Kinetics Study, and Proposed Mechanism for the Photochemical Reduction of Chromium (VI) by Iron(III)-mandelic acid Complexes in Aqueous Solutions

تناول البحث الحالي دراسة تفاعل الإرجاع الفوتوكيميائي للكروم السداسيّ المستحثّ بوساطة معقّدات مانديلات الحديد الثلاثيّ في المحاليل المائيّة. و تمّ إجراء تجارب مقارنة من أجل تحديد الشروط المثلى لتفاعل الإرجاع الضوئي للكروم السداسيّ في الجملة:؛ حيث دُرست تأثيرات كلّ من: - الوسط و التراكيز الابتدائيّة للمكوّنات المختلفة؛ الحديد الثلاثيّ و حمض المانديليك و الكروم السداسيّ، على فعالية إرجاع الكروم السداسيّ. أظهرت النتائج التجريبيّة أنّه يمكن لمعقّد مانديلات الحديد الفعّال ضوئياً إرجاع الكروم السداسيّ باستخدام الضوء فوق البنفسجي/ المرئي ، و أنّ قيمة المُثلى للإرجاع الفوتوكيميائي للكروم السداسيّ بوساطة هذا المعقّد تبلغ نحو . و تبيّن أنّ فعالية الإرجاع الضوئي للكروم السداسيّ تزداد بازدياد التراكيز الابتدائيّة لكلّ من الحديد الثلاثيّ و حمض المانديليك، و لكنّها تتناقص كلّما ازدادت التراكيز الابتدائيّة للكروم السداسيّ. و قد تمّ اقتراح آليّة محتملة لتفاعل الإرجاع الضوئي للكروم السداسيّ بوساطة معقد مانديلات الحديد الفعّال ضوئياً في المحلول المائي.

Spectrophotometric Study of Iron(III)-Lactic Acid Complexes, and Suggested Mechanism for the Photoredox Reaction of the Complex

The spectral characteristics of the iron(III) lactate complexes were examined by the spectrophotometric methode, and the absorbance of these complexes has been studied at diferente wavelengthes . The stoichiometry of the photoreactive complex formed in the iron(III)-lactate system has been investigated in aqeuous solution under determinative experimental conditions. Initial concentrations whether of Iron(III) or of lactic acid ranged from to , and -values were belonging to the range . The results showed, that the ratio of iron(III) to lactate in the photoreactive complex is 1:2, i.e. its formula is . This complex has a maximum absorption at 365 nm. Its molecular absorption coefficient is about ≈ and its dissociation constant is about . The tentative mechanism for the photochemical decomposition of the complex has been suggested, in agreement with the reference studys . The suggested mechanism depends on the relationship between the absorbance and the photoreaction kinetics, and it is not based on the qualitative or quantitative analysis of reaction products.

Kinetics and Mechanism for the UV-Visible Photolysis Ferrioxalate Complexes in the Absence and Presence of Oxygen, in Aqueous Solutions.

In this work, the UV-Visible photolysis aqueous ferrioxalate complexes has been studied kinetically and mechanistically, in the absence and presence of molecular oxygen.

A new spectrophotometric analytical reagent for determination of Fe(III)

This paper outline a new, simple, selective and sensitive spectrophotometric procedure for the quantitative determination of iron. The bidentate ligand of 2- (1-Acetyl-2-oxopropyl)acrylonitrile has been synthesized ,and determined by elemental analysis and infrared spectroscopy. The compound reacts with Fe(III) to form a colored complex with an absorption maxima at 400nm and 490nm. The effect of pH, amount of reagent, time, temperature and the interference of many ions on the Fe (III) determination was also estimated. Beer's law is obeyed for iron concentration in the range (0.23- 4.48μg/ ml) for spectrophotometric method and (0.56-8.4) for extraction spectrophotometric method. The molar absorptivity was in the rang 2.70x104-3.46 x 104 L.mol-1cm-1. Sandall's sensitivity was found to be 1.61 x 10 -3 – 2.07 x 10-3 μg . cm-2. The RSDs for both spectrophotometric and extraction spectrophotometric methods were below 3%. The analytical error SD/√n was within 0.021. The technique has been applied to the determination of iron in alloys and in pharmaceutical preparations.