Effects of graphitic carbon nitride in the formation of disinfection byproducts

Abstract

Graphitic carbon nitride (CN) was a promising candidate for efficient environmental remediation in the advanced oxidation processes (AOPs). However, whether CN itself had some potential environmental risks, such as affecting the production of disinfection byproducts (DBPs) was still unknown. This study investigated the formation potential of DBPs in the presence of CN. The experimental data revealed that CN had a high potential to form DBPs, and dichloroacetonitrile (DCAN) was the most produced species during the chlorination and chloramination processes. Moreover, the effects of chlorine time, chlorine dosage, pH, and CN dosage during the chlorination process were evaluated to understand the formation pattern of DBPs. The possible mechanism of DBPs formation was deduced by analyzing the results of FTIR, Raman, and XPS before and after chlorination. Finally, the DBPs formation potential and cytotoxicity of the CN leaching solution were investigated, indicating CN could leach the precursors of DBPs and that the potential toxicity of the leaching solution increased with the extension of CN immersion time. In general, this research adds an understanding of the DBP formation of CN in water treatment systems and sheds light on CN's environmental potential risks. HIGHLIGHTS g-C3N4(CN) has a high potential to form DBPs and dichloroacetonitrile (DCAN) was the dominant species.; Chorine dosage, pH, and CN dosage could significantly affect DBPs formation.; Chlorine attacked the N-containing aromatic ring and the surface amino group of CN to produce DBPs.; CN could leach the precursors of DBPs and DCAN was the major contributor to the formed DBPs cytotoxicity.;

Keywords

• chloramine
• chlorine
• dichloroacetonitrile
• disinfection byproducts
• graphitic carbon nitride
• leaching