Abstract
A water-isobutanol extraction-chromogenic system for NiII, based on the azo dye 5-methyl-4-(2-thiazolylazo)resorcinol (MTAR; H2L) and the ionic liquid Aliquat 336 (A336), was studied. Under the optimal conditions (cMTAR = 2.0 × 10-4 mol dm-3, cA336 = 5.6 × 10-3 mol dm-3, pH 8.5 and extraction time t = 1 min), NiII is extracted as a ternary complex which can be represented by the formula (A336+)2[Ni(L2-)2]. In the absence of A336, or in a slightly acidic medium, a binary complex, [Ni(HL-)2], with an absorption maximum at l = 548 nm and a shoulder at 590 nm is formed. The following extraction-spectrophotometric characteristics were determined at the above-mentioned optimal conditions: lmax (545 nm), molar absorptivity (5.0 × 104 dm3 mol-1 cm-1), Sandell's sensitivity (1.2 × 10-3 ∆g cm-2), Beer's law limits (0.05-3.1 mg cm-3), constant of extraction (Log K = 6.1) and fraction extracted (99.2%). The effect of foreign ions was studied; the most serious interferences were caused by CoII, CuII and CrIII.
Highlights
Nickel is a first-row transition metal with many industrial applications[1] and important functions in biology of microorganisms and plants.[2]. It is involved in a variety of products, such as stainless steels, alloys, rechargeable batteries, guitar strings, green colored glasses, permanent magnets and catalysts for large-scale industrial processes
At lower pH values (4.7; spectra 3 and 4), nickel is extracted to a negligible extent regardless of the presence or absence of Aliquat 336 (A336)
The absorbance of the blanks in the absence of A336 (2’ and 4’) is lower than that obtained in the presence of A336 (1’ and 3’, respectively)
Summary
Nickel is a first-row transition metal with many industrial applications[1] and important functions in biology of microorganisms and plants.[2] It is involved in a variety of products, such as stainless steels, alloys, rechargeable batteries, guitar strings, green colored glasses, permanent magnets and catalysts for large-scale industrial processes. Most of the nickel produced is used in stainless steels, ferrous and non-ferrous alloys and nickel plating.[3] The chief criteria of use are its resistance to air oxygen, alkalis and acids, lustrous shine, ductility, malleability, and excellent ability to alloy with both ferrous and nonferrous metals. Over 3000 alloys containing nickel are known. They have more than 250 000 applications.[4]
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