Iron Phthalocyanine Linked Covalently With Carbon Nanotubes For The Degradation Of Organic Contaminants

Water is one of the most important resources for human survival, it takes an irreplaceable position in nature. With the developing of society, the pollution of water has been growing concerned. Industrial waste is the largest source of water pollution, most of these wastewater contains large amounts of toxic pollutants, such as chlorinated aromatic compounds, antibiotics,conjugated dyes. These compounds are seriously harmful for organisms and humans. Therefore,it is very important to design a clean and efficient catalytic system to remove organic pollutants in water.Phthalocyanine metal complexes(MPcs) are structurally related to porphyrin complexes,which are widely used by nature in the active sites of cytochrome P-450. They are often used in various fields of catalysis, and there could be a variety of functions if different catalyst carriers were used. Carbon nanotubes(CNTs) can be used as an excellent partner for catalysts because of its excellent electrochemical properties. Besides, CNTs have similar π-conjugated structures to MPcs, which make it possible serve as phthalocyanine-supported material. Therefore, to investigat the interaction between carbon nanotubes and phthalocyanine and to reveal the mechanism of the catalytic reaction would be the basis for controlling catalytic process of phthalocyanine.We used carboxylic acid-functionalized MWCNTs to attach FeMATNPc through amide bonds to synthesize MWCNTs-CONH-FeTNPc, and raw MWCNTs were used to immobilize FeMATNPc via direct bonding to synthesize MWCNTs-FeTNPc. Acid Red 1(AR1) and4-chlorophenol(4-CP) were used as the main organic substances to investigate catalytic activity with H2O2 as oxidant. Both two catalysts exhibited excellent ability on contaminants removal with good regeneration performance. Effects factors such as pH, temperature, oxidant concentration and so on were discussed. Electron paramagnetic resonance(EPR) was used to probe the active species in the catalytic system and the electrical properties of MWCNTs. We designed a cyclic voltammetry experiment to investigate electron transfer between MWCNTs and phthalocyanine.The introduction of MWCNTs into the FeMATNPc catalyst system leads to a significant enhancement in catalytic activity, and active species of ?OH, ?OOH and Fe(IV)=O are formed in both systems. In the MWCNTs-FeTNPc/H2O2 system, a large amount of ?OH and ?OOH formed only in the presence of a small dosage of H2O2. Although less ?OH formed in the MWCNTs-CONH-Fe TNPc/H2O2 system, more active species of Fe(IV)=O participate in the catalytic degradation of AR1. A significant discrepancy exists in the formation of active species between MWCNTs-CONH-FeTNPc and MWCNTs-FeTNPc. On the basis of EPR and cyclic voltammetry experiment, we infer that abundant conduction electrons fill the MWCNTs, and electron transfer between MWCNTs and FePc is efficient. This behavior is very different for oxidized MWCNTs because of a lack of conduction electrons and poor performance in electron transfer. The discrepancy in electrical properties between MWCNTs-FeTNPc and MWCNTs-CONH-Fe TNPc may be the intrinsic reason for differences in the formation pathways of active species in the two catalytic systems. This research offers a new strategy to design highly efficient MWCNTs-supported catalysts and control the catalytic reaction process in organic synthesis, green chemistry and environmental treatment.