Removal of azodyes using natural phosphate doped by titanium dioxide (NP-TiO2) nanoparticles

Abstract

In this study, a batch system was applied to investigate the adsorption behavior of disperse dyes (Disperse Blue 79 [DB 79] and Disperse Blue 165 [DB 165]) and an anionic dye (Reactive Yellow 145 [RY 145]) on natural phosphate doped by titanium dioxide (NP-TiO2). The NP-TiO2 was characterized by X-ray diffraction, Fourier transform-infrared and Brunauer–Emmett–Teller surface area techniques. The established optimum contact time for DB 79, DB 165 and RY 145 was 60, 90 and 75 min, respectively, at a dye concentration of 50 mg/L, DB 79, DB 165 and RY 145 dye removal rates reached 97%, 99% and 78%, respectively. Kinetic parameters were estimated using the pseudo-first-order and pseudo-second-order kinetic models, the adsorption rate was fitted by pseudo-second-order model for DB 79 and RY 145. However, the DB 165 was described by pseudo-first-order model. Further investigations demonstrated that the adsorption isotherm fitted well with the Langmuir model for DB 79 and DB 165, but the RY 145 dye was described by the Freundlich model. The thermodynamic parameters were also studied.