Dynamic adsorption of heavy metals on functionalized and regeneratable biopolymeric aerogels: Fixed-bed column reactor modelling and dual functionality elution technique

A continuous fixed-bed column reactor was designed to analyse the adsorption of lead, zinc, and copper in a single metal system, multi-metal system, and a multi-component system using functionalised biopolymer-based aerogel beads. The effects of various conditions including the flow rate of the influent, bed depth, and initial metal ion concentration were investigated. The Thomas model was the best-fitting empirical model for the experimental data in terms of the regression value and prediction of the adsorption capacity. The maximum adsorption capacities for lead, zinc, and copper were 193.50, 51.18, and 54.30 mg/g, respectively. It was observed that the breakthrough time increased as the column height increased but reduced when the flow rate and initial metal ion concentration increased. Citric acid effectively functionalized the beads and eluted the adsorbed heavy metals from the spent aerogel beads. The dual-functionality property maximized the efficiency of the regeneration process. Moreover, the aerogels exhibited satisfactory adsorption performance in the presence of various other contaminants with the adsorption capacities of lead, zinc, and copper being 200.83 mg/g, 37.28 mg/g, and 85.05 mg/g, respectively, demonstrating the potential of the aerogel beads in practical applications.