Effective adsorption of trace phosphate and aluminum in realistic water by carbon nanotubes and reduced graphene oxides

Highlights: • MWCNT/rGO effectively adsorbed major phosphorus and aluminum oxyanions from two real water. • XPS analyses of the used adsorbent identified the existence of Al and P on MWCNT and rGO surfaces. • The Al and P removals decreased by 9.3%–18.4% and 11.2%–18.2%, respectively in the presence of Acetaminophen. • pH effect investigation further verified the existing hydrogen-bonding interaction between Al/P species and the adsorbent. -- Abstract: In this study, carbon nanotube (CNT) and reduced graphene oxide (rGO) were studied for their potentials as novel adsorbents for trace concentrations of phosphorus and aluminum in water and wastewater. Static adsorption results demonstrated that CNT and rGO employed in this study removed up to 65.6% of total dissolved Al and 98.9% of P from a natural surface water and a secondary wastewater effluent. Hydrogen-bonding interactions between CNT/rGO and oxyanions were hypothesized to contribute to the adsorption process. Accordingly, acetaminophen (AAP), a pharmaceutical compound known to form hydrogen bonding with CNT, was spiked into the real water as a competitor for P and Al adsorption. Subsequent sorption results showed that the presence of AAP reduced Al and P adsorption by CNT and rGO by 9.3%–18.4% and 11.2%–18.2%, respectively. These results suggest that hydrogen bonding interactions with CNT/rGO influenced the adsorption of P and Al species. In addition, pH effect investigation on Al/P removal further verified the above opinion. Overall, this study provided important evidence and insights into CNT/rGO adsorption of P and Al species from water and wastewater, which expanded our understanding on the ability of carbonaceous nanomaterials for advanced water and wastewater treatment.