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Study and Application of Determination of Trace Vanadium(Ⅴ) and Vanadium(Ⅳ) in Water by the Catalytic Kinetic Spectrophotometric Method

Author: ShaYuanYuan
Tutor: JiZuoWei
School: Ocean University of China
Course: Marine Chemistry
Keywords: Catalytic Kinetic Spectrophotometric Weak Acid Brilliant Blue Vanadium ( V ) Vanadium ( IV ) Seawater
CLC: X832
Type: Master's thesis
Year: 2009
Downloads: 110
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Abstract

Vanadium is an the life essential trace elements, bio-inorganic chemistry as one of the anti-cancer elements. Understanding of trace amounts of vanadium (V) and vanadium (IV) content and distribution of marine chemistry, environmental science and biogeochemistry research is of great significance. At present, at home and abroad for the determination of trace amounts of vanadium (V) and vanadium (IV) methods of analysis most of the need for sample pretreatment in order to carry out the tedious steps, harsh conditions, most still require heating, high cost analysis. Less reported in the literature on the direct determination of seawater vanadium. Catalytic Kinetic Spectrophotometric because of its high sensitivity, detection limit is low, the instrument inexpensive, simple operation, and has become the most attractive method for determination of trace metals. Therefore, according to the principle of Catalytic Kinetic study new Determination of Trace Vanadium (V) and vanadium (IV) reaction system and the reaction mechanism, the establishment of the system can be used in freshwater and seawater trace vanadium (V) and vanadium (IV) Determination of high sensitivity and selectivity of new analytical methods is very meaningful. The paper according to the principle of catalytic kinetic methods of analysis of trace vanadium (V) and vanadium (IV) and vanadium (V) and vanadium (IV) the kinetic parameters were determined. Through research, the establishment of new analytical methods for the direct determination of trace amounts of vanadium (V) and vanadium (IV). In this paper, the method is applied to the vanadium (V) and vanadium (IV) in freshwater and seawater in the determination of vanadium (V), and achieved satisfactory results. In this paper, the main results are the following: (1) successfully built a room temperature of new analytical methods for determination of trace vanadium (V). The method is characterized as follows: high-accuracy, high-precision, high sensitivity, high selectivity, low detection limit, wide linear range, and easy to operate for at room temperature. (1) through research, a new determination of trace vanadium (V) reaction system. This system is weak acid brilliant blue (RAWL) as indicator, potassium bromate as an oxidant, citric acid (C6H8O7) as an activator. By orthogonal experiments and single factor experiment to determine the best method analysis conditions: the concentration of weak acid brilliant blue c (RAWL) = 1 × 10-4mol / L, c (KBrO3) = 3.00 × 10-2mol / L measurement time t = 7.0min, measuring temperature T = 25.0 ° C, c (C6H8O7) = 9.00 × 10-3 mol / L, pH = 2.50. ③ in the optimum analytical conditions, this method relative standard deviation of 0.76% to 1.25%, and the recovery was 98.5% ~ 102%, detection limit is 0.407ng/mL, linear 0 to 70.0ng / mL. The interfering ion experiments show that: most of the cations and anions on the determination under the above conditions there was no significant interference. (4) Determination of the kinetic parameters obtained by experiment: RAWL response level alpha = 1.0151 ≈ 1 KBrO3 reaction order beta = 0.4569 ≈ 1/2, the reaction of the vanadium (V) series gamma = 0.9523 ≈ 1 , C6H8O7's reaction series theta = .5462 ≈ 1/2; kinetic equation; apparent reaction activation energy Ea = 36.20 kJ / mol, the apparent reaction rate constant K '= 0.0334 min-1. (5) will be established analysis method has been successfully applied to the determination of vanadium (V) content of the fresh water system. Tap water, the water of the Yellow River vanadium (V) determination, the determination of the relative standard deviation of 0.54% to 1.43%, the recovery in the range of 98.3% to 103.2%, to obtain satisfactory results. ⑥ The method is successfully applied to the determination of vanadium (V) in the seawater system. The determination of the relative standard deviation of 0.51% to 2.05% and the recovery in the range of 95.9% to 104.2% with satisfactory results. ⑦ Qingdao near sea water vanadium (V) were determined using the method draw maps of vanadium (V) in the sea surface level. (2) The paper also successfully established a direct determination of trace vanadium (IV) methods of analysis. The method is characterized as follows: high-accuracy, high-precision, high sensitivity, high selectivity, low detection limit, wide linear range. (1) through research, a new determination of trace vanadium (IV) reaction system. The reaction system: Weak Acid Brilliant Blue (RAWL) - potassium bromate - vanadium (IV) - citric acid (C6H8O7). By orthogonal experiments and single factor experiment to determine the best method analysis conditions: c (RAWL) = 7 × 10 - 5 mol / L, pH = 1.50, t = 5.0min c (KBrO3) = 8.00 × 10 -3mol / L, c (C6H8O7) = 1.20 × 10-2mol / L, T = 35.0 ℃. ③ in the optimum analytical conditions, this method relative standard deviation of 0.87% to 1.60%, and the recovery in the range of 97% to 101.5%, the detection limit is 0.461ng/mL linear in the range from 0 to 40.0 ng / mL. The interfering ion experiments show that: most of the cation and anion determination without significant interference in the determination of conditions of the method. ④ Determination of the corresponding kinetic parameters. Obtained by experiment: RAWL response level alpha = 1.0246 ≈ 1, the reaction of the vanadium (IV) series gamma = 0.9465 ≈ 1, the reaction of KBrO3 series beta = 1.0875, ≈ 1, C6H8O7 reaction series theta = 0.5725 ≈ 1 / 2. The kinetic equation:; apparent reaction activation energy Ea = 49.06 kJ / mol, the apparent reaction rate constant K '= 0.0144min-1. (5) will be established by the analysis method has been successfully applied to the determination of the content of freshwater systems and vanadium (IV). Tap water, the Yellow River water vanadium (IV) determination, the determination of the relative standard deviation of 0.53% to 1.32%, recoveries in the range of 98.6% to 104.8%, to obtain a satisfactory measurement results.

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