Defluoridation of drinking water using chitosan based mesoporous alumina

In the present research study, mesoporous alumina (MA450) with improved properties has been synthesized using biopolymer chitosan as a template and used for defluoridation of water. The adsorbent has been characterized with XRD, SEM, FTIR and EDAX studies. It was observed that MA450 works effectively over wide range of pH and showed a maximum adsorption capacity 8.264 mg g−1 at initial fluoride concentration of 5 mg l−1 which is much better than the conventional alumina. The experimental data fitted well in Langmuir isotherm and follows Pseudo-second order kinetics. Batch adsorption studies were performed to study the effect of pH, adsorbent dose, initial fluoride concentration and co-existing anions. Thermodynamic study reveals that fluoride adsorption on MA450 is spontaneous and exothermic process. MA450 showed significantly high fluoride removal in field water. The performance of MA450 was compared with many other reported adsorbent for fluoride removal and it was observed that the present adsorbent is effective in terms of fluoride removal performance and also appears to be cost effective. From the experimental data, it may be inferred that MA450 is a potential and indigenous adsorbent for defluoridation.

Mesoporous alumina synthesized using chitosan biopolymer as a template shows highly porous structure which provides high surface area providing large number of active sites for fluoride adsorption. Mesoporous alumina overcomes the limitation of narrow pH window for fluoride removal in conventional activated alumina while this mesoporous alumina works over wide range of pH from 5 to 9 significantly.Figure optionsDownload as PowerPoint slideResearch highlights
► Meso alumina has no significant effect of pH on fluoride adsorption in a wide range of pH from 5 to 11 which overcomes the problem of conventional adsorbent alumina of narrow pH range for fluoride adsorption.
► Meso porous alumina was synthesized by using chitosan biopolymer has high fluoride adsorption capacity and affinity for fluoride.
► Meso alumina synthesized has high surface area and highly porous in nature.