Study on structure regulation of porous carbon prepared from phenol/ammonium components of semi-coking wastewater

The production of semi-coke via low- and medium-temperature coal pyrolysis offers a promising avenue for coal utilization, yet the resultant wastewater poses significant treatment challenges due to its complex pollutants. This study introduces an innovative approach that shifts from “treatment” to “conversion,” utilizing phenolic substances and ammonium compounds in the wastewater to synthesize thermosetting phenolic resin (PR) and porous carbon (PC). These were activated with potassium hydroxide (KOH), yielding high-performance PC. Using response surface methodology (RSM), optimal conditions were identified: a KOH to PR ratio of 2.798:1, temperature of 816.43 °C, and duration of 1.22 h, achieving maximum iodine adsorption of 1457.22 mg/g. Thermal analysis and kinetic studies showed easier activation of PRs than methenamine, with mixed phenol-derived resins having the lowest activation energy. The pore structure analysis revealed that catechol, 2,3-dimethylphenol, and 2,6-dimethylphenol generated substantial mesopore and micropore volumes, whereas phenol and m-cresol primarily formed large pores. Ammonia addition rendered the PC pores round and regular. This research establishes a theoretical basis for transforming semi-coking wastewater into valuable resources and synthesizing advanced PC materials.