Radiation synthesis of IDAA functionalized loofah sponge for enhanced removal of Pb(II) and Cd(II): Behavior and mechanism investigation

Biomass has been deemed as the most promising adsorbent for metal ions capture due to its environment-friendly and easy functionalization. Within this work, we combined a green and powerful radiation grafting-ring opening method that yields high-density functional groups containing a large number of carboxylic acid groups with loofah sponge (LFs) to achieve a novel functionalized loofah sponge (LFs-PGMA-IDAA) as a Pb(II)/Cd(II) adsorbent. The as-prepared biosorbent could efficiently capture Pb(II) and Cd(II) ions in wastewater. Moreover, the biosorbent could quickly reach adsorption equilibrium within 80 min, and the kinetics data fit well with the pseudo-second-order model. The thermodynamic parameters reveal that the adsorbing process is both spontaneous and endothermic. Moreover, the biosorbent possessed excellent removal capacities towards Pb(II)/Cd(II), and the maximum uptake capacity of Pb(II) and Cd(II) were 237.85 and 169.81 mg/g at 318.15 K, pH = 5, respectively. Furthermore, the excellent Pb(II)/Cd(II) binding of LFs-PGMA-IDAA was primarily due to complexation, ion exchange, electrostatic interaction and pore adsorption. This research presents that iminodiacetic acid modified LFs could be utilized as a high-performance biosorbent for capturing heavy metal ions. It might serve as an eco-friendly adsorbent in practical wastewater treatment fields.