Bio-based Adsorbent for Removal of Safranin Dye from Aqueous Solutions

The potential of dried (CC) and anionic surfactant modified (MCC) prickly pear cactus cladodes as an ecofriendly and low cost material for safranin removal from simulated wastewater was evaluated. Effect of several operational parameters including; pH of safranin solution, counter ions, dosage etc. on the adsorption capacity and removal efficiency of safranin was investigated. Physiochemical characterization of the adsorbents was also undertaken. The experimental data obtained was then tested using different mathematical adsorption isotherms and kinetics. Results obtained in this study found that the modified cactus samples MCC performed better than the unmodified one CC in all experiments conducted. The adsorption capacity of both samples towards safranin decreased with increasing concentration of competing ions, ionic strength and dosage. Kinetic studies followed the pseudo second order kinetic model; intraparticle diffusion was involved but wasn’t the rate determining step while equilibrium process was well represented by the Freundlich model for MCC. Positive ΔH° (30.4 and 9.2 KJ/mol) and ΔS° (109.7 and 47.6 J/mol K) values coupled with negative ΔG° for both CC and MCC determined from the thermodynamic study confirmed the process to be a spontaneous, endothermic and random disorderly process. Generally, adsorption of safranin by CC and MCC proved to be effective and suggests that they can be used as an alternative adsorbent for wastewater rich in safranin.