What is the purpose of photodegradation?
What is the purpose of photodegradation?
photodegradation is used for many purposes for example degradation of dye in water and wastewater.
How do you calculate percent degradation of methylene blue?
The photo-degradation rate of methylene blue (MB) was calculated by the following Eq. (1) [19]:(1) Degradation ( % ) = A 0 − A t A 0 × 100 where A0 is the absorbance of initial MB; At is the absorbance of the solution after illumination at time t.
What parameters affect photodegradation?
The photodegradation depends on the some basic parameters which are concentration of substrate, amount of photocatalyst, pH of the solution, temperature of reaction medium, time of irradiation of light, the intensity of light, surface area of photocatalyst, dissolve oxygen in the reaction medium, nature of the …
Why is degradation of dye important?
Industrial dye degradation is any of a number of processed by which dyes are broken down, ideally into innocuous products. Many dyes, specifically in the textile industry such as methylene blue or methyl red, are released into ecosystems through water waste. Many of these dyes can be carcinogenic.
What is meant by photodegradation?
Photodegradation is the alteration of materials by light. Commonly, the term is used loosely to refer to the combined action of sunlight and air, which cause oxidation and hydrolysis. Often photodegradation is intentionally avoided, since it destroys paintings and other artifacts.
How does photodegradation occur?
Photodegradation is degradation of a photodegradable molecule caused by the absorption of photons, particularly those wavelengths found in sunlight, such as infrared radiation, visible light, and ultraviolet light. However, other forms of electromagnetic radiation can cause photodegradation.
How do you calculate dye degradation?
The decolorization and photocatalytic degradation efficiency have been calculated as Efficiency ( % ) = C 0 – C e C 0 × 100 where C0 and Ce correspond to the initial and final concentration of dye before and after photo-irradiation. In this equation E% shows the dye photocatalyst degradation percent (Chen, 2009).
How do you calculate efficiency of dye degradation?
Degradation Efficiency (%) = (1-N/N0)*100, where N and N0 are the total number of molecules left after reaction and the initial number of molecules in the system. The initial concentration of dye was considered before the adsorption-desorption equilibrium.
Why is photodegradation a problem?
Photodegradation is a major problem also for thermochromic materials, since solar radiation causes polymer chain breaking, altering chemical and mechanical properties as well as leading to a loss of the reversible thermochromic effect [13].
What do you mean by photodegradation?
Photodegradation – Process by which pesticides are broken down by the action of light, particularly sunlight. From: Biotreatment of Industrial Effluents, 2005.
Why methylene blue is used in photocatalysis?
Photocatalytic degradation oxidizes complex organic compounds into small molecular inorganic substances, such as carbon dioxide and water, under light. The reaction is thorough and causes no secondary pollution [1,2]. Methylene blue is used not only to dye paper and office supplies but also to tone up silk colors.
How do you degrade dyes?
Dye degradation under aerobic conditions is mainly catalyzed by enzyme called azo-reductase. Reports also indicate that some aerobic microorganisms were also used along with azo reductase enzyme to improve the kinetics of the dye degradation process.
How do you find the rate constant for dye degradation?
The rate constant (Figure 9a) for this reaction is obtained by using the expression K = – 2.303 x Slope is found to be K = 3.015 x 10 -4 sec-1 (Table 1 & 2). Table 1. A Typical Run- Dye = 1.5 x 10-4 M/L, Photocatalyst = 50 mg.
How do you calculate the rate of degradation?
How do I calculate annual degradation of my solar panels?
- Year 2 degradation = 100*(101,017 – 99,669) / 101,017 = 1.334%
- Year 3 degradation = 100*(99,669 – 99,268) / 99,669 = 0.402%
- Year 4 degradation = 100*(99,268 – 98,785) / 99,268 = 0.487%
What is the phenomenon of photodegradation?
The photodegradation or photolysis can be instrumental in the transformation of pollutants exposed to sunlight, especially at wavelengths below 400 nm [68]. These phenomena are dependent on the pH, oxygen, and composition of the interstitial water, namely the presence of some metals such as Cu2+ [69–71].
What unique problem is related to photodegradation of plastics?
What unique problem is related to photodegradation of plastics? Plastics break down, but into tiny bits that persist for an indefinite period.
What is the mechanism of photocatalysis?
Photocatalysis is a photo-activated chemical reaction occurring when free radical mechanisms are initiated as contact is made between the compound and photons that have sufficiently high energy levels….2.8. 3.1. 6 Photocatalysis.
| Sequence | Reaction |
|---|---|
| Excitation of the catalyst by photon energy greater than the band gap | [17] |
Is methylene blue an appropriate substrate for a photocatalytic activity test?
MB is often used as a substrate in photocatalytic degradation.
How can rate of degradation of dye be increased?
By reducing the size of the catalyst, the surface area increases, which increases the adsorption area and hence the degradation of the dye.
How do you calculate biodegradation rate?
The rate constant (k) is used to determine the “biological half life” of the xenobiotic in the test system. The biological half life, the time required for one half of a test compound to degrade, is calculated by: biological half life = In 2 = 0.693. t = time.
What is degradation rate?
A way of describing how quickly a substance (e.g. pollution in a river) will break down and be eliminated from an environment.
What is percentage degradation?
Degradation Rate = (Co- Ct) / Co. or Co is the concentration a to. and Ct the concentration at the moment t. To get the percentage, multiply to 100. Note that you must always calculate the concentration at different times in relation to its INITIAL concentration.
What factors affect the rate of degradation?
There are several factors that influence the overall rate of degradation, in addition to pH and copolymer composition. In general, polymer degradation is accelerated by greater hydrophilicity in the backbone or end groups, lesser crystallinity, lower average molecular weight, and smaller size of the finished device.
What kind of photodegradation can occur in plastics?
ultra violet (UV)
Photo-degradation in plastics is caused by the ultra violet (UV) component of solar radiation, that is radiation of wavelength from 0.295 to 0.400 um. This is absorbed by some plastics’ and causes the breakage of bonds in the polymers leading to photo-oxidation.
What is plastic photodegradation?
Photo-degradation in plastics is caused by the ultra violet (UV) component of solar radiation, that is radiation of wavelength from 0.295 to 0.400 um. This is absorbed by some plastics’ and causes the breakage of bonds in the polymers leading to photo-oxidation.
What is the photodegradation of methylene blue dye under natural sunlight?
The photodegradation of methylene blue dye was studied under natural sunlight. Taguchi method and ANOVA was used to optimize and analyse the influential process parameters. The photodegradation of a colourless organic compound like phenol was studied. The lowest amount of H 2 O 2 was used to enhance photodegradation.
What is the photodegradation of MB dye in the presence of photocatalyst?
The exposure of solar and UV irradiations (separately) over solution resulted in the photodegradation of MB dye in the presence of photocatalyst (C11) as shown in Fig. 10 b.
What is methylene blue and methyl orange dye?
The methylene blue (MB) and methyl orange (MO) dyes were investigated in this study. MO has an azo bond (-N N-) associated with two aromatic rings and is used for chemical, paper and colourations in textile industries. Its products cause serious environmental pollution and degrade human health.
What is the mechanism of photocatalytic activity of methylene blue?
Photodegradation of methylene blue (a, b and c) and methyl orange (d, e and f) solutions in absence and presence of catalysts under UV irradiation at different temperatures. The higher photocatalytic activity of xCu/ZnO catalysts could be associated with copper oxide, which acts as electron trap and inhibits e − -h + recombination.