Surface-catalyzed hydrolysis by pyrogenic carbonaceous matter and model polymers: An experimental and computational study on functional group and pore characteristics

Abstract

We employed a polymer network to understand what properties of pyrogenic carbonaceous matter (PCM; e.g., activated carbon) confer its reactivity, which we hereinafter referred to as PCM-like polymers (PLP). This approach allows us to delineate the role of functional groups and micropore characteristics using 2,4,6-trinitrotoluene (TNT) as a model contaminant. Six PLP were synthesized via cross-coupling chemistry with specific functionality (-OH, -NH₂, -N(CH₃)₂, or $\text{-N}{\left({\text{CH}}_3\right)}_3^{+}$) and pore characteristics (mesopore, micropore). Results suggest that PCM functionality catalyzed the reaction by: (1) serving as a weak base (-OH, -NH₂) to attack TNT, or (2) accumulating OH^- near PCM surfaces ($\text{-N}{\left({\text{CH}}_3\right)}_3^{+}$). Additionally, TNT hydrolysis rates, pH and co-ion effects, and products were monitored. Microporous PLP accelerated TNT decay compared to its mesoporous counterpart, as further supported by molecular dynamics modeling results. We also demonstrated that quaternary ammonium-modified activated carbon enhanced TNT hydrolysis. These findings have broad implications for pollutant abatement and catalyst design.

Keywords: Base catalysis; Molecular dynamics modeling; Nanopore characteristics; Pyrogenic carbonaceous matter; Quaternary ammonium groups.