| The phthalocyanine and its derivatives are characteristic of good heat, light stability and acid corrosion resistance due to its loose response range to the spectral and a high catalytic activity. The phthalocyanine has been widely used very wide range of potential applications in many areas, such as electroluminescent devices,solar cell materials, information recording materials and nonlinear optical materials.However, the insolubility in water and organic solvents and aggregation of phthalocyanine particles greatly limit its application range in photocatalytic field. In order to solve this problem, hydrophilic groups, such as Sulfonic acid or carboxyl functional groups, can be introduced into the benzene rings of the metal phthalocyanine to greatly improve their water solubility. In addition, phthalocyanine can be supported and dispersed on titanium dioxide surface to reduce its aggregation.In this paper, we prepared iron(III) 2, 9, 16, 23- tetracarboxy- and 2, 3, 9, 10, 16, 17,23, 24- octacarboxy phthalocyanine-sensitized titanium dioxide as photo catalysts.Upon loading TiO2 with phthalocyanine, the photoactivity of TiO2 was extended to the visible light region. Its photocatalytic activity was confirmed by effectively degrading methylene blue, rhodamine B, neutral red, acid red, and malachite green dyes upon visible light. Pseudo first-order degradation kinetics equations were derived. The details are as follows:Fe(III) 2, 3, 9, 10, 16, 17, 23, 24- phthalocyanine octacarboxylic acid and Fe(III)2, 9, 16, 23- phthalocyanine tetracarboxylic acid were synthesized by solid fusion method. The purified iron phthalocyanine was applied to sensitize titanium dioxide to prepare photocatalyst materials. Qualitative analysis of iron phthalocyanine and photocatalyst were determined by UV-Vis and FI-IR spectrum. XRD results showed that crystalline form of titanium dioxide was anatase and it did not change when supported by phthalocyanine. N2 adsorption- desorption experimental results showed that the specific surface area of titanium dioxide decreased due to the surface of theactive site occupied by phthalocyanine. PL and DRS demonstrated that there was energy transfer between the phthalocyanine and carbon dioxide and band gap narrowing. Finally, XPS further confirmed that phthalocyanine supported by titanium dioxide did not change metal valence. The carboxyl group promotes the electronic coupling between the electron donating TiO2 and electron accepting iron phthalocyanine.In the photocatalytic experiments, the methylene blue, rhodamine B, neutral red,acid red and malachite green were chosen as the degradation substrates to evaluate the photocatalytic activities. Dye degradation kinetics curve fitting showed that the photocatalytic degradation process was in line with pseudo first-order reaction kinetics. Effect of pH was tested, which indicated that degradation efficiency was reduced under strong acid or alkali conditions. Metal phthalocyanine loaded with titanium dioxide particle with different size can greatly influenced catalytic degradation efficiency, phthalocyanine octacarboxylic acid displayed the best photocatalytic activity when the titanium dioxide particle size was 60 nm. Otherwise,phthalocyanine tetracarboxylic acid exhibited the superior performance when titanium dioxide particle size was 100 nm.Finally, the degradation mechanism was discussed. Hydroxyl radicals and peroxide radicals were tested by degradation experimentsusing tert-butanol,p-benzoquinone, silver nitrate and EDTA as a capture agent. |
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