Preparation Of Heterogeneous Metal Phthalocyanine Catalysts And Photodegradation Of Toxic Organic Pollutants

The application of metal organic complexes used as photocatalyst has attracted great attention, because they are environmental friendly, can be acitivated by visible light irradiation and degrade pollutants through activating hydrogen peroxide (H2O₂) and molecular oxygen (O₂) under neutral pH condition. The technology involvded metal organic complexes is becoming the hot research by scholars both at home and abroad, comparing with other treatments of pollutants. In this paper, different supports, including inert supports (resin IRA 900 and molecular sieve MCM 41) and active oxide supports (mesoporous TiO₂, TiO₂ nanoribbon, TiO₂@SiO₂ and WO₃) were used to load manganese phthalocyanine tetrasulfonic acid (MnPcS), iron-phthalocyanine tetrasulfonic acid (FePcS) and 2, 9, 16, 32-tetracarboxylic phthalocyanine manganese (MnPcTc). Besides, hydrophobicly heterogeneous photocatalyst (perchlorinated iron-phthalocyanine, FePcCl₁₆) was prepared. The degradation of toxic organic pollutants rhodamine B (RhB), salicylic acid (SA) and 2, 4-dichlorophenol (2, 4-DCP) was studied by different types of heterogeneous metal phthalocyanine photocatalyst activated by ultraviolet light (λ≤387 nm) and visible light irradiation (λ≥420 nm). The mechanism of degradation was explored through determing the intermediate oxidation species. This will provide scientific basis for the wastewater treatment of actual water bodies.2 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 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. ESR results indicated that the oxidation process was dominated by the hydroxyl radical (?OH) and superoxide radical (O₂-?) generated in the system.3 Compound catalyst FePcS-TiO₂ was prepared using TiO₂ nanobelt as support to load FePcS. UV-Vis DRS was employed to characterize the catalyst. The photocatalytic degradation of organic dye RhB and and colorless small molecular organic substance SA were used as probe reactions to evaluate the photocatalytic activity of the catalyst. The results indicated that FePcS-TiO₂ had good photocatalytic properties under visible light irradiation. RhB and SA can be efficiently degraded by FePcS-TiO₂ under visible light irradiation. The photocatalytic degradation of toxic organic pollutants was a process of deep oxidation and the oxidative process was predominated mainly by the ?OH.4 Immobilized MnPcTc-WO₃ was prepared by the method of in-situ syntheses. Infrared spectrum (IR) and UV-Vis DRS were employed to characterize the catalyst. The photocatalytic degradation of organic dye RhB and colorless small molecule organic compound 2, 4-DCP under visible light irradiation were used as probe reactions to discuss the effect of physical and chemical factors on the catalytic activity. The results of the content change of reactive oxygen species, including H2O₂ and ?OH, showed that the oxidative process was predominated mainly by the ?OH.5 Metal organic compound FePcCl₁₆ was prepared and used as photocatalyst. The heterogeneous photocatalytic degradation of RhB and SA by FePcCl₁₆ activated by O₂ under ultraviolet light and by H2O₂ under visible light irradiation were studied. The experimental results indicated that organic pollutants can be effectively degraded under both ultraviolet light and visible light. The degradation process involved the oxidation of ?OH, according to the results from benzoic acid ?uorescence method. The hydrophobic photocatalyst FePcCl₁₆ was stable in aqueous media system. The photocatalytic degradation system had wide pH adaptability (3 11). The heterogeneous photocatalyst can be recycled reused and degrade toxic organic pollutants under ultraviolet light and visible light.