Method of the qualitative determination of magnesium in the oils

FIELD: chemical industry; petrochemical industry; analysis of the materials by the chemical methods.

SUBSTANCE: the invention is pertaining to the field of analysis of the materials by the chemical methods (by titration, with utilization of chemical indicators), containing the organic compounds of magnesium and may be used in chemical and a petrochemical industry at exercising control over the quality of petroleum. The invention provides, that magnesium chloride from the oil test is produced by impregnation of the ash-free filter with the tested oil with its subsequent incineration up to the complete ashing. Then the ash is dissolved in 30-40 cm3 of the weak 6 Mole/dm3 solution of hydrochloric acid. The produced solution id boiled within 15-20 minutes, transferred by a spray of the distilled water into the graduated flask. Take the aliquot, in which add the distilled water and neutralize it with ammonia (dropwise) up to pH=10.0, introduce the ammoniacal buffered solution and the indicating device the chromogen black ЕТ-100 and titrate 0.025 Mole/cm3 with the B-trilonum solution till the change of the a crimson-violet color into blue- pale blue, and quantity of magnesium (in mass%), is determined by the empirical formula. The invention allows to reduce the time duration for determination of the contents of magnesium, to improve the labor conditions due to exclusion from the process of the toxic and flammable benzole without reduction of requirements on toxicity and reliability of the produced results.

EFFECT: the invention ensures reduction of the time for determination of the contents of magnesium, improvement of the labor conditions, exclusion from the process of the toxic and flammable benzole without reduction of requirements to toxicity and reliability of the produced results.

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The invention relates to the field of material analysis by chemical methods, in particular by titration using chemical indicators, mainly motor oils, and can be used in the chemical and petrochemical industry for the quantitative determination of magnesium content in petroleum products.

Constant renewal of the car Park leads to the need to raise the level of quality performance materials. In this regard, tougher requirements including oils. One of the ways to improve the operational characteristics of the oils is to use an effective package of additives. So, to improve the detergent-dispersant and anti-wear properties used metal-containing additives on the basis of salts of BA, CA, Zn. (Sgerman, Abhipur, Iagraov. Oils and additives for tractor and combine engines. The Handbook. M: mechanical engineering, 1984, s, 128).

Currently in the domestic market of oil products, there are many oils that use of magnesium-containing additives (Rmartens, Assonov, Aiyeku, Usergames. The engine oil. Production. Properties. The classification. Application. M - S-Pb.: Alpha Lab., 2000 - p.41).

The need for quantitative determination of magnesium in the oil due to what elicium normalized indicator in the technical specifications. For example, in the technical specifications for motor oil "Fret" rule on the quantitative content of magnesium is not less than 0.05 wt.% (Universal motor oil "Lada", THE 0253-001-48095174).

For determination of magnesium content in the oils can be used x-ray fluorescence method (Collection of scientific papers. Edited Gerhard. M.: metallurgy, 1985, - s), and atomic-absorption and atomic emission spectral analysis methods (Schureman. Atomic spectroscopic analysis of petroleum products. M.: Chemistry, 1985, s).

However, these methods are relatively time consuming and require a considerable amount of software testing laboratories expensive instrumentation equipment by highly qualified technicians.

Closest to the invention to the technical nature, achieved a positive effect and is used as a prototype is a method of quantitative determination of magnesium sulphonate additives, based on the extraction of the oil sample and chlorides of magnesium and chelatometric their titrovanie the Trilon B (EDTA) indicator Chromogen black ET-100 (Methods of analysis and exploration of oil and oil products. Proceedings of the VNII NP, issue XVIII. M., 1999, p.8-10).

The essence of the well-known method of determining the quantitative content of magnesium is dissolved sample additives in benzene and extras is the response of magnesium with hydrochloric acid when heated. In aliquot parts octarepeat magnesium ions with EDTA in the presence of eriochrome black T (Chromogen black ET-100) in alkaline medium.

The disadvantage of this method is its duration (repeated processing of the sample), toxicity and rating through the use of benzene.

The technical result of the invention is to reduce the time of the determination of magnesium, the improvement of working conditions by eliminating toxic and flammable benzene, without compromising on the accuracy and validity of the obtained results.

This technical result is achieved by the fact that in the known method for quantitative determination of magnesium in oils with additives, including sampling, obtaining a solution of magnesium chloride, the selection of an aliquot of the resulting solution, which add distilled water, neutralized with aqueous ammonia to adjust pH, add ammonia buffer solution and the indicator Chromogen black ET-100 and titrated with a solution of the trylon B to switch the color of the solution with the subsequent calculation of the amount of magnesium in the empirical formula, according to the invention define the ratio of gram equivalents of magnesium and zinc, determine the titer of 0.025 mol/DM3solution trylon B, expressed in grams of zinc on 1 cm3and the solution of magnesium chloride obtained by impregnation obezzolennogo filter analysis the dummy oil, which burned to complete combustion, after which the ash is dissolved in 6 mol/DM3hydrochloric acid solution, and an aliquot of the resulting solution of magnesium chloride is titrated 0,025 mol/DM3solution trylon B when the value of pH of 10.0, measure the amount of titrant that went on titration to change crimson-purple color in blue, and the number of magnesium, wt.%, define the following dependencies:

where Xmagnesiumthe amount of magnesium in oil, wt.%;

K1the dilution ratio is equal to 50;

V - measured amount of 0.025 mol/DM3the trylon B, followed by titration to change crimson-purple color in the blue and cm3;

T - the title of 0.025 mol/DM solution trylon B, expressed in grams of zinc on 1 cm3(determined according to GOST 13538);

To2the ratio of gram equivalents of magnesium and zinc (K=0,3718 specified);

m is the sample of the product,

The method is implemented as follows: take a sample of oil with artificially introduced magnesium content of 0.05 wt.%. Get the solution of magnesium chloride, which mix the sample for 3 min, then in a quartz Cup taken 20 g (m) cooked oil. Obessilennyj filter is folded into a cone and placed in a bowl. After the filter is soaked with oil, it set on fire. A bowl of carbonaceous residue is transferred to wafel, heated to 300°and gradually heated to 750°C and maintained until complete ashing residue. The Cup is removed from the muffle and put on the asbestos or stand for cooling. Dissolve the ash 30 cm36 mol/DM3solution of hydrochloric acid, cover with watch glass and boil 15 minutes

The resulting solution of magnesium chloride stream of distilled water, transferred into a volumetric flask with a capacity of 250 cm3. From this flask is taken for titration of an aliquot of 5 cm3(K1- the dilution factor, K1=250/5=50).

Universal indicator paper neutralized aliquot of aqueous solution of ammonia (solution prepared in the ratio 1:1) to a pH of 10.0. Add 15 cm3ammonia buffer solution, 0.02-0.05 g indicator Chromogen black ET-100 and titrated with a solution of the trylon B until color changes from crimson-violet to blue. Measure the amount of 0.025 mol/DM3the trylon B (V), went to the titration of a sample until color changes. Having obtained the values of m, K1, V, T, K2calculate the quantity of magnesium in the oil by the formula:

where Xmagnesiumthe amount of magnesium in oil, wt.%;

To1the dilution ratio is equal to 50;

V - measured amount of 0.025 mol/DM3the trylon B, followed by titration to change crimson-purple color in blue-the goal is th, cm3;

T - the title of 0.025 mol/DM3solution trylon B, expressed in grams of zinc on 1 cm3(determined according to GOST 13538);

To2the ratio of gram equivalents of magnesium and zinc (K=0,3718 specified);

m is the sample of the product,

The claimed method was tested oils with known (introduced) magnesium content. Samples were prepared on the basis of industrial oils without additives. These oils were introduced magnesium-containing additives with known content of magnesium (see table 1) and the obtained test results of the samples presented in table 2.

Table 1
Samples prepared for testing by the claimed method
№ p/pBase oilThe number entered magnesium, %
123
1Industrial oil I-200,050
2Industrial oil I-200,070
3Industrial oil I-200,100
4Industrial oil I-200,110
5Industrial oil I-200,120

As shown by the test results, the inventive method allows to determine the amount of magnesium in oils with additives, ensures the reliability and accuracy of results (up to 5 Rel.%, see table 2), with the duration of analysis is not more than 2 hours.

After metrological certification of the method is planned changes to GOST 13538 "Additives and oil additives. Method for the determination of barium, calcium and zinc complexvitamin"that will extend the range of detectable metals in oils with additives, including BA, CA, Zn and Mg.

The method of quantitative determination of magnesium in oils with additives, including sampling, obtaining a solution of magnesium chloride, the selection of an aliquot of the resulting solution, which add distilled water, neutralized with aqueous ammonia to adjust pH, add ammonia buffer solution and the indicator Chromogen black ET-100 and titrated with a solution of the trylon B to switch the color of the solution with the subsequent calculation of the amount of magnesium in the empirical formula, wherein specify the ratio of gram equivalents of magnesium and zinc, determine the titer of 0.025 mol/DM3solution trylon B, expressed in grams of zinc on 1 cm3and the solution of magnesium chloride obtained by impregnation obezzolennogo filter analyzed oil that is burned to complete combustion, the village is e and the ash dissolved in 6 mol/DM 3hydrochloric acid solution, and an aliquot of the resulting solution of magnesium chloride is titrated 0,025 mol/DM3solution trylon B when the value of pH of 10.0, measure the amount of titrant that went on titration to change crimson-purple color in blue, and the number of magnesium, wt.%, define the following dependencies:

where Xmagnesiumthe amount of magnesium in oil, wt.%;

To1the dilution ratio is equal to 50;

V - measured amount of 0.025 mol/DM3the trylon B, followed by titration to change crimson-purple color in the blue and cm3;

T - the title of 0.025 mol/DM3solution trylon B, expressed in grams of zinc on 1 cm3;

To2the ratio of gram equivalents of magnesium and zinc K2=0,3718;

m is the sample of the product,



 

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