(max 200 words): The contamination of groundwater is a serious concern for ecosystems and human health. In this regard, biochar represents a promising low-cost and sustainable material for in-situ groundwater remediation. Herein, biochar waste of biomass energy production process derived from pine wood gasification at 950°C was used as active carbonaceous material in combination with different biopolymers: chitosan (CS), alginate (ALG), potato starch (PST), and carboxymethylcellulose (CMC) to produce BC@biopolymer composite materials. Different concentrations of biochar (0.3–1.0 g·L-1) and biopolymers (0.2–20.0 g·L-1) were tested and blending mode was used as simple and straightforward strategy to obtain BC composites. Scanning electron microscopy (FE-SEM), UV-Visible, infrared (FT-IR) spectroscopy, specific surface area (BET method), pore volume, and pore size distribution (textural parameters), dynamic light scattering (DLS), and ζ-potential were used to investigate the composite chemical structure, stability, and to assess the interaction among counterparts. On optimized formulations, breakthrough tests and batch adsorption isotherms on trichloroethylene (TCE) as a model contaminant were performed to evaluate the capability of composites to be delivered through a porous medium determining the transport properties, (hydrodynamic dispersion retention percentage, and adsorption capacity). This biopolymer-modified biochar holds significant promise as a sustainable and effective solution to address various groundwater pollution challenges.

A novel type of graphene-like quantum dots, synthesized by oxidation and cage-opening of C60 buckminsterfullerene, has been studied as a fluorescent and absorptive probe for heavy-metal ions. The lattice structure of such unfolded fullerene quantum dots (UFQDs) is distinct from that of graphene since it includes both carbon hexagons and pentagons. The basic optical properties, however, are similar to those of regular graphene oxide quantum dots. On the other hand, UFQDs behave quite differently in the presence of heavy-metal ions, in that multiple sensitivity to Cu2+, Pb2+ and As(III) was observed through comparable quenching of the fluorescent emission and different variations of the transmittance spectrum. By dynamic light scattering measurements we confirmed, for the first time in metal sensing, that this response is due to multiple complexation and subsequent aggregation of UFQDs. Nonetheless, the explanation of the distinct behaviour of transmittance in the presence of As(III) and the formation of precipitate with Pb2+ require further studies. These differences, however, also make it possible to discriminate between the three metal ions in view of the implementation of a selective multiple sensor.