food, soil and water. However, drinking water with excessive fluoride remains the primary pathway of human exposure to hazardous levels of fluoride from the environment. In the present study, defluoridation has been applied using sulphonated polystyrene (SPS) investigated for fluoride adsorption. The material was collected from Eldoret dump site, sorted, ground, weighed, treated and tested for fluoride removal in water. The adsorbent was modified using solutions containing Ca2+, Mg2+ and Al3+ ions. Fluoride adsorption properties for the adsorbent were then assessed with respect to changes in adsorbent dosage, contact time, agitation rate, solution pH, temperature and initial fluoride concentration. Fluoride adsorption from aqueous solutions using SPS was studied using batch experiments and the adsorbent was characterized by FTIR and SEM methods. F- adsorption data correlated to the Freundlich and Langmuir models and could be classified as C-Type according to Giles classification of isotherms. The psueudo-first and pseudo-second order kinetic models and the Weber and Morris intra particle diffusion model equation were applied onto the adsorbent. The adsorbent could be used as a low-cost adsorbent for adsorption of F- ions from aqueous streams