Abstract
The presented article is devoted to the study of oil-collecting and oil-dispersing properties of the quaternary ammonium salt (DAD), formed by hexadecane (6-DT) and heptadecanoic acid (7-DT) with triethanolamine (TEA) {triethanolammonium salt of hexadecanoic acid (6-DAD) and triethanolammonium salt of heptadecanoic acid (7-DAD)}, as well as its use as an analytical reagent for the extraction-photometric determination of manganese in the form of a mixed-ligand complex (MLC) with 2-hydroxy-5-chlorothiophenol (H2L, L) and DAD in various objects. DAD solutions with a concentration of 0.025%, 0.05%, 0.75%, 0.1% form a colloidal solution in water, and are readily soluble in ethyl and isopropyl alcohols. From a comparison of DADs, it is clear that 6-DAD is superior in its ability to disperse oil in drinking and sea water (6-DAD: CD=82.2; 7-DAD: 86.2%). 6-DAD exhibited high surface activity, showing a decrease in surface tension from 62.2 mN/m to 34.4 mN/m (and for 7-DAD from 59.8 mN/m to 33.3 mN/m). DAD was studied as an oil collector and oil dispersant when treating the surface of water that was turbid due to an oil layer 0.17 nm thick. The spectrophotometric method was used to study the complex formation of manganese(II) with L and DAD. The maximum absorption of MLC Mn(II)-L-DAD is observed at λ = 545-550 nm (pHop.3.5–5.9). The molar absorption coefficients range from (2.58-2.71)·10⁴. With a single extraction using chloroform, 99.1–99.3% of manganese is extracted as MLC. The optimal conditions for the formation and extraction of MLC are 1.3·10⁻³ M L and (1.2–1.5)·10⁻³ M-DAD. Beer's law is followed within the range of 0.2–100 µg/mL of manganese. Large amounts of alkali, AEM, and REE do not interfere with the determination of manganese. The interfering effect of Fe(III) was eliminated using thioglycolic acid or a 20% solution of SnCl₂, Cu(II) and Cr(VI) were addressed with thiourea, Ti(IV) was treated with ascorbic acid, and Zr(IV), Nb(V), and Ta(V) with fluoride ions. The results of the studies on the formation and extraction of Mn(II) MLC with L and DAD were applied for the extraction-photometric determination of manganese in water.