Optimized preparation for large surface area activated carbon from date (Phoenix dactylifera L.) stone biomass

Abstract

The preparation of activated carbon from date stone treated with phosphoric acid was optimized using rotatable central composite design of response surface methodology (RSM). The chemical activating agent concentration and temperature of activation plays a crucial role in preparation of large surface area activated carbons. The optimized activated carbon was characterized using thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the larger surface area of activated carbon from date stone can be achieved under optimum activating agent (phosphoric acid) concentration, 50.0% (8.674 mol L−1) and activation temperature, 900 °C. The Brunauer–Emmett–Teller (BET) surface area of optimized activated carbon was found to be 1225 m2 g−1, and thermogravimetric analysis revealed that 55.2% mass of optimized activated carbon was found thermally stable till 900 °C. The leading chemical functional groups found in the date stone activated carbon were aliphatic carboxylic acid salt ʋ(CO) 1561.22 cm−1 and 1384.52 cm−1, aliphatic hydrocarbons ʋ(C–H) 2922.99 cm−1 (C–H sym./asym. stretch frequency), aliphatic phosphates ʋ(P–O–C) 1054.09 cm−1, and secondary aliphatic alcohols ʋ(O–H) 3419.81 cm−1 and 1159.83 cm−1.