Effect of acidic activating agents on surface area and surface functional groups of activated carbons produced from Acacia mangium wood

• Acacia mangium wood was utilized for the preparation of activated carbon.
• Two acidic activating agents were used to compare the changes in the activated carbons.
• Powder XRD showed some crystalline peak for AC-ZnCl2 due to zinc oxide and carbides.
• AC-H3PO4 has high acidic surface functional groups than AC-ZnCl2.
• The pHzpc for AC-H3PO4 and AC-ZnCl2 was found 2.05 and 6.07, respectively.

The acidic chemical activating agents have a significant effect on surface area formation and surface functional groups during activation of lignocellulosic materials into activated carbon (AC). The aim of this study is to find out the changes occurring in Acacia mangium wood-based activated carbons during activation with phosphoric acid (H3PO4) and zinc chloride (ZnCl2). The surface area of the formed phosphoric acid treated A. mangium wood activated carbon (AC-H3PO4) and zinc chloride treated A. mangium wood activated carbon (AC-ZnCl2) were determined by physical adsorption of N2 gas at −195.65 °C. Total Brunauer, Emmett and Teller (BET) surface area has been found to be 1038.77 ± 4.48 m2/g and 957.47 ± 7.39 m2/g for AC-H3PO4 and AC-ZnCl2, respectively. Potentiometric titration was also conducted to find the proton adsorption capacity for AC-H3PO4 and AC-ZnCl2 carbons as −0.9379 mmol/g and 0.0006 mmol/g, respectively. Fourier transform infrared (FTIR) spectroscopy was used for surface functional group identification, and powder X-ray diffraction was used for crystalline structure study of the prepared activated carbon. Surface morphology and elemental constituents of the activated carbons were done by field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectroscopy (EDX). Carbon content of AC-H3PO4 and AC-ZnCl2 was found to be 76.2% and 76.6% by weight, respectively.