Figure 7 7: Intra-particle diffusion model for heavy metals
Related Figures (13)
Fig. 3: Effect of pH on the removal of heavy metal in wastewater using nitric acid modified adsorbent, Fig. 2: FTIR spectrum of nitric acid modified kola nut pod adsorbent after adsorption Fig. 1: FTIR spectrum of nitric acid modified kola nut pod before adsorption the optimum value (49.3mg/g) was adsorbed which corresponds to 98.16% reached at pH 6. Fig 4: Effect of contact time on percentage removal of metal ions The lines of best fit for the plots were constructed to obtain the slopes, intercepts and correlation coefficient (R” and ‘it can be suggested that the removal of these metal ions showed strong conformity with PSO models based on correlation coefficient, (R* = 0.900) and closeness of (qeexp) values 9.88, 9.94 and 9.90 and Qe cal.) Values 9.88, 9.93 and 9.71 for Pb (II), Co UI) and Cd (ID) ion respectively. Fig. 6 reveals the intra- Table | showed the various kinetic parameters for the adsorption of Pb (II), Co (II) and Cd (ID) ions from their metal solutions using MKNP adsorbent. The R? value of PFO for Pb (II) ion was 0.557, for Co (ID ion 0.2806, and Cd (ID ion was 0.1924. The values for Co (I) and Cd (II) ions were far below 0.50000, indicating the non-conformity with PFO kinetic model but a fair conformity was observed for Pb (II) ion. For Pb (ID ion, the qeexp) was 9.8924, while the qe(cai.) Was 0.0021, for Co (ID) ion, the qerexp.) was 9.9390 while the e(cal.) Was 0.0024 and for Cd (II) ion, the qe(exp.) was 9.9425 and the qe(cai.) was 0.0754 respectively. It was observed that there was a wide gap between the qecexp,) and the qeccal. values for the metal ions, suggesting no conformity with the pseudo first order kinetic model. It can be concluded that the Pseudo-first order kinetic model was not obeyed in the removal of Pb (II), Co (I) and Cd (I) ions from aqueous solutions using nitric acid modified adsorbent. However, in pseudo- second order kinetic model, the value of R* for Pb (II) ion was (0.900), Co (ID ion was 0.9050 and Cd (II) ion was 0.9010 indicating. Pseudo-second order was strongly obeyed in the removal of metal ions from wastewater. In a similar development, the ge exp for Pb (I) ion was 9.8924 while the geca value was 9.8814, for Co (II) ion, the qeexp value was 9.9390 while the qecal Value was 9.9305 and the qecexp) for Cd (II) ion was 9.9425 and the deca) value was 9.9305. Comparing the two qerexp) and Qe(cai.) values for these metal ions removal, the two values were close to each other, this further revealed that the PSO kinetic model was fully obeyed in the removal process of these metals. Fig. 8: Effect of Temp on lead removal Temperature dependents studies on the removal of heavy metals in wastewaters: The removal of Pb (II) ion using nitric acid modified adsorbent at different temperatures (298, 313, 328, 343 and 358K) across the concentrations interval (25-150 ppm) was shown in Fig. 8. It was observed that an increase in temperature leads to decrease in removal of Pb (II) ion. This implies that the adsorption process for the removal of Pb (II) ion was exothermic. The removal of Co (ID) and Cd (ID ions also follows similar trend. This reduction could be attributed to the energy input upon temperature increase which invariably increase the disorderliness and set the adsorbates species into motion preventing them from being adhered to the pores of the adsorbent. Table 2: Thermodynamic study for lead at different concentration using HNO; modified adsorbent Table 3: Thermodynamic study for cobalt at different concentration using HNO; modified adsorbent Table 4: Thermodynamic study for cadmium at different concentration using HNO; modified adsorbent ADELEKE, A. E; ONIFADE, A. P; SANGOREMI, A. A; ANIFOWOSE, A. J; ISOLA, O. E; OLAWOYE, B. M. Fig. 10: Effect of Temp on cadmium removal
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