| Abstract: By using gas chromatograph, spectrophotometer and acidimeter, we studied the photoreduction of Fe(Ⅲ)-phen (1,10 phenanthroline) in solution, The results of the investigation reveal that, the photoreduction reaction of Fe (Ⅲ)-phen in solution is also dependent on the composition of the solution system. Under suitable pH condition (pH > 2), by using sunligitomhigh-pressure fluorescent bulb as light source, the photochemical reduction produce the solution containing Fe(Ⅲ)-phen only. This meant that water appeared to be an electron donor. In the presence of citric acid and other organic ligands, CO2 produced. In this case the organic ligands were the electron donors. On using acetic acid instead of citric acid, the photochemical reduction produce O2 and CO2. In this case, both water and acetic acid were the electron donors. When pH value of the solution became less than 1.0, the photochemical reduction would not happen. After the photochemical reduction, pH value of the solution became low. We hypothesize that photoreduction mechanism of the Fe(Ⅲ)-phen solution is involving the formation of the mononuclear or polynuclear complex in Fe(Ⅲ)-phen solution-Fe(Ⅲ)x(phen)YLz(where, L = OH-, neutral molecules such as H2O etc., or organic ligands, X,Y,Z≥1,respectively), that is, the electron donor-accepter complex DAC formed as a starting material. Then the DAC would be reduced to Fe(phen)32+ by light with excess phen. The experiment indicates that different L induces different reactions in solution. |
