Biosorption of fluoride on Neem (Azadirachta indica) leaf powder

Neem leaf powder prepared from mature, dried Neem (Azadirachta indica) leaves was investigated to assess its ability to remove fluoride from aqueous solutions using batch adsorption process. Effects of solution pH, contact time, adsorbent amount and solution temperature on fluoride sorption had been investigated. The biosorbent was effective at the pH range of 5.0–7.0 and its fluoride removal capacity was found to be above 80%. The equilibrium time for fluoride sorption was found at 60 min and the process followed the second order kinetic mechanism. The adsorption process was exothermic in nature and obeyed Freundlich, Langmuir and Temkin isotherm models. SEM study of the biosorbent showed a morphological change of the surface after sorption and FTIR study indicated the involvement of some surface functional groups in fluoride sorption. These results indicated that Neem leaf powder might be an effective adsorbent for treatment of water contaminated with fluoride.