Keywords: wastewater treatment, Acacia nilotica sawdust, batch adsorption, FTIR, SEM, Swiss blue dyes, dye sequestration, biosorbents, dye removal, kinetics
Swiss blue dye sequestration by adsorption using Acacia nilotica sawdust
Batch adsorption studies were conducted to investigate the potential of Acacia nilotica sawdust as biosorbent for removal of basic Swiss blue dye from wastewater. Sawdust was subjected to formaldehyde pretreatment (FSD) and boiling (BSD). Maximum dye removal was observed after 120 min for all conditions – FSD: 97.5% and BSD: 95.9% at pH 6, 50 mgL
−1dye concentration and 0.2 g/50 mL adsorbent dosage. Adsorption was endothermic and was accompanied by an increase in entropy and a decrease in Gibbs free energy for 288?333 K. Equilibrium data fitted excellently with the Langmuir isotherm (FSD: R² = 0.9955, BSD: R² = 0.9914). Adsorption kinetics was found to follow pseudo-second-order model (R² > 0.99, FSD and BSD). It can be concluded that formaldehyde-treated sawdust (FSD) can be used as a more efficient and low-cost alternative to the chemically untreated sawdust in aqueous solution for Swiss blue dye removal.