Spectrophotometric study of iron oxidation in the iron(II)/thiocyanate/acetone system and some analytical applications

Abstract

The possibility of using thiocyanate to determine iron(II) and/or iron(III) in water-acetone mixture has been re-examined as part of a systematic and comparative study involving metallic complexes of pseudohalide ligands. Some parameters that affect the complete oxidation of the ferrous cations, their subsequent complexation and the system stability have been studied to optimize the experimental conditions. Our results show the viability and potentiality of this simply methodology as an alternative analytical procedure to determine iron cations with high sensitivity, precision and accuracy. Studies on the calibration, stability, precision, and effect of various different ions have been carried out by using absorbance values measured at 480 nm. The analytical curve for the total iron determination obeys Beer's law (r = 0.9993), showing a higher sensitivity (molar absorptivity of 2.10x10(4) L cm-1 mol-1) when compared with other traditional systems (ligands) or even with the "similar" azide ion [1.53x10(4) L cm-1 mol-1, for iron-III/azide complexes, in 70% (v/v) tetrahydrofuran/water, at 396 nm]. Under such optimized experimental conditions, it is possible to determine iron in the concentration range from 0.5 to 2 ppm (15-65% T for older equipments, quartz cells of 1.00 cm). Analytical applications have been tested for some different materials (iron ores), also including pharmaceutical products for anemia, and results were compared with atomic absorption determinations. Very good agreement was obtained with these two different techniques, showing the potential of the present experimental conditions for the total iron spectrophotometric determinations (errors < 5%). The possibility of iron speciation was made evident by using another specific and auxiliary method for iron(II) or (III).

Magnetite Synthesis in the Presence of Cyanide or Thiocyanate under Prebiotic Chemistry Conditions

“…After this time, the absorbance of the samples was measured at the 267-nm wavelength using a 1-cm quartz cuvette. Quantification of thiocyanate ions was performed using a modification of the method described by Martins et al, which is based on the formation of a complex between iron (III) and the thiocyanate ion [38]. The reactive iron solution was prepared using 2.410 g of FeCl 3 •6H 2 O dissolved in 10% HNO 3 solution.…”

Spectrophotometric Determination of Iron(II) and Cobalt(II) by Direct, Derivative, and Simultaneous Methods Using 2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone

“…The data in the above table reveals that the proposed method of determination of iron is more sensitive than those reported by Malik and Rao [27], Patil and Dhuley [28], Nagabhushana et al [29], Wang et al [30], Zhang et al [31], and Martins et al [36]. The methods proposed by Katmal and Hoyakava [24], Morales and Toral [25], and Reddy et al [26] are more sensitive than the present method.…”

Acid mine drainage wastewater photoelectrolysis for hydrogen fuel generation: Preliminary results

“…The presence of iron can be confirmed by complexing with thiocyanate and an electronic transition at 460 nm was observed. 20 In addition, it was observed that during electrolysis, there was an increase in the deposition of the metal, probably in the form of hydroxide. In this way, electrolysis contributes to the removal of this ion from the aqueous residue and obtaining hydrogen gas, which is a clean energy source.…”

“…Iron analysis was performed on the residue formed during photoelectrolysis according to the methodology proposed in ref. 20 The concentration of dissolved iron and manganese in the collected samples was analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) (Optima 3000 DV). Turbidity determination was performed by the nephelometric method using a turbidimeter (Hanna Instruments HI83414).…”