Emergence of robust carbon quantum dots as nano-tracer for groundwater studies

The use of conventional tracers are often limited due to high diffusion rates and difficulties in estimating very low water flow velocities of the order 0.00001 to 0.001 m/s. The first ever large scale synthesis and testing of carbon quantum dots (CQDs) as hydrogeological tracers is reported here. CQDs, as they are now popularly termed, are a new class of environmentally friendly and highly fluorescent nanomaterial mainly used for bio-imaging and catalytic applications. In this manuscript, we have used fluorescence emission and surface functionalization of the CQDs as parameters to study flow of water in simulated laboratory columns and in field. It was found that the properties of CQDs prepared through scale-up method was very similar to that of the samples prepared in small scale method which shows feasibility of the CQDs to be used as nano-tracers. Comparison of fluorescence properties of PSS-CQDs at various pH, temperatures, pressure and in the presence of corrosive acids and bases, robustness of the emission property and stickiness in laboratory simulated soil columns as well as in actual field conditions with traditional tracers provided very encouraging results. Replacement of conventional tracers with the novel PSS-CQDs can be a significant contribution of nano technology in the field of hydrogeology.


Citation Taufique Warsi, Lopamudra Bhattacharjee, S. Thangamani, Sanjeev K. Jat, Kallol Mohanta, Rama Ranjan Bhattacharjee,c, Rangarajan Ramaswamya, C. Manikyamba, T. Vinoda Rao; Diamond & Related Materials 103 (2020) 107701, https://doi.org/10.1016/j.diamond.2020.107701