From waste corn straw to graphitic porous carbon: A trade-off between specific surface area and graphitization degree for efficient peroxydisulfate activation

Electron transfer pathways have been verified as overriding regimes when peroxydisulfate (PDS) was activated by porous carbon. The incorporation of graphitic structure into carbon matrix was favorable to the rapid electron transfer, but excessive graphitization would deteriorate the specific surface area (SSA), weakening the catalytic performance. The reasonable trade-off between SSA and graphitization degree was necessary and challenging for the preparation of efficient carbon based PS-activators. Herein, a series of graphitic porous carbon with discrepant SSA and graphitic structure were fabricated. The incorporation of graphitization tracks into ultra-thin edges on porous carbon film was verified by multifarious structural characterization. After trade-off, the optimum catalyst exhibited superior catalytic performance with degradation rate constant (kobs) exceeding that of ungraphitized precursor by up to 16.0 times. Mechanistic investigations substantiated that the sufficient SSA of catalyst provided favorable conditions for its affinity towards PDS and sulfadiazine (SDZ), resulting in the formation of PDS⁎ complexes and SDZ adsorption, while the appropriate graphitization degree ensured the reinforced electron transfer rate, which collectively accelerated SDZ oxidation through electron-transfer pathway. The multivariate linear regression model linking kobs to SSA and graphitization degree was established providing basis to construct efficient catalysts for PDS activation. Environmental implication SDZ has been detected in aquatic environment, and its long-term accumulation can cause irreversible damage to ecosystem and human health. Porous carbon was verified as promising catalyst in persulfate activation for SDZ removal. Herein, the incorporation of graphitic structure into porous carbon was proved to further promote its catalytic performance, but excessive graphitization would deteriorate it instead. After trade-off between specific surface area and graphitization degree, the optimum catalyst exhibited superior catalytic performance with degradation rate exceeding that of ungraphitized precursor by 16.0 times. This work provided basis to construct efficient catalysts for SDZ removal.