Do you have a good reference dealing specifically with the optimization of the thermal desorption process?
Dear Flavio,
I suggest to you a links and attached files in topics.
- Optimized thermal desorption for improved sensitivity in trace ...
https://www.ncbi.nlm.nih.gov/pubmed/22498665
- Optimization of a Dynamic Headspace–Thermal Desorption–Gas ...
www.sciencedirect.com/science/.../S00399140110033...
- A Guide to Thermal Desorption - Kansas State University Engineering
www.engg.ksu.edu/HSRC/Tosc/desorp.pdf
Best regards
Adsorption concentrates the adsorbed substance and hence is accompanied by a decrease in confrontational entropy, delta Sconf. Since total entropy Stot must increase, if adsorption is to occur there must be a more than compensating increase in thermal entropy delta Stherm = delta H/T, where delta H is the enthalpy change accompanying adsorption (assuming constant pressure). The total entropy change delta Stot = 0 at the temperature T at which delta Sconf = delta H/T, i.e., at T = (delta H)/(delta Sconf). Below this temperature adsorption dominates, above it desorption dominates. This temperature T obviously depends on the pressure P of the substance to be adsorbed when it is in the gaseous phase (its partial pressure if other gases are also present): it decreases with decreasing P because at lower P adsorption requires concentration by a greater ratio and hence a larger delta Sconf. The optimum condition for desorption is the highest T and lowest P consistent with practical constraints on the design of the system.
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