Enzymatic construction of quinine derivative of dextrin/PVA based hybrid gel film for the simultaneous detection and removal of copper and lead ions in real water samples

Abstract

The research work carried out involves synthesis of quinine derivatized hydrogel film (Q-gel film) based on dextrin and Polyvinyl alcohol hybrid mixture. The maximum percentage swelling obtained for the synthesized gel-film was 295% for 1.88 mol/L acrylamide concentration, 0.266 mol/L glutaradehyde concentration, 5.48 × 10−2 mol/L ammonium persulphate concentration, 30 ml water at 70 °C after 4 h reaction time. It was converted to its quinine derivative using lipase enzyme based condensation (Q-gel film). The Q-gel film could detect the lowest concentration of 0.0421 μM and 0.0521 μM of copper and lead ions, respectively which was well below the Environmental Protection Agency(EPA) standards. The removal efficiency was around 95.77% and 92.89% for toxic copper and lead ions, respectively in distilled water. It followed a pattern of Flory Huggins and Langmuir adsorption isotherms for the case of copper and lead ions, respectively. Second order kinetics was being followed for all concentrations of copper and lead nitrates. Stern Volmer linearity at lower concentrations signified complex formation with the film via interaction with its functional groups. Intraparticle diffusion model refers to two steps followed during adsorption which is being followed in addition to second order kinetics. After the repetitive five cycles of desorption-adsorption, maximum percentage adsorption obtained for copper and lead ions was 82.45% and 79.45%, respectively. The application of the Q-gel film on real water samples revealed that it could remove 96.45% and 92.115% of copper ions in case of tap and drinking water. The percentage removal obtained in case of lead ion was 93.79% and 90.12%, respectively for tap and drinking water. The synthesized sample is biodegradable and follows a nature friendly greener approach.