Reusable carbon dot/chitin nanocrystal hybrid sorbent for the selective detection and removal of Cr(VI) and Co(II) ions from wastewater

The last few decades have seen a dramatic increase in heavy metal ions in industrial wastewater, especially Cr6+ and Co2+ ions, which have been shown to adversely affect human health; thus, there is a great need for their removal. Existing removal methods are time-consuming, expensive, and require high technical skills; therefore, there exists a need for a quick, simple, and cost-effective method. Chitin was selected from natural materials (shrimp waste), and an inexpensive, biodegradable, fluorescent carbon dot/chitin nanocrystal (C-dot/ChNC) sorbent for the simultaneous detection and removal of heavy metal ions from wastewater was synthesized from it. C-dot/ChNC shows high selectivity and sensitivity to Cr6+ and Co2+ ions and has high chromium(VI) and cobalt(II) adsorption capacities. These ions are weakly adsorbed on the C-dot/ChNC surface and are easily removed during regeneration, showing high cyclability. Thus, C-dot/ChNC is a viable sorbent for the removal of heavy metal ions during wastewater treatment.

Automated summary

The concentration of heavy metal ions in industrial wastewater, especially Cr6+ and Co2+ ions, has drastically increased in the past few decades, leading to adverse effects on human health. There is a need for a quick, simple, and cost-effective method to remove these ions, as existing methods are time-consuming, expensive, and require high technical skills. In this study, chitin was selected from shrimp waste as a natural material, and a fluorescent carbon dot/chitin nanocrystal (C-dot/ChNC) sorbent was synthesized for the simultaneous detection and removal of heavy metal ions from wastewater. C-dot/ChNC showed high selectivity and sensitivity to Cr6+ and Co2+ ions and exhibited high adsorption capacities for chromium(VI) and cobalt(II). These weakly adsorbed ions were easily removed during regeneration, indicating high cyclability. Therefore, C-dot/ChNC is a viable sorbent for heavy metal ion removal during wastewater treatment.