Solar Red and Brittle Blue direct dyes adsorption onto Eucalyptus angophoroides bark: Equilibrium, kinetics and thermodynamic studies

Solar red BA (SR-BA) and solar brittle blue A (SBB-A) direct dyes adsorption using Eucalyptus angophoroides bark (EAB) biomass was studied. The effect of process variables i.e., pH, contact time, particle size, temperature, initial dyes concentration, adsorbent dose and NaCl addition were investigated. The adsorption isotherms (Langmuir, Freundlich and Temkin), kinetics models (pseudo-first and pseudo-second-order) and thermodynamics parameters (ΔH°, ΔS° and ΔG°) were employed to evaluate the adsorption mechanism. Thermodynamic studies indicated the spontaneous and exothermic adsorption process of both dyes onto EAB. Maximum adsorptions of SBB-A and RR-BA onto EAB were 49 mg/g and (43.5 mg/g), respectively at 2 pH, 0.25 mm particle size, 303 K, 0.1 g adsorbent dose, 0.05 M NaCl, 25 mg/L dyes initial concentration and contact time 180 min (SBB-A) and 240 min (RR-BA). The SEM and FTIR studies of dye loaded and unloaded biomass were performed in order to check the surface morphology and functional group involved in dye adsorption. The optimized conditions were applied for the adsorption of dyes from textile wastewater and up to 65.4% ± 3.20 dye removal was achieved. Results indicated that the EAB could be an efficient and low cost adsorbent for the adsorption of dyes form textile effluents.