Vol. 1, Issue 1 (2017)
Extraction-spectrophotometric determination of cobalt (ii) in a liquid-liquid extraction system containing 4-nitro-2-hydroxythiophenol and diphenylguanidine, determination of cobalt (ii) in steel
Author(s): Abel M Maharramov, Shahla A Ibrahimova, Naila A Verdizadeh, Ali Z Zalov, Kamala O Isgenderova
Abstract: The complex formation and a liquid-liquid extraction in the cobalt (II) - 4-Nitro-2-hydroxythiophenol (HNTP) - diphenylguanidine (DPG) - water - chloroform system was studied. The optimum extraction-spectrophotometric conditions were found. The molar ratio of the reacting species was determined to be 1:2:2 (Co: HNTP: DPG). The following equilibrium processes were quantitatively examined: the association between the anionic chelate, [Co2+(HNTP)2]2–, and the diphenylguanidine (lgβ =4.8); the distribution of the ternary complex between the aqueous and organic phases (lg KD=0.88); and the extraction from water to chloroform (lgKex=lgβ +lgKD=5.6). The effect of foreign ions and reagents on the extraction was studied. A sensitive (ε560=4.3×104 L mol–1 cm–1) and simple extraction-spectrophotometric procedure for cobalt determination was developed.