Investigation of regeneratable biopolymer-based aerogels for heavy metal decontamination from water: Quantum chemical analysis and experimental investigation

Heavy metals pose a significant threat to human health and ecological security due to their high toxicity, mobility, and persistence in the environment. Herein, the synthesis of a novel cellulose nanofiber-based aerogel using non-toxic biopolymers such as sodium alginate and polyglutamic acid to eradicate lead, zinc, and copper from water is described. The physical characterisation and the adsorption performance of the aerogels were evaluated in both monolithic and bead configurations. The study revealed superior adsorption performance for the aerogel beads compared to the monolithic configuration. The aerogel beads achieved a maximum adsorption capacity of 171.7 mg/g, 100.0 mg/g, and 142.0 mg/g for lead, zinc, and copper respectively. The aerogel beads exhibited a higher specific surface area compared to the monolithic aerogels. The presence of functional groups including carboxyl, amino, and hydroxyl groups on the aerogels likely facilitated the adsorption through coordinate bond formation and electrostatic interactions. Density Functional Theory calculations supported the role of oxygen and nitrogen containing groups on the aerogel in capturing heavy metal ions. The aerogels displayed a remarkable regeneration ability and were reused 20 times, without any significant reduction in the adsorption performance indicating its potential as a sustainable adsorbent for heavy metals removal from water.