Dear Professors, I need to know that whether there is a direct or inverse relation in adsorption of dye on the surface of catalyst and degradation. I will be thankful if you kindly provide your precious views with some relevant literature.
The relationship between adsorption and photodegradation is not fully clear. The behavior may be mostly depends on the dye structure and characteristics of catalyst surface . The relationship between adsorption and photodegradation of deferent dyes may not always show the same trend. There are three proposed mechanisms for heterogeneous photocatalysis.First proposed that photodegradation of organic compound is enhanced by hydroxyl radicals in solution, second suggest that molecules are firstly adsorb on the photocatalyst surface before reaction with electron- hole pairs and surface bounded hydroxyl radicals. The third mechanism involves two above mechanisms.
To investigate what mechanism is domain ,you must to study the effects of dye concentration,pH and presence of scavenger of electrones,holes and hydroxyl radical.
Also ,it's necessary to apply Langmuir–Hinshelwood (LH) kinetics equation which is the most commonly used kinetic model for heterogeneous catalytic processes during the photodegradation of organic contaminants in solution. Both reaction rate constant and the equilibrium constant for the adsorption of the molecules on the catalyst surface are determined on applying of Langmuir–Hinshelwood model.
Dye adsorption involves the adsorption of the dye molecules on the surface of a suitable adsorbent. This process removes the dye component from the medium. It is however not suitable technique as it simply transfers the dye molecules from one medium onto the other medium. In contrast dye photo degradation involves the decomposition of dye molecules in the presence of photocatalysts assisted through UV VI's light. Photocatalysts can degrade the dye molecules adsorbed on their surfaces as well as present in the medium. Photo degradation involves the formation of reactive oxygenated species and hydroxyl free radicles which are strong oxidizing agents.
Further, the optimization of the concentration of the dye and photo catalytic amount is also necessary. Greater the adsorption of the dye molecules more is the rate of dye degradation but only valid for low concentrations. higher concentrations of the dye restricts the light to penetrate properly into the medium and lowers the rate of formation of oxidizing species as stated in the earlier answer.
Excellent Dr. Rajesh Thank you. You confirm my query as i get results according to your second reply.
My pleasure sir,
You can check my publications in particular a review article based on photodegrafation of methyl orange and I can provide you the papers if required.
The relationship between adsorption and photodegradation is not fully clear. The behavior may be mostly depends on the dye structure and characteristics of catalyst surface . The relationship between adsorption and photodegradation of deferent dyes may not always show the same trend. There are three proposed mechanisms for heterogeneous photocatalysis.First proposed that photodegradation of organic compound is enhanced by hydroxyl radicals in solution, second suggest that molecules are firstly adsorb on the photocatalyst surface before reaction with electron- hole pairs and surface bounded hydroxyl radicals. The third mechanism involves two above mechanisms.
To investigate what mechanism is domain ,you must to study the effects of dye concentration,pH and presence of scavenger of electrones,holes and hydroxyl radical.
Also ,it's necessary to apply Langmuir–Hinshelwood (LH) kinetics equation which is the most commonly used kinetic model for heterogeneous catalytic processes during the photodegradation of organic contaminants in solution. Both reaction rate constant and the equilibrium constant for the adsorption of the molecules on the catalyst surface are determined on applying of Langmuir–Hinshelwood model.
photodegradation need to adsorb dye molecules onto catalyst surface to complete the degradation redox reaction.
- Badges
- Science topic
- Similar topics
- Chemistry
- Biochemistry
- Biochemical Techniques
- Blotting Techniques
- Immunoblotting
- Dyes