Poly(AA-co-NVIm-co-AAm) sensor hydrogels for the simultaneous visual detection and removal of Cu2+ ions from aqueous media

The ability to detect Cu2+ ions in aqueous media was investigated using poly(AA-co-NVIm-co-AAm) sensor hydrogels (RVH-1 to RVH-6) that have been synthesized by free radical polymerization. Synthesized hydrogels were characterized by FTIR, SEM-EDX, and TGA analysis. The swelling and rheological studies were performed to measure the maximum water retaining capacity of synthesized hydrogels and to understand the gel behavior. Among all the synthesized hydrogels, RVH-05 sensor hydrogel shows faster swelling with the highest swelling percentage (22,870%), which is responsible for the fast detection and enhanced adsorption of Cu2+ ions at a very low concentration. RVH-05 acts as a visual detector for Cu2+ ions by changing their color to blue with a limit of detection of 0.1 mg/L and also shows simultaneous removal capability with the enhanced adsorption of Cu2+ ions from their aqueous media. The effect of the removal conditions like contact time, pH, temperature, and initial metal ion concentration on the adsorption of Cu2+ ions has been tested and found maximum adsorption of 160 mg/g of Cu2+ ions. Adsorption isotherms were introduced and found Langmuir adsorption isotherm model best fitted for the chemical adsorption of the Cu2+ ions on the surface of RVH-05. RVH-05 shows fast detection, and effective adsorption of Cu2+ ions can reuse with high efficiency by simply soaking in a solution of disodium EDTA.