Removal of natural organic matter in drinking water sources by carbon nanomaterials

Carbon nanomaterials are effective adsorbents for water treatment. The objective of this study is to investigate the natural organic matter (NOM) removal from drinking water with combined coagulation processes using single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Conventional coagulation using aluminum sulfate (alum) and ferric chloride (FeCl3) was also conducted using Ulutan Lake water (ULW) samples collected in four seasons. The removal was characterized by ultraviolet absorbance at 254 nm (UV254) and dissolved organic carbon (DOC). The proposed process was more effective than using alum and FeCl3. The highest removal occurred for FeCl3 with SWCNTs in winter (94.13% DOC and 96.14% UV254). In spring and fall, DOC (90% and 84.63%) and UV254 (95.87% and 88.8%) removal was highest when using FeCl3 with MWCNTs. The DOC removal was lowest in summer (67–71% for alum and 72–79% for FeCl3). Summer UV254 removal was similar to DOC removal for combined coagulation. Hydrophobic NOM in winter ULW samples is more easily removed by SWCNTs than by MWCNTs, while MWCNTs were more effective in other seasons. The results explain that the combined coagulation process is more effective than the conventional coagulants alone in different seasons