Enhanced adsorptive removal of a model acid dye bromothymol blue from aqueous solution using magnetic chitosan‐bamboo sawdust composite: Batch and column studies

The removal of an acid dye bromothymol blue (BTB) from aqueous solution using Fe 2 O 3 /chitosan‐bamboo sawdust (FeCBSD) composite was studied. Isotherm modeling indicated that the data best followed Langmuir isotherm, with adsorption capacity ( q m ) of 217.39 mg/g at a contact time of 30 min and an adsorbent dose of 0.5 g/L. In column studies, the data fitted well into the Thomas model with an adsorption capacity of 225.13 mg/g at a flow rate of 20 mL/min and a bed height of 5 cm. The breakthrough capacity, breakthrough time and exhaustion time decreased with the increasing flow rate. The adsorption process followed pseudo‐second order kinetics, which was controlled by both liquid‐film and intra‐particle diffusion mechanisms. The negative values of Δ G o (7.24–10.94 kJ/mol), positive values of Δ H o (41.27–109.13 kJ/mol) and Δ S o (0.15–0.38 J/mol/K) indicated spontaneity, endothermic nature and an increased randomness at solid‐solution interface, respectively. The results indicated that the FeCBSD effectively removed BTB from wastewater, which may be magnetically recovered.