Silica‐Based NTPC ‐Fly Ash for Dye‐Removal Application and Effect of Its Modification

Silica‐based fly ash ( FA ) received from the N ational T hermal P ower C orporation ( NTPC ), I ndia has been utilized for determining its dye‐adsorption capacity. The dye adsorption using the NTPC ‐ FA has been examined by varying the initial methylene blue dye concentration (7.5–150 μ M ) and initial solution‐ pH (2.5–11.5). The dye‐adsorption capacity of NTPC ‐ FA has been found to be 0.43 mg/g. To increase the dye‐adsorption capacity, the NTPC ‐ FA is subjected to the hydrothermal treatment and typical washing cycles without and with the coating of sol–gel derived anatase‐titania. The hydrothermally treated NTPC ‐ FA and hydrogen titanate–silica composite thus obtained exhibit dye‐adsorption capacity higher than that of NTPC ‐ FA .