Abstract

ADSORPTION OF FLUORIDE FROM AQUEOUS SOLUTION BY USING CHALK POWDER

*N. Gandhi¹, D. Sirisha¹ and K.B. Chandra Shekar²

¹Center for Environment and Climate Change, School of Environmental Sciences, JawaharlalNehru Institute of Advanced Studies (JNIAS-JNTUA), Hyderabad – A.P

²Department of Chemistry, Jawaharlal Nehru Technological University Anantapur – A.P.

ABSTRACT

Fluoride exists naturally in water. It is 13th most common element in earth crust. Fluoride helps to prevent tooth decay at early stages, but excess of fluoride level causes various diseases such as dental fluorosis, Alzheimer diseases, skeletal fluorosis, thyroid cancer and chronic insomnia. By studying the impact of fluoride on health, low cost deflourination technique has been developed. In the present experiment the batch adsorption studies are carried out by using waste material such as chalk powder. Porosity and void ratio of chalk powder is very high. Because of high porosity of chalk powder and chemical composition it is studied as adsorbent. It is found that the adsorption phenomenon is directly proportional to contact time, concentration, and adsorbent dosage. The data fitted into Langmuir and freundlich adsorption isotherms. Pseudo first and second order kinetic models explained the intensity and capacity of the adsorbent. The adsorption of fluoride by chalk powder is an exothermic and spontaneous in nature.

Keywords: Chalk powder, defluoridation, batch adsorption, temperature, contact time, adsorbent dosage.