The aim of this work was to investigate the adsorptive performance of the polypyrrole-based KOH-activated carbon (PACK) in the removal of the basic dye crystal violet (CV) using a batch adsorption system. The equilibrium data, obtained at different initial CV concentrations ( ) and temperatures (25–45°C), were interpreted using the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, with the Langmuir model providing a better fit ( ) and a maximum adsorption capacity of 497.51 mg/g at 45°C. Under the examined conditions, the values of the thermodynamic parameters free energy, enthalpy, and entropy indicate a spontaneous, endothermic, and physisorption adsorption process. The kinetic data of the adsorption process were very well described by a pseudo-second-order model ( ). However, surface diffusion seems to be the main rate-controlling step. Thus, we concluded that PACK shows commercial potential for the removal of cationic dyes such as CV from industrial effluent.

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.