Artik Elisa Angkawijaya, Ahmed E. Fazary, Erzalina Hernowo, Suryadi Ismadji, Yi-Hsu Ju
Binary and mixed-ligand complexes of Ni2+ and Co2+ involving L-norvaline (Nva) and ferulic acid (FA) have been investigated in aqueous solutions by pH potentiometry and UV-visible spectrophotometric techniques, at 298.15 K and fixed ionic strength (0.15 moldm3, NaNO3). The overall stability constants of the Ni2+ and Co2+ complexes with the ligands studied were obtained by the HYPERQUAD2008 program from the pHpotentiometric data. As a result of the numerical treatment, a model composed of seven species NiNva+, NiNva2, NiNvaH1, NiNva- 2, NiFA, NiFAH- 1 and NiNvaFA was obtained for the Ni2+ + Nva + FA system, whereas for the Co2+ + Nva + FA system the complexes CoNva+, CoNva2 , CoNvaH1, CoNvaH- 2, CoFA, CoFAH- 1, and CoNvaFA were obtained. The complex species distributions in certain pH ranges were calculated by the HySS2009 simulation program. Spectroscopic UV-visible measurements were carried out to give qualitative information about the complexes formed in these solutions. © Springer Science+Business Media, LLC 2012.
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106-07, 43 Keelung Road, Taiwan; Chemistry Department, Faculty of Science, King Khalid University, Abha 9004, Saudi Arabia; Applied Research Sector, Egyptian Organization for Biological Products and Vaccines, Cairo, Egypt; Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Surabaya 60114, Kalijudan 37, Indonesia