High efficiency enrichment of organochlorine pesticides from water by nitrogenous porous carbon materials towards their extremely low concentration detection

A class of nitrogenous porous carbon materials (OAMPCs) has been successfully fabricated for the enrichment of ultra-trace hexachlorocyclohexane (HCH) in real water samples. The obtained optimal nitrogenous porous carbon material (OAMPC-700) has a porous curled graphene-like carbon-nanosheets morphology, large surface area (506.4 m2 g−1) and large pore volume (2.49 cm3 g−1), as well as abundant oxygen- and nitrogen-containing functional groups. Based on such unique structural characteristics, OAMPC-700 exhibits rapid uptake kinetics (99.2% HCH within just 1 min) and a superior maximum capacity (751.6 mg g−1). After six cycles of tests, OAMPC-700 still maintains a 94.27% removal percentage towards HCH, which is only 5.53% lower than that of original OAMPC-700, demonstrating the outstanding reusability. OAMPC-700 was applied to pre-enrich ultra-trace HCH from water sample with a portable enrichment equipment, demonstrating fast speed, high efficiency, and low energy consumption. Corresponding standard curves were obtained between enrichment (Cen) and initial (Cin) concentrations of HCH with a correlation coefficient (R2 =0.9901), significantly pushing down the detection limit of common analytical instruments. The enrichment mechanism for OAMPC-700 towards HCH mainly includes the synergism of hydrophobicity and hydrogen-bonding. This work may open a new avenue to the fabrication of unique carbon materials for the adsorption, enrichment, separation, and ultimate detection of ultra-trace organic pollutants.