Physical, chemical and adsorptive characteristics of local oak sawdust based activated carbons

Abstract

Objective: The aim of this study was to prepare and characterize activated carbon from local oak sawdust in order to relate the preparation conditions (carbonization and chemical activation) to the carbon's essential physical, chemical and adsorptive properties. Methodology: Activated carbons were prepared from raw sawdust carbon (SDC) and by first activation with 3.07 NH3PO4(PASC). The carbon yield for SDC was 33.8% while, phosphoric acid activated sawdust carbon (PASC) showed 29.4% of carbon yield. The pH values for the SDC and PASC solutions were found to be 7.4 and 6.0, respectively. The electrical conductivities for the SDC and PASC solutions were found to be 144 and 327 μS cm-1. Moisture contents for SDC and PASC were 5.4 and 4.6% and ash contents for SDC and PASC were 6.8 and 6.6% respectively. The surface concentration of the functional groups on SDC titrated by the equilibrium Boehm method is 1.508 mmol g-1, of which 1.062 mmol g-1 have acidic and 0.446 mmol g-1 have basic character. While, the surface concentration of the functional groups on PASC titrated by the equilibrium Boehm method is 2.615 mmol g-1, of which 2.467 mmol g-1 have acidic and 0.148 mmol g-1 have basic character. Results: The values of iodine number obtained for PASC (872.4 mg g-1) is greater than the value obtained for SDC (554.6 mg g-1). The methylene blue number obtained for PASC (306.0 mg g-1) is greater than the value obtained for SDC (180.3 mg g-1). The Langmuir maximum adsorption capacity of phenol on the resultant PASC and SDC was equal 99.0 and 72.4 mgg-1 respectively. Conclusion: The results show that agricultural waste oak sawdust can be used as a promising precursor material for the production of low cost activated carbon.