Batch and circulated fluidized bed adsorption of nickel ions on algae: equilibrium, thermodynamic and mass transfer studies

In this study, the biosorption potential of algae mixture (80% (Chrysophyta), 5% (Cyanophyta), and 14% (Chlorophyta)) to remove nickel ions from aqueous solution was investigated through batch and circulating fluidized bed (CFB). The effect of feed pH, dosage, the particle size of algae, and temperature in the batch mode was examined. The pH point zero charges (pH pzc ) was found equal to 5.8. The highest removal efficiency and mass transfer coefficient were 96.56% and 1.87 × 10 –5 m/s, respectively. Also, results show that more than 79% adsorbed metal ion was desorbed by using 0.1 M HNO 3 in the first cycle. The effect of Ni(II) initial concentration, bed depth, and flow rate on the behavior of breakthrough curves was explained. The results showed that CFB has a better performance and lasts more than 5 h before the bed biomass exhausted in comparison with traditional fluidized bed, and the highest mass transfer coefficient (K L ) found equal to 2.118 × 10 –5 m/s.