Catalysis of organic pollutant photodegradation by metal phthalocyanines immobilized on TiO2@SiO2

A TiO2@SiO2 hybrid support was prepared by the sol-precipitation method using n-octylamine as a template. The photocatalyst manganese phthalocyanine tetrasulfonic acid (MnPcS) was immobilized on the support to form MnPcS-TiO2@SiO2. X-ray diffraction (XRD) and UV-Visible diffuse reflectance spectra (UV-Vis DRS) were employed to characterize the catalyst. The photocatalytic degradation of rhodamine B (RhB) and the catalytic oxidation of o-phenylenediamine (OPDA) under visible light irradiation were used as probe reactions. The mineralization efficiency and the degradation mechanism were evaluated using chemical oxygen demand (CODCr) assays and electron spin resonance (ESR), respectively. RhB was efficiently degraded by immobilized MnPcS-TiO2@SiO2 under visible light irradiation. Complete decolorization of RhB occurred after 240 min of irradiation and 64.02% CODCr removal occurred after 24 h of irradiation. ESR results indicated that the oxidation process was dominated by the hydroxyl radical (·OH) and superoxide radical (O 2 · ) generated in the system.