Capim-annoni (eragrostis plana nees) in natura para remoção do corante violeta de metila 10b de solução aquosa

Abstract

In the present work South African Lovegrass (CA) was used in natura as biosorbent in order to remove the dye Methyl Violet 10B (VM 10B) of the aqueous solution. The following analytical techniques were used to prepare and characterized the CA in question: Scanning Electron Microscopy (SEM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), B.E.T Method (Brunauer, Emmet and Teller) and B.J.H (Barret, Joyner and Halenda), Soxhlet Extraction and Boehm Method. To investigate the ideal experimental conditions for adsorption between dye and biosorbent, the influence of the biosorbent mass concentration, pH solution, contact time and initial dye concentration, stirring speed and temperature were used. Results show that with 150.0 mg CA, pH solution 8.0, contact time of 180 min. and stirring speed at100 rpm presented adsorption conditions that were more favorable. The adsorption kinetic of VM 10B in CA was investigated using the classical kinetic models of pseudo-first and pseudo-second-orders. The pseudo-second-order was found to provide the best adjustment to the experimental data. Sips Isothermal Model has proven to be the most adequate to describe the adsorption mechanism presenting the smallest values for the statistical parameter Error Function (erf) and the closest values of the unit for the coefficient of determination (R2). The maximum adsorption capacity obtained through the Sips model was 76.20 mg g -1 at 60 °C. Desorption Studies of VM 10B in CA show that it is possible to regenerate the biosorbent satisfactorily using 1.0 mol L-1 acetic acid as an eluent. Thermodynamic studies show that adsorption of VM 10B in CA is an endothermic process, spontaneous and commanded by a physical adsorption mechanism. The application of CA in the removal of the VM 10B from simulated textile effluents was satisfactory showing that it can be used to treat colored industrial waters.