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  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