Performance of Powdered Activated Coke Produced by One-Step Rapid Process from Lignite: Phenol Adsorption from Synthetic Wastewater and Hydrothermal Regeneration

Low-cost powdered activated coke (PAC) produced by a one-step rapid method with lignite was used as an adsorbent for the advanced treatment of phenol-containing wastewater to evaluate the feasibility of replacing high-cost commercial powdered activated carbon. Characterization using infrared spectral analysis, SEM, and BET showed that the PAC mesopores were well developed. PAC exhibited a high adsorption performance for phenol in static experiments. The adsorption was almost in equilibrium within 20 min, and the removal efficiency reached 85.4% with 1.5 g L−1 PAC and 99.9% with 4 g L−1 PAC. As common components in wastewater, NaCl and Na2SO4 did not exhibit significant competitive adsorption with phenol in PAC. The adsorption process occurred in accordance with the Langmuir model and the pseudo-second order kinetic model. Furthermore, the effects of hydrothermal regeneration on PAC adsorbing phenol were studied, and the adsorption capacity of PAC after five regeneration cycles was 86.1% of that of the new PAC, which still had good adsorption performance. PAC offers significant advantages in terms of adsorption capacity, economic feasibility, regeneration, and recycling, providing a practical solution to the problem of phenol-containing wastewater pollution.