Plotting The deviation exist in linear consists of

Plotting Qt vs. t1/2 give straight line did not pass through the origin with Ki (intraparticle diffusion constant) =0.74, 0.85 and 0.57 mg/g min0.5, (R2 = 0.53, 0.59, 0.73) as shown in fig.1b. The intercept values (film thickness) were 1.01, 0.71 and 1.03 for the sorption of Br.G, To.B and Tr.B. the boundary layer effect is higher for Tr.B as a great value of C. The deviation exist in linear consists of two stages (Moawed et el., 2014), the first stage, the diffusion rate is high then, decreased with the time pass in the second stage. The values of ki (1), ki (2) of these stages are (2.74, 0.089 mg g-1 min1/2) for Br.G, (2.65, 0.032 mg/g min1/2) for To.B and (1.35, 0.2 mg/g min1/2) for Tr.B. ki (2) always lower as active centers were blocked by adsorbed dye molecules. The first stage is a transport step for the adsorbed solution into adsorbent, it is too fast step. The second stage is equilibrium step which represents a diffusion of adsorbate molecules from the external of the adsorbent into the pores of adsorbent molecules (Tran et el., 2017), proving adsorption process controlled by double steps. Rate of diffusion of To.B > Br.G >Tr.B which mean ki dependent on the molecular size of dyes. The lighter molecule’s weight as To.B will diffuse faster in contract Tr.B which has heavier molecule’s weight. Larger ki, better adsorption mechanism which related to improved bonding between adsorbate molecules with adsorbent particles


I'm Owen!

Would you like to get a custom essay? How about receiving a customized one?

Check it out