Synthesis of Poly(aniline-co-benzene)-Based Hypercrosslinked Polymer for Hg(II) Ions Removal from Polluted Water: Kinetic and Thermodynamic Studies

Abstract

The aim of this work was to investigate the adsorption performance of a highly crosslinked poly(aniline-co-benzene) (PAB) copolymeric network. This hypercrosslinked polymer (HCP) was obtained via the Friedel–Craft reaction in the presence of FeCl3 as an alkylation catalyst. The HCP was characterized using FTIR, SEM, TGA-DTA-DSC thermograms, and BET surface area. The analysis revealed a major mesoporous (an average pore diameter of 4.96 nm) structure, a surface area of 987 m2/g, and adequate chemical and thermal stability, thus supporting its potential as an adsorbent. The PAB HCP capability as an adsorbent for removing mercury ions (Hg2+) from wastewater was examined, and the data obtained were kinetically and thermodynamically modeled. The data were found to fit PFO well (R2 = 0.999), suggesting a physisorption process and a rate-limiting step involving the diffusion process, as proven with IPD and LFD models. The adsorption of Hg2+ on PAB was spontaneous (ΔG° is negative; −4.41 kJ/mol at 298 K), endothermic (ΔH° is positive; 32.39 kJ/mol), and random (ΔS° is positive; 123.48 J/mol·K) at the adsorption interface. The thermodynamic analysis also suggested a physical adsorption mechanism (ΔG° between −20 and 0 kJ/mol). These findings promote the potential application of PAB HCP as an efficient adsorbent for removing Hg2+ ions and other heavy metal ions from polluted environments.