[nisha1]

sir, in the case of adsorption the process is said to be exothermic and as the solute particles which are in dispersed phase gets assimalated on the surface of adsorbent the entropy should decrease. But when i have gone through some references (based on adsorption) it was seen that the process was showing favourability towards endothermic process (they have worked on 30 ^oC, 40 ^oC and 50 ^oC). Moreover the references showed it as physical adsorption having positive entropy. Sir my question is, can such case arise in adsorption process? If yes, then what perticular conditions governs the process?

[Hunt]

What's the reference and what kind of system are they refering to ?

[nisha1]

sir, in the case of adsorption the process is said to be exothermic and as the solute particles which are in dispersed phase gets assimalated on the surface of adsorbent the entropy should decrease. But when i have gone through some references (based on adsorption) it was seen that the process was showing favourability towards endothermic process (they have worked on 30 ^oC, 40 ^oC and 50 ^oC). Moreover the references showed it as physical adsorption having positive entropy. Sir my question is, can such case arise in adsorption process? If yes, then what perticular conditions governs the process?

thankyou sir, beneath is the site address of the research paper. Actually i am also thinking to do a similar research work but could'nt understand some theritical aspect. can you please explain it in an easy way.
http://pubs.acs.org/doi/pdf/10.1021/ie051075k?cookieSet=1
thank you

[Hunt]

You should read it yourself and try to figure things out on your own. Refer to the literature for better understanding. If things get too complicated, you can try asking on the forums.

[nisha1]

You should read it yourself and try to figure things out on your own. Refer to the literature for better understanding. If things get too complicated, you can try asking on the forums.

thanks sir but still i am unable to understand why entropy is coming out to be positive, yes we are increasing the temperature thus more is the randomness then also adsorption is also higher which is the state of more stability? am i right?

[Hunt]

Well yes generally the entropy has decrease , which is why i asked about the type of system involved. Perhaps you can make a summary of what they did , what adsorbs on which type of surface at specific conditions, etc.

[nisha1]

Well yes generally the entropy has decrease , which is why i asked about the type of system involved. Perhaps you can make a summary of what they did , what adsorbs on which type of surface at specific conditions, etc.

Sir in the research paper the authors have done the work on adsorption. In this, they have worked on the adsorption of 2-aminophenol on two different adsorbent namely activated carbon (fertilizer waste) and activated slag (steel industry waste). Firstly they carried out the batch analysis in which they did the adsorption of 2-amionphenol on the different adsorbents under different conditions of concentration of adsorbate, amount of adsorbent, contact time, temperature. From these studies they have evaluated different parameters like kinetics of the process, from concentration studies obtained different Freundlich and Langmuir adsorption isotherms (which in turn was used to evaluate thermodynamic parameters.
     the result shown in the paper are:
1) The process was found to be endothrmic in case of both adsorbents as adsorption increased with temperature (though it is said that adsorption is an endothermic process.
2) The process of adsorption was found to be greater in case of activated carbon than in case of activated slag (while the entropy of activated carbon is calculated larger than the activated slag)
3) Is their any use of finding Freundlich isotherm?

[nisha1]

Well yes generally the entropy has decrease , which is why i asked about the type of system involved. Perhaps you can make a summary of what they did , what adsorbs on which type of surface at specific conditions, etc.

Sir in the research paper the authors have done the work on adsorption. In this, they have worked on the adsorption of 2-aminophenol on two different adsorbent namely activated carbon (fertilizer waste) and activated slag (steel industry waste). Firstly they carried out the batch analysis in which they did the adsorption of 2-amionphenol on the different adsorbents under different conditions of concentration of adsorbate, amount of adsorbent, contact time, temperature. From these studies they have evaluated different parameters like kinetics of the process, from concentration studies obtained different Freundlich and Langmuir adsorption isotherms (which in turn was used to evaluate thermodynamic parameters.
     the result shown in the paper are:
1) The process was found to be endothrmic in case of both adsorbents as adsorption increased with temperature (though it is said that adsorption is an endothermic process.
2) The process of adsorption was found to be greater in case of activated carbon than in case of activated slag (while the entropy of activated carbon is calculated larger than the activated slag)
3) Is their any use of finding Freundlich isotherm?

Sorry sir i am asking you another question before you give the answer of my previous question .
Sir in the site given below
http://pubs.acs.org | doi: 10.1021/ie960442c
on page no. 2211 the author has given an equation to obtain favourability factor 'r'
in that they have mentioned that if 'r' is greater than 1 then the process is unfavourable
Sir my question is that will we ever get a value greater than one using this equation
Do you think equation is correct?
thank you sir

[Hunt]

I cannot answer you directly and I cant access the papers now. I will try to answer you ASAP when my time allows.