Removal of toxic chromium (VI) from the wastewater under the sunlight-illumination by functionalized carbon nano-rods

Abstract

The minimally explored form of nano-carbon known as carbon nano-rods (CNR) has been used for removal of toxic Cr(VI) from different types of wastewater samples under the illumination of natural sunlight. The CNR was functionalized with monomeric amine molecule named as 2, 2'-(ethylenedioxy)bis(ethylamine) (EDA) to synthesize its amine functionalized water soluble version named as functionalized soluble carbon nano-rods (f-CNR). f-CNR were dialyzed to achieve most functionalized portion which was used for the sunlight-induced removal of toxic Cr(VI) from wastewater. The specific selectively for choosing toxic Cr(VI) was based on a simpler fluorescence quenching experiment, where the fluorescence emission of f-CNR was specifically quenched by Cr(VI). For practical applicability of the overall process, different types of wastewater were used such as laboratory prepared synthetic wastewater, residual wastewater collected from the undergraduate laboratory named as real wastewater, and the external spiking of Cr(VI) in unknown industrial wastewater. Compared to the dark conditions, sunlight illuminated f-CNR showed much better results for removal of toxic Cr(VI).