N-Acetyl-N'-Salicylhydrazin als Reagens f�r die industrielle Analyse titanh�ltiger Erze und Minerale

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N-Acetyl-N'-Salicyl Hydrazine (ASH) has been found to be a better reagent for the gravimetric determination of microquantities of titanium in ores and minerals. The precipitation is quantitative in the pH range 3.5-5. The composition of the

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  Mikrochimica Acta [Wien] 1979 II, 397--402 9 by Springer-Verlag 1979 Chemical Section, Directorate of Geology and Mining, U. P. 2-Way Road, Lucknow-226001, India N-Acetyl-N'-Salicyl Hydrazine as a Reagent for Industrial Analysis of Titanium in Ores and Minerals By S. R. Tewari, S. K. Bajpai, V. N. Misra, and D. Prakash (Received August 24, 1978. Revised March 23, 1979) Introduction Several papers have appeared since the analytical chemistry of titanium was reviewed by Classen 1 and Fresenius et al. ~, dealing with volumetric 3, colorimetric 4, 5 and gravimetric r 7 methods. How- ever, only a few gravimetric procedures are available and little work appears to have been done on substituted hydrazines as reagent 8 for.titanium. The present communication describes the use of N- acetyl-N'-salicyl hydrazine as a selective reagent for determining microquantities of titanium in ores and minerals. In acidic medium, it gives bright yellow coloured granular precipitate which is insoluble in common organic solvents except pyridine, and is stable up to 2500 . The interference of several metal ions can be prevented by masking with EDTA. Thus the method is simpler, more efficient and less time consuming than the methods commonly used 4,v. xperimental Reagents Preparation of reagent (ASH) and its solution. 10 g of salicyl hydrazine (prepared by refluxing methyl salicylate L. R. BDH and hydrazine hydrate L. R. BDH in 2:1 molar ratio) was dissolved in 20 1111 of glacial acetic acid (A. R. BDH), and 20 ml of acetic an- hydride (A. R. BDH) was added gradually with vigorous shaking. On addition of ice cold distilled water (100 ml) to the mixture, 26 Mikrochim. Acta 1979 II/S 6 0026-3672/79/7902/0397/ 01.20  398 S.R. Tewari et al.: a white crystalline solid separated out which was filtered, washed with cold water and recrystallized from hot ethanoP [m. p. 1830 (yield = 65 )]. 1 ethanolic solution of N-acetyl-N'-salicyl hydra- zine (ASH) was used as reagent. Standard titanium solution. Standard solution of titanium 4 was prepared by placing 3.68 g of (A. R. BDH) potassium titanyl oxalate [K2TiO(C204)2-2H20] into a 300-ml Kjeldahl flask to which 8 g of (NH4)2SO4 and 100 ml of conc. H2SO4 were added. The mixture was first heated gradually and then boiled for 10 min. The solution was transferred into 1-1itre measuring flask, cooled and diluted to 1 litre by adding distilled water. 1.0 ml of this solution contains 0.50 mg of titanium. Buffer solution. The buffer solution was prepared by mixing 3 ml of acetic acid and 7 ml of sodium acetate (each 0.2 M strength). Solutions of other metal salts. Solutions of various metal salts of either BDH (A. R.) grade or E. Merck (G. R.) grade in distilled water were employed. Procedure Accurately weighed (0.5 g) titanium-containing samples (ores and minerals) were fused with 5-fold potassium bisulphate in silica crucibles. The fused mass in each crucible was cooled, extracted with hot 1.0 N sulphuric acid and filtered into 400-ml beaker. Now 15 ml of 1 reagent solution in ethanol was added to the filtrate, followed by 5--10 ml of 0.4 EDTA solution until the violet colour changed to yellow. The pH of the mixture was adjusted to ~5 by using sodium acetate and acetic acid buffer. The solution and pre- cipitate were then heated on the steam bath for 45 rain. After cool- ing to room temperature (25--35~ the precipitate was collected on G4 sintered crucible under gentle suction. The precipitate was washed with hot (50--60 ~ water to remove SO4 ~- (tested by BaC12) and finally with diethyl ether. It was dried at 1200 in an electrical oven for 30 min. The percentage of TiO2 was calculated from the for- mula: TiO2 = y x 100 x 0.132s where x is the weight of sample, y is the weight of precipitate and 0.3125 is the conversion factor (TiO2/TiOCgHsOaN2 = 0.3125). The results with various industrial samples are shown in Table I. Results and Discussion Effect of pH Titanium forms 1 : 1 complex with the reagent and is precipitated quantitatively in the pH range 3.5--5. Below  N-Acetyl-N'-Salicyl Hydrazine as a Reagent for Industrial Analysis 399 this pH range, low results are obtained due to incomplete precipi- tation, whereas high results are found above this pH range due to co-precipitation of other ions. Table I. Results Showing the Estimation of Titanium in Industrial Samples by Standard Method 4 and With N-acetyl-N'-salicyl Hydrazine (ASH) Ore/Mine- Major constituents TiO2 Dif- rals/Std. Locality of Ore- Std. ASH fer- compound Fe203 A1203 method method ence, Laterite Rajhuan area, 4.95 42.85 2.27 2.26 -0.01 Banda 2.28 2.26 - 0.02 2.28 2.26 - 0.02 Bauxite Bela Pathar 20.65 42.26 7.39 7.39 + 0.00 area, Banda 7.39 7.40 + 0.01 7.40 7.40 + 0.00 Bauxite Rajhuan area, 33.35 35.08 9.32 9.30 - 0.02 Banda 9.33 9.30 - 0.03 9.33 9.31 -0.02 Laterite Rajhuan area, 21.66 40.41 10.62 10.64 +0.09 Banda 10.63 10.65 +0.02 10.64 10.65 +0.01 Aluminous Turka hill 14.96 49.02 16.49 16.50 + 0.01 Laterite area, Banda 16.50 16.50 + 0.00 16.51 16.50 -0.01 Bauxite Turka area, 9.87 44.06 19.66 19.67 + 0.01 Banda 19.67 19.68 +0.01 19.67 19.68 + 0.01 Pot. Titanium K2TiO(C20@2. Cal. Ti02=22.55 22.50 22.53 +0.03 Oxalate 2HzO 22.51 22.53 +0.02 (A. R. BDH) 22.52 22.53 +0.01 Ilmenite Geology Cal. Ti02 = 52.65 52.60 52.62 +0.02 (Purified) Dept. L.U. 52.60 52.62 +0.02 52.62 52.63 + 0.01 Effect o[ diverse ions. Zn ~+, Ca 2+, Ba 2+, Sr 2+, Mg ~+, Cd 2+, Hg 2+, Ni 2+, Mn 2+, Fe z+, Pb ~+, Sb z+, Bi 3+, Zr 4+, Th 4+, Hf 4+, Nb 5+, Ta 5+, CI-, Br-, I-, CHzCOO-, SO42-, N03-, SCN-; S ~-, S2Oz 2-, C2042- ion do not interfere in the pH range 3.5--5. Interferences of Fe 8+, A18 , Cr z , UO2 2 , VO 2 , and Co 2+ can be prevented by masking with EDTA. Because titanium is masked by C6H5073-, F- I)O413- and H202, determination of titanium cannot be done in their pres- ence. Cerium and tin also interfere seriously. Small amounts of copper (up to 25 nag) do not interfere while larger amounts (more than 25 nag) of it are not tolerable. The samples (ores and minerals) tested in this investigation do not contain significant amounts of Bi z+, Sb z+, Pb 2+, Zr 4+, Th 4+, Hf 4+, Nb 5+, Ta 5+ ions. 26*  400 S R Tewari et al : For quantitative precipitation of titanium the pH should be adjusted to 5 only after the reagent solution has been added, fol- lowed by 0.4 EDTA solution (see procedure), because introduction of EDTA before adding the reagent solution prevents the precipi- tation of titanium. Titanium is precipitated from the sample solu- tions along with A13+, Cr 3+, Fe z+, UO22+, VO 2+ and Co 2§ but the precipitates of the named ions redissolve upon addition of EDTA. The reagent (ASH) has been found to be a better gravimetric reagent for titanium in the pH range 3.5--5. The precipitate ob- tained with this reagent is a low density solid. Besides it is not wetted by water and is easily freed from moisture. The non-hygro- scopic nature of the precipitate and its inertness towards the atmo- sphere have simplified the final weighing process. The precipitate obtained in the case of N-acetyl-N'-salicyl hydra- zine is granular, bright yellow in colour and more easily separated by filtration in comparison to salicyl hydrazine s. When cupferon 7 is used as reagent for titanium estimation, Fe 3+, Zr 4+, V 5+, Sn 2+, Sb 3+ and Bi 3+ interfere; no interference occurs with the new re- agent, except Sn 2+ and Sn 4+ (due to hydrolysis). The high formula weight of the precipitate is another advantage. Structure of titanium complex The i. r. spectrum of titanium complex shows a broad band centred at 3120 cm -1 assignable to mixed vibration of ~ OH and r NH which suffers a negative shift of 30 cm -1 as compared to ligand (at 3150 cm -1) due to involve- ment of these groups in complexation m~~ A band of ligand at 1660 cm -1 suffers a negative shift and appears in the complex at 1600 cm -1, indicating the coordination of C=O and C=N groups (C=N arises due to enolization of acetyl part of ligandg). Further, the coordination of NCO group is evident from the band at 1560 cm -1 in the complex 11. The bands at 580 cm -1 and 430 cm -1 in the complex have been assigned to Ti-O and Ti-N modes re- spectively 12. On the basis of these i. r. spectral data and elemental analysis ( found Ti = 18.80, C =42.20, H =3.10, N = 10.90, re- quired for TiO(CgHaO~N2) Ti=18.75, C=42.18, H=3.12, N = 10.93) the following structure of titanium complex is postu- lated: TiO 0 ~ 2 ~ 0 C -- NH N%c -- CH3 I Ti.q O 2 )io ( o3 N2)]  N-Acetyl-N'-Salicyl Hydrazine as a Reagent for Industrial Analysis 401 cknowledgement The authors are grateful to the Director, Geology Mining U. P., Lucknow, for his keen interest in the work, and to Dr. S. K. Misra of the Chemistry Department, Lucknow University for his help. Summary N-Acetyl-N -SalicyI Hydrazine as a Reagent for Industrial Analysis o~ Titanium in Ores and Minerals N-Acetyl-N'-Salicyl Hydrazine (ASH) has been found to be a better reagent for the gravimetric determination of microquantities of titanium in ores and minerals. The precipitation is quantitative in the pH range 3.5--5. The composition of the precipitate cor- responds to formula TiO(CoHsOaN2). Zusammenfassung N-Acetyl-N -SaIicylhydrazin als Reagens /~ir die industrieIle Analyse titanh~iltiger Erze und MineraIe N-Acetyl-N'-Salicylhydrazin hat sich als Reagens ftir die gravimetrische Bestimmung von Mikromengen Titan in Erzen und Mineralen bew~ihrt. Im pH-Bereich 3,5--5 ist die F~illung quantitativ. Die Zusammensetzung des Niederschlages entspricht der Formel TiO(CgHsOaN~). References 1 A. Classen, Chem. Weekblad 39, 23 (1942). 2 L. Fresenius and W. M. Hartmann, Z. analyt. Chem. 73, 202 (1933). a S. Ishimaru, J. Chem. Soc. Japan 56, 71 (1935). 4 A.I. Vogel, A Text Book of Quantitative Inorganic Analysis. London: Longmans-Green. 1973. pp. 543--545, 788. 5 R. M. Sherwood and F. W. Chapman Jr., Analyt. Chemistry 27, 88 (1955). 6 S. C. Shome, Analyst 75, 27 (1950). v K. L. Cheng, Analyt. Chemistry 30, 1941 (1958). 8 j. Haldar, N. R. Sen Gupta, and S. N. Poddar, J. Ind. Chem. Soc. 47, 33 (1970). 9 R. Gopal, V. N. Misra, and K. K. Narang, Ind. J. Chem. 13, 186 (1975).
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