Synthesis of Mesoporous Zn(1−x)M(x)Al(2)O(4) Substituted by Co(2+) and Ni(2+) Ions and Application in the Photodegradation of Rhodamine B

A new mesoporous Zn(1-x)M(x)Al(2)O(4) photocatalyst was prepared using the metal-chitosan complexation method with different degrees of Zn(2+) cation substitution with cobalt and nickel ions (M = Co(2+) and Ni(2+)). Characterization using X-ray diffraction (XRD), Infrared absorption spectrometry (FTIR), energy dispersion spectroscopy (EDS), diffuse reflectance spectrometry (DRS), scanning electron miscoscopy (SEM), transmission electron miscroscopy (TEM), N(2) adsorption- desorption isotherms using the Barrett-Joyner-Halenda (BJH) method, thermogravimetric analysis (TG) and differential thermal analysis (DTA) confirmed the formation of the spinel phase and high purity for all samples. N(2) adsorption/desorption and size pore distribution confirmed the high surface area. The photocatalytic activity of Zn(1-x)M(x)Al(2)O(4) and the effect of replacing Zn(2+) ions with Ni(2+) and Co(2+) on the degradation of rhodamine B under ultraviolet light were studied in detail. The sample containing 0.1 mol of cobalt had the highest removal rate reaching 83%, favored by surface area and material bandgap (109 m(2) g(−1) and 2.19 eV, respectively).