Abstract
A new adsorbent namely bentonite/chitosan beads has been synthesized and studied for its defluoridation efficiency. Bentonite was activated and the beads were prepared using the inverse suspension polymerization method. The bentonite/chitosan beads (bentonite dosage of 3.0 g) showed an adsorption capacity of 0.895 mg/g whereas chitosan beads had only 0.359 mg/g. The optimal pH value was observed at pH 5 where the adsorbent reached the maximum defluoridation capacity of 1.164 mg/g. The effect of temperature, contact time and initial fluoride concentration on the adsorption capacity of the adsorbent has also been investigated. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and Fourier-transform infrared spectrometry (FTIR) were used to characterize the adsorbent. The adsorption of fluoride onto the adsorbent followed Freundlich isotherm model and pseudo-second order kinetic model. The fluoride loaded adsorbent could be regenerated using sodium hydroxide.
Highlights
Adsorption technology is an efficient method for fluoride removal from water and has been widely studied [1]
Bentonite is a common group of clay minerals, which is a hydrous aluminium silicate, and it has been reported as an economical material for adsorption of fluoride from water
− ce w where qe is the adsorption capacity of the adsorbent at equilibrium; c0 and ce are the initial and equilibrium fluoride concentrations, respectively; V is the volume of solution (L) and W is the mass of adsorbent (g)
Summary
Adsorption technology is an efficient method for fluoride removal from water and has been widely studied [1]. Chitin composite [2], modified chitosan beads [3], synthetic apatites [4] and bentonite clay [5] have been demonstrated effective adsorbents for fluoride adsorption. The present study deals with the bentonite and chitosan with crosslinker to form an inexpensive and efficient adsorbent. The effect of various parameters such as bentonite dosage, pH, temperature, initial fluoride concentration and contact time on adsorption capacity of bentonite/chitosan beads was studied. SEM, EDAX and FTIR analysis were used to characterize the bentonite/chitosan beads before and after fluoride adsorbed. The regeneration experiments were performed to check the reusability of bentonite/chitosan beads for defluoridation
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