Adsorptive removal of PAR and Arsenazo-III from radioactive waste solutions by modified sugarcane bagasse as eco-friendly sorbent

Abstract

Abstract In this paper, sugarcane bagasse (SCB) was modified using phosphoric acid. The modified sugarcane bagasse (MSCB) has been used to remove 4-(2-pyridylazo)resorcinol (PAR) and Arsenazo-III (Ar-III) from liquid radioactive waste. The surface morphology and functional groups of the MSCB were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Adsorption ability of MSCB has been tested by batch mode through some relevant factors like initial pH, reaction time, initial coloring reagents (PAR and Ar-III) concentrations, and adsorbent weight. At adsorption equilibrium time 180 min and pH values of 3 and 1 for PAR and Ar-III; the maximum removal (%) for both PAR and Ar-III were 93 and 57%, respectively. The adsorption isotherm data are representative well to Freundlich isotherm model. The mean free energy of adsorption, E (kJ/mol), has been estimated as 5.75 and 2.28 kJ/mol for PAR and Ar-III, respectively, which suggests that the adsorption occurred physically. The maximum adsorption capacity of MSCB for PAR and Ar-III is 96.62 and 15.18 mg/g, respectively. The adsorption kinetics are better fitted by the pseudo-second-order model. The partial film along with intra-particle diffusion controlled the diffusion of coloring reagents from the solution bulk to the particle interior pores. Application of MSCB for removing PAR and Ar-III from simulated liquid radioactive waste containing U(VI) and Th(VI) ions has been achieved successfully.