Abstract
To reduce the environmental impact of phosphate waste product, these materials were proposed as a removal agent of a colored Basic Blue 41 dye (BB-41) from artificially contaminated solution. The effect of calcination of this waste was also investigated on its removal properties. These materials were characterized beforehand, as is intended for the removal tests, by chemical analysis, powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis-differential thermal analysis, scanning electronic microscopy, and N-2 adsorption isotherms. The phosphate waste rock exhibited higher removal capacity of 207 mg g(-1) of BB-41 than the natural rock with a value of 57 mg g(-1) of BB-41, as estimated from Langmuir model. Upon calcination, the removal capacities were reduced by 22%-60%, depending of heating temperatures. Higher removal amounts were achieved at pH values greater than 7. The removal procedure was found to be spontaneous and endothermic process. 60%-80% removal efficiency was maintained after four cycles of regeneration, depending on the spent byproducts. A single stage batch absorber was designed based on the optimum Freundlich isotherm. For example, the masses of 237 and 542 g for phosphate waste and natural phosphate rocks were required to reduce the BB-41 amount of 90% in 10 L of solution with an initial concentration of 200 mg L-1.