Adsorption of acid fuchsin onto LTA-type zeolite derived from fly ash

A facile strategy without organic template was developed for the conversion of fly ash to LTA-type zeolite (LTA-Z), which could be used as a good adsorbent for the removal of acid fuchsin (AF). XRD results indicated that the pure crystalline product was obtained with the structure of LTA-type zeolite. SEM investigations showed that the well-defined LTA-Z crystals exhibited uniform size with the same cubic shape. The maximum AF adsorption amount was observed at pH=5, slightly lower than pH(PZC) of LTA-Z. Higher temperature favored AF adsorption onto LTA-Z and it was an endothermic process. Furthermore, AF adsorption amount increased with initial AF concentration increasing and LTA-Z dosage decreasing. Surface sorption governed this process at the initial 120 min period, followed by the internal diffusion of AF molecules between porous sites. The Langmuir model was determined as the adsorption isothermal, suggesting that the monolayer coverage of AF on LTA-Z surface was involved.