Structural Features and Combustion Behaviour of Waste Bamboo Chopstick Chars Pyrolysed at Different Temperatures

Exploring appropriate carbonisation process parameters is important for optimising the recycling of waste bamboo chopsticks as an alternative solid fuel for traditional ironmaking. The purpose of this research was to reveal the influence of the pyrolysis temperature on the structural features and combustion behaviour of waste bamboo chopstick chars. The fixed carbon content of waste bamboo chopstick chars increased from 46.57% to 82.83% and the volatile content decreased from 56.43% to 6.86% with pyrolysis temperature increasing from 573 to 973 K. At the same time, the O/C and H/C values gradually decreased from 0.23 to 0.08 and from 0.05 to 0.02, respectively. The surface area of waste bamboo chopstick chars first increased sharply from 2.15 m 2 /g at 773 K to 11.04 m 2 /g at 873 K, and then decreased to 1.96 m 2 /g at 973 K. The combustion behaviour had a close relationship with the pore structure of waste bamboo chopstick chars, and the best combustion properties were exhibited at a pyrolysis temperature of 873 K. It was found that volumetric model was the most suitable model for describing the combustion process of waste bamboo chopstick chars pyrolysed below 673 K, while random pore model was the best one for the chars pyrolysed above 673 K. The combustion activation energies of the waste bamboo chopstick chars ranged from 116.89 to 156.07 kJ/mol. There was an obvious kinetic compensation effect during the combustion.