Adsorption Properties of Single-Wall Carbon Nanotube- Graphene Hybrid Papers for the Removal of Organic Compounds from Aqueous Environments

Graphene and single-wall carbon nanotubes (SWCNT) have been a primary focus for the development of a variety of new applications, including improvements in water filtration and wastewater treatment via adsorption. Removal of a model organic compound, 1-pyrenebutyric acid (PBA), by graphene and SWCNTs are compared to the commonly used activated carbon to show their effectiveness at removing organic compounds from aqueous environments. Studies are done using graphene, in house and commercial SWCNTs, and a hybrid mixture of graphene and commercial SWCNTs. Using a UV/Visible/NIR spectrophotometer, the absorbance of PBA is measured under short time (< 3 hours) to understand the adsorption kinetics (rates) and long time ( >4 weeks) to study equilibrium behavior (adsorption capacities). Adsorption of 2,4-dichlorophenoxyacetic acid is also studied due to its common use as an herbicide. Untreated graphene shows twice the adsorption rate of PBA as activated carbon and approximately the same adsorption rate of 2,4-D. For the kinetics studies the hybrid papers performed best with 25 times the adsorption of activated carbon and graphene, which is double the adsorption rate of commercial SWCNTs by themselves. In house SWCNTs show approximately 20 times the adsorption rate of activated carbon and graphene for both PBA and 2,4-D. Commercial SWCNTs show approximately 10 times the adsorption capacity of activated carbon and graphene for PBA while in house SWCNTs and hybrid papers show approximately 15 times the adsorption capacity of activated carbon and graphene. Further studies using a mixture of in house SWCNTs and graphene and the use of different adsorbates will help to show the effectiveness of single-wall carbon nanotubes, graphene, and their hybrid forms as viable everyday adsorbents for filtration processes.