ZnO, CuO and Fe₂O₃ green synthesis for the adsorptive removal of direct golden yellow dye adsorption: kinetics, equilibrium and thermodynamics studies

Abstract

Abstract In the present investigation, ZnO, CuO and Fe 2 O 3 were prepared via green route and utilized for the sequestration of DGY (Direct Golden Yellow) dye. Affecting variables i.e., temperature, contact time, adsorbent dose and pH were optimized for maximum sequestration of dye from aqueous medium. The pH 2, adsorbent dose 0.1 g/50 mL dye solution, temperature 30 °C and 50 mg/L dye initial concentration were best levels for efficient dye adsorption and equilibrium was attained in 30 min reaction time. The dye sequestration on to ZnO, CuO and Fe 2 O 3 was an exothermic process. Freundlich and Temkin adsorption isotherms explained well the dye adsorption onto nanoadsorbents and dye adsorption followed pseudo first order kinetic model. Effect of electrolytes and heavy metal ions was also investigated and both affected the adsorption process significantly. In the presences of surfactant/detergent, the removal of dye was reduced and 0.5 N NaOH efficiently desorbed the dye from nanoadsorbents. Findings depicted that the nanoadsorbents are effectual for the sequestration of DGY dye, which can be employed for the remediation of textile effluents.