Hydrophobic zeolites as efficient adsorbents for removing chloroform in drinking water

Chloroform is one of the most prevalent disinfection byproducts found in drinking water, posing significant risks to human health and aquatic ecosystems due to its carcinogenic properties. Since chloroform is present at very low concentrations (tens to hundreds of ppb), it is crucial to develop effective adsorbents capable of strong interactions with chloroform even in a water-dominant environment. In this study, we investigated the effects of different chemical compositions (Si/Al ratios), silanol defects, and pore topologies (CHA, MFI, and BEA) of zeolites on their chloroform adsorption behavior. The results showed that zeolites with higher Si/Al ratios and fewer silanol defects exhibit greater surface hydrophobicity, leading to effective chloroform uptake properties in aqueous solutions. Adsorption experiments using hydrophobic pure-silica zeolites with different pore topologies revealed that a micropore aperture size of ≥10-membered rings (MFI and BEA) is required for efficient chloroform adsorption, as small-pore zeolites with 8-membered ring apertures (CHA) impose significant diffusion limitations for chloroform. The hydrophobic zeolites demonstrated excellent reusability compared to conventionally used activated carbon and also showed good adsorption performance for other trihalomethanes. These findings highlight the potential of hydrophobic zeolites as efficient adsorbents for removing extremely low concentrations of toxic trihalomethanes from drinking water.