Development of lignin-derived carbon from black liquor for conductive carbon material

Lignin from black liquor, a waste product of EFB delignification, should be treated due to its resistance to decomposition and strong basicity; otherwise, it will pollute the environment. Alternatively, any carbon derived from biomass residues is extensively used as electrode material due to its excellent electrical properties, such as high conductivity. Biomass, in general, when treated with an alkaline solution, forms porosity through slow pyrolysis. Slow pyrolysis was conducted at various temperatures, 500, 600, 700, and 800 °C, and a holding time of 60 min. Physicochemical characterization was observed through CHN analysis, TGA, XRF, FTIR, XPS, BET and SEM-EDS. Moreover, electrochemical analysis was conducted using voltammetry. As a result, many inorganic substances were detected, which affected the characteristics of pyrolyzed lignin. Slow pyrolysis cracked and increased lignin rather than expanding the surface area. At the lowest temperature, 500 °C, this cracking caused hollows, but at higher temperatures, pyrolyzed lignin appeared more pronounced. Higher slow pyrolysis temperatures resulted in increased inorganic content. The inorganic elements dissolved and were distributed on the surface of the pyrolyzed lignin. Pyrolysis at 800 °C resulted in physicochemical power density and energy density exothermicity of 360.381 W/kg and 115.389 Wh/kg, respectively. The inorganic material exhibited enhanced electrochemical properties and was self-doped. Capacitance measurements in 1 M H 2 SO 4 showed 53.255 F/g. Both physicochemical and electrochemical analyses revealed that LCC was suitable for use as supercapacitor, energy storage, denitrification, catalyst and H 2 storage. To save energy, Cr was increased in treated LCC at 600 °C and capacitance reached 55.864 F/g. This study demonstrates the significant potential of utilizing lignin from black liquor as a low-cost electrode material for high-performance energy storage.