Removal of Congo Red from Aqueous Solution Using Cuttlefish Bone Powder

Adsorption experiments were carried out as a part of the removal of Congo red (CR), a textile dye, from aqueous solutions using the powder of cuttlefish bone (Sepia) as a new potential adsorbent. The prepared powder was characterized by FTIR, XRD, SEM and elemental analysis. The effects of solution pH, adsorbent amount, CR concentration, temperature and contact time on the CR adsorption were investigated. The experimental results showed that maximum pH was about 2 for efficient uptake of CR. The equilibrium was attained in 60 min. The adsorption of Congo red was found to be exothermic in nature (ΔH° = 8.41 kJ mol-1), while the positive value of entropy 20.85 J mol-1 K-1 indicated an increased randomness at the solid/liquid interface. The experimental data were analyzed using Langmuir and Freundlich isothermal models. The best fit was obtained by Langmuir model with a maximum monolayer adsorption capacity of 69.9 mg g-1. Adsorption kinetics data were properly fitted with the pseudo second-order kinetic model.