A controlled preadsorption and targeted reduction process for efficient dechlorination of highly toxic 2,4,6-TCP by Al0: Enhanced selectivity.

Chlorophenolic compounds have been prioritized for urgent regulatory control due to their widespread presence and toxicity. Among them, the extremely toxic 2,4,6-trichlorophenol (2,4,6-TCP), as a typical chlorophenol, needs to be selectively removed from complex water as a priority. However, it is very stable and difficult to dechlorinate by common redox methods. Now, we achieved efficient and selective reduction dechlorination of 2,4,6-TCP in the face of strong competition by using an iron/carbon-modified zero-valent aluminum composite, Al0-Fe-C, which has strong adsorbability and reducibility. Notably, the material can selectively remove > 95 % of 2,4,6-TCP with > 90 % dechlorination even when competitive inorganic ions (Cu2+, Cr(VI) and NO3-) and organics (phenol) coexist, and even under harsh pH conditions (3-11). The presence of iron species in Al0-Fe-C can both disrupt Al0's oxide film through cutting action to release electrons and act as an electron-regulating medium to promote selective electron transfer. Meanwhile, the carbon coating on Al0-Fe-C enhances its oil-adsorption properties, enabling selective adsorption of organic compounds. Additionally, the carbon coating endows Al0-Fe-C with a high density of surface defects, thereby improving the composite's graphitization and electrical conductivity. Above all, this system facilitates the preferential removal of highly toxic chlorophenol organics against strong competition.