DD219289A1 - PROCESS FOR THE COLORIMETRIC DETERMINATION OF PHENOLES - Google Patents

Abstract

The aim of the process is to quantitatively analyze phenols in water containing ammonium ions, effluents and solutions. The ammonium ion-induced disturbance of the known phenol determination method using p-nitraniline is eliminated by alkalizing the phenol-containing analyte sample with alkali hydroxide prior to combining with the aqueous diazonium salt solution, treating it with an inert gas and adding an amount of mineral acid equivalent to the amount of alkali hydroxide, depending on the Phenol concentration, the whole or an adequate portion of the sample pretreated in this way is made up to a volume equal to 50% to 85% of the total volume defined with distilled water. Alkali hydroxide is used in a molar excess of at least 10%, based on the amount of ammonia and / or its salts, calculated as ammonia. The inert gas treatment is carried out at a flow rate of 30 to 70 l / h over a period of 20 to 30 minutes.

Description

VEB Leuna-Werke Leuna, the

"Walter Ulbricht"

LP 83.128

Title of the invention;

Method for the calorimetric determination of phenols Field of application of the invention

The present invention relates to a method for the colorimetric determination of phenols using p-üitranilin. Through their use, it is possible to quantitatively detect phenols in the presence of ammonia and / or its salts. "Preferred field of application is the analysis of aqueous solutions and wastewaters.

Characteristic of the known technical solutions

It is known to convert steam-volatile phenols into azo dyes by means of p-nitrani-Hn and to use the extinctions of the azo dyes formed as a measure of the concentration of the phenols (Selected Methods of Water Analysis, Volume 1, Jena 1.971 »Part: Organic Substances , Phenols,

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1 - 7). However, the implementation of this method is bound to the use of relatively high amounts of sample and requires a 'relatively high expenditure on equipment and time · In addition, there is another Hachteil that not waaserdampffflüchtige phenols are not detected. A further disadvantage is that this method for the determination of total phenols in industrial wastewater can not be applied, since it was determined by own investigations that in addition to the known interfering ¹ compounds, cyanides, sulfides, optionally steam-volatile urea and acids, especially ammonia and / or its Even in the absence of phenols, in the presence of ammonia and / or its salts, colored compounds are formed which absorb in the range of azo dyes formed from phenols the size of the perturbing effect is significantly dependent on the conditions when carrying out the coupling reaction between phenols and the diazonium salt of p-nitraniline.

Object of the invention

The aim of the invention is to modify the known method for the colorimetric determination of wasaerdampfflüchtigen phenols using p-hitraniline in such a way that when using small amounts of sample and with little time and equipment for the determination of total phenols in ammonium ion-containing barrels, waste water and solutions suitable is.

Explanation of the essence of the invention

It was therefore the task of finding conditions under which the disturbing influence of ammonium ions on the colorimetric determination of phenols using p-hitraniline is excluded.

This object is achieved according to the invention by a method for the colorimetric determination of phenols in the presence of ammonia and / or its salts by combining a phenol-containing gene analysis sample with an aqueous diazonium salt solution, followed by the addition of an aqueous sodium carbonate solution. Forming an azo dye, filling to a defined total volume with distilled water and measuring the absorbance by alkalizing the phenol-containing analytical sample with alkali hydroxide before combining with the aqueous diazonium salt solution, treating it with an inert gas and adding thereto a quantity of mineral acid equivalent to the amount of alkali hydroxide Depending on the phenol concentration, the entire or an adequate portion of the pretreated analog sample is filled up with distilled water to a volume which corresponds to 50 % to 85 % of the defined total volume.

Suitably, the alkali metal hydroxide, preferably sodium hydroxide, as 1n aqueous solution with a molar excess of at least 10%, based on the amount of ammonia and / or its salts, calculated as ammonia, is used; accordingly, the amount of mineral acid equivalent to the amount of alkali hydroxide is advantageously added as 1N aqueous solution of preferably sulfuric acid.

Purely the treatment with an inert gas, preferably nitrogen, at a favorable flow rate of 30 to 70 l / h, a period of 20 to 30 min is required. Within these limits, if the gas flow is reduced, the gassing time is correspondingly increased as the gassing time is reduced. However, an increase in the gas flow over 70 l / h is disadvantageous because then occur losses of phenols.

The determination of phenols in the concentration range of 0.1-0.1 g / l may be carried out in waste waters with an ammonia content of 15 g / l, calculated as HH-1, according to the following instructions: - 3 ml of the sample to be tested are mixed with 3 ml of 1N aqueous sodium hydroxide solution. An inert gas is passed through the resulting solution at a flow rate of 30 to 70 l / h for 20 to 30 minutes, and after fumigation, 3 ml of 1N sulfuric acid and 75 ml of distilled water are added. The solution thus prepared is treated with 5 ml of an aqueous p-uritrophenyl diazonium salt solution prepared from an aqueous solution of p-ure- ranilin (1 l contains 0.69 gp-histaniline, 12.5 ml of conz, HGl and 1.0 ml of conc. H, ΡΟ,) and 1 drop of an aqueous solution of sodium nitrite (11 contains 40 g of UaHOp) per 5 ml of p-hitraniline solution, and then treated with 5 ml of a 1N aqueous solution of soda and made up to 10 ml with distilled water. After ten minutes of standing, calculated from the addition of the soda solution, the absorbance at 495 nm is measured with a portion of this 100 ml and the phenol concentration is determined on the basis of a calibration curve.

In compliance with this provision, in particular taking into account the presence of a volume of about 90 ml before the addition of the soda solution, the reproducibility of the phenol concentration to be determined is within the accuracy of the device used to determine the extinction,

Due to the limited measuring range for the photometric extinction determination, it is necessary to reduce the concentration by suitable measures in samples with phenol concentrations> -0.1 g / l. Thus, for example, it is possible to reduce the phenol concentration in the range of 0.1 to 1.0 g / l by reducing the sample solution to 0.3 ml or better by diluting the sample after the treatment according to the invention by alkali metal hydroxide.

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Adaptation, fumigation with inert gas and additions with mineral acid and subsequent reduction of an adequate amount · Depending on the measure chosen, the rule outlined may be varied to some extent. However, compliance with the volume prior to addition of the diazonium salt solution is absolutely necessary. Since the measures for lowering the phenol concentration are associated with a simultaneous reduction in the ammonium ion content, correspondingly higher phenol concentrations of 0.1 to 1.0 g / l can be achieved in the samples to be investigated Levels of 15 g / l, calculated as IiH ,, are permitted without altering the analytical procedure. However, the process is not limited to a maximum level of ammonium ions if the amounts of alkali metal hydroxide and mineral acid according to the invention are adhered to. Therefore, it is also only expedient and advantageous to work over a wide range of phenol concentration with alkyl hydroxide solutions and mineral acids of equivalent concentrations.

In principle, the method according to the invention can also be applied to samples to be investigated with phenol concentrations> -1.0 g / l. However, due to the necessary measures for reducing the concentration, ammonium contents are permitted in the samples to be examined, which makes an application only necessary in special cases.

Of course, the process according to the invention is not limited to the determination of phenols in waste water. It is also possible to use non-aqueous, but water-miscible phenolic solutions directly. If the phenols are present in liquids immiscible with water, they must be known before being determined Process into water or water-miscible liquids

In principle, all phenolic components which form azo dyestuffs by coupling with p-ITitrophenyldiazonium salts can be determined as phenols. As a result, even nicothenolic compounds which absorb in the region of the azo dyes formed from phenols are also disturbing.

According to the method of the invention, a determination of both individual phenolic species and phenolic mixtures is possible. It always takes place on the basis of a calibration curve for the extinction at a corresponding wavelength of the azo dyes of the individual species or of the mixtures. The method according to the invention does not impose any specific requirements on the device used for text-inducement measurement. ;

The inventive method is supported by the following embodiments and explained in more detail.

embodiments

Example 1a and 1b

In a 100 ml volumetric flask, 3 ml of an aqueous analytical sample (0.030 g / l phenol, 15.0 g / l ammonia) were alkalinized with 3 ml aqueous 1N HOH. Nitrogen was passed through the alkalized sample at a flow rate of 60 l / h in 30 minutes using an inlet tube. After passage of the nitrogen, 3 ml of 1η H ₂ SO, and 75 ml of (la) and 45 ml of (1b) of distilled water were added. 5 ml of p-nitrophenyl diazonium salt solution, prepared from an aqueous solution of p-ure- ranilin (1 l, contained 0.69 g of p-hitraniline, 12.5 ml of concentrated HCl and 1.0 ml of concentrated Η-, ΡΟ. ) and 1 drop of aqueous sodium nitrite solution (1. 1 contained 40 g of HaUO ₂ ) per 5 ml of p-hitraniline solution. ,

The. The resulting solution was added with 5 ml of a 1N aqueous soda solution and made up to 100 ml with distilled water. , ':. After standing for ten minutes, calculated from the addition of the soda solution, the absorbance of the. 100 ml of filled-in solution with the help of the "Spekol 10" of the TSB Carl Zeiss Jena using KÜvetten the layer thickness 0, 995 cm measured against a reference sample of distilled water. From the absorbance value at a wavelength of 495 nm, the phenol concentration of the analyte sample was determined on the basis of a calibration curve:.

Example volume before addition E ^c phenol of the diazonium salt solution (g / l)

(Ml)

1a 84 0.245 0.031

1b 54 ^:. 0.255 0.032

Comparative Example 1 a and Ib

Composition of the analytical sample and the reagent solutions as well as the performance of the determination corresponded to Example 1a. Only the amount of distilled water added was reduced to 0 ml (1a) or 20 ml (1b). The following results were obtained:

Comparative volume before addition E Phenol example of diazonium salt solution (g / l)

(Ml)

1a 9 0.340 0.043 ^:

1b 29 0.290 0.037

Beiapiel 2 '. ,

The analytical sample of a partially dephenolated wastewater (0.033 g / l phenols, determined by _X GC, 2.8 g / l of immonium compounds, determined by titration with 0.1 η H ₂ SO.sub.2 against methyl orange and calculated as NH.sub The determination of the phenol concentration led to the following result:.

E = 0.250, corresponding to 0.032 g / l phenols. Comparative Example 2

An analytical sample according to Example 2 was added without alkalization, omitting the gassing with nitrogen and without addition of H ₂ SO, with 81 ml of distilled water and worked up according to Example 1. Ss-the following result was obtained:

Ξ β 0.78, corresponding to 0.100 g / l phenols.

Example 3a to 3c, .. '

An aqueous sample containing both phenol and ammonium sulphate (0.030 g / l phenol, 9.0 g / l ammonium sulphate calculated as UHO was worked up according to Example 1a but at different inert gas flow rates.The determination of the phenol concentration gave the following results

nissen: Flow rate of the inert gas (l / h) ε: ⁰ phenol oil (g / l) example 40 0,220 0.028 3a 60 0,235 0,030 3b 70 0.225 0,029 3c

Comparative example 3a bia 3c

An analysis sample., According to example. 3 was worked up according to Example 1a. Only the flow rate of the inert gas was changed. The following results were obtained _:

Comparative example

Example 4a and 4b

An aqueous sample containing not only phenol but also ammonium carbonate (0.008 g / l phenol, 8.5 g / l ammonium carbonate, calculated as HEU) was worked up according to Example 1a. Ss was changed only the duration of the inert gas treatment. The following results were obtained:

Example · Duration of inert gas Ξ ^c phenol treatment.

(min) (g / l)

4a 20 0.075 0.009 .-.

4b 30 0.060 0.007

Flow rate of the inert gas (l / h) 0 e ^c phenol (g / l) O 0 , 58 0.074 10 0 340 0.043 100 190 0.024

Comparative Examples 4a and 4b; \ '

Bine aqueous AnaLysenprobe according to, Example 4 was worked up according to Example 1a. Only the duration of the inert gas treatment was changed. The following results were obtained:

Comparative example Duration of inert gas treatment (min) Ξ ^c phenol (g / l) ; 4a 4b 10 0.255 0.155 0.032 0.019 Example 5

3 nil of an aqueous sample containing phenol and ammonium bicarbonate (0.480 g / l phenol, 10.0 g / l, ammonium bicarbonate, calculated as SHo) were alkalized according to Example 1 with sodium hydroxide, treated with inert gas and treated with sulfuric acid. It was then made up to a volume of 100 ml with distilled water. 10 ml of this solution were transferred to a 100 ml volumetric flask and diluted with 75 ml of distilled water. Addition of the diazonium salt solution and the sodium carbonate solution and filling with distilled water and determination of the extinction were again carried out according to Example 1. The following result was obtained; ·

E «0.375, corresponding to 0.473 g / l of phenol.

Claims (4)

-. 11 - Claim for invention 1. Verfahren'zur colorimetric determination of phenols in the presence of ammonia and / or its salts by. Combining a phenol-containing analytical sample with an aqueous diazonium salt solution, then adding an aqueous soda solution to form an azo dye, making up to a defined total volume with distilled water and measuring absorbance, characterized in that the phenol-containing analyte alkalizes with alkali hydroxide before combining with the aqueous diazonium salt solution treated with an inert gas and with one of the ', Al-. amount of equivalent amount of mineral acid is added and, depending on the phenol concentration, the entire or an adequate portion of the analytical sample pretreated in this way is filled up with distilled water to a volume which corresponds to 50 % to 85 % of the defined total volume. 2, Method according to item 1, characterized in that the alkali hydroxide, or »natronlauge, as 1 η aqueous solution with a molar excess of at least 10 %, based on the 'amount of ammonia and / or its salts, calculated as ammonia, is used · Method according to item 1, characterized in that the amount of mineral acid equivalent to the amount of alkali metal hydroxide is used as a 1 η aqueous solution of sulfuric acid or sulfuric acid. 4. The method according to item 1, characterized in that the treatment with inert gas, or · nitrogen, over a period of 20 to 30 minutes at a flow rate of 30 to 70 l / h is performed.