Preparation of activated carbon from corncob and magnetic activated carbon for removal of phenol from aqueous solutions-adsorption isotherms, kinetics and thermodynamic studies.
Rinku Jaiswal a,*, Shripal Singhb & Hemant Pandec
a & b, CIMFR Nagpur Unit-II, 17/C-Telenkhedi area, Civil Lines, Nagpur-440001 cHislop college, Civil Lines, Nagpur
Abstract In the present study activated carbon is prepared from corncob using orthophosphoric acid as activating agent in a modified muffle furnace. Corncob activated carbon (CAC) is used to synthesise magnetic activated carbon (MAC) by a simple co-precipitation method. Aqueous suspensions of activated carbon and Fe3O4 were mixed followed by treatment with NaOH. A variety of techniques such as N2-BET…show more content… Langmuir parameters Q0 and b were calculated from the slope and intercept of the linear plots of 1/Qe vs. 1/Ce as given in fig. 6-11. Fig.6. Langmuir Adsorption Isotherm, Fig.7. Langmuir Adsorption Isotherm CAC-MAC-250C CAC-MAC-300C -
Fig.8. Langmuir Adsorption Isotherm, Fig.9. Langmuir Adsorption Isotherm CAC-MAC-350C CAC-MAC-400C
Fig.10. Langmuir Adsorption Isotherm Fig.11. Langmuir Adsorption Isotherm graph of adsorbate at different graph of adsorbate at different temperature, Phenol-CAC system temperature, Phenol-MAC…show more content… The results show that magnetic activated carbon has a lower adsorption capacity (Q0 =0.001123mol g-1 ) than activated carbon(Q0 =0.001157 mol g-1 ). This is due to the covering of surface of activated carbon with Fe2O3 as evident from the decrease in the N2-BET surface area and SEM.
4.2. Freundlich isotherm The adsorption data for phenol was also analyzed by the Freundlich adsorption model. The Freundlich isotherm [41] is an empirical equation employed to describe heterogeneous systems. The linear form of Freundlich adsorption model is as follows:
Log (Qe) = LogKf + 1/n Log (Ce) ------------ (3)
Where Ce is the equilibrium concentration (molL–1), Qe is the amount adsorbed (mol g–1). Kf and n are Freundlich constants related to adsorption capacity and adsorption intensity respectively. Log Qe was plotted against Log Ce for the equilibrium data of phenol and shown in Figs. 12-13. The Freundlich constants Kf and n for activated carbon and magnetic activated carbon were calculated from the slope and intercept of the plot and given in Table 5. The correlation coefficients for both adsorbents in Table 5 are low and therefore the values of K and n cannot be compared. The best fit was observed with Langmuir and BET models as the correlation