Covalent organic frameworks as an efficient adsorbent for controlling the formation of disinfection by-products (DBPs) in chlorinated drinking water

Abstract

2,5-Dimethyl-p-phenylenediamine–1,3,5-triformylphloroglucinol covalent organic frameworks (PATP COF) were prepared and used as novel adsorbent for controlling the formation potential (FP) and reducing the toxic potential of both carbonaceous disinfection by-products (C-DBPs) and nitrogenous DBPs (N-DBPs) during their subsequent chlorination. During the PATP COF adsorption pretreatment process, the FP of C-DBPs, N-DBPs and total organic halogen (TOX) were reduced by 86.5, 75.4 and 81.1%, respectively. These removal efficiencies were significantly higher when compared with those obtained using a traditional activated carbon (AC) adsorption pretreatment process (42.7, 19.4 and 28.7%, respectively). By comprehensive toxicity calculations, a significant reduction in both the acute and chronic toxic potential of C-DBPs and N-DBPs were observed during the PATP COF adsorption process (with reduction rates of ~85 and ~ 75% observed for the C-DBPs and N-DBPs, respectively), which were comparable to the removal efficiencies observed for C-DBPs FP and N-DBPs FP by weight, suggesting the simultaneous and effective control of DBPs FP and their toxic potential. Cycling tests and stability trial also showed the excellent reusability, wide pH adaptability, and high stability of PATP COF, demonstrating its great potential application to the treatment of drinking water.