Flocculation performance and mechanism of graphene oxide for removal of various contaminants from water

• Graphene oxide (GO) is employed as a novel flocculant for the first time.
• GO shows good flocculation performance in various kinds of synthetic wastewater.
• GO can successfully remove various contaminants by sweeping flocculation effect.
• Fractal theory was applied to explore the flocculation mechanisms of GO.

The application of nanomaterials in water treatment plants has attracted significant attention recently. This study investigates the possibility of using graphene oxide (GO) as a novel flocculant to remove contaminants with different surface charges from water, including two particulate ones (kaolin and hematite) and two soluble ones (humic acid (HA) and cationic light yellow 7GL dye (7GL)). The flocculation performances of traditional polyaluminum chloride (PAC) and original graphite were also tested for comparison. Fractal theory was applied to evaluate the floc properties and explore the flocculation mechanism in combination with zeta potential measurements. For negatively charged contaminants, kaolin and HA, GO was observed to remove these contaminants successfully via the sweeping flocculation effect under acidic and neutral conditions. However, GO was less efficient than PAC. For positively charged contaminants, hematite and 7GL, the flocculation performances of GO were significantly improved than those of PAC via patching effect for hematite suspension and charge neutralization effect for 7GL solution. The results highlighted the extensive potential applicability of GO as a suitable flocculant in water treatment.

Graphene oxide (GO) demonstrated good flocculation performances for various synthetic wastewaters.Figure optionsDownload high-quality image (277 K)Download as PowerPoint slide