FTIR-SPECTROSCOPIC INVESTIGATION OF SODIUM TUNGSTATE AND SODIUM MOLYBDATE SOLUTIONS IN WIDE RANGE OF рH
Abstract
For citation:
Matveichuk Yu.V. FTIR-spectroscopic investigation of sodium tungstate and sodium molybdate solutions in wide range of рH. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 1. P. 56-63.
A FTIR spectroscopic study of aqueous solutions of sodium tungstate and molybdate (solution concentration was 0.1 mol/l) over a wide pH range (factor (level) of acidity Z, Z = C (H+)/C (WO42-) or Z = C (H+)/C(MoO42-)) was carried out. In solutions of sodium tungstate complex frequency band at 885-865 cm-1 correspoding to the stretching vibrations ν(W-O-W) was fixed. The frequency bands of 1720-1700 cm-1, 990, 985 and 1025 cm-1 corresponding to bending vibrations δ(W-OH) were fixed that indicates a significant change in composition of the solution as a result of hydrolytic and polycondensation processes. The sodium molybdate solution has not bands corresponding to the stretching vibrations v(Mo-O-Mo). Only the characteristic bands of the deformation vibrations δ(Mo-OH) were recorded. The low intensity complex band in the area of 885-865 cm-1 corresponding to the stretching vibrations ν(W-O-W) even for freshly prepared 0.1 mol/l sodium tungstate solution was appeared as well as the band at 1720-1700 cm-1 attributed to deformation vibrations δ(W-OH) that indicates a fast change in the solution composition. For solutions of sodium molybdate bands of stretching vibrations v(Mo-O-Mo) are fixed at a pH less than 6 after standing for several days. With Hydra/Medusa program diagrams of distribution of molybdate and tungsten particle depending on the pH were calculated. In relatively dilute solutions, the diagrams received with Hydra/Medusa program showed the only protonated (monomeric) form of molybdate ions, where as in the sodium tungstate solution until pH of 9 W6O216- and HW6O215- particles exist that agrees with the results of IR spectroscopy. The results of IR spectroscopy and modeling with Hydra/Medusa program will be used to support the pH operating range for molybdate and tungstate-selective electrodes, since they are an important feature of any analytical ion-selective electrodes. For tungstate-selective electrode it is necessary to maintain the pH less than 9, for molybdate-selective electrode - less than 8 (with dilute ammonia). Considering the changes in the composition of sodium molybdate and tungstate solutions, for the design of molybdate and tungstate-selective electrodes the freshly prepared solutions have to be only used, rather than stored for more than two days.
References
Mokhosoev M.V., Shevtsova N.A. The state of molyb-denum and tungsten ions in aqueous solutions. Ulan-Ude: Buryatsk Book Publishing. 1977. 168 p (in Russian).
Wang J., Wang L., Han Yu., Jia J., Jiang L., Yang W., Sun Q., Lv H. PVC membrane electrode based on tri-heptyl dodecyl ammonium iodide for the selective determina-tion of molybdate(VI). Anal. Chim. Acta. 2007. V. 589. N 1. P. 33−38.
Polyakov E.V., Manakova L.I., Maksimova L.G., Gyr-dasova O.I. Tungstate-Selective Electrode. J. Anal. Chem. 2002. V. 57. N 5. Р. 452−455.
Gupta V.K., Chandra S., Chauhan D.K., Mangla R. Membranes of 5,10,15,20-Tetrakis(4-Methoxyphenyl) Por-phyrinatocobalt (TMOPP-Co) (I) as MoO42- - Selective Sen-sors. Sensors. 2002. V. 2. N 5. Р. 164−173.
Sibirkin A.A., Zamyatin O.A., Churbanov M.F. Mutual transformation of molybdenum (VI) isopolycompounds in aqueous solution. Vestn. Nizhegorod. un-ta. name. N.I. Lo-bachevsky. 2008. N 5. P. 45−51 (in Russian).
Khramenkova A.V. Preparation of composite and polymer-immobilized catalytically active oxide coatings by non-stationary electrolysis. Dissertation for candidate degree on technical sciences. Novocherkassk: Yuzhno-ros. gos. politekh. un-t im. M.I. Platova. 2014. 245 p. (in Russian).
Svintenok S.V. Molybdenum (V), molybdenum (VI) and tungsten (VI) compounds in aqueous solutions of some oxy-acids. Dissertation for candidate degree on technical sciences. Kazan: Kazan. gos. un-t. 2003. 147 p. (in Russian).
Nersisyan L.G., Babayan G.G., Pirumyan G.P., Vlasov V.K., Kiryukhin O.V. Physico-chemical and thermo lumi-nescent parameters of molibdatum of terbium and its applica-tion in dosimetry. Chem. J. Armenia. 2004. V. 57. N 4. P. 36−40 (in Russian).
Nersisyan L.G., Babayan G.G., Grigoryan S.K. Synthesis and propeties of simple hydromolibdats of rare earth ele-ments. Chem. J. Armenia. 2002. V. 55. N 3. P. 67−73 (in Russian).
Rozantsev G.M., Radio S.V., Gumerova N.I., Baumer V.N., Shishkin O.V. Phase formation in system Ni2+-WO42--H+–H2O Z= 1.00). Crystal structure and properties of sodi-um heteropolyhexatungstatonickelate (2+) Na4[Ni(OH)6W6O18]·16H2O. J. Struct. chem. 2009. V. 50. N 2. P. 311−319 (in Russian).
Rozantsev G.M., Radio S.V., Zagalskaya E.Yu. Synthe-sis of сalcium paratungstate. Naukovі pratsі of Donetsk nat. tehn. unіv. Serіya «Khіmіya i khіmіchna tehnologіya».
V. 134. Donetsk: Donetsk National Technical University. 2008. P. 47–53 (in Russian).
Gumerova N.I., Kasyanov E.V., Notich A.V., Rozantsev G.M., Radio S.V. Synthesis and surface morphology of eu-ropium and lutetium heteropolyhexatungstatonickelats(II). Vestn. Donetsk Nat. univ. Ser. A: Sci. nature. 2013. N 2. P. 118−122 (in Ukraine).
Gumerova N.I., Semenova K.A., Rozantsev G.M., Radio S.V. Formation of polyoxometalate Anions in Acidified Aqueous Solutions of Sodium Tungstate in the Presence of Co(II) and Ni(II). J. Siberian Fed. Univ. Chem. 1. 2012. N 5. P. 73−85 (in Russian).
Bazarova Ts.T., Sarapulova A.E., Bazarov B.G. Vibra-tional spectra of ternary molybdates of thallium, divalent met-als and zirconium. Vestn. Buryat. gos. un-ta. 2011. N 3. P. 3−7 (in Russian).
Dulenin A.P., Lokhova N.G., Pirmatov E.A., Pirmatov A.E., Matyushkin A.V., Shoinbaev A.T. Influence of mo-lybdates structure on the electrolytic properties of their solu-tions. Proceedings Nat. Academy Sci. Rep. Kazakhstan. Ser. Khim. 2007. N 3. P. 78−82 (in Russian).
Maxe L.P., Tomov A.V., Markov P.I. BY Patent N 11876 C1. 2009 (in Russiaan).
Nakamoto K. Infrared and Raman spectra of inorganic and coordination compounds. New York: John Wiley&Sons. 1986. 536 p.
Troitskaya I.B., Gavrilova T.A. Nanoplates of h-WO3: synthesis, micromorphology, characterization. Pis’ma o Materialakh. 2011. V. 1. P. 65−69 (in Russian).
Shurdumov G.K. Synthesis of molybdates and tungstates of lead in melts of [KNO3-NaNO3-Pb(NO3)2]evt.–Na2Mo(W)O4 [(K,Na,Pb//NO3,Mo(W)O4)] systems. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2014. V. 57. N 2. Р. 91−96 (in Russian).
Hydra/Medusa. http://www.kemi.kth.se/medusa.
