| The current version does not support copying Cyrillic text to the Clipboard. You should activate the programThe effect of the dosage of iron oxides, initial concentration of oxalic acid (Cox), initial pH value and initial concentration of orange I on the photochemical degradation of orange I in the iron oxides-oxalic acid system was investigated. The results showed oxalic acid could greatly promote the photochemical degradation of orange I, and there was an optimal Cox- The apparert first-order kinetic constant of orange I photochemical degradation increased firstly and then decreased with the increase of Cox when Cox was more than the optimal value. The optimal Cox should be 1.8 mmol-L"1, 1.6 mmol-L" , 3.5 mmol-L"1, 3.0 mmol-L"1 and 0.8 mmol-L"1 for y-FeOOFL IO-250> IO-320, IO-420. IO-520 respectively. Acidity medium was suitable to orange I photochemical degradation. On the contrary, orange I was hardly degraded in neutral medium and alkaline medium. And there was an optimal pH value. The optimal pH value was 3.94 for y-FeOOH and pH value was 3.95 for IO-320, whose k' should be 4.256xlO"2min"' and 3.463xlO'2min"' respectively. The apparert first-order kinetic constant of orange I degradation would become small with the increase of initial concentration of orange I. The optimal concentration was Smg-L'1 for y-FeOOH and IO-320, whose k' should be 4.261x10"min" and 4.387x10" min" respectively. The results also showed that photochemical activity of iron oxides for orange I degradation decreased with the increase of sintering temperature. The k' value of y-FeOOH, IO-250, IO-320, IO-420, IO-520 at the optimal Cox should be 1.717xlO"2 min"1, 1.656xlO"2 min"1, 1.624xlO"2 min"1, 1.361xlO"2 min"1, 0.922xl0"2 min"1, respectively.3. Photochemical Degradation of DiuronThe effect of the iron oxides and initial concentration of oxalic acid (Cox) on the photochemical degradation of diuron in the iron oxides-oxalic acid system was investigated. The results showed oxalic acid could greatly promote the photochemical degradation of diuron, and there was an optimal Cox- The apparert first-order kinetic constant of diuron photochemical degradation increased firstly and then decreased with the increase of Cox when Cox was more than the optimal value, which was 0.8 mmol-L"1 for all iron oxides. To be interested, the results showed that photochemical activity of iron oxides for diuron degradation increased with the increase of sintering temperature. The k' value of diuron of y-FeOOH, IO-250, IO-320, IO-420 at the optimal Cox should be 0.1477 min4, 0.1897 min\ 0.2123 min"\ 0.3245 min"! after 15 min, respectively.4. Mineralization of Organic PollutantsThe generation of products including Cl" and the removal of TOC implies two organic pollutants was effectively mineralized in the iron oxide-oxalic acid system.5. The Discussion of Photochemical MechanismThe experiment results showed that oxalic acid could enhance iron oxides to be dissolved. Obviously, the concentration of total-Fe ion and Fe(II) ion increased gradually with the increase of Cox- Iron oxides/Fem-oxalic acid complexes should be form in presence of oxalic acid. And then radicals and H2O2 also form. The photochemical mechanisms including heterogeneous photocatalysis, heterogeneous photo-Fenton-like reactions and homogenous photo-Fenton-like reactions were discussed.The originals of this investigation includes (1) Setting up the photochemical system of iron oxides-oxalate to simulate natural geocatalysis; (2) Investigating the effect of the dosage of iron oxides, initial concentration of oxalic acid (Cox), initial pH value and initial concentration of orange I and diuron on the photochemical degradation of orange I in the iron oxides-oxalic acid system. Two organic pollutants had different regular of photochemical degradation; (3) Discussing the mechanism of photochemical reaction including hetero geneous photocatalysis, heterogeneous photo-Fenton-like reactions and homogenous photo-Fenton-like reactions.
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