Photocatalytic Activity of Metalloporphyrin–Titanium Mixtures in Microemulsions

Abstract

This report explores the photocatalytic activity of TiO 2 , Ti(IV) citrate and Zn(II) tetraphenyl porphyrin (ZnTPP) and its mixtures in water/oil (W/O) and O/W microemulsion (lE). The 4-chlorophenol was used to assess the efficiency of the photoactive compounds in a degradation process. A simple photoelectrochemical study based on cyclic voltammetry was also developed. The results revealed that most of the photocatalytic procedures developed are effective in the degradation process. However, phenol was the major product obtained.

Mechanistic aspects of photocatalytic activity of metalloporphyrin–titanium mixtures in microemulsions

“…The results of the treatment in aqueous solution presented above, matched the results in oil-in-water (O/W) microemulsions obtained in our previous research, 7 considering the uncertainties in the values obtained. This confirms the effectiveness of using O/W microemulsion for the treatment of poorly soluble organohalogen compounds without compromising the efficiency of the process.…”

“…Titanium dioxide, zinc (II) tetraphenylporphyrin and titanium citrate were synthesized in previous research. 7 All other chemicals were reagent grade. The solutions were prepared in distilled and demineralized water after percolation through a demineralizer system of Milli-Q Reagent Water System, with a resistance higher than 15 MW/cm.…”

“…The prepared suspension was irradiated with UV and visible light to check the effect of the mixture on the degradation and to compare with the results obtained in previous studies. 7 Titanium citrate absorbs in the UV region and its effect on degradation could be significant and even be reinforced when the compound is confined within the micelle that might act as a micro-reactor. The value obtained for the conversion of 4-CP in W/O microemulsion, 75%, is higher than the value obtained in O/W microemulsion, 52%, and the last result comparable with the value obtained in aqueous solution, 58%.…”

“…[1][2][3] The photochemical activity of titanium dioxide and its efficiency when combined with porphyrins, have been well studied, 1,[4][5][6][7] however, few reports have been devoted to investigate the photoactivity of titanium citrate mixtures. 8 The role of citrate ion in biological processes has been well established.…”

“…Tzou et al 16 found that the reduction of Cr (VI) by means of titanium citrate in aqueous solution undergoes a further increase due to the presence of Fe (III), thus proposing that the iron (III) citrate complex is excited by light and reduced to iron (II) citrate, which in turn reduces the Cr (VI). Furthermore, Madriz and co-workers 7 demonstrated the efficient photocatalytic effect of the titanium citrate, individually and in combination with porphyrins. The efficiencies have been tested by degradation of 4-chlorophenol (4-CP) in microemulsions.…”