Facile synthesis of anthranilic acid based dual functionalized novel hyper cross-linked polymer for promising CO₂ capture and efficient Cr³⁺ adsorption

A novel hyper cross-linked polymer of 2-Aminobenzoic acid (HCP-AA) is synthesized for the adsorption of Cr³⁺ and CO₂. The Brunauer–Emmett–Teller surface area of HCP-AA is 615 m² g⁻¹. HCP-AA of particle size 0.5 nm showed maximum adsorption of Cr³⁺ for lab prepared wastewater (93%) while it was 88% for real industrial wastewater. It is might be due to electrostatic interactions, cation-π interactions, lone pair interactions and cation exchange at pH 7; contact time of 8 min; adsorbent dose 0.8 g. The adsorption capacity was calculated 52.63 mg g⁻¹ for chromium metal ions at optimum conditions. Freundlich isotherm studies R² = 0.9273 value is the best fit and follows pseudo second order kinetic model (R² = 0.979). The adsorption is found non-spontaneous and exothermic through thermodynamic calculations like Gibbs free energy (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were 6.58 kJ mol⁻¹, − 60.91 kJ mol⁻¹ and − 45.79 kJ mol⁻¹ K⁻¹, respectively. The CO₂ adsorption capacity of HCP-AA is 1.39 mmol/g with quantity of 31.1 cm³/g (6.1 wt%) at 273Kwhile at 298 K adsorption capacity is 1.12 mmol/g with quantity 25.2 cm³/g (5 wt%). Overall, study suggests that carboxyl (–COOH) and amino (–NH₂) groups may be actively enhancing the adsorption capacity of HCP-AA for Cr³⁺ and CO₂.