On the Photometric Determination of Trace Nickel in Oils and Petroleum Products
Abstract Generated abstract
The paper examines photometric determination of trace nickel in crude oils and petroleum products, with emphasis on sample preparation methods that minimize metal loss during decomposition. Several wet ashing procedures are compared, including sulfuric acid treatment with additions of hydrochloric acid and hydrogen peroxide, followed by photometric determination with dimethylglyoxime in alkaline medium and masking of interfering metals. The results indicate that sulfuric acid decomposition with hydrogen peroxide, with or without hydrochloric acid, gives more favorable preparation conditions by reducing processing time and limiting volatilization losses. The selected procedure was applied to oils from thirteen fields and to tar, producing nickel values that were reported to agree satisfactorily with spectral analysis.
Full Text
On the Photometric Determination of Trace Nickel in Crude Oils and Petroleum Products
L. L. Skripova, Yu. A. Karbainov, L. S. Kulmanakova
(Presented by the scientific seminar of the Department of Analytical Chemistry)
This work is a continuation of studies on the determination of trace nickel in crude oils and petroleum products and on the development of optimal
Table 1
Results of the analysis of crude oil
| No. | Decomposition method | Found Ni, % | % ε | Note |
|---|---|---|---|---|
| 1 | With sulfuric acid | \(5.85 \cdot 10^{-4}\) | 7.5 | Oil sample about 3.5 g |
| 2 | With sulfuric acid with addition of hydrochloric acid | \(5.21 \cdot 10^{-4}\) | 8.25 | Oil sample about 3.5 g |
| 3 | With sulfuric acid with addition of hydrogen peroxide | \(7.66 \cdot 10^{-4}\) | 8.3 | Oil sample about 3.5 g |
| 4 | With sulfuric acid with addition of hydrochloric acid and hydrogen peroxide | \(7.94 \cdot 10^{-4}\) | 3.94 | Oil sample about 3.5 g |
| 5 | By the spectral method | \(6.4 \cdot 10^{-4}\) | — | Oil sample about 3.5 g |
Table 2
Results of the analysis of gudron
| No. | Decomposition method | Found Ni, % | % ε | Note |
|---|---|---|---|---|
| 1 | With sulfuric acid | \(9.22 \cdot 10^{-4}\) | 12.1 | Sample about 4.0 g |
| 2 | With sulfuric acid with addition of hydrochloric acid | \(11.76 \cdot 10^{-4}\) | 10.0 | Sample about 4.0 g |
| 3 | With sulfuric acid with addition of hydrochloric acid and hydrogen peroxide | \(14.67 \cdot 10^{-4}\) | 15.0 | Sample about 4.0 g |
conditions for preparing the sample for analysis. The results of previous studies are presented in [1].
Table 3
Results of statistical processing of experimental data on the determination of nickel in crude oils and petroleum products
| No. | Field | \(n\) | \(\bar{x}\cdot10^{4}\) | \(S_{\bar{x}}\cdot10^{4}\) | \(t_{0.95}\) | \(\pm \varepsilon\cdot10^{4}\) | \(\varepsilon,\%\) | Determination results, \(\%\cdot10^{-4}\) | Determined by the spectral method, % |
|---|---|---|---|---|---|---|---|---|---|
| 1 | TN-23 | 7 | 10.0 | 0.0594 | 2.247 | 0.13 | 1.3 | \(10.0\pm0.13\) | — |
| 2 | Northern 207 | 5 | 17.42 | 0.332 | 2.776 | 0.92 | 5.29 | \(17.42\pm0.92\) | — |
| 3 | Novopokrovskoye 79 | 8 | 0.40 | 0.0524 | 2.36 | 0.07 | 17.5 | \(0.40\pm0.07\) | \(0.55\cdot10^{-4}\) |
| 4 | South Cheremshanskoye 335 | 9 | 10.22 | 0.0678 | 2.306 | 0.15 | 1.53 | \(10.22\pm0.15\) | — |
| 5 | Sovetskoye 41 | 4 | 7.74 | 0.0426 | 3.182 | 0.13 | 1.68 | \(7.74\pm0.13\) | \(4.3\cdot10^{-4}\) |
| 6 | Myldzhinskoye 7 | 4 | 2.02 | 0.0956 | 3.182 | 0.19 | 9.35 | \(2.02\pm0.19\) | \(2.7\cdot10^{-4}\) |
| 7 | Kiev-Eganskoye 350 | 3 | 1.79 | 0.0151 | 4.303 | 0.06 | 3.5 | \(1.79\pm0.06\) | \(1.2\cdot10^{-4}\) |
| 8 | Matyushkinskoye 34 | 5 | 19.5 | 0.0363 | 2.776 | 0.10 | 5.1 | \(19.5\pm0.10\) | \(17\cdot10^{-4}\) |
| 9 | Samotlor 324 | 4 | 3.54 | 0.0169 | 3.182 | 0.054 | 1.52 | \(3.54\pm0.054\) | — |
| 10 | Tuymazinskoye 25 | 7 | 1.48 | 0.0677 | 2.247 | 0.15 | 10.1 | \(1.48\pm0.15\) | — |
| 11 | Russkoye 13 | 8 | 7.94 | 0.1338 | 2.36 | 0.31 | 3.97 | \(7.94\pm0.31\) | \(6.4\cdot10^{-4}\) |
| 12 | Tazovskoye 11 | 7 | 3.10 | 0.2279 | 2.247 | 0.51 | 16.4 | \(3.10\pm0.51\) | \(2\cdot10^{-4}\) |
| 13 | Trekh-Ozernoye 527 | 8 | 1.60 | 0.1196 | 2.36 | 0.28 | 17.5 | \(1.60\pm0.28\) | \(2\cdot10^{-4}\) |
| 14 | Gurun | 15 | 9.65 | 0.5476 | 2.145 | 1.17 | 12.1 | \(9.65\pm1.17\) | — |
In dry ashing of crude oil and petroleum products, a certain amount of trace elements is lost [2, 3]; therefore we investigated various methods of wet ashing, namely: decomposition of an oil sample with sulfuric acid, with sulfuric acid with the addition of hydrochloric acid, or with hydrogen peroxide. The charred mass is then heated on a sand bath until sulfur oxides cease to evolve. The resulting coke is burned to ash in a muffle furnace at 500–550°C. To determine nickel, the ash is dissolved in 5 ml of HCl (1:1), the solution is transferred to a 25 ml volumetric flask, and diluted to the mark with water.
Nickel was determined photometrically using dimethylglyoxime with an oxidizing agent in an alkaline medium [4]. Tartaric acid, ammonium citrate, and Trilon B were used as masking agents for iron, aluminum, copper, and manganese [5].
The study to select a rational method for decomposing the sample was carried out on crude oil from the “Russkoe 13” field and on tar. The results of the studies are given in Tables 1 and 2.
The analytical data show that, among the methods tested, the best method for preparing the sample is decomposition with sulfuric acid with the addition of hydrogen peroxide, or with sulfuric acid with the addition of hydrogen peroxide and hydrochloric acid. This reduces the processing time and decreases the loss of metal due to volatility.
Using the method we selected, nickel was determined in crude oils from thirteen fields and in tar. The results of the determinations are given in Table 3. The results obtained agree satisfactorily with the results of spectral analysis.
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