Fluoride is the major worldwide problem now facing mainly through drinking water.Several defluoridation methods have been adopted but adsorption processes have been found to be most satisfactory. Adsorption process using plant species are advantageous and eco-friendly. So, biosorption processes have been investigated using the plant species Brachiaria distachya.
Brachiaria distachya is an annual grass having a large volume of biomass which grows in tropical regions. Brachiaria distachya leaves (BDL) were used as biosorbent in powdered form for defluoridation. The efficiency of the leaves to remove fluoride from water has been investigated by varying parameters such as contact time, pH, adsorbent dosage, temperature and initial fluoride concentration. The maximum fluoride removal was observed at pH - 6.0 with adsorbent dosage of 8.5 g using 100 mL of water containing 40 ppm of fluoride in 120 minutes. Under these conditions, temperature variation studies were also carried out from 30-600 C and the removal efficiency of fluoride was found to be 92.5 % at pH - 6.0 and temperature 600 C. The biosorption process is endothermic following both Langmuir and Freundlich isotherms. The fluoride biosorption process follows pseudo first order kinetics. The results showed that the biosorbent used is cost-effective for treating fluoride containing water.