Can' adopt a specific relation to evaluate mass transfer coefficient of Activated Carbon in general (applicable to all equally);

the coefficient of Adsorption related to Adsorbent - adsorbate pair, surface area & pore definition and porosity of adsorbent, here activated carbon. PAC & GAC have different coefficient.

Even for same adsorbent, mass transfer ability reduces on reaching towards surface saturation

I think I have an answer for you, but I need understand what`s RhB means and how the process occur. See the paper attached and verify if it`s usefull for you. I`d like to receive a feedback from you.

Thank you Eliezer Ladeia Gomes sir for your comment. Basically RhB(

Rhodamine B) is a dye so I used it as a adsorbate and activated carbon as a adsorbent in my adsorption project work. So i need to find the liquid to particle mass- transfer coefficient in the adsorption process so for that i need some correlations. So if you have some references related to this then it will be very helpful for me.

This can be done by having knowledge of some characteristics of the adsorbent material: surfacearea, particle size, porousity, density, etc. and the prameters like concentration of adsorbate of dye adsorbed at any time t and at equilibrium and a few other parameters. Then by using simple mass transfer models, coefficient of mass transfer be calculated!

The following model could be used:

qt/q_e =C_i/(C_i- C_e ) [1-exp⁡{-k_f A/V t } ] Where qt and qe refers to the amount of OG adsorbed (mg/g) at any time, t (min), and at equilibrium respectively, Ci and Ce is the initial concentration of the adsorbate and remaining concentration in aqueous solution at equilibrium respectively, kf is the external mass transfer coefficient (m/min) and A/V is the volumetric area of the particle (m-1).

Thank you "Dear Yogesh C Sharma" sir for the answer. It's really very helpful for my work.