Introduction of 5,10,15,20-tetrakis(4-hydroxyphenyl)-porphine iron(III) into humic acid via formaldehyde polycondensation

To stabilize an iron(III)-porphyrin catalyst in the presence of peroxide such as KHSO5,5,10,15,20-tetrakis(4-hydroxyphenyl)-porphine iron(III) (FeTPP(OH)(4)) Was introduced into a humic acid (HA) via formaldehyde polycondensation to produce a resol catalyst. FeTPP(OH)(4) can have four phenolic hydroxyl groups for HA-binding. The self-degradation kinetics for prepared resol catalysts using FeTPP(OH)(4) were compared with those synthesized prepared from 5-(p-hydroxyphenyl)-5,10,15,20-tetrasulfonatophenylporphine iron(III) (FeTPPSOH) that has one site for HA-binding. In the presence or KHSO5, half-lives of the self-degradation was much larger in resol catalysts using FeTPP(OH)(4) (3.4-3.5s), compared to those using FeTPPSOH (0.08 s). These results show that use of FeTPP(OH)(4) for the synthesis of resol catalysts is useful for stabilization of iron(III)-porphyrin catalyst and retardation of the self-degradation. In addition, the catalytic activity of prepared resol catalysts was evaluated by 2,4,6-trichlorophenol (TrCP) oxidation. In particular, mineralization to CO2 was significantly greater for the resol catalysts (17-18%) than for FeTPP(OH)(4) alone (4%). These results indicate that resol catalysts effectively enhance oxidative degradation of TrCP due to retardation of catalyst self-degradation. (C) 2008 Elsevier B.V. All rights reserved.