Sulfuric acid-doped conjugated microporous poly(aniline)s enabled unconventional Hg (II) adsorption from aqueous solution

New strategies are required to modify adsorbents that possess numerous accessible chelating sites with high utilization, in order to achieve both rapid uptake and high capacity for the contaminants, which are still urgently needed. This study introduces a novel integration of a conjugated microporous polymer (CMP) material with conventional polyaniline, representing the first instance of such a combination. By amalgamating the doping properties of polyaniline with the highly stable structure and extensive microporous attributes of CMP, we achieve a synergistic effect. The conjugated microporous polyaniline is subjected to a concentrated sulfuric acid modification (SD-CMPA), enabling simultaneous oxidation, doping, and pore channel modification in a single step. The resulting SD-CMPA exhibits a record-breaking maximum adsorption capacity for Hg²⁺, reaching as high as 1720 mg·g⁻¹, as well as a benchmark distribution coefficient of 2.5 × 10⁸ mL·g⁻¹. Moreover, it demonstrates robust reusability, retaining over 96% of its adsorption capacity for at least six cycles. These remarkable features enable the achievement of ultra-deep-water purification to 0.452 ppb in an effective manner. The impressive performance of SD-CMPA can be attributed to the abundance of nitrogen-containing groups, particularly the tertiary amine nitrogen in the material skeleton, as supported by X-ray photoelectron spectroscopy and density functional theory calculations. The results presented in this study demonstrate the exceptional potential of SD-CMPA for high-performance environmental remediation.