Intra Particle Diffusion Model

The linearised intra-particle diffusion model deduced for this work are illustrated in Figs. 48, 49, 50, 51, 52 and 53 followed by a summary of results giving the aforesaid parameters in Table 12. The R2 values were higher than 0.800 for most of the batch experiments such as for dye concentrations of 40, 80, 100 and 120 mg/L when adsorbent dosage was 7.5 g/L, and the R2 values were 0.827, 0.906, 0.808 and 0.827 for dye concentrations of 20, 40, 60, 80 mg/L respectively when adsorbent dosage was 20 g/L. These high values of correlations indicated that the experimental data was well fitted to the model. However, the R2 values were in the range of 0.040-0.799 for a few batch experiments. The kid values were in the range of 0.029-37.325 h-1 whereby high values of kid demonstrated that the dyes molecules were transported to the external surface of the CAC's through film diffusion and its rate was fast while the low values indicated that rate of transfer of dye molecules from the solution to the adsorbent was low. The low values of kid might be due to the use of improperly chemically prepared adsorbent.

Few Particle Diffusion
Fig. 49 The linearized intra particle diffusion adsorption isotherms of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 10 g/L; pH: 2
Intra Particle Diffusion
Fig. 50 he linearized intra particle diffusion adsorption isotherms of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 12.5 g/L; pH: 2
Fig. 51 The linearized intra particle diffusion adsorption isotherms of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass concentration: 15 g/L; pH: 2
Fig. 52 The linearized intra particle diffusion adsorption isotherms of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 17.5 g/L; pH: 2

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Fig. 53 The linearized intra particle diffusion adsorption isotherms of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 20 g/L; pH: 2

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