Comparative adsorption study of mango (Mangifera indica) leaves and neem (Azadirachta indica) leaves, as an adsorbent for dye removal

The study attempted to evaluate and compare the adsorption capacity (Methylene Blue removal) of non-conventional adsorbents prepared from Neem (Azadirachta indica) leaf and Mango (Mangifera Indica) leaf and Langmuir model or Freundlich model were analyzed. The leaves from Neem and Mango were collected, cleaned, dried (115°C) and powdered. The physiochemical properties were studied. Methylene blue dye was used as the pollutant since it is a frequently used dye for adsorption studies. A series of batch experiments were carried to evaluate the adsorption capacity of Neem leaf adsorbent and mango leaf adsorbent with different dosages and different initial adsorbate concentrations (100, 150, 200 and 250 mg/L). Neem leaf showed the highest adsorption capacity of 83%. The adsorption capacity of the Mango leaves was around 79%. Adsorbent dose and adsorption rate have a positive relation. Adsorption rate increases with adsorbent dose and decreases with increases of adsorbate initial concentration. Langmuir isotherm showed a high coefficient of determination. Both Langmuir separation factor (RL) and Freundlich constant (nF) suggest the favorable adsorption of the dye onto the adsorbents. The results indicated that both neem and mango leaves have an attractive property to remove dye from water. Therefore, both can be used as alternative green adsorbents for pollutant removal.