Medium-low temperature coal tar pitch based activated carbon prepared by self-pressurized modification and thermal conversion combined of activation for efficient phenol adsorption

To promote the efficient utilization of medium-low temperature coal tar pitch (MLP) and address the challenge of phenol-containing wastewater, this study proposes an approach for preparing activated carbon using self-pressurized modification combined with thermal conversion and activation. By optimizing the modification conditions and activation parameters, activated carbon with a high specific surface area and a well-developed pore structure was successfully prepared. The adsorption performance of the activated carbon for phenol was systematically evaluated, and its adsorption mechanism and recyclability were also investigated. The results indicate that during self-pressurized modification, the modification temperature is a crucial parameter in regulating the molecular structure and thermal stability of the tar. The synergistic effect of modification temperature and pressure determines the mechanical properties of the tar pitch by controlling its optical microstructure. The prepared activated carbon (RC P -AC) exhibited a high specific surface area of 2889.10 m²/g and a phenol adsorption capacity of 131.27 mg/g. The adsorption process followed the pseudo-second-order kinetic model and was well described by the Freundlich isotherm model. After five cycles of ethanol regeneration, RC P -AC retained a phenol regeneration rate of 80.44%. Fixed-bed column experiments demonstrate that 0.5 g of RC P -AC is capable of completely purifying 1290 mL of a 50 mg/L phenol solution. Density functional theory (DFT) calculations further elucidated the interaction mechanisms between RC P -AC and phenol molecules, covering synergistic effects involving hydrogen bonding, π-π interactions, electrostatic forces, and pore filling. This study provides theoretical support for the high-value utilization of MLP and the treatment of phenolic wastewater.