Preparation and characterization of chitosan/clay composite for direct Rose FRN dye removal from aqueous media: comparison of linear and non-linear regression methods

In the present study, sorption efficacy of chitosan (β-(1→4)-linked d -glucosamine and N-acetyl- d -glucosamine) composite for synthetic direct Rose FRN dye removal from aqueous media was investigated. Chitosan and clay were subjected to chemical modifications to prepare chitosan/clay composite. Batch sorption affecting parameters like pH, composite dose, volume, initial dye concentration, time and temperature were optimized. Maximum sorption capacity (17.18 mg/g) was found within first 40 min of contact. Point of zero charge was found to be 7.0. Linearized and non-linearized regression forms of pseudo 1st and 2nd order kinetic models were used to predict the nature of rate limiting steps involved in the sorption process. Sorption equilibrium data was revealed by applying linear and non-linear equilibrium Langmuir, Freundlich and Redlich–Peterson isotherm models. Calculated values of thermodynamic factors showed that sorption process is exothermic, spontaneous and feasible. Desorption studies were performed for the regeneration of chitosan/clay composite by using different eluting agents. The synthesized composite were characterized by X-ray diffraction (XRD), surface analysis (Brunauer, Emmett and Teller: BET), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The developed method was also applied on the real textile effluent for the efficient removal of dyes.