DE3046446A1 - Automatic cuvette for determining COD - with rapid removal of hydrogen chloride by rotating inclined cuvette - Google Patents

Abstract

A method or rapidly determining the chemical oxygen demand by increasing the surface area of the substance under test with removal of hydrogen chloride and simultaneous processing of a number of specimens (6,12, 18 or 24) comprises rotating the specimen vessels in a vertical or pref. slightly inclined position about their own axis. Pref. a number of specimens are mounted upright and slightly inclined in a circular or rectangular formation and are rotated each about its own axis. A slight vacuum may be applied to the cuvettes to reduce the vapour pressure. Heat is applied to accelerate evaporation of hydrogen chloride. Used for determining the chemical oxygen demand of water, where the potassium dichromate quantity is determined as a measure of the oxygen equivalent. By exposing a larger surface of the liquid, the hydrogen chloride is more rapidly removed and thus the process carried out more rapidly.

Description

R O L L G E RÄ T

A serial laboratory device, characterized in that several Vessels at the same time in individual guides or holders through a common Drive can be rotated.

The vessels can be rotated all at the same time or only partially will.

Rolling device for shortened HCl blowing out with the help of a filter candle. The inclined position of the vessel and the simultaneous rotating movement creates a liquid film on the inner wall of the vessel that forms the evaporation surface enlarged.

Cuvette rotomat for faster HCl removal when determining COD For the CS3 determination (chemical oxygen demand), the measured value is the Oxygen equivalent amount of potassium dichromate determined by the oxidizable substances contained in one liter of the water to be examined certain standardized reaction conditions is consumed.

Interfering chloride ions are produced from sulfuric acid solution as Hydrogen chloride is transferred into a closed steam room and there by calcium hydroxide or equivalent funds.

Since the individual COD determination should be carried out in one day, it is important to keep the chloride elimination step as short as possible design. This has not been possible until now, as the sample vessel, the cuvette, installed individually on a magnetic stirrer after the adsorber has been attached was to with about 200 revolutions per minute for several hours at room tempera ture to stir. This is always very time-consuming and usually not on a d-hour working day to manage something.

.in a faster work pace with the CSB confirmation is thereby to achieve that the HCl removal is accelerated by the surfaces that border on the vapor phase, be made even coarser and he molecule exchange is accelerated in the liquid.

The procedure described below achieves this by turning of the entire sample vessel (cuvette) together with several others in a single one Apparatus.

The new procedure will be completely new and special Apparatus invented for this purpose, the cuvette rotomat, a larger number Sample containers (cuvettes), preferably 6, 12, 1rs or 24, preferably in a slightly inclined position together and yet each turned individually so fast that the centrifugal force greatly enlarged surface of the liquid a strong, rotating exchange with the other parts of the liquid is exposed.

Due to the decrease in the gas space caused by the absorbent the partial vapor pressure of hydrogen chloride (HCl) diffuses over the liquid Now more HCl very quickly afterwards from the liquid and evaporates, is absorbed etc. The normally very time-consuming llCl evaporation is greatly accelerated, that in fact the chloride removal time is reduced by more than 60%, whereby the requirement to carry out a complete COD determination in a single day, conveniently enough can be done.

The machine is driven by a conventional motor while the transmission of the drive to the multitude of cuvettes is a completely new design required.

Claims (4)

Claims Method for faster COD determination by enlarging the surface the test substance during the removal of HCl and simultaneous esterification of several samples, preferably 6, 12, 18 or 24 cuvettes, characterized in that the sample container or containers Rotate around your own axis in a vertical, but preferably slightly inclined, position. 2. The method according to claim 1, characterized in that several Samples in a circular or rectangular formation standing inclined at the same time and can be rotated where the rotation of each sample holder around the own axis takes place. 5. The method according to claim 1 and 2, characterized in that the arrangement of the sample containers is characterized by optimal use of space, the drive motor conventional type, but transmission is new type. 4. The method according to claims 1 to 3, characterized in that that a slight vacuum can be applied to the cuvettes in order to lower the vapor pressure. b. Method according to claims 1. t) is 4., characterized in that that the solution to be examined is heated in order to accelerate the evaporation of the IICl. b. Process according to claims 1 to 5, characterized in that that the inclination of the cuvettes can be varied and not always all cuvettes must be in operation at the same time, which is achieved by zoning. /. Device for holding sample holders (cuvettes), preferably 12 or 24, characterized in that by means of new transmitter parts each pioneer holder with a speed of 50 to 500 revolutions per minute, preferably 130 to 180, is rotated about its own axis in such a way that the outer surface of the liquid to be tested in the cuvette is enormously enlarged, the inner molecule exchange is greatly accelerated by the rotation, and that thereby the HCl absorption takes place much faster in the special absorbers, and that the transmitter parts consist of modern plastics.