Title - Enhanced absorption and fluorescence quenching method for detection of Cr(VI) ions using avocado seed-derived carbon quantum dot as pseudo derivatising reagents

UN Sustainable Development Goal 6: Clean Water and Sanitation. 

Chromium(VI) is a toxic environmental pollutant that requires sensitive, selective, and affordable monitoring methods for water quality assessment. In this study, sulfur and nitrogen co-doped carbon quantum dots (S,N-CDs) were synthesised from avocado seed waste using a hydrothermal method and evaluated as dual-probe optical nanosensors for Cr(VI) detection.The synthesised carbon dots were characterised using TEM, SEM, FT-IR, XPS, and other spectroscopic techniques. Detection of Cr(VI) was achieved through host–guest surface interaction absorption (HGSIA) and fluorescence quenching mechanisms. Both sensing approaches demonstrated good selectivity, sensitivity, and analytical performance for the quantitative determination of Cr(VI) in water samples.

The methods were successfully validated using spiked river water and Cr(VI)-contaminated samples, demonstrating their potential for low-cost environmental monitoring. By converting avocado seed waste into functional nanomaterials, this work supports sustainable resource utilization and contributes to UN Sustainable Development Goal 6: Clean Water and Sanitation.