Abstract
Purpose The study was designed to investigate how ammonia and ammonium acetate modification of activated carbon produced from coconut and palm kernel shells can influence the physicochemical characteristics, morphology, thermal properties, surface functionalities and porous structure of the activated carbon. Methods Surface modification of activated carbons was confirmed by FTIR spectroscopy. Elemental microanalyser and Boehm titration method were used to determine elemental (C, H, N) analysis and surface functional groups, respectively. Atomic force microscopy was employed to determine the morphology. Thermal characteristic was measured by thermogravimetry. The pore structures of the carbons were examined by nitrogen adsorption measurement and SEM. Results The carbon yields were 48.7 +/- 0.2 and 44.5 +/- 0.1% for coconut shell and palm kernel shell, respectively. The surface areas of the activated carbons were in the range of 934-1646 m(2)/g. The FTIR spectroscopy showed N-H and C-N bands, and their presence were confirmed by Boehm titration. A little pore widening of the modified activated carbons was observed from SEM images, which could have been caused by the impregnation process. The BET surface areas of the carbons were slightly increased as evident by the pore size increase and the weight losses were significantly reduced as shown by the TGA curves. There was no significant difference between the spherical shapes of modified and unmodified activated carbons as shown by AFM images. Conclusion Surface modification produced activated carbons with weakly alkaline functional group. A series of thermally stable activated carbons with noticeable increased surface area, pore size and basic character were obtained.