Riboflavin Functionalized Dextrin-Sodium Alginate Based Fluorescent Sensor: Detoxification of Cu²⁺ and Ni²⁺ Ions

The research work performed and described here is in regard to synthesis of dextrin-sodium alginate based hybrid hydrogel film. It showed the maximized percentage swelling at 1145% after optimization of all reaction parameters. It was further functionalized with a fluorophore, i.e., riboflavin, to introduce luminescent behavior to the film. The RDSA film can not only remove but also sense the copper and nickel ions in the surroundings very sensitively up to 0.4445 μM and 0.2571 μM, respectively, which is in the desired range of EPA limits. The RDSA film could detoxify the 5 μM copper and nickel ion concentrated solution to an extent of 95.54% and 91.30%, respectively. The adsorption followed the Flory–Huggins model along with second-order kinetics specifically for higher metal ion concentrations. The detection and adsorption occur as a result of complex formation between the film and metal ion. The intraparticle diffusion mechanism is of two steps and occurs through the outer surface to the inner pores. The ions can also be desorbed with EDTA to reuse the film for further recovery of the metal ions. It can be done for multiple cycles, and finally the film can be degraded biologically when it is of no use. It is due to natural materials being used for the synthesis.