Cellulosic aerogel-encapsulated carbon dots for enhanced mercury detection and adsorption in aqueous systems with subsequent upcycling for organic pollutant photocatalytic degradation

The nitrogen and boron co-doped carbon dots (N, B-CDs), synthesized via a hydrothermal method, were specifically designed for the detection of mercury and subsequently encapsulated within a three-dimensional (3D) porous aerogel matrix. The resulting aerogels displayed an exceptional adsorptive capacity for heavy metals, achieving a maximum adsorption capacity of 319.49 mg/g for Hg (II) and 263.16 mg/g for Cd (II). Notably, the aerogel provided a rapid response to Hg (II) at extremely low concentrations of 3.5 μM within a mere 15 min. Furthermore, the study highlighted the aerogel's sustainability by assessing its potential for regeneration and subsequent resource utilization. Remarkably, after five cycles of regeneration, the aerogel maintained up to 75 % of its original adsorption capacity. Additionally, the Cd (II)-adsorbing adsorbent was repurposed through sulfurization treatment for the catalytic degradation of methylene blue (MB), achieving a high degradation efficiency of 95 %. This integrated approach not only provides an effective strategy for managing heavy metal contamination in wastewater but also contributes to the goal of resource recovery and sustainable material use.