Neem (Azadirachta indica) Leaf Powder: A Plant-Based Adsorbent for Removal of Textile Acid Azo Dye from Aqueous Solution

A plant-based adsorbent was prepared from Neem (Azadirachta indica) leaf and adsorption of two textile acid azo dyes, Acid Red 18 and Acid Orange 7, from aqueous solution was examined. Batch adsorption test showed that extent of dye adsorption depended on contact time, pH and adsorbent dose. Equilibrium adsorption was attained in 5 h and maximum adsorption occurred at pH 2. Dye adsorption followed pseudo secondorder kinetics. Equilibrium adsorption data were described by the Langmuir and Freundlich adsorption isotherm models. Acid dye adsorption capacity of the Neem leaf powder was compared with that of other plant-based adsorbents and activated carbons. Neem leaf powder is effective in adsorptive removal of acid dyes from aqueous solution and textile dye waste.