Electrochemical Determination of Some Triphenylmethane Dyes by Means of Voltammetry

AbstractThis paper provides the investigation of electrochemical properties of triphenylmethane dyes using a voltammetric method with constant-current potential sweep. Malachite green (MG) and basic fuchsin (BF) have been chosen as representatives of the triphenylmethane dyes. The electrochemical behavior of MG and BF on the surface of a mercury-film electrode depending on рН, the nature of background electrolyte and scan rate of potential sweep have been investigated. The conditions of registration have been determined for MG and BF detecting in the solution. It is demonstrated that the reduction peak currents of MG and BF increase linearly with their concentration in the range of 9.0·10-5- 7.0·10-3 mol/dm3 for MG, 6.0·10-5 – 8.0 10-3 mol/dm3 for BF with correlation coefficients of 0.9987 and 0.9961, respectively. The detection limit of MG is 5.0·10-5 mol/dm3 and for BF - 2.0·10-5 mol/dm3

Lobanovite, K2Na(Fe2+4Mg2Na)Ti2(Si4O12)2O2(OH)4, a new mineral of the astrophyllite supergroup and its relation to magnesioastrophyllite

Lobanovite, K2Na(Embedded ImageMg2Na)Ti2(Si4O12)2O2(OH)4, is a new mineral of the astrophyllite supergroup from Mt. Yukspor, the Khibiny alkaline massif, Kola Peninsula Russia. It has been known previously under the following names: monoclinic astrophyllite, magnesium astrophyllite, magnesiumastrophyllite and magnesioastrophyllite but has never been formally proposed and approved as a valid mineral species by the Commission on new Minerals, Nomenclature and Classification of the International Mineralogical Association. It has now been revalidated and named lobanovite after Dr. Konstantin V. Lobanov, a prominent Russian ore geologist who worked in the Kola Peninsula for more than forty years (Nomenclature voting proposal 15-B). Lobanovite has been described from pegmatitic cavities on Mt. Yukspor where it occurs as elongated bladed crystals, up to 0.04\u2005mm wide and 0.2\u2005mm long, with a straw yellow to orange colour. Associated minerals are shcherbakovite, lamprophyllite, delindeite, wadeite, umbite and kostylevite. Lobanovite is biaxial (\u2013) with refractive indices (\u3bb\u2009=\u2009589\u2005nm) \u3b1\u2009=\u20091.658, \u3b2calc.\u2009=\u20091.687, \u3b3\u2009=\u20091.710; 2Vmeas.\u2009=\u200981.5\u201383\ub0. Lobanovite is monoclinic, space group C2/m, a\u2009=\u20095.3327(2), b\u2009=\u200923.1535(9), c\u2009=\u200910.3775(4) \uc5, \u3b2\u2009=\u200999.615(1)\ub0, V\u2009=\u20091263.3(1) \uc53, Z\u2009=\u20092. The six strongest reflections in the powder X-ray diffraction data [d (\uc5), I, (hkl)] are: 3.38, 100, (003); 2.548, 90, (063); 10.1, 80, (001); 3.80, 60, (042,131); 3.079, 50, (132,062); 2.763, 90, (-171). The chemical composition of lobanovite was determined by electron-microprobe analysis and the empirical formula (K1.97Ba0.01)\u3a31.98(Na0.65Ca0.14)\u3a30.79(Fe2+0.18Mg2.02Na1.00Mn0.72)\u3a36.92(Ti1.99Nb0.06)\u3a32.05[(Si8.01Al0.06)\u3a38.07O24]O2(OH)4.03F0.19 was calculated on the basis of 30.2 (O\u2009+\u2009OH\u2009+\u2009F) anions, with H2O calculated from structure refinement, Dcalc.\u2009=\u20093.161\u2005g cm\u20133. In the structure of lobanovite, the main structural unit is the HOH block, which consists of one close-packed O (Octahedral) and two H (Heteropolyhedral) sheets. The M(1\u20134) octahedra form the O sheet and the T4O12 astrophyllite ribbons and [5]-coordinated Ti-dominant D polyhedra link through common vertices to form the H sheet. The HOH blocks repeat along [001], and K and Na atoms occur at the interstitial A and B sites. The simplified and end-member formulae of lobanovite are K2Na[(Fe2+,Mn)4Mg2Na]Ti2(Si4O12)2O2(OH)4 and K2Na(Fe2+4Mg2Na)Ti2(Si4O12)2O2(OH)4, respectively

Acid Properties of Cesium-Nickel-Zirconium Complex Phosphates: Effect on Isobutanol Dehydration

Abstract: The physicochemical and catalytic properties of Cs1 – 2xNixZr2(PO4)3 (x = 0, 0.15, 0.25, 0.50) systems are studied. Double and triple nickel-containing phosphates with the NASICON structure are obtained by the sol–gel method. It is shown that these phosphates are active and stable isobutanol dehydration catalysts. The relationship between the catalytic activity in the dehydration reaction over triple cesium-zirconium phosphates and their crystallographic characteristics and surface acidity is established. It is shown that upon partial or complete replacement of cesium ions with nickel ions an increase in dehydration activity correlates with an increase in the number of acid sites determined by the pyridine adsorption titration method. © 2020, Pleiades Publishing, Ltd