CZ308365B6 - Method of continuous measurement of photocatalysis of dye simulants - Google Patents

Abstract

The method of continuously measuring photocatalysis of dye simulants uses a new formula for evaluating the optical absorption of dissolved dye directly in a liquid dispersion (2), which contains solid photocatalyst nanoparticles. This formula is different from the standard form of the Lambert-Beer law, which describes the absorption of light in pure liquids without disperse particles. The above method can be used in rapid and accurate control testing of samples of photocatalytic materials from laboratory and industrial production

Description

Field of technology

The invention falls within the field of testing samples of photocatalytic materials from laboratory and industrial production.

Prior art

At present, the efficiency of the photocatalyst is measured by the method of repeated sampling in cuvettes, which are then individually evaluated by measuring the absorbance in an external UV VIS spectrometer. When measuring photocatalytic efficiency in a liquid medium, the photocatalyst particles are dispersed, so in all current devices it is an essential part of their separation from the liquid by filtration, centrifugation, or other methods. Only in the case of a pure liquid is the optical absorbance of the dye subsequently measured, or alternatively its concentration is measured. Thus, at present, in standard photocatalytic efficiency measurements, it is necessary to take dispersion samples at cuvettes at preselected times. Disperse particles must be removed from these samples by pressure filtration or centrifugation. Only pure solution can be analyzed in an optical UV VIS absorption spectrometer using standard Lambert-Beer law. This affects the batch and requires refilling and new multiple measurements with different sampling times to achieve accuracy.

The essence of the invention

The above disadvantages are eliminated by the invention described below. Measurement of photocatalysis of dye simulants uses new formulas to evaluate the optical absorption of dissolved dye directly in a liquid dispersion that contains solid photocatalyst nanoparticles. This formula is different from the standard form of Lambert-Beer law, which describes the absorption of light in pure liquids without disperse particles.

For the ratio of the optical intensity 7 (C) of the scattered test light with the C concentration of the dye simulant and the optical intensity 7 (0) of the scattered test light with the zero concentration of the dye simulant, the following formula was derived and verified experimentally based on a physical model:

7 (C) e - ^ - β / (O) “1-β

When applied to the evaluation of a specific dispersion liquid with a dye simulant and photocatalytic particles, it is necessary to perform a calibration that will provide specific numerical values of the empirical parameters a and β. This is done by evaluating the intensity ratio for the initial maximum concentration of dye simulant C _by photocatalytic measurement and its additional measurement for its concentration by half C _o / 2.

The device for performing the above measurement, i.e. a continuous photocatalytic reactor, operates in a new, continuous mode of measuring the decrease in the concentration of dye simulants under the influence of optical radiation from the violet part of the spectrum.

The exemplary embodiment illustrates a configuration for continuously measuring the absorbance of a dye dissolved in a liquid dispersion.

- 1 CZ 308365 B6

The laser light enters the liquid obliquely to the surface deformed by stirring so that its back reflection is not detected by the optical probe. After entering the volume of the liquid dispersion, the light is:

a) dispersed on photocatalyst particles,

b) absorbed by the dissolved dye in the space between the particles.

After multiple scattering, part of it is then detected by an optical probe. Due to the fact that the used formula contains two parameters, it is necessary to measure the simple calibration response of the sample with half the concentration of the dye with respect to the initial maximum in the photocatalysis before the actual photocatalytic measurement.

It is important that this method enables very fast and accurate in-situ measurement, which does not violate the set process conditions by physical sampling and will be important especially for continuous control of the efficiency of photocatalysts directly during their production.

Explanation of drawings

Figure 1 shows an apparatus for carrying out this method of measurement - it is a laboratory photocatalytic reactor.

Examples of embodiments of the invention

The method is used for rapid and accurate testing of samples of photocatalytic materials in a laboratory photocatalytic reactor in Figure 1.

The glass beaker 1 is filled with a liquid dispersion 2 of photocatalyst nanoparticles (e.g. T1O2, ZnO, CsN4, ZnS, CdS, etc.), in which the required amount of dye (methylene blue, indigo carmine, etc.) is simultaneously dissolved. It is then placed in a tempered reactor 3, which is shown in the diagram by a dark vessel. Below the bottom of the beaker 1 there is a drive of the electromagnetic stirrer 4 and above the bottom the body 5 of the magnetic stirrer rotates, which continuously stirs the liquid dispersion 2. In the middle part of the reactor lid 6 there is a powerful LED 7 cooled by a cooler 8 which emits to dispersion level. 2 UV radiation initiating photocatalytic decomposition of dye molecules. The ongoing decrease in its concentration is measured by the absorption of laser light 9, which is detected by a measuring probe 10 after multiple scattering. The process temperature is continuously measured by a thermocouple 11.

Industrial applicability

The method can be used for fast and accurate control testing of samples of photocatalytic materials from laboratory and industrial production.

Claims (2)

PATENT CLAIMS 1. A method for the continuous measurement of photocatalysis of dye simulants, characterized in that the decrease in the concentration of dye simulant molecules upon the impact of UV radiation on the liquid -2 CZ 308365 B6 dispersion (2) of photocatalyst particles is continuously measured "in situ" by the absorbance of the light emitted by the laser (9) in the spectral environment of the absorption maximum of the dye simulant, according to the formula J (c) e- and ^C -fi r (o) 1-β 5 wherein I (C) is the ratio of the optical intensity of the scattered test light with the C concentration of the dye simulant and the optical intensity 1 (0) of the scattered test light with the zero concentration of the dye simulant, further a is the absorption parameter, β is the scattering parameter. Method for continuous measurement of photocatalysis of dye simulants according to claim 1, characterized in that the laser radiation (9) in the spectral environment of the absorption maximum of the dye simulant penetrates through a free surface into the stirred liquid dispersion (2) and after multiple scattering on photocatalyst particles and absorption attenuation. dye is detected by the measuring probe (8) above the surface.