Please, could anyone tell me about an adsorption mechanisms of ion impurities on the surface of nanoparticles in organic colloidal medium? What is the typical coupling energy of ions and nanoparticles?
It all depends. If the pH is suitable for a +/- electrostatic attraction, then the energies of adsoprtion are low, in the range of 2-10 kJ/mol. If actual bonds are formed and complexation occurs, the energies can reach 70-100kJ/mol. There is no consensus on exothermic versus endothermic reactions. In my incomplete experience, the electrostatic mechanisms tend to be slighly endothermic, or entropy driven. I hope that helps, somewhat.
What is the particle made of? What is the solvent? Which is the ion?
Physical sorption (also written as "physisorption") and chemical sorption (also written as "chemisorption").
Physical sorption results from the electrostatic and van der Waals interactions (forces).
Chemical sorption: ion exchange*, chelation, complexation (coordination).
* some authors do not "put" ion exchange "under" chemical sorption.
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